Vitis vinifera L. grown in Galicia (Northwest of Spain) in 2018 and 2019 vintages. The percentage of total NAN with respect to the total polyphenol content (TPC) values was calculated for each sample and established into three categories: high percentage NAN varieties (NANV), those varieties showing low percentages of NAN (ANV), and finally those varieties showing medium percentages of NAN (NANAV). ‘Xafardán’ and ‘Zamarrica’, classified as NANAV, had high values of TPC and showed good percentages of flavonol and flavanol compounds. Principal component analyses (PCA) were performed with flavonol, flavanol, and phenolic acid profiles. The flavonol and flavanol profiles allowed a good discrimination of samples by variety and year, respectively. The flavonol profile should therefore be considered as a potential varietal marker. The results could help in the selection of varieties to be disseminated and in the identification of the most appropriate agronomic and oenological techniques that should be performed on them.Non-anthocyanin compounds (NAN) such as flavonol, flavanol, and phenolic acids should be considered in the characterization of minority red grapevine varieties because these compounds are involved in copigmentation reactions and are potent antioxidants. Sixteen NAN were extracted, identified, and quantified by High Performance Liquid Chromatography (HPLC) from grapes of 28 red genotypes of  Grapes are an important source of polyphenolic compounds, secondary metabolites which perform different functions. Some compounds also have a protective function against climate change effects and could even mediate induction responses to counteract pathogens . Polyphenolic compounds contribute to sensory characteristics such as color, flavor, astringency, and hardness of wine directly or by interaction with proteins, polysaccharides, or other phenolic compounds ,3. The pColor, an important factor for evaluating the quality of red wine, is linked to the ac-cumulation of anthocyanins (AN) in the grape berry skin. However, it is not only the anthocyanin concentration and profile that is responsible for wine color; copigmentation phenomena can account from 30% to 50% of color in young wines . PreviouOn the other hand, the antioxidant activity of plant polyphenols is well known. It is a well-established fact and a widely accepted concept that grapes constitute one of the most important sources of dietary polyphenolic antioxidants and the relationship of total phenolic content and different phenolic groups according to their antioxidant activity has been investigated by different research groups ,11.It is known that the total phenolic content and its distribution in grapes largely de-pends on varieties ,10,12,13According to Menna and Walsh , mature On the other hand, the winemaking industry has become very important in recent times, and a careful analysis should be carried out in terms of controlling the authenticity and traceability of wines to avoid forgeries . These cRecently, we outlined the anthocyanin profile of 28 grapevine varieties, most of them minority varieties, from the northwest of the Iberian Peninsula, established in the germplasm bank of ‘Estación de Viticultura y Enología de Galicia’ (EVEGA) . In thatHI was 2580.72 and 2388.88 for 2018 and 2019 vintages, respectively. This implies that the HI in the study area corresponded with warm climate  in 2018 and warm temperate climate  in 2019, as described in the GCCCM System . CI for As −1) of varieties investigated. The aim was to harvest the grapes at 22 °Brix  and according to their health status. This was possible for most of the samples, with certain exceptions shown in p < 0.05 in 16 of them). As was reported by Díaz-Fernández et al. [z et al. , meteoroz et al. ,36,37.−1 FW in both years, were reached in ‘Evega 3’. In the opposite side, ‘Espadeiro’, ‘Garnacha’, ‘Gran Negro’, and ‘Mandón’ did not reach 300 mg·kg−1 FW any year. Values higher than 1000 mg·Kg−1 FW of AN in both years were registered in ‘Caiño Bravo’, ‘Castañal’, ‘Espadeiro, ‘Ferrón’, and ‘Sousón’, while ‘Evega 3’, ‘Garnacha’, ’Híbrido’, and ‘Picapoll Negro’ were varieties with low AN values, less than 200 mg Kg−1 FW in both years. Thus, in both years, the highest values of TPC were registered in ‘Caiño Bravo’, ‘Castañal’, ‘Corbillón’, ‘Espadeiro’, ‘Ferrón’, and ‘Sousón’, while ‘Garnacha’, ‘Híbrido’, and ‘Picapoll Negro’ were listed as the lowest phenolic varieties.The highest NAN values, higher than 1000 mg·kgIn terms of decreasing year variability, and to characterize varieties, the percentage of NAN and AN with respect to the TPC were calculated ,38. % NAFLAVO are secondary metabolites that act as photo-protectors; they are largely located in the grape skins as flavonol glycosides of quercetin, kaempherol, myricetin, and isorhamnetin. They also have antioxidant properties that are released from the grape to the wine during the maceration process . −1 FW) ranged from 0.76 in ‘Garnacha’ to 41.07 in ‘Tempranillo’, the Iso-Rut compounds varied from 0.89 in ‘Sousón’ to 25.01 in ‘Híbrido’, and the Kaemp-Glc ones from 1.32 in ‘Mouratón’ to 10.77 in ‘Merenzao’. Finally, values from 14.86 (‘Sousón’) to 87.22 (‘Zamarrica’) were recorded when the sum of quercetin compounds (∑ Quer) was evaluated. The following year, the minimum and maximum values were 3.76 and 73.37, registered in ‘Garnacha’ and ‘Sousón’, respectively, for My substances, 0.32 and 19.47 were found in ‘Zamarrica’ and ‘Tempranillo’, respectively, for the Iso ones, Kaemp compounds ranged from 0.88 in ‘Evega 3’ to 16.58 in ‘Sousón’, and values from 34.36 in ‘Moscatel de Hamburgo’ to 132.59 in ‘Xafardán’ were found for the ∑ Quer substances. Therefore, according to previous works, ‘variety’ and ‘year’, and more specifically ‘variety’, were considered as variability factors in the values registered for these compounds [In 2018, My-Glc values . On the other hand, as a general trend, every FLAVO compound except for Kaemp-Glc showed higher contents in the 2019 vintage. This effect had a significative effect in My-Glc, Quer-Glc, and Quer-Rut. The highest interannual variations were registered in My-Glc (64.70%) and Quer-Glc (61.92%). Moreover, results from Looking at the FLAVO pattern, the main compounds in most of the analyzed samples were My and Quer compounds, and more specifically Quer-Glc, a compound that is generally higher in red-fleshed cultivars . AccordiFlavonols play critical roles in colour stabilization, as cofactors with free anthocyanins in copigmentation of young red wines, and in the evolution of complex pigments during wine aging ,45,46 ThOn the other hand, and considering the importance of FLAVO compounds, it has been considered of interest to examine the FLAVO profile of the samples. For this reason, and with the main objective of reducing the ‘year’ variability and thus obtaining a better characterization of the varieties, My, Iso, Kaemp, and Quer percentages with respect to their TPC were calculated for each sample and year. As Finally, In wine as well as in grapes, FLAVA are found in monomeric, dimeric, oligomeric (3 to 10 units of flavan-3-ols), and polymeric forms (more than 10 units of flavan-3-ols). FLAVA such as monomers  and flavan-3,4-diol dimers such as procyanidins B1, B2, and B3 are present in the skin and mainly in grapes seeds. The type of flavan-3-ols in grape berries is variable between species, developmental stage, and tissue types. It is very well known that skins contain both catechins and gallocatechins and their correspondingly derived proanthocyanidins , whereas seeds present only catechins and procyanidins; they are secondary metabolites that trigger bitterness and astringency .FLAVA are quite high reactive substances and, together with anthocyanins, would trigger the formation of different pigments and tannins in the wine-making process that modify the wine color and taste . During −1 FW of catechin (Cat), epicatechin (Epi), gallocatechin , epicatechin-gallate , and the dimers PB1 and PB2 identified and quantified in grapes of different varieties from the galician EVEGA germplasm bank in 2018 and 2019 vintages. Cat in 2018 and Galo in 2019 were the major FLAVA compounds in almost every variety. The exceptions to this general behavior were ‘Ferrón’, ‘Gran Negro’, and ‘Sousón’, with PB1 as the major FLAVA in both vintages and ‘Espadeiro’ in 2018 with PB2. In general, the minority FLAVA compounds were GaloEpi in 2018, and this last one and Epi in 2019. Previous works reported Cat as the most important individual FLAVA in both skins and seeds ,54 and P−1 FW). In 2019, the values ranged from 88.08 in ‘Gran Negro’ up to 1194 in ‘Corbillón’. The minimum procyanidin total values, as Σ , corresponded to ‘Híbrido’ (30.19), and the maximum to ‘Evega 3’ (330.67), while in 2019 they corresponded to ‘Gran Negro’ (42.05) and ‘Corbillón’ (195.31), respectively. Liang et al. [−1 FW for Cat, Epi, and GaloEpi, and 9.4 and 2 for PB1 and PB2 when polyphenolic profiles in the berry samples of 344 European grape (Vitis vinifera L.) cultivars were evaluated after removing all seeds for two consecutive years. The grapes of cv ‘Tempranillo’, the reference variety in this work, registered values of 69.13 and 129.41 for the sum of monomers and 42.83 and 51.12 as dimers in 2018 and 2019, respectively. Thus, ‘Corbillón’ and ‘Evega 3’ were characterized by the highest FLAVA values of monomers and dimers. These facts must be considered in the winemaking process of these varieties.Since a wide range of concentrations can be observed in every compound, the ‘variety’ factor was significant and explained a big percentage of variation (>50%) in all of them except for GaloEpi. When the sum of monomers Σ , is considered in 2018, ‘Mouratón’, considered as an ANV, registered the lowest value (59.89) while ‘Corbillón’, classified as an NANV, registered the highest one  and high of FLAVO could be considered for this purpose. Finally, it should be emphasized that Pérez-Álvarez et al. [On other hand, Álvarez et al.  reportedz et al.  found a As can be seen, except for PB2, every FLAVA compound showed higher values in 2019. ANOVA found a significant effect of the ‘year’ in Galo, GaloEpi, and sum of catechins (Σ Cat). The ‘year’ effect explained a low percentage of the variance . On the other hand, it should be noted that different varieties were affected by the ‘year’ effect in a different way; Thus, ‘Albarín Tinto’, ‘Brancellao’, ‘Caiño Tinto’, ‘Evega 4’, ‘Evega 6’, ‘Gran Negro’, ‘Mandón’, ‘Merenzao’, ‘Pan y Carne’, ‘Pedral’, ‘Sousón’, and ‘Tempranillo’ were those varieties that showed interannual significant differences among years for a lower number of FLAVA compounds, which could initially be interpreted as more regular varieties among years. A significant effect for the interaction ‘variety x year’ was also found for the values of every compound studied, accounting for more than 34% of variation in case of GaloEpi. Thus, according to previous works, the amount and distribution of FLAVA are determined by genetic factors and are affected by meteorological factors ,61,62,63Phenolic acids exist predominantly as hydroxybenzoic (HBA) and hydroxycinnamic acids (HCA) that occur in free or conjugated form.−1 FW), ‘Evega3’ (10.98 and 3.65), and ‘Evega 6’ (6.44 and 3.24). According to Garrido and Borges [−1 FW) and ‘Tempranillo’ (0.88) in 2018, and in ‘Brancellao’ (0.0) and ‘Zamarrica’ (0.24) in 2019. In front, ‘Evega 6’ (2.27) and ‘Pedral’ (1.66) registered the maximum values in 2018 and 2019. Finally, with respect to CF, it is noticed that there were generally higher values in 2019, ‘Caiño Longo 2’ and ‘Espadeiro’ being those varieties with maximum values. With respect to FR, it was the acid that showed the smallest quantities, with ‘Sousón’ and ‘Espadeiro’ recording the highest values in 2019. Thus, regarding to the global hydroxycinnamic compounds, the richest varieties were ‘Corbillón’ in 2018 (4.41) and ‘Sousón’ in 2019 (4.78).d Borges , GA is uVitis, it is possible to distinguish the different varieties through the amount of p-coumaroyl and caffeoyl tartaric esters present on them, which is why they are mentioned in the literature as taxonomic markers of both grapes and wine [As in flavonoid compounds, the effect ‘variety’ was significative for almost every compound. Several studies have shown that the phenolic content in grapes may vary according to varieties, environmental factors, and agronomic techniques ,14,17. Aand wine . In thisand wine , in whicBrettanomyces yeasts through the decarboxylation of hydroxystyrenes, which are subsequently reduced to ethyl phenols [The short shelf life of wines of certain varieties requires careful control of their chromatic characteristics, with the copigmentation effect generally being an important tool for improving their chromatic characteristics. As mentioned above, several works have revealed that the best copigments found in red wines are FLAVO and HCA. In addition, HCA participates in the formation of new anthocyanin-derived pigments in wine, known as hydroxyphenyl-pyranoanthocyanins. Moreover, GA seems to be stable along the wine aging process , and the phenols .The percentages of each phenolic acid with respect to the TPC were calculated and To better understand the potential of these families of phenolic compounds as a tool for varietal classification, as well as to classify the varieties under study, the results obtained were subjected to PCAs analysisTo determine their potential as chemotaxonomic tools of FLAVO, FLAVA, and AC (HCA + HBA) families, a first PCA was performed with their respective global percentage values with respect to TPC.Samples from the two years of ‘Sousón’ (SO-18 and SO-19), ‘Castañal’ (CS-18 and CS-19), ‘Caiño Bravo’ (CB-18 and CB-19), ‘Caiño Longo 1’ and ‘Caiño Longo 2’ , ‘Ferrón’ (FE-18 and FE-19), and ‘Espadeiro’ (ES-18 and ES-19), and, from 2019, for ‘Caiño Tinto’ (CT-19), were located in the negative side of F1 and most of them in the positive side of F2 (first quadrant). These varieties that had low % of non-anthocyanin families were included in the same reconstructed population (RPP), RPP1a, by Díaz-Losada et al. , and othThe following PCAs were focused on determining the capacity of the different compounds belonging to FLAVA, FLAVO, and HAC and HBA families to discriminate cultivars. In these cases, the percentages of each compound (or the same aglycone) with respect to the respective NAN values were used.For FLAVO compounds, the percentages of % Iso, Kaemp, Quer, and My with respect to the NAN from the 2018 and 2019 were used. V. vinifera cultivars, they found that Que and My efficiently discriminated varieties.F1 and F2 explained 84.23% of the total variance . From the PCA results, different FLAVO compounds contribute to F1 in percentages of 39, 37, 18, and a 6 by % Quer, % My, % Kaemp, and % Iso, respectively, while they do it to F2 in percentages of 68, 23, 5, and 4 by % Iso, % Kaemp, % My, and % Quer, respectively. Three groups can be distinguished: the first one includes those varieties characterized by their % Kaemp in 2018 and 2019, including samples from ‘Gran Negro’ (GN-18 and GN-19), ‘Mandón’ (MA-18 and MA-19), ‘Mencía’ (ME-18 and ME-19), and ‘Caiño Longo 2’ (CL2-18 and CL2-19); the second one includes samples with high % My which includes ‘Sousón’ (SO-18 and SO-19), ‘Ferrón’ (FE-18 and FE-19), ‘Castañal’ (CS-18 and CS-19), ‘Espadeiro’ (ES-18 and ES-19), ‘Caiño Bravo’ (CB-18 and CB-19), ‘Caiño Longo 1’ (CL1-18 and CL1-19), ‘Caiño Tinto’ (CT-18 and CT-19), and ‘Pan y Carne’ (PC-18 and PC-19); the third group includes those varieties with high % Quer in both year: ‘Moscatel de Hamburgo’ (MH-18 and MH-19), ‘Brancellao’ (BR-18 and BR-19), and ‘Xafardán’ (XA-18 and XA-19). It is noted that, in general, for a given variety, samples from 2018 are located close to those of 2019 and a clear interannual differentiation did not exist. When Ferrandino et al.  tested tThe resulting plot of PCA carried out with FLAVA compounds percentages  with respect to the NAN from the years 2018 and 2019 is shown in The last PCA shown in It is noticed that, especially in the non-anthocyanin profile’s PCA , as wellVitis vinifera L. red grapes from ‘Estación de Viticultura y Enología de Galicia’ (EVEGA) germplasm bank were analyzed in 2018 and 2019 vintages. The vineyard is situated in Leiro, Ourense, Galicia , in the Eurosiberian biogeographic region, with a marked Mediterranean influence. Vines are grafted on 196-17C rootstock, trained to a vertical trellis system (VSP) on Cordon Royat and spaced 1.2 × 1.8 m. Their average age is 30 years old, and every cultivar is present in duplicate plots of 6 to 11 vines. The site has an adamellitic granite soil of two micas (IGME). The germplasm bank has a surface area of 8600 m2 and an east–west orientation. Meteorological conditions  were registered by an automatic meteorological station  located in the vineyard. Two climate indices related to thermal conditions were calculated: Heliothermal index (HI) [Twenty-eight genotypes of dex (HI)  and Cool−1) was determined according to official methods [In both vintages, the probable alcoholic degree (PAD) of grapes was monitored weekly from veraison to harvest. The goal was to harvest the grapes at 12.5–13.5° PAD  and according to their health status. As is reflected the  methods .Acetonitrile, formic acid, and methanol (MeOH) were of HPLC-gradient grade and were purchased from Panreac . The water was treated in a Milli-Q system . Catechin, epicatechin, catechin gallate, epicatechin gallate, procyanidins B1 and B2, myricetin-3-glucoside, myricetin-3-galactoside, querce-tin-3-glucoside, quercetin-3-glucuronide, kaempherol-3-glucoside, kaempherol-3-rutinoside, isorhamnetin-3-glucoside, and isorhamnetin-3-rutinoside were purchased by Extrasynthese  and gallic, caffeic, ferulic, and coutaric acids were purchased from Aldrich .v/v/v/v) according to the method described by Portu et al. [Polyphenolic substances of approximately 50 g of healthy, frozen whole grapes were extracted with 50 mL methanol/water/formic acid  methanol aqueous solution.The eluate containing FLAVO, FLAVA, HCA, and HBA was separately dried in a rotary evaporator (40 °C) and redissolved in 1.5 mL of 20%  100 RP-18 reversed-phase column  with pre-column Licro-spher® 100 RP-18 . We injected 20 μL of each sample in triplicate and chromatographic conditions were based on those described by Castillo-Muñoz et al. [v/v/v), (B) acetonitrile/water/formic acid , and (C) methanol/water/formic acid , maintaining the column at 40 °C and the flow rate in 0.63 mL·min−1. The linear solvents gradient was as follows: 0 min, 96% A, and 4% B; 7 min, 96% A, and 4% B; 38 min, 70% A, 17% B, and 13% C; 52 min, 50% A, 30% B, and 20% C; 52.5 min, 30% A, 40% B, and 30% C; 57 min, 50% B, and 50% C; 58 min, 50% B, and 50% C; 65 min, 96% A, and 4% B.Identification and quantification of phenolic compounds were performed by HPLC analysis. An Agilent 1200 LC system , equipped with a degasser, quaternary pump, column oven, 1290 infinity autosampler, UV-Vis diode-array detector (DAD), fluorescence spectrophotometer detector (FLD), and the Chemstation software package for LC 3D systems  to control the instrument and for data acquisition and analysis, were used. Separation was performed in a Licrospherz et al. . The folAbsorbances at 320, 360, and 520 nm were measured by the DAD detector to quantify phenolics acids, flavonols, and anthocyanin. Excitation at 280 and emission at 320 nm were measured by the FLD detector to quantify the flavanols compounds.−1 fresh berry weight (FW). FLAVA identified were: (+)-catechin, (−)-epicatechin, gallocatechin, epigallocatechin, and the procyanidins B1 and B2. These were quantified as mg of (+)-catechin·kg−1 FW. FLAVO identified were myricetin, kaempherol, quercetin, isorhamnetin, and the 3-glucosides and 3-rutinoside of quercetin and kaempherol, quercetin-3-galactoside and quercetin-3-glucuronide. These were quantified as mg of quercetin-3-glucoside·kg−1 FW. Finally, gallic, caffeic, ferulic, and coutaric acid were identified and quantified as mg of caffeic acid·kg−1 FW.ANs present in extracts were identified and quantified as simple glucosides-nonacylated, acetyl derivatives, and coumaroyl-derivative forms of delphinidin, cyanidin, petunidin, peonidin, and malvidin. The total amount of AN was given in mg of malvidine-3-glucoside·kgEach result is the mean value of 6 determinations (2 HPLC/extract × 3 extracts/sample).p ≤ 0.001, p ≤ 0.01, and p ≤ 0.05 for significance of comparisons. The interaction between varieties and years was evaluated by calculating the least-squares means (LS means) selecting p ≤ 0.001, p ≤ 0.01, and p ≤ 0.05 for significance of comparisons. Significance of differences between each year was based on Student’s t-test. The data of non-anthocyanin compounds profiles were submitted to principal component analysis (PCA) with the aim of differentiating varieties based on the studied variables association.Sample analyses were performed with XLSTAT-Pro 201610  statistical software package. With the aim of investigating the influences of ‘variety’, ‘year’, and their interaction ‘variety × year’ on each parameter evaluated, data were subjected to analysis of variance (ANOVA), selecting Vitis vinifera L. grapes from the EVEGA germplasm bank were defined in two consecutive vintages. To the best of our knowledge, for almost all the varieties under study, this is the first time that this characterization is reported. The percentage of total NAN with respect to the total polyphenol content (TPC) values was calculated for each sample and established into three categories: those high percentage NAN varieties (NANV), those varieties showing low percentage of NAN (ANV), and finally those varieties showing medium percentages of NAN (NANAV). ‘Xafardán’ and ‘Zamarrica’, classified as NANAV, had high values of TPC and showed balanced percentages of anthocyanins and NAN compounds that can potentially act as copigments. On the other hand, some NANV, such as ‘Corbillón’, ‘Evega 3’, and ‘Evega 6’, could be considered in terms of their flavanols and gallic acid in plurivarietal winemaking, a possible line of future research being the analysis of these varieties in terms of whether their color stability complies with the results obtained in this investigation.In this study, flavanol, flavonol, and phenolic acids profiles (non-anthocyanin phenolic compounds NAN) of 28 genotypes of These results could help in the selection of varieties to be disseminated and in the identification of the most appropriate agronomic and oenological techniques that should be performed on them. Additionally, this work provides information about the differentiating capacity of phenolic compounds and their use as varietal markers and chemotaxonomic tools. Flavonol compounds  were found to be useful compounds in the differentiation the different NANV samples.


ACF) and per unit yield (YCF) of eight crops for the period of 1990 to 2019. Our results showed that the ACF for all major crops showed an increasing trend with time before 2016 but slowly decreased afterward, while the YCF decreased by 16–43% over the past 30 years due to the increase in crop yield. The three main grain crops, rice (4871 ± 418 kg CO2-eq · ha−1), wheat (2766 ± 552 kg CO2-eq · ha−1), and maize (2439 ± 530 kg CO2-eq · ha−1), showed the highest carbon footprint and contribution to the total greenhouse gas (GHG) emissions, mainly due to their larger cultivated areas and higher fertilizer application rates. CH4 emission was the major component of the carbon footprint for rice production, accounting for 66% and 48% of the ACF and YCF, respectively, while fertilizer production and usage were the largest components of carbon footprint for dryland crops, making up to 26–49% of the ACF and 26–50% of the YCF for different crops. The present study also highlighted the spatial and temporal patterns of the carbon footprint for major crops in China, which could serve as references for the development of best management practices for different crop production in China, to mitigate agricultural GHG emission and to pursue low-carbon agriculture.As a major agricultural country, the comprehensive accounting of the dynamics and composition of the carbon footprint of major crops in China will provide a decision-making basis for environmental management and agricultural green development in the whole process of the major crop production system in China. To investigate the spatiotemporal dynamics of the carbon footprint for major crops in China, a life cycle-based carbon footprint approach was used to evaluate the carbon footprint per unit area ( Agricectively ,6. ThereLife cycle assessment (LCA) is a methodology for assessing the environmental aspects and potential impacts associated with a product . Agricul2 emission of a product or service in the life cycle process [2 equivalents (CO2-eq), which permits the quantification of the whole life cycle of a product manufactured within a certain system [ACF) was 0.78 ± 0.08 t CO2-eq ha−1. Yan, et al. [ACF of rice, wheat, and maize were 6.0 ± 0.1, 3.0 ± 0.2, and 2.3 ± 0.1 t CO2-eq ha−1, respectively, while the carbon footprint per unit yield (YCF) were 0.8 ± 0.02, 0.66 ± 0.03, and 0.33 ± 0.02 kg CO2-eq kg−1, respectively. Hillier, et al. [, et al. [Recently, carbon footprint has been widely adopted as an efficient environmental indicator for climate change feedbacks, which is defined as the direct and indirect CO process . The carn system . Cheng, n system  used nat, et al.  calculat, et al.  reported, et al.  estimateTo quantify the mitigation potential of management strategies in China’s agriculture, we evaluated the spatiotemporal dynamics of the carbon footprint for major crops in China from 1990 to 2019, based on national and local statistical data. In order to provide a decision-making basis for the whole process of environmental management of China’s main crop production system, the influencing factors on the carbon footprint for major crop production were further analyzed. The specific objectives were: (1) to quantify the temporal and spatial variation in the carbon footprint of major crop production in China over the last 30 years and (2) to identify the main influencing factors on carbon footprint for different crop production systems in different regions.The carbon footprints of major crop production were calculated for 31 provinces of China from 1990 to 2019. Over the past 30 years, the averaged total sown area of crops in China has been 156,800 ha, among which eight major crops, including rice, wheat, maize, soybean, rapeseed, peanut, cotton, and highland barley, accounted for 62% to 96% of the total sown area for different provinces . Therefohttps://toutiao.nongjitong.com/ (accessed on 20 April 2022). The emission factors of agricultural inputs mainly came from Ecoinvent database [Agricultural input data of major crops mainly include chemical fertilizers, seeds, pesticides, fuel, agricultural machinery and tools, and irrigation electricity consumption. Crop yields were calculated from the sown area and total yield from the China Statistical Yearbook series throughout the period of 1990–2019 . The inpdatabase  and reladatabase   were defined based on both the area and product in this study, i.e., the kg CO2-eq ha−1 of sown area and kg CO2-eq kg−1 of crop yield. FU based on area were used to compare the environmental effects, while FU based on the product were used to compare the production efficiency.Total GHG emissions throughout the whole crop production process were quantitatively assessed in this study. The system boundary of crop production in this study was defined as the whole life cycle from the process of mining, production, and transportation of agricultural materials , to the completion of crop harvesting . Therefoinput jCE, kg CO2-eq · ha−1) for crop j were estimated using the equation:i,jD is the input of the ith agricultural material for crop j (kg ha−1 or kWh ha−1) and i,jEF is the emission factor of the ith agricultural material for crop j (kg kg−1 or kg GJ−1).Total GHG emissions from agricultural inputs in the carbon equivalent  were calculated using the equation:D,N2O,jF (kg N2O ha−1) is the direct N2O emission from chemical N fertilizer application for crop j; A,N2O,jF and L,N2O,jF (kg N2O ha−1) are the indirect N2O emission caused by atmospheric deposition, leaching, and runoff, respectively, for crop j; and 265 is the global warming potential value of N2O at the 100-year time horizon [In particular, total N2O emission D,N2O,jF for crop j (kg N2O ha−1) was calculated using the equation:input,jN (kg ha−1) is the amount of N fertilizer application for crop j in farmland; F,j1 (kg N2O-N kg−1) is the N2O direct emission factor caused by N fertilizer application for crop j; and 44/28 is the ratio of N2O-N to N2O molecular weight.Direct N2O emission A,N2O,jF and L,N2O,jF (kg N2O ha−1) for crop j were calculated using the equations:A,jR is the volatilization rate of ammonia and NOx from agricultural land for crop j; RL,jis the N leaching and runoff rate of farmland for crop j; Fj2, (kg N2O-N kg−1) is the indirect emission factor of N2O caused by nitrogen deposition for crop j; and Fj3, (kg N2O-N kg−1) is the indirect emission factor of N2O caused by leaching and runoff for crop j.Indirect N4 emissions from paddy fields in the carbon equivalent  were estimated using the equation:CH4F (kg CH4 ha−1) is the CH4 emission factor for paddy fields and 28 is the global warming potential of CH4 at the 100-year time horizon [Furthermore, CH horizon .j  were calculated using the equation:Therefore, total GHG emissions in the carbon equivalent for crop A,jCF, kg CO2-eq · ha−1) and carbon footprint per unit yield  for crop j in different provinces were calculated using the equations:jA is the sown area of crop j (ha) and jY (kg ha−1) is the yield of crop j.Carbon footprint per unit area  and CF per unit yield  for each province were calculated using the equations by considering all the crops together:Furthermore, the total mean carbon footprint per unit area  at the level of 5% were used to compare the differences in the software .ACF) showed significant differences for different crops regardless of interannual variation (2-eq · ha−1), followed by wheat (2123–3091 kg CO2-eq · ha−1), maize (1838–2766 kg CO2-eq · ha−1), highland barley (1653–2182 kg CO2-eq · ha−1), rapeseed (1378–1984 kg CO2-eq · ha−1), cotton (1109–1516 kg CO2-eq · ha−1), peanut (878–1178 kg CO2-eq · ha−1), and soybean (753–940 kg CO2-eq · ha−1). Generally, the ACF for all major crops showed an increasing trend with time, which increased rapidly from 1990 to 1998, slowed down after 1999, and slowly decreased from 2016 to 2019.The carbon footprint per unit area  showed an overall decreasing trend with fluctuation in some years , followed by rapeseed (0.75–0.96 kg CO2-eq · kg−1), highland barley (0.53–0.76 kg CO2-eq · kg−1), rice (0.51–0.75 kg CO2-eq · kg−1), wheat (0.40–0.64 kg CO2-eq · kg−1), maize (0.22–0.96 kg CO2-eq · kg−1), peanut (0.27–0.44 kg CO2-eq · kg−1), and soybean (0.22–0.38 kg CO2-eq · kg−1). The higher YCF of cotton and rapeseed could mainly be attributed to their lower yield but higher fertilizer requirements.In contrast, the carbon footprint per unit yield  for cropping lands in different provinces were calculated by averaging the values from 1990 to 2019  ha−1. Lower mACF values of crop production were obtained in Qinghai, Guizhou, Sichuan, and Chongqing, where the mACF was below 2000 kg (CO2-eq) ha−1. In general, the mACF values were higher in the eastern and western provinces but lower in the middle provinces (YCF for major crops in China ranged from 0.34 to 0.78 kg (CO2-eq) kg−1  kg−1, which were mainly obtained in the southwest and northeast regions of China. However, other provinces with a higher annual mean mYCF were distributed in the northwest and eastern coastal regions of China.In order to take all major crops together into consideration, the annual total mean carbon footprints (m to 2019 . The higrovinces a. On theeq) kg−1 b. The mC4 emission from paddy fields, N2O emission from N fertilizer application, and electricity consumption by irrigation. The relative contribution of these components to the ACF and YCF for different provinces were calculated and their annual mean values from 1990 to 2019 are shown in ACF and YCF) of different crops showed slight differences among different provinces, the rank of these components was consistent for each crop  , et al. . Therefo, et al. . During fterward a, resultfterward  by the iACF values of rice, wheat, and maize are generally higher than those of other crops  could realize high yields and N use efficiency as well as low environmental impacts. In addition, rice production consumes more electricity per unit area than other crops for irrigation, which is also an important factor leading to a higher carbon footprint for rice. Solar energy-assisted electricity is suggested as a renewable energy source for irrigation [Our results show that the , et al.  also fou of rice . Rice isin China , among tmissions . Zhang, , et al.  found thrigation .Rice, wheat, and maize have the three largest cultivated areas in China , which f−1. Zhang, et al. [In contrast, soybean, rapeseed, peanut, cotton, and highland barley contributed a relatively much lower carbon footprint during the study period, mainly due to the significantly smaller cultivated areas of these five crops . On the , et al.  found th, et al. . China iYCF (, et al. [2O emissions as well as improve water use efficiency. Powell, et al. [2O emissions. Therefore, decreasing fertilizer rates or replacing them with polymer-coated urea while improving cotton yields with more efficient production techniques should be considered by future cotton producers.Although both the cultivated area  and yielCFY b due to , et al.  suggeste, et al.  found th4 emissions from paddy fields should be considered in the south, while conservation tillage measures should be implemented to mitigate future increases in GHG emissions in the north. Therefore, proper management could enhance carbon sequestration, reduce GHG emissions, as well as increase crop yields simultaneously, and subsequently decrease the carbon footprint of crop production [However, different strategies should be considered for different provinces. For instance, reducing chemical N fertilizer use and controlling the pathways of N loss were important GHG mitigation strategies across China ,51. Reduoduction ,52.ACF and/or YCF for all major crops in this study were markedly higher than those reported for other countries, which provided greater potential for mitigating GHG emissions in Chinese cropland. CH4 emission from paddy fields is the biggest contributor to the ACF of rice, followed by fertilizer production and usage, while the ACF and YCF for all dryland crops were dramatically dependent on chemical fertilizer. Therefore, cutting chemical fertilizer use and adopting science-based fertilizer applications, controlling N leaching, runoff, and volatilization losses after application by using deep placement and/or other techniques, as well as using organic fertilizer and other amendments, will offer a great option to cut down the carbon footprint of crop production in China.In this study, the spatiotemporal dynamics of the carbon footprint of major crops in China from 1990 to 2019 were investigated to quantify the mitigation potential of management strategies in Chinese agriculture. Our results showed that the carbon footprint of the eight major crop productions estimated in the present study corresponded to ~7% of the national total emissions, revealing the importance of GHG emissions from crop production in China. The


Pocillopora spp. under elevated P2CO. Area-normalized net calcification was compared between branches (nubbins), aggregates of nubbins (complex morphologies without integration) and whole colonies  at 400 versus approximately 1000 µatm P2CO. Net calcification was unaffected by P2CO, but differed among colony types. Single nubbins grew faster than whole colonies, but when aggregated, nubbins changed calcification to match whole colonies even though they lacked integration among branches. Corallum morphology causes the phenotype of branching corals to differ from the summation of their branches.For nearly 50 years, analyses of coral physiology have used small coral fragments (nubbins) to make inferences about larger colonies. However, scaling in corals shows that linear extrapolations from nubbins to whole colonies can be misleading, because polyps in nubbins are divorced of their morphologically complex and physiologically integrated corallum. We tested for the effects of integration among branches in determining size-dependent calcification of the coral  We focused on P2CO because it drives ocean acidification to which the response of corals, especially for traits like calcification, is being widely addressed using nubbins [Despite the continued use of nubbins in coral biology, many studies with corals ,16,17, a nubbins .. 2 (a)Pocillopora spp. , ‘artificial colonies’ (aggregates) of nubbins from the same genotype that are glued to a plastic base in an array creating the branch spacing of natural colonies (but lacking integration because the nubbins are not connected by tissue or skeleton) and intact colonies (colonies).The experiment was completed with ora spp.  from therphology , althougrphology ,37 and, −2 s−1 (2019) or 563 ± 60 µmol photons m−2 s−1 (2022) . Corals remained in this tank for 3 (2019) or 9 days (2022) before being weighed and allocated to treatments. Treatment tanks were maintained at 28.9 ± < 0.1°C  and illuminated at a mean maximum PFD of 561 ± 1 µmol photons m−2 s−1 (2019) or 484 ± 7 µmol photons m−2 s−1 (2022) , on a 12 : 12 h light : dark photoperiod with ramping .Following preparation, corals were placed in a 1000 l tank to adjust to laboratory conditions at approximately 29°C and a mean maximum photon flux density (PFD) of 511 ± 6 µmol photons m (b)P2CO on corals at approximately 28.9°C. One nubbin and one paired aggregate of nubbins (sharing a host genotype), as well as one intact colony, were randomly allocated to each of the four tanks at ambient or elevated P2CO. The elevated P2CO represented a pessimistic projection for the end of the century ..PCO2 on n = 16 genotypes, approximately 12 cm diameter) were collected from 10 m depth, prepared as nubbins, aggregates and colonies, and transferred to the 1000 l tank to adjust to laboratory conditions. On 8 April, they were buoyant weighed  and randomly placed in the tanks on 9 April. Tanks were illuminated at a mean maximum PFD of 561 ± 1 µmol photons m−2 s−1  on a 12 : 12 h light : dark photoperiod with ramping. The corals were moved daily within each tank, and after 21 days, were buoyant weighed, and their areas determined by wax dipping [−2 d−1).On 5 April, corals ( dipping . Changes (c)n = 24 genotypes, approximately 12 cm diameter) were collected from 10 m depth when ambient seawater temperature was approximately 29.0°C. Corals were prepared as nubbins, aggregates and colonies.In 2022, the experiment was repeated, but the design slightly changed due to logistical constraints. On 5 April, corals  on a 12 : 12 h light : dark photoperiod with ramping. The corals were moved daily within each tank, and after 21 days, were buoyant weighed, and their areas were determined by wax dipping [−2 d−1).Prepared corals were transferred to the approximately 1000 l tank on 6 April, and on 13 April they were buoyant weighed and randomly allocated to three tanks at each of ambient  dipping . Changes (d)P2CO on net calcification were modelled using a Gaussian linear mixed effects model implemented in R using the glmmTMB package [P2CO were assessed using log-likelihood ratio tests with α = 0.05. Pairwise differences among colony types were calculated using the estimated marginal means using the emmeans package in R. p-Values were adjusted for multiple comparisons using the Tukey method.The effects of colony type  and  package . Year an. 3−2 d−1 to 0.92 mg cm−2 d−1 (a). In 2022, one coral lost weight through breakage and was excluded from the analysis, and the remaining corals calcified at between 0.08 mg cm−2 d−1 and 0.71 mg cm−2 d−1 (a).The conditions in the tanks are described in the electronic supplementary material. In 2019, the corals maintained positive net calcification ranging from 0.05 mg cmcm−2 d−1 a. In 202cm−2 d−1 a.Figure2 = 9.980, d.f. = 2, p = 0.007), but not between P2CO treatments , and there was no interaction between the main effects . Net calcification in single nubbins was 0.171 mg cm−2 d−1  higher than that for intact colonies  . Furthermore, net calcification was 0.097  mg cm−2 d−1 lower for aggregates of nubbins compared to single nubbins, but this effect could not be statistically distinguished from zero .Across two trials, net calcification differed among colony types (χ= 0.005) . However−2 d−1, which identified them as biological outliers. When these values were excluded, net calcification in aggregates of nubbins was significantly lower than in single nubbins  mg cm−2 d−1) . All other results remained qualitatively similar .One nubbin (in 2022) and one colony (in 2019) calcified at less than or equal to 0.09 mg cm. 4Pocillopora spp., without tissue or skeletal connections among them, display the physiological phenotype of intact colonies, with trait values higher when separated. This outcome highlights the importance of bio-physical coupling between corals and the environment  in determining phenotype, although currently we cannot reject an alternative hypothesis, that the growth of isolated nubbins is elevated through repair of their fractured base and calcification stimulated by the lack of shading by adjacent branches [A colonial modular design is central to the success of scleractinians, because it allows indeterminate size , and thebranches . Our resPocillopora spp., these effects appeared subordinate to the consequences of closely spacing branches, causing aggregates of nubbins to behave as intact colonies (a), particularly when two outlying corals that barely grew were excluded . While the lack of effect of P2CO on calcification is inconsistent with previous studies [Scientific understanding of scleractinian biology has long reflected a duality of approaches, one addressing intrinsic aspects of their design, including coloniality, symbiosis, and the cnidarian bauplan , and thecolonies a, partic studies , this ou studies ).Pocillopora spp. represent an assemblage of cryptic species with differential bleaching susceptibility [Pocillopora spp., we have shown that morphological taxonomy [per se. Any differences among species would create variance in our result, rather than bias any treatment affects, since all colonies were randomly allocated to treatments.In Moorea, spawning tibility . In Pocitaxonomy  is a pootaxonomy ,37, and taxonomy , it is aper se, this outcome underscores the interactions of branching coralla with flowing seawater [The outcome of our experiment is ecologically significant because net calcification underpins the ecosystem engineering role of scleractinians  and geneseawater ,51, and seawater ,52 in de


APOE) ε4 allele represents the greatest genetic risk factor for developing AD. Extensive research has been conducted to determine whether frequent PA can mitigate the increased AD risk associated with APOE ε4. However, thus far, these attempts have produced inconclusive results. In this context, one possible explanation could be that the influence of the combined effect of PA and APOE ε4 carriage might be dependent on the specific outcome measure utilised.Wide evidence suggests that physical activity (PA) confers protection against Alzheimer’s disease (AD). On the other hand, the apolipoprotein E gene  and tau deposition and clearance, neuronal resilience and neurogenesis, lipid function and cerebrovascular alterations, brain immune response and glucose metabolism. Finally, combining all this information, we have built an integrative model, which includes evidence-based and theoretical synergistic interactions across mechanisms. Moreover, we have identified key knowledge gaps in the literature, providing a list of testable hypotheses that future studies need to address.In order to bridge these discrepancies, the aim of this theoretical article is to propose a novel model on the interactive effects of PA and APOE ε4 allele will enable the creation of new protocols using exercise along pharmaceuticals in combined therapeutic approaches.We conclude that PA influences a wide array of molecular targets involved in AD neuropathology. A deeper understanding of where, when and, most importantly, how PA decreases AD risk even in the presence of the  APOE ε4 contribute to AD risk in opposite directions.Physical activity (PA) and APOE ε4 varies across several mechanisms in AD.The combined effect of PA and APOE ε4 damage.We propose an integrative model of how PA might partially offset This integrative model could aid to formulate new combined therapeutic strategies.APOE) ε4 gene allele. Hence, one relevant question emerges: Does the APOE genotype influence the relationship between PA and AD risk? In other words, can a modifiable factor (i.e. PA) mitigate some of the risks of a non-modifiable factor (APOE ε4 carriage)?Physical activity (PA) engagement is one of the most effective methods for reducing the risk of multiple diseases, including cancer, dementia and cardiovascular disease . One exaPA is defined as any bodily movement that raises energy expenditure above basal consumption and can be differentiated from exercise which is a planned, structured and repetitive type of PA that serves a specific goal , 2. ThroAPOE ε4 allele is present in 60–80% of AD cases and increases AD risk in a dose-dependent manner [APOE polymorphisms can substantially change the structure and function of the protein, modifying its binding properties. In a recent publication, Flowers and Rebeck [On the other hand, the t manner . Apolipod Rebeck  have sumAPOE genotype interact in their contribution to AD risk as a complex disease. Over the last two decades, scientists have attempted to answer this question, yielding vastly inconsistent results [APOE ε4 carriage might be dependent on the specific outcome measure used. Studies examining various AD-related traits  might show diverse results because the biological pathways involved are differentially influenced by PA, APOE ε4 carriage and their interaction.Here, we intend to detangle how PA and  results , 12. In APOE ε4 carriage, independently and in combination, may alter well-established mechanisms underlying AD pathogenesis. The reviewed mechanisms include amyloid beta (Aβ) and tau deposition and clearance, neuronal resilience and neurogenesis, lipid function and cerebrovascular alterations, brain immune response and glucose metabolism. The list of mechanisms addressed has been primarily ordered based on their involvement in AD pathology and only secondarily on the amount of evidence available regarding how they are affected by PA and APOE genotype. Moreover, our integrative model includes evidence-based and theoretical synergistic interactions across mechanisms, as well as a proposal of testable hypotheses that future studies need to address. A better understanding of where, when and most importantly, how, PA decreases AD risk in the presence of the APOE ε4 allele is essential to formulate combined therapeutic approaches in the absence of a cure for AD.The aim of this theoretical article is to propose a novel model of how PA and APOE ε4 carriers show increased levels of soluble Aβ compared to non-carriers, detailing the central role of apoE Aβ metabolism [Aggregation of Aβ and the resultant plaque formation is one hallmark of AD, initiating a series of pathological cascades leading to neuronal death and cognitive decline . An intetabolism , and exetabolism .In their review, Brown et al. concluded that in animal models, both exercise and PA  are associated with lower levels of cortical Aβ . ImportaAPOE ε4 carriers only [ApoE4 plays a central role in driving Aβ accumulation, through both facilitating Aβ aggregation and inhibiting Aβ clearance . For exaers only . Additioers only . Howeverers only . It remaers only . Finallyers only .APOE ε4 allele carriers, compared to ε4 non-carriers [APOE gene allele carriage, physical activity, inflammatory factors and Aβ.Current evidence from human research indicates PA-induced reductions in brain Aβ may be greater for carriers . Althougcarriers . Theoretcarriers . Howevercarriers . Thus, icarriers . Post-mocarriers , 34, 35.Neurofibrillary tangles (NFTs) are a second hallmark of AD  and are composed of hyperphosphorylated or abnormally phosphorylated tau aggregates . ImportaAPOE ε4, but not APOE ε3 carriers [ApoE4 increases tau hyperphosphorylation; however, it is currently unclear whether this relationship is dependent on the presence of Aβ , 42. Indcarriers , supportThere is very limited evidence for how ApoE and PA may interact to influence tau pathology. However, a recent study  showed tAn integral component of PA-promoted neuroprotection is the proliferation of neurotrophins, which are a group of endogenous proteins critical for neuronal survival, regeneration and growth . In the A single bout of aerobic or resistance exercise can result in discernible increases in peripherally circulating BDNF , both in healthy older adults and those exhibiting cognitive decline , 54. AltAPOE ε4 allele may play a key role in neurotrophic response to PA and exercise. Serum BDNF levels are lower in APOE ε4 AD participants compared to both non-APOE ε4 carriers diagnosed with AD and cognitively normal older adults [APOE ε4 carriers [APOE status could occur via multiple pathways, including the direct inhibition of astrocytic expression of BDNF in ε4 carriers [APOE genotype and IGF-1, where transgenic mice modified to carry the human APOE ε4 allele had reduced cortical IGF-1 protein and hippocampal IGF-1 mRNA, compared to mice carrying the APOE ε2 allele. There was little difference in IGF-1 gene expression between ε4 and ε3 mice [APOE ε4 transgenic mice had a reduced concentration of hippocampal VEGF compared to APOE ε3 animals [The presence or absence of the r adults , 62. Furcarriers . The varcarriers  and/or ecarriers . Similarcarriers  reported ε3 mice . Additio animals .APOE ε4 carriers benefit from PA engagement, ε4 carriage, especially in homozygotes, can diminish neurotrophic function [APOE ε4 allele on BDNF secretion and maturation. Exercise-induced BDNF could still support neurogenesis and synaptogenesis in APOE ε4 carriers, yet less effectively than in ε3 and ε2 carriers. Animal studies have shown that PA can increase levels of BDNF, its TrkB receptor  and synaptophysin (a marker of synaptic function) in transgenic ε4 mice, to the level of ε3 mice [APOE ε4 mice and increased neurogenesis in APOE ε3 mice [The interaction between ApoE, PA and neurotrophic factors is likely complex and multi-faceted. Although function , potenti ε3 mice . Accordi ε3 mice . AlthougAPOE genotype is also poorly understood, owing to diverse findings in the peripheral and central expression of VEGF in AD samples compared with cognitively normal older adults [APOE ε4 transgenic mice have a reduced concentration of hippocampal VEGF compared to ε3 animals, while subsequent treatment with intra-hippocampal VEGF-A injections reversed aggregation of Aβ-42 and p-tau in APOE ε4 mice [p-tau. Higher expression of VEGF and a co-receptor (neuropilin 1) have been associated with poorer cognitive performance in APOE ε4 carriers, while the inverse was true for non-carriers, suggesting any VEGF-derived neuroprotection was attenuated by possession of the ε4 allele [APOE genotype along with downstream effects on neurocognitive health is warranted. Figure APOE gene allele carriage, physical activity and neurotrophic factors.The association between VEGF expression and r adults . APOE ε4 ε4 mice . Since t ε4 mice , it is p4 allele . HoweverPA exerts a positive response in the cardiovascular system, which may also benefit the brain. Greater PA engagement is associated with increased cerebral blood flow and vascular perfusion, reduced resting pulse (which prevents microbleeds resulting from prolonged intense pulsatile stress on arteries), enhanced endothelial function and improved small vessel integrity , 71–73. APOE ε4 carriage plays a major role. As described in the review on the vascular contribution to AD by Altman et al. (2010) [Conversely, lipid dysfunction, endothelial injury and vascular disease are risk factors for the development and progression of various types of dementia, including AD, where . (2010) , the con. (2010) ). ApoE4,. (2010) ).APOE ε4 carriers [APOE ε4 carriers seem to be non-linear and age- and region-dependent, where hyperperfusion is observed in cognitively normal ε4 carriers as a compensatory mechanism to meet the metabolic demands of hyperactive neuronal activity [ApoE or its receptors are expressed in most cells participating in the formation, maintenance  and interaction (e.g. macrophages and microglia) with the BBB. Wide evidence (including a study using bioengineered human vessels) supports that ApoE4 compromises the integrity of the BBB, inducing degeneration of brain capillary pericytes and producing increased leakiness and deficient Aβ clearance through the BBB , 79. A lcarriers . Ultimatactivity , 82.APOE ε4 carriage. For example, animal models show exercise prevents age-related decline in the integrity and function of the neurovascular unit in the frontoparietal cortex and the hippocampus, including greater preservation and coverage of pericytes [APOE knockout mice, APOE ε4 transgenic mice and human carriers also show lower brain levels of ApoE. Therefore, it seems that PA might not be sufficient to preserve neurovascular health in APOE ε4 carriers. Alternatively, greater levels of PA engagement than those registered by Soto et al. (2015) [APOE genotype [APOE ε4 carriers were reportedly over-represented, meaning that PA might be able to prevent the need for the activation of a potentially compensating mechanism [APOE ε4 carriers show higher cerebral blood flow than non-carriers in the hippocampus as a function of longer sedentary time [APOE gene allele carriage, physical activity and cerebrovascular risk factors.There is evidence that cerebrovascular adaptations following increased levels of PA might restore some, but not all, of the functions which are negatively affected by ericytes . However. (2015)  might be. (2015) . Still, genotype . Moreoveechanism . In factary time . Figure Bouts of PA are associated with a transient increase in anti- and pro-inflammatory cytokines, such as IL-1, IL-10, IL-18, IL-1 receptor antagonist (IL-1ra), IL-6 and C-reactive protein. However, while pro-inflammatory substances are released after exercising, physically fit individuals exhibit lower basal levels in comparison to their unfit and overweight counterparts, the latter of which tend to show a chronic state of low-level inflammation . As a reAPOE genotype can modulate the innate immune response after an inflammatory stimulus, in animal models and humans, in vitro and in vivo. Specifically, ε4 allele carriage has been associated with increased immune reactivity. The ApoE4 protein is linked with a greater increment in the number of microglia, astrocytes and infiltrating T-cells and enhanced secretion and longer-lasting elevations of cytokines such as IL-1B, TNF-a and NO [APOE ε4 mice show basal structural and functional brain differences, including activated morphology of the microglia even in the absence of an inflammatory stimulus [APOE ε4 homozygous mice compared to APOE ε3 homozygous mice, which might be indicative of differences in basal postsynaptic densities across genotypes. These differences might arise from chronic inflammation, which could make the brain more susceptible to damage accumulation across time [APOE ε4 allele has been consistently reported to increase the susceptibility to inflammation in a dose-dependent manner [The a and NO –98. Addistimulus . Zhu et oss time , 98. Othoss time . In any t manner , 96.The mechanisms through which ApoE4 contributes to the enhancement of inflammation are still being elucidated see Fig. . ImpairmAPOE ε4 allele carriage on cognitive performance, Aβ deposition and dementia risk could be mitigated or compensated by regular, moderate levels of PA .Growing evidence suggests that the detrimental effects of the iewed by , 102). SJAMA perspective publication, glucose metabolism impairments have been suggested to trigger vascular dysfunction in the brain, and such impairments are considered a modifiable causal factor, rather than a symptom of AD [Cerebral glucose hypometabolism is commonly observed in AD, which has been referred to as brain-specific “diabetes mellitus type 3” . In a reom of AD . In factom of AD .Exercise can elicit a series of adaptations improving insulin signalling, glucose transport (mostly through GLUT4 translocation) and glucose metabolism in muscles . SAPOE ε4 non-carriers seem to benefit from nasal insulin administration in terms of improved memory performance [APOE ε4 carriers in a region-specific [APOE ε4 carrier MCI patients [APOE ε4 gene-targeted replacement (TR) mice and in APOE ε4 carrier AD patients compared to non-carriers, indicating hindered neuronal glucose uptake [APOE ε4 TR mice show lower levels of glucose transporters (mostly GLUT3), synthesise less hexokinase (an enzyme involved in glycolysis) and produce lower glycolytic outcomes as they age, leading to less efficient energy production in brain cells [On the other hand, mouse studies suggest that ApoE4 may impair insulin signalling and insulin-mediated mitochondrial respiration and glycolysis . Among mformance . Cerebraspecific , 116 andspecific . Furtherspecific  and glucpatients . Neuronspatients . Relevane uptake . APOE ε4in cells , 123. Inin cells .APOE ε4 carriage and PA on cerebral glucose metabolism. However, available data on each independent mechanism suggest that PA might counteract the detrimental effects of genetic risk.Unfortunately, there is a lack of empirical evidence on the combined effect of APOE interaction is associated with various mechanisms involved in AD pathology (as discussed above). Where there is evidence to suggest that multiple outcomes may be influenced by PA and APOE in a bi-directional or synergistic manner, they have been included in the same model  in termrization . For exarization . In thisrization . PA seemrization , but itsAPOE ε4 carriage modulate tau is very scarce. Preventing tau pathology is crucial, since this biomarker is more closely associated with neurodegeneration and cognitive decline than amyloid pathology alone [APOE ε4 allele), might prevent increased tau pathology. This hypothesis could be examined by longitudinal examinations of brain Aβ and tau in relation to physical activity levels, with examination of the moderating effects of APOE ε4 allele carriage.Another defining feature of AD is tau pathology, although research on how PA and/or gy alone , 127. Tagy alone , 42. In APOE ε4 carriers [APOE ε4 carriage with opposing effects), in that increased inflammatory cytokines may lead to greater Aβ, but also the neurotoxic environment induced by Aβ may lead to greater inflammation [APOE ε4 allele.A vast body of evidence shows that basal levels of pro-inflammatory molecules are higher among carriers , 96 and carriers . Surprisammation –130. Aniammation , 132. Meammation , providiAPOE ε4 allele [APOE ε4 allele might moderate the acute neurotrophic response to a bout of PA, a hypothesis that requires further investigation. Still, it appears that in APOE ε4 carriers neurotrophic function (i.e. BDNF and TrkB levels) is partially restored in response to habitual PA [APOE ε4 allele on the PA-induced changes to other neurotrophins and their impact on AD pathology. For example, it seems plausible that PA-induced VEGF could potentiate neuroprotection and prevent Aβ and p-tau aggregation. Additionally, some of these associations may be bi-directional, as aggregation of Aβ plaques can also downregulate BDNF and IGF-1 expression [APOE isoform-dependent neurotrophic expression is influenced by inflammatory factors, and further research is required.Probably the most investigated mechanism through which PA exerts its beneficial effects on brain health is the upregulation of neurotrophic factors , 58, 59,4 allele , 65, 66,itual PA . Future pression , althougpression . HoweverAPOE ε4 carriage result from the alteration of lipid transport in the brain, which ultimately deteriorates neural remodelling and repair mechanisms, disrupting neuronal communication [APOE ε4, even when the neurotrophic response to exercise is preserved. Furthermore, lipid transportation impairment has been associated with greater pro-inflammatory responses, via TLR activation, which would lead to the cascade of effects explained above [Some of the most pernicious outcomes associated with nication . Accordied above , 99. Gived above , 92, incAPOE ε4 in animal models [APOE ε4 carriers [APOE ε4 carriage negatively impacts glucose metabolism in the brain. Conversely, PA improves insulin signalling, glucose transport and glucose metabolism [APOE ε4 carriage on brain glucose metabolism has not been addressed to date. Still, given that both factors act on the same pathways, PA could become a strategic tool to prevent insulin resistance and vascular dysfunction in ε4 carriers, two features that characterise AD neuropathology.ApoE4 is exceedingly detrimental to the integrity of the BBB, which undermines Aβ clearance, making the brain more susceptible to toxins , 79, 134l models . Howevercarriers . PA-inducarriers , and APOtabolism , 107. Thtabolism –112. HowAPOE ε4 carriage promotes AD pathology through multiple pathways, where its effects on cerebrovascular health and Aβ pathology are particularly detrimental. Although Aβ deposition has not been identified as a main contributor to clinical symptomatology in AD, Aβ oligomerization exerts a series of downstream effects that trigger additional pathological effects (e.g. the exacerbation of tau pathology). Moreover, Aβ oligomers, directly and indirectly, seem to impede the capacity of PA-induced protective mechanisms to operate. In this line, the neurotrophic response to PA is likely the most powerful tool to compensate for AD pathology in a clinically relevant manner. Yet, neuroinflammation and altered lipid transportation as a result of APOE ε4 carriage and/or Aβ oligomerization hinder PA-induced neurogenesis, synaptogenesis and angiogenesis as well as neuronal and vascular repair. Therefore, it urges to investigate:In early life and at the preclinical stages of the pathology, whether PA can reduce the first hallmarks of the disease (including Aβ oligomerization).At more advanced stages, whether specific PA regimes (e.g. exercise at higher intensity) can overcome the above-listed impairments of PA-induced protective mechanisms or whether pharmaceutical agents improving lipid transportation or ameliorating neuroinflammation can be combined with PA to achieve the desired outcomes.In brief, This and other key questions for future research have been included in Table APOE ε4 carriage and PA engagement at multiple levels, which ultimately modulate AD risk. From our perspective, at least part of the variability within this field emerges as a result of the usage of different outcome measures to characterise the interaction between these two contributing factors. For instance, as we have reported here, the detrimental effect of APOE ε4 carriage on Aβ pathology seems to be counteracted by PA engagement, at least at the early stages of the disease. However, PA does not seem to be protective enough against the damage APOE ε4 carriage causes to the BBB, which eventually might lead to additional downstream impairments, including an exacerbation of Aβ pathology. AD is a complex disease and the multiple mechanisms involved in AD pathogenesis are interrelated [all relevant associations between the AD-related outcomes discussed above. Therefore, in addition to our proposed integrative model, we also suggest directions for future research to allow the development of such a comprehensive model . However, there are important differences in the APOE gene between mice and humans, complicating research on the field [APOE ε4 variant, where they often induce the expression of classical AD biomarkers, such as Aβ. Finally, in human studies, PA levels and exercise routines are often poorly measured and described, while animal studies impose certain limitations on the PA and exercise regimes that can be tested . More research is needed to establish the PA parameters  that maximise beneficial outcomes on specific mechanisms in at-risk populations and at different disease stages. These much-needed pieces of information are key to upgrade the model proposed.There are key methodological considerations that should be carefully addressed when designing prospective studies. Firstly, methodological variations in biomarkers assessment hinder comparisons across studies. Moreover, there is currently a critical lack of longitudinal studies examining both PA and he field , 140. MoAPOE ε4 carriage, independently and in combination, influence the pathogenesis of AD. Looking at the reviewed mechanisms, we identify potential pathways through which the beneficial effects of PA might offset some of the detrimental outcomes of APOE ε4 carriage. Nonetheless, PA does not seem to be able to entirely prevent or revert the noxious effects of genetic risk. This is in line with the idea that PA delays rather than prevents AD neuropathology. Accordingly, the potential of PA to exert its benefits might be dependent on the disease stage and the extent of the damage to the above-reviewed mechanisms. Still, given that the molecular alterations associated with AD remain silent for up to 20 years, delays in the onset and progression of neuropathological changes could be clinically meaningful. Moreover, compared to pharmaceutical approaches to AD, which usually tackle one specific pathway, PA influences a wide array of molecular targets that all lie somewhere in the stream of AD risk. Therefore, although PA may not be sufficient to prevent or cure AD, it represents a strong complementary therapeutic tool to be combined with more precise pharmacological interventions.Through this theoretical article, we aim to propose a novel integrative model of how PA and