Changes during leaf expansion of ΦPSII temperature optima in Gossypium hirsutum are associated with the degree of fatty acid lipid saturation.
In this project, we hypothesize that cotton (Gossypium hirsutum) leaf temperature and the responses of leaf photosynthesis to temperature will change as the leaves expand and that differences between young and mature leaves will be associated with the proportion of saturated fatty acids in thylakoid and other membrane lipids. To that end, we studied main stem leaves obtained from plants growing in a temperature controlled greenhouse and at different times in the field season. We found that young leaves (∼5d old) had higher mid day temperatures, lower stomatal conductance and higher thermal optima as measured by ΦPSII temperature curves than did more mature leaves (∼13d old). Young leaves also had significant differences in fatty acid saturation with the warmer, young leaves having a higher proportion of palmitic acid (16:0) and lower linoleic acid (18:3) in total lipid extracts and higher 16:0 and lower palmitoleic acid (16:1) in the chloroplast membrane phosphoglycerides, digalactosyldiacylglycerol (in the greenhouse) and phosphatidylglycerol when compared with cooler, more mature leaves. Later in the growing season, leaf temperature, stomatal conductance and ΦPSII temperature curves for young and more mature leaves were similar and the proportion of 16:0 fatty acids decreased and 16:1 increased in phosphatidylglycerol. We conclude that changes in temperature as cotton leaves expand leads to alterations in the fatty acid composition of thylakoid and other membranes and, consequently, influence photosynthesis/temperature responses.
['Hall|Trent D|TD|', 'Chastain|Daryl R|DR|', 'Horn|Patrick J|PJ|', 'Chapman|Kent D|KD|', 'Choinski|John S|JS|']
D000064:Acclimatization D002734:Chlorophyll D002736:Chloroplasts D002940:Circadian Rhythm D005227:Fatty Acids D005453:Fluorescence D003368:Gossypium D008027:Light D019787:Linoleic Acid D019308:Palmitic Acid D010788:Photosynthesis D045332:Photosystem II Protein Complex D018515:Plant Leaves D054046:Plant Stomata D018526:Plant Transpiration D011891:Rain D012621:Seasons D013696:Temperature
Leaf expansion Gossypium hirsutum Fatty acid saturation Chlorophyll fluorescence Photosynthetic thermotolerance