Natural variation in cytokinin maintenance improves salt tolerance in apple rootstocks.
Plants experiencing salt-induced stress often reduce cytokinin levels during the early phases of stress-response. Interestingly, we found that the cytokinin content in the apple rootstock "robusta" was maintained at a high level under salt stress. Through screening genes involved in cytokinin biosynthesis and catabolism, we found that the high expression levels of IPT5b in robusta roots were involved in maintaining the high cytokinin content. We identified a 42 bp deletion in the promoter region of IPT5b, which elevated IPT5b expression levels, and this deletion was linked to salt tolerance in robusta×M.9 segregating population. The 42 bp deletion resulted in the deletion of a Proline Response Element (ProRE), and our results suggest that ProRE negatively regulates IPT5b expression in response to proline. Under salt stress, the robusta cultivar maintains high cytokinin levels as IPT5b expression cannot be inhibited by proline due to the deletion of ProRE, leading to improve salt tolerance.
['Feng|Yi|Y|0000-0002-8174-2078', 'Liu|Jing|J|', 'Zhai|Longmei|L|', 'Gan|Zengyu|Z|', 'Zhang|Guifen|G|', 'Yang|Shuhua|S|', 'Wang|Yi|Y|', 'Wu|Ting|T|', 'Zhang|Xinzhong|X|', 'Xu|Xuefeng|X|', 'Han|Zhenhai|Z|']
D003583:Cytokinins D018506:Gene Expression Regulation, Plant D017343:Genes, Plant D014644:Genetic Variation D018551:Lycopersicon esculentum D027845:Malus D018517:Plant Roots D030821:Plants, Genetically Modified D000077323:Salt Stress D055051:Salt-Tolerant Plants
cytokinin apple rootstock genetic variation isopentenyl transferase salinity