[Background] Soil salinity seriously affects cotton growth, leading to the reduction of yield and fiber quality. Recently, genetic engineering has become an efficient tool to increase abiotic stress tolerance in crops.
[Results] In this study, isopentyl transferase (IPT), a key enzyme involved in cytokinin (CTK) biosynthesis from Agrobacterium tumefaciens, was selected to generate transgenic cotton via Agrobacterium-mediated transformation. A senescence-inducible SAG12promoter from Arabidopsis was fused with the IPT gene. Ectopic-expression of SAG12::IPT significantly promoted seed germination or seedling tolerance to salt stress. Two IPTtransgenic lines, OE3 as a tolerant line during seed germination, and OE8 as a tolerant line at seedling stage, were selected for further physiological analysis. The data showed that ectopic-expression of SAG12::IPT induced the accumulation of CTKs not only in leaves and roots, but also in germinating seeds. Moreover, ectopic-expressing IPT increased the activity of antioxidant enzymes, which was associated with the less reactive oxygen species (ROS) accumulation compared with control plants. Also, ectopic-expression of IPT produced higher K+/Na+ ratio in cotton shoot and root.
[Conclusions] The senescence-induced CTK accumulation in cotton seeds and seedlings positively regulates salt stress partially by elevating ROS scavenging capability.
[Title] An isopentyl transferase gene driven by the senescence-inducible SAG12 promoter improves salinity stress tolerance in cotton
[Authors] SHAN Yi, ZHAO Peng, LIU Zhao, LI Fangjun* & TIAN Xiaoli
Journal of Cotton Research. 2019, 2: 15