An isopentyl transferase gene driven by the senescence-inducible SAG12 promoter improves salinity stress tolerance in cotton

摘要

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 SAG12 promoter 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 Conclusion:The senescence-induced CTK accumulation in cotton seeds and seedlings positively regulates salt stress partially by elevating ROS scavenging capability.