衰老诱导型启动子SAG12诱导异戊烯基转移酶基因提高棉花耐盐性

单艺^#，赵鹏^#，刘钊，李芳军^*，田晓莉

摘要：

    [背景] 土壤盐渍化严重影响棉花生长，导致棉花产量和纤维品质下降。近年来，利用基因工程技术提高作物对非生物胁迫耐受性已成为有效手段之一。

    [结果] 利用农杆菌介导的基因转化构建细胞分裂素（CTK）生物合成关键酶——异戊烯基转移酶基因IPT（源于农杆菌）转基因棉花材料。源于拟南芥的衰老诱导型启动子SAG12与IPT基因融合驱动基因表达。盐胁迫条件下，异源表达SAG12::IPT显著提高种子萌发率以及幼苗耐盐性。萌发期较为耐盐株系OE3和苗期较为耐盐株系OE8用于进一步的生理机制研究。结果表明，异源表达SAG12::IPT诱导CTK在叶片和根中的积累以及在萌发种子中的积累。盐胁迫条件下与对照相比，异源表达IPT基因提高了植株的抗氧化酶活性，减少了活性氧的积累，并且增加了棉花叶片和根中的K⁺/Na⁺比值。

[结论] 衰老诱导型启动子诱导棉花种子和幼苗中CTK积累，通过提高转基因植株对活性氧的清除能力提高其耐盐性。

关键词：异戊烯基转移酶基因（IPT），细胞分裂素，转基因，耐盐性，棉花

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.

Conclusion

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

https://doi.org/10.1186/s42397-019-0032-3

https://jcottonres.biomedcentral.com/articles/10.1186/s42397-019-0032-3