外源Spd对盐胁迫下黄瓜SAMs基因表达的影响及SAMs蛋白的生物信息学分析

 以黄瓜品种‘津春2号’为材料，采用营养液栽培，研究了外源亚精胺（Spd）对NaCl胁迫下黄瓜幼苗S–腺苷甲硫氨酸合酶基因（SAMs）表达的影响，分析了SAMs的生物学信息。结果表明，在75 mmol · L-1 NaCl胁迫下，SAMs基因在盐胁迫3、6和12 h内诱导表达上调，24 h后表达受到抑制，低于对照水平；盐胁迫下，外源Spd处理在3、6和12 h内下调了SAMs基因表达，24 h后表达量接近对照水平，表明外源Spd介导了盐胁迫下黄瓜幼苗SAMs基因的差异表达，可能通过修正SAM合成途径响应盐胁迫，增强黄瓜植株耐盐性。黄瓜SAMs蛋白生物信息学分析表明，SAMs蛋白比较稳定，含有多个磷酸化位点，其氨基酸序列中第89位半胱氨酸残基和246 ~ 255位的保守序列DAGLTGRKII对SAMs酶的功能起着重要的作用，同时推导了黄瓜SAMs蛋白的三维结构。

Effects of Exogenous Spd on Expression Analysis of Cucumber SAMs Gene Under Salt Stress and Bioinformatics Analysis of SAMs Protein

The experiment was carried out to study the effects of exogenous Spd on SAMs gene expression in cucumber（Cucumis sativus L.‘Jinchun 2’）seedlings under salt stress with solution culture. The results showed that expressions of SAMs were up-regulated at 3，6，12 h by salt stress，and then were down-regulated after 24 h compared with that at normal level. Compared to salt stress，expressions of SAMs were down-regulated at 3，6，12 h with spraying Spd，and then were closed to control level after 24 h. The results revealed that exogenous Spd could mediate cucumber SAMs gene expression differentially，may regulate the biosynthesis pathway of SAM to enhance salt tolerance of cucumber. Protein bioinformatics analysis showed that the SAMs protein were relatively stable and have multiple phosphorylation sites. Cysteine residue of the 89 amino acid bit and the conserved sequence of 246 to 255 bits of DAGLTGRKII may play an important role in the function for SAMs enzyme. Meanwhile，we also derived three-dimensional structure of SAMs protein.