SlmiR319a调控TCPs介导茉莉酸路径响应番茄低钾胁迫的分子机制

Tomato is one of the crops required large amounts of potassium. The production and quality are often influenced by the lack of potassium. We got the "resistant to low potassium" JZ34 and the "sensitive to low potassium" JZ18 by the early screening. Our studies concluded that SlmiR319a was related to the response to low potassium stress in tomatoes by miRNA-Seq data，but the mechanism is not clear. It's known that the target genes TCPs regulated by SlmiR319a was believed to be involved in jasmonic acid synthesis, based on this, one hand, we construct SlmiR319a expression vector and transfer to JZ34 to obtain transgenic tomatoes, and test the transgenic plants' resistance to low potassium and screen the TCPs response to low potassium, further using EMSA and yeast one hybrid verify the interaction of the target TCPs and the candidate gene which were selected significantly different expressed by the transcriptome data under low potassium, clarify the key TCPs in the regulation of SlmiR319a in response to low potassium stress; on the other hand, analyse the changes of JA content with the expression of TCPs under low potassium condition, testify the induction of exogenous JA on candidate genes expression by transient expression. It will be clear that target gene TCPs regulated by SlmiR319a mediating JA pathway in response to low potassium stress. It lays the foundation of molecular theory for the cultivation of Low Potassium Tolerant tomato.

番茄是需钾量较大的作物种类之一，生产上常因钾素不足而影响其产量和品质。申请人前期筛选出耐低钾型番茄JZ34和低钾敏感型番茄JZ18两个品系，高通量测序结果认为SlmiR319a与番茄响应低钾胁迫密切相关，但其响应机制尚不清楚。已知SlmiR319a调控的靶基因TCPs可以参与茉莉酸合成，在此基础上，本研究一方面构建SlmiR319a表达载体并转入JZ34中，检测转基因植株耐低钾性并筛选响应低钾的TCPs，进一步通过EMSA和酵母单杂交验证TCPs与低钾胁迫下转录组数据筛选的差异表达的候选基因启动子的互作，明确SlmiR319a调控的关键TCPs在番茄低钾胁迫中的响应；另一方面，测定低钾胁迫下内源JA含量随TCPs表达的变化，通过瞬时表达验证JA对候选基因启动子的诱导，明确SlmiR319a的靶基因TCPs介导JA参与低钾胁迫响应。为耐低钾型番茄的培育奠定分子理论基础。

番茄是需钾量较大的作物种类之一，生产上常因钾素不足而影响其产量和品质。本团队前期通过研究已经筛选出耐低钾型番茄JZ34和低钾敏感型番茄JZ18，通过高通量测序发现SlmiR319的表达水平在不同耐低钾性番茄中具有显著性差异。本研究在此基础上，进一步明确了SlmiR319对番茄响应低钾胁迫的关键作用，通过5’RACE鉴定出SlmiR319的新靶基因SlTCP10，通过酵母单杂和EMSA试验证实了SlTCP10可以调控SlJA2，同时作为NAC转录因子家族的SlJA2通过双荧光素酶试验证实可以调控HKT1;1和HAK5；与此同时，已知TCP基因家族对茉莉酸合成具有重要作用，OE-SlmiR319耐低钾性降低可能是由于茉莉酸含量的变化造成，因此进一步分析表明OE-miR319根系在低钾胁迫下茉莉酸含量降低，且茉莉酸对SlHKT1;1的表达活性具有促进作用；利用茉莉酸突变体spr2也证明了茉莉酸合成受阻会影响番茄根系在低钾胁迫下的发育及钾离子含量。综上所述，SlmiR319调控的靶基因SlTCP10通过转录因子SlJA2调控下游钾离子转运基因同时利用茉莉酸合成路径对番茄根系响应低钾胁迫的分子机制产生影响。本项目研究成果目前发表SCI论文1篇，中文核心期刊3篇，申请专利1项，软件著作权2项，培养博士研究生1名，硕士研究生2名。本研究中茉莉酸合成路径对调控番茄响应低钾胁迫的作用对于指导番茄缺素生产及提高番茄产量和品质具有重要意义。