番茄转录因子SlTOE1调控茉莉酸介导的抗逆反应和番茄产量形成的机理研究

A bottleneck problem in breeding practice is that increased plant resistance is often associated with reduced growth. Jasmonate (JA) is an important plant hormone that usually promotes resistance while inhibits growth. In previous studies, we have identified that the tomato AP2-type transcription factor SlTOE1 promotes JA-mediated plant resistance while negatively regulates yield formation. First, the expression of SlTOE1 is induced by JA in a JA-receptor dependent manner. Second, JA-regulated defense gene expression is reduced in SlTOE1-RANi transgenic plants compared with that in wild-type plants. Consistently, SlTOE1-RANi transgenic plants shows reduce resistance to herbivore attack and pathogen infection. Third, compared to wild-type plants, SlTOE1-RANi plants show higher expression level of the florigen gene SFT, early flowering and increased inflorescence number, which lead to increased yield. In this application, we propose to elucidate the action mechanism of SlTOE1 in regulating JA-mediated plant resistance and yield formation using a functional genomics strategy. This study promises to shed new light on our understanding of the trade-off between plant resistance and growth.

植物的生长发育和抗逆反应通常存在负相关。打破作物生长发育和抗逆反应的负相关是育种实践中面临的瓶颈问题。茉莉酸既调控植物的抗逆反应也调控植物生长发育的诸多方面。我们前期的研究发现，番茄AP2类转录因子SlTOE1受茉莉酸诱导表达，并且与野生型植物相比，在SlTOE1-RNAi植物中，茉莉酸诱导的抗性基因表达显著降低，对昆虫和病原菌的抗性下降；同时，SlTOE1-RNAi植物中成花素基因SFT的表达量升高，开花时间提前，花序数目增多，最终导致产量提高。这些结果表明SlTOE1既正向调控茉莉酸介导的抗逆反应同时又负向调控番茄产量形成。本申请将以上述发现为基础，系统研究SlTOE1调控茉莉酸介导的抗逆反应和产量形成的分子机理，为阐明植物抗逆反应和生长发育负相关的机制提供创新性知识积累，同时为创制番茄高产高抗新种质提供理论指导。

番茄AP2类转录因子SlTOE1既参与茉莉酸介导的抗逆反应，又是番茄产量形成的重要调节因子。本项目通过深入研究SlTOE1的生物学功能，发现SlTOE1通过与番茄茉莉酸信号途径中的抑制子蛋白JAZ6，JAZ7，JAZ8互作，形成转录因子-转录抑制子组合，正向调控茉莉酸介导的抗性反应。另一方面，SlTOE1通过直接结合到番茄成花素基因SFT的启动子区，调控SFT的表达，从而调控番茄的开花时间和产量形成。我们利用CRISPR/Cas9介导的基因编辑技术将SlTOE1敲除，得到了SlTOE1-cr材料。通过分析该材料的表型，发现开花明显提前，产量显著增加。我们的研究为作物培育早花高产品种提供了新的靶标。