水稻OsSRO1c基因在干旱胁迫诱导的叶片衰老中的功能研究

Drought stress is one of the most important constraints in crop production around the world. Increasing evidence suggests that plant responsiveness to abiotic stress is closely associated with leaf longevity. Thus, understanding the regulatory mechanism of leaf senescence under abiotic stress conditions in rice has important theoretical and application value for improving rice abiotic stress resistance, and reduces yield loss caused by stresses. In the prophase work, OsSRO1c was identified as one of the target genes of stress related transcriptional factor SNAC1, and have a role in promotion of stomatal closure in rice. This project will further investigate the function of OsSRO1c in drought stress-induced senescence through phenotypic analysis of mutant and transgenic plants, combined with the transcriptomic analysis. Moreover, the function of downstream genes and interaction proteins of OsSRO1c in abiotic stress response will be also analyzed in detail. Thereby the key factors in OsSRO1c-medicated drought stress response pathway will be uncovered. In summary, the function of OsSRO1c in the stress response and the molecular networks of OsSRO1c-mediated drought stress response will be comprehensive analytic in this project. The results of this project will enrich our understanding of the complex regulation network of drought stress response, and provided theoretical basis and genetic resources for genetic improvement of drought resistance in rice.

干旱是全球作物生产最重要的制约因素之一。叶片的寿命与植物非生物逆境抗性紧密相关。研究胁迫条件下水稻叶片衰老的调控机制，对于提高水稻抗逆性，减少非生物逆境胁迫造成的产量损失具有重要理论和应用价值。前期的工作中，项目申请人鉴定了水稻抗逆转录因子SNAC1的一个靶基因OsSRO1c在促进气孔关闭中的作用。最近的研究显示OsSRO1c还特异地参与了干旱胁迫诱导的叶片衰老调控。本项目通过突变体和转基因材料的表型鉴定，结合转录组分析，揭示OsSRO1c在干旱胁迫诱导叶片衰老中的作用机制。通过深入研究OsSRO1c下游基因和互作蛋白的功能，揭示OsSRO1c介导干旱胁迫应答途径中的关键因子和分子网络调控机制。通过本项目的研究，不仅有助于全面解析OsSRO1c在逆境应答中的功能，更丰富了对水稻干旱胁迫应答复杂调控网络的认识，为水稻耐旱遗传改良提供了理论基础和基因资源。

SRO (SIMILAR TO RCD ONE)家族是植物特有的基因家族，在植物生长发育和逆境响应中都发挥着重要作用。前期研究发现水稻OsSRO1c不仅作为抗逆转录因子SNAC1的一个靶基因促进气孔关闭而且还特异地参与了干旱胁迫诱导的叶片衰老调控。本项目研究发现，OsSRO1c的表达随着叶片的发育和衰老而升高。与苗期干旱敏感表型不同，ossro1c-1突变体和OsSRO1c amiRNA抑制植株成株期抗旱性增强。干旱胁迫加速了野生型植株的叶片衰老，但ossro1c-1突变体和OsSRO1c amiRNA抑制植株的叶片失绿显著低于对照。随后的实验表明，持续黑暗和氧化胁迫诱导的叶片衰老在ossro1c-1突变体中也显著延迟。对ossro1c-1突变体进行基因表达谱分析显示，许多与逆境应答和次生代谢相关的基因表达发生了改变。在正常和干旱胁迫条件下，ossro1c-1突变体中包括谷胱甘肽转移酶和过氧化物酶在内的许多活性氧清除基因上调。进一步研究显示，ossro1c-1突变体中超氧化物歧化酶和谷胱甘肽转移酶活性增加，导致干旱胁迫下ossro1c-1突变体H2O2积累减少。这些结果表明，OsSRO1c通过调节活性氧稳态促进胁迫诱导的叶片衰老。