研究发现水稻LC3调控生长素信号和叶倾角

11月29日，PLoS Genetics 在线发表了中国科学院分子植物科学卓越创新中心/植物生理生态研究所薛红卫研究组题为SPOC domain-containing protein Leaf inclination3 interacts with LIP1 to regulate rice leaf inclination through auxin signaling 的研究论文。该研究发现水稻中的一个含有SPOC结构域的蛋白Leaf inclination3 (LC3)通过结合转录因子LIP1共同调控生长素信号，从而调控水稻叶倾角。

水稻是重要的单子叶模式植物，也是我国乃至世界上最主要的粮食作物之一。株型对作物的生产和产量有着重要关系，而叶倾角又是水稻株型的关键组分之一。研究表明，适当的叶倾角有利于提高水稻光合效率，通过合理密植，能够有效提高产量。尽管早已发现植物激素生长素影响叶倾角大小，且其代谢调控因子GH3和信号通路的关键组分IAA、ARF等被报道参与了叶倾角的调控，但对相关上游调控因子及机制仍了解较少，有待进一步阐明。研究组在前期工作中发现水稻缺失突变体LC3表现出叶倾角增大的表型。进一步的遗传学、细胞生物学等分析表明LC3蛋白作为一个转录抑制子通过与LC3互作的转录因子LIP1协同抑制下游基因OsIAA12和OsGH3.2表达，通过抑制生长素信号，最终调控水稻叶倾角。此外，OsIAA2通过与OsARF17互作抑制生长素信号，揭示了OsIAA2-OsARF17在叶倾角发育调控中的特定功能。

该研究有助于对生长素信号调控网络的理解。也对研究植物中具有SPOC结构域的蛋白的功能提供了借鉴。值得一提的是，这是首次发现的仅含有SPOC结构域而不含RRM SPEN家族的成员。

博士生陈素卉和周莉娟为论文第一作者。相关工作得到国家自然科学基金项目(91535201)以及“万人计划”的资助。（来源：中国科学院植物生理生态研究所）

SPOC domain-containing protein Leaf inclination3 interacts with LIP1 to regulate rice leaf inclination through auxin signaling

Abstract Leaf angle is an important agronomic trait and influences crop architecture and yield. Studies have demonstrated the roles of phytohormones, particularly auxin and brassinosteroids, and various factors in controlling leaf inclination. However, the underlying mechanism especially the upstream regulatory networks still need being clarified. Here we report the functional characterization of rice leaf inclination3 (LC3), a SPOC domain-containing transcription suppressor, in regulating leaf inclination through interacting with LIP1 (LC3-interacting protein 1), a HIT zinc finger domain-containing protein. LC3 deficiency results in increased leaf inclination and enhanced expressions of OsIAA12 and OsGH3.2. Being consistent, transgenic plants with OsIAA12 overexpression or deficiency of OsARF17 which interacts with OsIAA12 do present enlarged leaf inclination. LIP1 directly binds to promoter regions of OsIAA12 and OsGH3.2, and interacts with LC3 to synergistically suppress auxin signaling. Our study demonstrate the distinct effects of IAA12-ARF17 interactions in leaf inclination regulation, and provide informative clues to elucidate the functional mechanism of SPOC domain-containing transcription suppressor and fine-controlled network of lamina joint development by LC3-regulated auxin homeostasis and auxin signaling through.

原文链接：https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1007829