GA介导的细胞分裂空间调控阐明了栽培稻与野生稻叶片大小的差异

叶片大小是影响作物性能的主要决定因素，通过影响叶片的生理过程，如光的捕获、蒸腾和气体交换。因此，了解叶片大小调控的遗传基础是作物改良的当务之急。作物叶片大小的自然变异是了解叶片大小调节的一个有价值的遗传资源。研究了栽培稻和野生稻对叶片长度的控制机理，结果表明，栽培稻和野生稻叶片长度特征存在显著差异。

比较转录组分析表明，赤霉素(GA3)、生长调节因子(GRF)和细胞周期参与了水稻叶片大小的调控。叶片运动学研究表明，与栽培品种相比，野生稻叶片细胞分裂活动区域的增加以及更快的细胞生产率驱动了澳洲稻的长叶。澳洲稻叶片中高水平的 GA 和 GA 通过增加细胞分裂区而引起的水稻叶片长度的增加，强调了 GA 在水稻叶片长度调节中的关键作用。

赤霉素生物合成和信号转导基因的区域特异性表达和沉默证实了 OsGRF7和 OsGRF8在赤霉素下游起控制细胞周期决定水稻叶片长度的作用。水稻叶片长度调控的 GA-GRF细胞周期模块可能有助于在驯化过程中优化叶片特征，也可能是植物实现叶片可塑性响应环境的一种途径。

Leaf size is a major determinant of crop performance by influencing leaf physiological processes, such as light capture, transpiration, and gas exchange. Therefore, understanding the genetic basis of leaf size regulation is imperative for crop improvement. Natural variation in leaf size for a crop plant is a valuable genetic resource for a detailed understanding of leaf size regulation. We investigated the mechanism controlling the rice leaf length using cultivated and wild rice accessions that showed remarkable differences for the leaf features. Comparative transcriptomic profiling of the contrasting accessions suggested the involvement of Gibberellic Acid (GA), Growth Regulating Factor (GRF) transcription factors, and cell cycle in the rice leaf size regulation. Leaf kinematics studies showed that the increased domain of cell division activity along with a faster cell production rate drove the longer leaves in the wild rice Oryza australiensis compared to the cultivated varieties. Higher GA levels in the leaves of Oryza australiensis, and GA-induced increase in the rice leaf length via an increase in cell division zone emphasized the key role of GA in rice leaf length regulation. Zone-specific expression and silencing of the GA biosynthesis and signaling genes confirmed that OsGRF7 and OsGRF8 function downstream to GA for controlling cell cycle to determine the rice leaf length. The GA-GRF-cell cycle module for rice leaf length regulation might have contributed to optimizing leaf features during the domestication and could also be a way for plants to achieve leaf plasticity in response to the environment.

原文链接：

https://doi.org/10.1101/2021.05.06.443003

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