State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Plant Physiol. 2019 Oct;181(2):669-682. doi: 10.1104/pp.19.00639. Epub 2019 Jul 29.
During growth, plant cells must coordinate cell expansion and cell wall reinforcement by integrating distinct regulatory pathways in concert with intrinsic and external cues. However, the mechanism underpinning this integration is unclear, as few of the regulators that orchestrate cell expansion and wall strengthening have been identified. Here, we report a rice () Class II KNOX-like homeobox protein, (), that interacts with different partners to govern cell expansion and wall thickening. A loss-of-function mutation in enhanced wall mechanical strength and cell expansion, resulting in improved lodging resistance and grain size. Overexpression of gave rise to the opposite phenotypes, with plants having weaker cell walls and smaller grains. Biochemical and gene expression analyses revealed that rice KNAT7 interacts with a secondary wall key regulator, NAC31, and a cell growth master regulator, Growth-Regulating Factor 4 (GRF4). The KNAT7-NAC31 and KNAT7-GRF4 modules suppressed regulatory pathways of cell expansion and wall reinforcement, as we show in internode and panicle development. These modules function in sclerenchyma fiber cells and modulate fiber cell length and wall thickness. Hence, our study uncovers a mechanism for the combined control of cell size and wall strengthening, providing a tool to improve lodging resistance and yield in rice production.
在生长过程中，植物细胞必须通过整合内在和外在的线索，协调不同的调节途径，以协调细胞扩张和细胞壁加固。然而，这种整合的机制尚不清楚，因为很少有协调细胞扩张和细胞壁强化的调节剂被鉴定出来。在这里，我们报告了一个水稻（）Class II KNOX-like homeobox 蛋白，（），它与不同的伙伴相互作用，以控制细胞扩张和细胞壁增厚。在 中功能丧失的突变增强了细胞壁的机械强度和细胞扩张，从而提高了抗倒伏能力和粒重。过表达 导致了相反的表型，植物的细胞壁较弱，籽粒较小。生化和基因表达分析表明，水稻 KNAT7 与次生壁关键调节剂 NAC31 和细胞生长主调节剂 Growth-Regulating Factor 4 (GRF4) 相互作用。我们在节间和穗发育中表明，KNAT7-NAC31 和 KNAT7-GRF4 模块抑制了细胞扩张和细胞壁强化的调节途径。这些模块在厚壁组织纤维细胞中起作用，并调节纤维细胞长度和细胞壁厚度。因此，我们的研究揭示了细胞大小和细胞壁强化的联合控制机制，为提高水稻生产中的抗倒伏能力和产量提供了一种工具。
