State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Laboratory for Lingnan Modern Agriculture, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
Plant Physiol. 2022 Sep 28;190(2):1260-1274. doi: 10.1093/plphys/kiac338.
Grain size is one of the crucial factors determining grain yield. However, the genetic and molecular mechanisms of florigen repression complexes (FRCs) underlying grain size in rice (Oryza sativa L.) have not been reported. Here, we report that the rice CENTRORADIALIS (CEN) family member OsCEN2 (also known as Rice TFL1/CEN homolog, RCN1), a phosphatidylethanolamine-binding protein (PEBP) family protein, negatively controls grain size in rice. Overexpression of OsCEN2 led to small grains, and knockout of OsCEN2 resulted in large, heavy grains. OsCEN2 influenced grain size by restricting cell expansion in the spikelet hull and seed filling. In in vivo and in vitro experiments, OsCEN2 physically interacted with a G-box factor 14-3-3 homolog, GF14f, which negatively regulates grain size. Bimolecular fluorescence complementation and yeast two-hybrid assays revealed that GF14f directly interacts with the basic leucine zipper (bZIP) transcription factor, OsFD2. Plants overexpressing OsFD2 produced smaller and lighter grains than wild-type plants. We found that OsFD2 also influences grain size by controlling cell expansion and division in the spikelet hull. Our results reveal the molecular mechanisms of the OsCEN2-GF14f-OsFD2 regulatory module in controlling grain size. Additionally, our study provides insight into the functions of the FRC in rice and suggests a strategy for improving seed size and weight.
粒型是决定粒重的关键因素之一。然而，水稻（Oryza sativa L.）中控制粒型的成花素抑制复合物（FRC）的遗传和分子机制尚未报道。在这里，我们报告称，水稻 CENTRORADIALIS（CEN）家族成员 OsCEN2（也称为 Rice TFL1/CEN homolog，RCN1），一种磷脂酰乙醇胺结合蛋白（PEBP）家族蛋白，负向调控水稻的粒型。OsCEN2 的过表达导致小粒，而 OsCEN2 的敲除导致大粒、重粒。OsCEN2 通过限制小穗壳和种子灌浆过程中的细胞扩展来影响粒型。在体内和体外实验中，OsCEN2 与 G 盒因子 14-3-3 同源物 GF14f 发生物理相互作用，GF14f 负向调控粒型。双分子荧光互补和酵母双杂交实验表明，GF14f 直接与碱性亮氨酸拉链（bZIP）转录因子 OsFD2 相互作用。过表达 OsFD2 的植株产生的粒小而轻，比野生型植株小。我们发现 OsFD2 还通过控制小穗壳中的细胞扩展和分裂来影响粒型。我们的结果揭示了 OsCEN2-GF14f-OsFD2 调控模块控制粒型的分子机制。此外，我们的研究为 FRC 在水稻中的功能提供了新的见解，并为改善种子大小和重量提供了策略。
