State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Changsha 410125, China.
College of Agronomy, Hunan Agricultural University, Changsha 410128, China.
Plant Physiol. 2021 Jun 11;186(2):1060-1073. doi: 10.1093/plphys/kiab106.
Seed setting rate is one of the critical factors that determine rice yield. Grain formation is a complex biological process, whose molecular mechanism is yet to be improved. Here we investigated the function of an OVATE family protein, Embryo Sac Development 1 (ESD1), in the regulation of seed setting rate in rice (Oryza sativa) by examining its loss-of-function mutants generated via clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated9 (Cas9) technology. ESD1 was predominantly expressed at Stage 6 of panicle development, especially in the ovules. esd1 mutants displayed reduced seed setting rates with normal stamen development and pollen tube growth but abnormal pistil group. Investigation of embryo sacs revealed that during the mitosis of functional megaspores, some egg cells degraded during differentiation in esd1 mutants, thereby hindering subsequent fertilization process and reducing seed setting rate. In addition, the transcriptional level of O. sativa anaphase-promoting complex 6, a reported embryo sac developing gene, was significantly reduced in esd1 mutants. These results support that ESD1 is an important modulator of ESD and seed setting rate in rice. Together, this finding demonstrates that ESD1 positively regulates the seed setting rate by controlling ESD in rice and has implications for the improvement of rice yield.
结实率是决定水稻产量的关键因素之一。籽粒形成是一个复杂的生物学过程，其分子机制尚待完善。在这里，我们通过检查经簇状规则间隔短回文重复 (CRISPR)/CRISPR 相关 9 (Cas9) 技术生成的功能丧失突变体，研究了卵形家族蛋白 Embryo Sac Development 1 (ESD1) 在调节水稻 (Oryza sativa) 结实率中的作用。ESD1 在小穗发育的第 6 期（尤其是在胚珠中）表达丰富。esd1 突变体表现出结实率降低，花药发育正常，花粉管生长正常，但雌蕊群异常。胚珠的研究表明，在功能大孢子的有丝分裂过程中，esd1 突变体中的一些卵细胞在分化过程中降解，从而阻碍了随后的受精过程，降低了结实率。此外，在 esd1 突变体中，报告的胚珠发育基因 O. sativa 后期促进复合物 6 的转录水平显著降低。这些结果表明 ESD1 是水稻 ESD 和结实率的重要调节剂。总之，该发现表明 ESD1 通过控制水稻中的 ESD 来正向调节结实率，对提高水稻产量具有重要意义。
