Jiangsu Key Laboratory of Crop Genetics and Physiology, Key Laboratory of Plant Functional Genomics of the Ministry of Education, Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Agricultural College of Yangzhou University, Yangzhou, China.
Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China.
Plant Commun. 2020 Jul 2;2(1):100092. doi: 10.1016/j.xplc.2020.100092. eCollection 2021 Jan 11.
Cellularization is a key event in endosperm development. Polycomb group (PcG) genes, such as (), are vital for the syncytium-to-cellularization transition in plants. In this study, we found that , a rice homolog of the PcG gene (), plays a role similar to that of in regard to seed development, although there is limited sequence similarity between the genes. Delayed cellularization was observed in , associated with an unusual activation of type I MADS-box genes. The cell cycle was persistently activated in caryopses, which was likely caused by cytokinin overproduction. However, the overaccumulation of auxin was not found to be associated with the delayed cellularization. As is a maternally expressed gene in the endosperm, a paternally inherited functional allele was unable to recover the maternal defects of . Many imprinted rice genes were deregulated in the defective hybrid seeds of (♀)/9311 (♂) (m9). The paternal expression bias of some paternally expressed genes was disrupted in m9 due to either the activation of maternal alleles or the repression of paternal alleles. These findings suggest that OsEMF2a-PRC2-mediated H3K27me3 is necessary for endosperm cellularization and genomic imprinting in rice.
细胞化是胚乳发育的关键事件。多梳组（PcG）基因，如 （），对于 植物合胞体到细胞化的转变至关重要。在这项研究中，我们发现，水稻 PcG 基因 （）的同源物 ，尽管基因之间的序列相似性有限，但在种子发育方面发挥着与 相似的作用。在 中观察到细胞化延迟，与 I 型 MADS-box 基因的异常激活有关。细胞周期在 中持续激活，这可能是由于细胞分裂素的过度产生。然而，没有发现生长素的过度积累与细胞化延迟有关。由于 是胚乳中母系表达的基因，父系遗传的功能等位基因无法恢复 的母系缺陷。在 （♀）/9311（♂）（m9）的缺陷杂种种子中，许多印迹水稻基因被失调。由于母系等位基因的激活或父系等位基因的抑制，一些父系表达基因在 m9 中的父系表达偏向被打破。这些发现表明，OsEMF2a-PRC2 介导的 H3K27me3 对于水稻胚乳细胞化和基因组印迹是必要的。
