State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou 510642, China.
Guangdong Provincial Key Laboratory of Plant Molecular Breeding, South China Agricultural University, Guangzhou 510642, China.
J Exp Bot. 2024 Aug 28;75(16):4802-4821. doi: 10.1093/jxb/erae180.
The development of the embryo sac is an important factor that affects seed setting in rice. Numerous genes associated with embryo sac (ES) development have been identified in plants; however, the function of the DEAD-box RNA helicase family genes is poorly known in rice. Here, we characterized a rice DEAD-box protein, RH52A, which is localized in the nucleus and cytoplasm and highly expressed in the floral organs. The knockout mutant rh52a displayed partial ES sterility, including degeneration of the ES (21%) and the presence of a double-female-gametophyte (DFG) structure (11.8%). The DFG developed from two functional megaspores near the chalazal end in one ovule, and 3.4% of DFGs were able to fertilize via the sac near the micropylar pole in rh52a. RH52A was found to interact with MFS1 and ZIP4, both of which play a role in homologous recombination in rice meiosis. RNA-sequencing identified 234 down-regulated differentially expressed genes associated with reproductive development, including two, MSP1 and HSA1b, required for female germline cell specification. Taken together, our study demonstrates that RH52A is essential for the development of the rice embryo sac and provides cytological details regarding the formation of DFGs.
胚囊的发育是影响水稻结实的一个重要因素。在植物中已经鉴定出了许多与胚囊（ES）发育相关的基因；然而，在水稻中，DEAD-box RNA 解旋酶家族基因的功能知之甚少。在这里，我们描述了一个水稻 DEAD-box 蛋白 RH52A，它定位于细胞核和细胞质中，在花器官中高度表达。rh52a 敲除突变体表现出部分胚囊不育，包括胚囊（21%）退化和存在双雌配子体（DFG）结构（11.8%）。DFG 从一个胚珠中靠近合点端的两个功能大孢子中发育而来，在 rh52a 中，3.4%的 DFG 能够通过靠近珠孔极的囊受精。发现 RH52A 与 MFS1 和 ZIP4 相互作用，这两者在水稻减数分裂中的同源重组中都发挥作用。RNA-seq 鉴定出 234 个与生殖发育相关的下调差异表达基因，包括两个基因 MSP1 和 HSA1b，它们是雌性生殖细胞特化所必需的。总之，我们的研究表明，RH52A 对水稻胚囊的发育是必不可少的，并提供了关于 DFG 形成的细胞学细节。
