Graduate School of Green-Bio Science & Crop Biotech Institute, Kyung Hee University, Yongin, South Korea.
Physiol Plant. 2024 May-Jun;176(3):e14354. doi: 10.1111/ppl.14354.
Female gametogenesis has been rarely studied due to gametophyte lethality and the unavailability of related genetic resources. In this study, we identified a rice ATP-binding cassette transporter, OsABCB24, whose null function displayed a significantly reduced seed setting rate by as much as 94%-100% compared with that of the wild type (WT). The reciprocal cross of WT and mutant plants demonstrated that the female reproductive organs in mutants were functionally impaired. Confocal microscopy observations revealed that, although megasporogenesis remained unaffected in CRISPR/Cas9 osabcb24 mutants, the formation of female gametophytes was interrupted. Additionally, the structure of the syncytial nucleus was impaired during the initial stages of endosperm formation. Histochemical analysis showed that OsABCB24 was preferentially expressed at the conjunction of receptacle and ovary, spanning from the functional megaspore stage to the two-nucleate embryo sac stage. Further, OsABCB24 was identified as an endoplasmic reticulum membrane-localized protein. Notably, the overexpression of OsABCB24 triggered a 1.5- to 2-fold increase in grain production compared to the WT. Our findings showed that OsABCB24 plays a key role in both female gametophyte development and the early development of seeds.
由于配子体致死和相关遗传资源的缺乏，雌性配子体发生很少被研究。在这项研究中，我们鉴定了一个水稻 ATP 结合盒转运蛋白 OsABCB24，其缺失功能导致结实率比野生型（WT）降低了 94%-100%。WT 和突变体植物的正反交表明，突变体的雌性生殖器官功能受损。共聚焦显微镜观察表明，尽管 CRISPR/Cas9 osabcb24 突变体中的大孢子发生仍然不受影响，但雌性配子体的形成被中断。此外，在胚乳形成的初始阶段，合胞核的结构受损。组织化学分析表明，OsABCB24 在受体和子房的连接处优先表达，跨越功能大孢子阶段到双核胚囊阶段。此外，OsABCB24 被鉴定为内质网膜定位蛋白。值得注意的是，与 WT 相比，OsABCB24 的过表达导致籽粒产量增加了 1.5 到 2 倍。我们的研究结果表明，OsABCB24 在雌性配子体发育和种子早期发育中都起着关键作用。
