FGM1/rPPR4-dependent female gamete maturation is essential for subsequent seed development initiation in Arabidopsis

Gamete maturation are critical for fertility of both animals and plants; however, the molecular mechanisms underlying these processes remain poorly understood in plants. Here, we report the female gamete maturation 1 (FGM1/rPPR4) in Arabidopsis directly interacts with the mitochondrial protein GAMETE CELL DEFECTIVE 1 (GCD1) and plays an essential role in female gamete maturation and subsequent zygote-embryo transition and endosperm development. FGM1/rPPR4 binds to mitochondrial ribosome 26S ribonucleic acid (RRN26) to fine-tuneensure mitochondrial translation and further impacts nuclear transcription, which is required for female gamete maturation. Thus, we reveal that FGM1/rPPR4, assisted by GCD1, is an essential factor for female gamete maturation. We also confirm that female gamete maturation is necessary for the capacity of post-fertilization development, but not for double fertilization, indicating that essential mechanisms are established during female gamete maturation to provide a molecular basis for seed development initiation and plant fertility.

配子成熟对于动植物的生育能力均至关重要；然而，植物中该过程的分子机制仍未得到充分解析。本研究发现，拟南芥（Arabidopsis）中的雌配子成熟1基因（FGM1/rPPR4）可直接与线粒体蛋白配子细胞缺陷1（GAMETE CELL DEFECTIVE 1, GCD1）相互作用，并在雌配子成熟以及后续合子-胚胎转化与胚乳发育过程中发挥不可或缺的作用。FGM1/rPPR4可结合线粒体核糖体26S核糖核酸（RRN26），以精准调控线粒体翻译，并进一步影响核转录，该过程是雌配子成熟所必需的。综上，本研究揭示，在GCD1的辅助下，FGM1/rPPR4是调控雌配子成熟的关键因子。本研究同时证实，雌配子成熟对于受精后的发育能力必不可少，但并非双受精过程所必需，这表明雌配子成熟阶段已建立了必要的分子机制，为种子发育起始与植物生育能力提供了分子基础。