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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. [ABSTRACT FROM AUTHOR]

Brown planthopper [BPH, Nilaparvata lugens (Stål)] is considered one of the most important pests of rice (Oryza sativa L.), which poses a serious threat to rice production. Identifying resistant Oryza germplasm can provide reliable accessions for breeding BPH resistant rice cultivars. In this study, the stem evaluation method (SEM) was first applied to identify the BPH resistance of 1,221 accessions of common wild rice (O. rufipogon Griff.) collected from three different regions of Guangxi Province, China. From this screening, 58 BPH resistant accessions were screened a second time, with 33 accessions ultimately identified as stable, highly resistant germplasm as confirmed by a third identification at the adult‐plant stage. The distribution of the 58 BPH‐resistant common wild rice accessions varies significantly from region to region. Genotypic analyses based on 42 simple sequence repeat (SSR) markers revealed that these 58 BPH‐resistant accessions were genetically diverse, reflecting the rich genetic diversity reported in Guangxi common wild rice. Furthermore, results verified that the SEM is efficient for rapid and accurate screening of BPH‐resistant germplasm, especially when a limited number of seeds are available or elite breeding lines need to be screened immediately. Also, SEM is the best method for evaluating BPH resistance at the adult stage because fewer insects are needed, and it is possible to repeat the evaluation in the same crop season. The 33 resistant rice accessions are a potential source of novel BPH resistance genes for developing cultivars with improved BPH resistance. Core Ideas: We used a new stem evaluation method (SEM) to evaluate rice accessions for resistance to BPH.The discovery of these resistant resources will provide more basic resources for further study.Genetic diversity of BPH‐resistant accessions in rice deserves further study.Discovery of resistant resources should focus on sampling from the lower reaches of Xijiang.Guangxi Oryza rufipogon was taken as experimental accessions, which shows superiority. [ABSTRACT FROM AUTHOR]