An ATP‐binding cassette transporter, OsABCB24, is involved in female gametophyte development and early seed growth in rice

• Published in: Physiologia plantarum 2024-05, Vol.176 (3), p.e14354-n/a
• Main Authors: Nguyen, Van Ngoc Tuyet, Usman, Babar, Kim, Eui‐Jung, Shim, Su‐Hyeon, Jeon, Jong‐Seong, Jung, Ki‐Hong
• Format: Article
• Language: English
• Subjects: ATP; ATP-Binding Cassette Transporters - genetics; ATP-Binding Cassette Transporters - metabolism; Binding; Cassettes; Confocal microscopy; CRISPR; Endoplasmic reticulum; Endosperm; Females; Gametogenesis; Gametophytes; Gene Expression Regulation, Plant; Genetic resources; Histochemical analysis; Lethality; Membrane proteins; Mutants; Mutation - genetics; Oryza - genetics; Oryza - growth & development; Oryza - metabolism; Ovule - genetics; Ovule - growth & development; Ovule - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; Plants, Genetically Modified; Reproductive organs; Rice; Seeds; Seeds - genetics; Seeds - growth & development; Seeds - metabolism
• ISSN: 0031-9317; 1399-3054
• 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.