The phosphatidylethanolamine-binding proteins OsMFT1 and OsMFT2 regulate seed dormancy in rice

• Published in: The Plant cell 2024-09, Vol.36 (9), p.3857-3874
• Main Authors: Shen, Jun, Zhang, Liang, Wang, Huanyu, Guo, Jiazhuo, Li, Yuchen, Tan, Yuanyuan, Shu, Qingyao, Qian, Qian, Yu, Hao, Chen, Ying, Song, Shiyong
• Format: Article
• Language: English
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1093/plcell/koae211

Seed dormancy is crucial for optimal plant life-cycle timing. However, domestication has largely diminished seed dormancy in modern cereal cultivars, leading to challenges such as pre-harvest sprouting (PHS) and subsequent declines in yield and quality. Therefore, it is imperative to unravel the molecular mechanisms governing seed dormancy for the development of PHS-resistant varieties. In this study, we screened a mutant of BASIC HELIX-LOOP-HELIX TRANSCRIPTION FACTOR4 (OsbHLH004) with decreased seed dormancy and revealed that OsbHLH004 directly regulates the expression of 9-CIS-EPOXYCAROTENOID DIOXYGENASE3 (OsNCED3) and GIBBERELLIN 2-OXIDASE6 (OsGA2ox6) in rice (Oryza sativa). Additionally, we determined that two phosphatidylethanolamine-binding proteins, MOTHER OF FT AND TFL1 and 2 (OsMFT1 and OsMFT2; hereafter OsMFT1/2) interact with OsbHLH004 and Ideal Plant Architecture 1 (IPA1) to regulate their binding capacities on OsNCED3 and OsGA2ox6, thereby promoting seed dormancy. Intriguingly, FT-INTERACTING PROTEIN1 (OsFTIP1) interacts with OsMFT1/2 and affects their nucleocytoplasmic translocation into the nucleus, where OsMFT1/2-OsbHLH004 and OsMFT1/2-IPA1 antagonistically modulate the expression of OsNCED3 and OsGA2ox6. Our findings reveal that OsFTIP1-mediated inhibition of nuclear translocation of OsMFT1/2 and the dynamic transcriptional modulation of OsNCED3 and OsGA2ox6 by OsMFT1/2-OsbHLH004 and OsMFT1/2-IPA1 complexes in seed dormancy in rice.