State Key Laboratory of Rice Biology and Breeding, Zhejiang Provincial Key Laboratory of Crop Genetic Resources, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China.
Hainan Institute of Zhejiang University, Yongyou Industry Park, Yazhou Bay Sci-Tech City, Sanya, Hainan 572000, China.
Plant Cell. 2024 Sep 3;36(9):3857-3874. 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 preharvest 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.
种子休眠对于植物生命周期的最佳时间至关重要。然而，驯化在很大程度上降低了现代谷类作物品种的种子休眠，导致了诸如收获前发芽（PHS）和随后产量和质量下降等问题。因此，揭示控制种子休眠的分子机制对于开发抗 PHS 的品种是当务之急。在这项研究中，我们筛选了一个 BASIC HELIX-LOOP-HELIX TRANSCRIPTION FACTOR4（OsbHLH004）突变体，其种子休眠性降低，并揭示了 OsbHLH004 直接调节 9-顺式-环氧类胡萝卜素双加氧酶 3（OsNCED3）和赤霉素 2-氧化酶 6（OsGA2ox6）在水稻（Oryza sativa）中的表达。此外，我们确定了两个磷酸乙醇胺结合蛋白，FT 和 TFL1 的母体（OsMFT1 和 OsMFT2；以下简称 OsMFT1/2）与 OsbHLH004 和理想植物结构 1（IPA1）相互作用，调节它们在 OsNCED3 和 OsGA2ox6 上的结合能力，从而促进种子休眠。有趣的是，FT 相互作用蛋白 1（OsFTIP1）与 OsMFT1/2 相互作用，并影响它们核质转运到细胞核内，其中 OsMFT1/2-OsbHLH004 和 OsMFT1/2-IPA1 拮抗调节 OsNCED3 和 OsGA2ox6 的表达。我们的研究结果揭示了 OsFTIP1 介导的 OsMFT1/2 核质转运抑制以及 OsMFT1/2-OsbHLH004 和 OsMFT1/2-IPA1 复合物在水稻种子休眠中对 OsNCED3 和 OsGA2ox6 的动态转录调节。
