Rice seed germination is a critical step that determines its entire life circle, with seeds failing to germinate or pre-harvest sprouting both reduce grain yield. Nevertheless, the mechanisms underlying this complex biological event remain unclear. Previously, gibberellin has been shown to promote seed germination. In this study, a delayed seed germination rice mutant was obtained through screening of the EMS induced mutants. Besides of delayed germination, it also shows semi-dwarfism phenotype, which could be recovered by exogenous GA. Through re-sequencing on the mutant, wild-type and their F2 populations, we identified two continuous mutated sites on ent-kaurene oxidase 1 (OsKO1) gene, which result in the conversion from Thr to Met in the cytochrome P450 domain. Genetic complementary analysis and enzyme assay verified that the mutations in OsKO1 gene block the biosynthesis of GA and result in the defect phenotypes. Further analyses proved that OsKO1 could catalyze the reaction from ent-kaurene into ent-kaurenoic acid in GA biosynthesis mainly at seed germination and seedling stages, and the mutations decrease its activity to catalyze the step from ent-kaurenol to ent-kaurenoic acid in this reaction. Transcriptomic and proteomic data indicate that the defect on GA biosynthesis decreases its ability to mobilize starch and attenuate ABA signaling, therefore delay the germination process. The results provide some new insights into both GA biosynthesis and seed germination regulatory pathway in rice.

中文翻译：

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ent-kaurene氧化酶1编码基因的突变减弱了其催化从ent-kaurene到ent-kaurenoic酸反应的酶活性，并导致水稻发芽延迟。

水稻种子发芽是决定其整个生命周期的关键步骤，种子发芽失败或收获前发芽均会降低谷物产量。然而，这种复杂的生物事件的机制尚不清楚。以前，赤霉素已被证明能促进种子发芽。在这项研究中，通过筛选EMS诱导的突变体获得了延迟种子发芽水稻突变体。除了延迟发芽外，它还表现出半侏儒表型，可以通过外源GA恢复。通过对突变体，野生型及其F2种群进行重新测序，我们确定了ent-kaurene氧化酶1（OsKO1）基因上的两个连续突变位点，从而导致在细胞色素P450域中从Thr转变为Met。遗传互补分析和酶法测定证明，OsKO1基因的突变会阻止GA的生物合成，并导致缺陷表型。进一步的分析表明，OsKO1可以在种子萌发和幼苗阶段催化GA生物合成过程中的从新戊烯醛到新戊烯酸的反应，并且该突变降低了其催化从新戊烯醇到新戊烯酸的步骤的活性。反应。转录组和蛋白质组学数据表明，GA生物合成的缺陷降低了其动员淀粉和减弱ABA信号传导的能力，因此延迟了发芽过程。研究结果为水稻的GA生物合成和种子萌发调控途径提供了新的见解。进一步的分析表明，OsKO1可以在种子萌发和幼苗期催化GA生物合成中从新戊烯醛到新戊烯酸的反应，并且该突变降低了其催化从新戊烯醇到新戊烯酸的步骤的活性。反应。转录组和蛋白质组学数据表明，GA生物合成的缺陷降低了其动员淀粉和减弱ABA信号传导的能力，因此延迟了发芽过程。研究结果为水稻的GA生物合成和种子萌发调控途径提供了新的见解。进一步的分析表明，OsKO1可以在种子萌发和幼苗阶段催化GA生物合成过程中的从新戊烯醛到新戊烯酸的反应，并且该突变降低了其催化从新戊烯醇到新戊烯酸的步骤的活性。反应。转录组和蛋白质组学数据表明，GA生物合成的缺陷降低了其动员淀粉和减弱ABA信号传导的能力，因此延迟了发芽过程。该结果为水稻的GA生物合成和种子萌发调控途径提供了新的见解。转录组学和蛋白质组学数据表明，GA生物合成的缺陷降低了其动员淀粉和减弱ABA信号传导的能力，因此延迟了发芽过程。研究结果为水稻的GA生物合成和种子萌发调控途径提供了新的见解。转录组和蛋白质组学数据表明，GA生物合成的缺陷降低了其动员淀粉和减弱ABA信号传导的能力，因此延迟了发芽过程。研究结果为水稻的GA生物合成和种子萌发调控途径提供了新的见解。