水稻是我国的主要粮食作物,而我国栽培的水稻主要包括籼稻和粳稻两个亚种。籼稻和粳稻在长期的育种选择过程中形成了巨大的差异,不仅表型特征有明显区别,基因组水平的差异也非常大。那么籼粳之间究竟在产量形成机制上有何异同?揭开这个谜题对水稻遗传改良大有裨益。

在这方面,华中农业大学水稻产量生物学实验室邢永忠课题组开展了近12年的研究,发现了水稻产量形成的新途径,解析了重要增产基因GY3的调控机制,为水稻高产育种提供了重要基因资源。

该团队利用籼稻品种特青和粳稻品种02428构建的遗传群体,克隆出了增产基因GY3。结果发现,粳稻来源的GY3等位基因具有明显的增产效应。进一步研究表明,GY3参与了细胞分裂素的合成途径。敲除或抑制GY3表达,可避免底物的无效消耗,从而提高活性细胞分裂素含量,增加水稻产量。

数据显示,大多数粳稻和少部分籼稻携带GY3增产等位基因,但当前推广的籼稻品种几乎没有这一有益等位基因。这意味着GY3在籼稻育种中仍大有可为。该团队将GY3等位基因导入多 个籼稻品系,发现品系产量显著提高,配制的杂交种产量也较原始杂交种有7-15%的增加。

GY3基因为籼稻高产提供了重要资源。该项研究由华中农业大学作物遗传改良国家重点实验室完成,获得多项国家级项目资助。希望能进一步推动我国水稻产量的大幅度提高,确保国家粮食安全。

Abstract:

One-step and two-step pathways are proposed to synthesize cytokinin in plants. The one-step pathway is mediated by LONELY GUY (LOG) proteins. However, the enzyme for the two-step pathway remains to be identified. Here, we show that quantitative trait locus GY3 may boost grain yield by more than 20% through manipulating a two-step pathway. Locus GY3 encodes a LOG protein that acts as a 5′-ribonucleotide phosphohydrolase by excessively consuming the cytokinin precursors, which contrasts with the activity of canonical LOG members as phosphoribohydrolases in a one-step pathway. The residue S41 of GY3 is crucial for the dephosphorylation of iPRMP to produce iPR. A solo-LTR insertion within the promoter of GY3 suppressed its expression and resulted in a higher content of active cytokinins in young panicles. Introgression of GY302428 increased grain yield per plot by 7.4% to 16.3% in all investigated indica backgrounds, which demonstrates the great value of GY302428 in indica rice production.

https://www.nature.com/articles/s41588-023-01454-3

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