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小穗发育是决定水稻产量的主要农艺性状,鉴定控制小穗发育的关键基因对研究和分析调控农艺性状的分子机理是至关重要的。本文中,我们鉴定了一组小穗数目明显减少的突变体,命名为decreased spikelets(des),这里详细研究des2和des5两个突变体。结果显示des2是由单基因隐性位点控制,图位克隆将此位点定位到6号染色体的长臂上,并最终克隆了此基因,发现des2是moc1的一个新的等位突变体。定位克隆和序列分析显示在des5中,LAX基因的编码HLH(螺旋-环-螺旋)结构域的区域发生了一个点突变,暗示des5是lax的一个新的等位突变体。我们的结果暗示小穗和水稻叶腋分枝的发育受相同的遗传途径调控。
Spikelet development is the major agronomic trait that determines rice yield. Identification of the key genes that control spike development is crucial to the study and analysis of the molecular mechanisms governing agronomic traits. In this paper, we identified a group of mutants with a significantly reduced number of spikelets, named decreased spikelets (des), where the two mutants, des2 and des5, were studied in detail. The results showed that des2 was controlled by a single recessive locus. The site-directed cloning mapped this locus to the long arm of chromosome 6 and finally cloned this gene. Des2 was found to be a new allelic mutant of moc1. Site-directed cloning and sequence analysis showed a point mutation in the region of the HLX (helix-loop-helix) domain of the LAX gene in des5, suggesting that des5 is a new allelic mutant of lax. Our results suggest that the development of axillary branches in spikelets and rice is regulated by the same genetic pathways.