一个水稻散生突变体tag1的遗传分析及基因定位

Genetic analysis and fine-mapping of a tiller spreading mutant in rice

株型对水稻产量有着重要影响。作为影响株型的重要因素之一,分蘖角度是水稻高产育种上考虑的重要农艺性状。散生突变体tag1(tiller angle 1)在水稻品种台北309转基因后代中被发现。与野生型相比,主要突变表型为分蘖角度和叶夹角显著增大,并伴随株高、穗长、结实率和枝梗数等性状上的变化。遗传分析表明,tag1的突变性状由一对隐性基因控制。利用F2(tag1/明恢63)群体作为定位群体,突变基因被定位在第11染色体长臂In Del标记AC35795和M7之间,遗传距离分别为0.38 c M和0.95 c M。在该区间内存在一个已被克隆的控制水稻分蘖角度的基因LAZY1。测序比对分析发现,突变体的TAG1存在一个119 bp的缺失,包括第4个外显子50 bp,第4个内含子69 bp,及二者间的剪切位点。因此TAG1是LAZY1的一个新的等位基因,重新命名为LAZY1-2。lazy1和tag1在突变表型上存在一定差异,这可能是LAZY1基因序列的突变位点不同造成的。

Plant architecture plays an important role in rice （Oryza sativa L.） yield. As a key component of rice plant architecture, tiller angle has been considered as an important agronomic trait in ideal plant architecture and high-yield breeding. The mutant in this study originated from offspring of transgenic plants in japonica rice cultivar TP309. Compared to the wild type, the mutant exhibits wider tiller angle and leaf angle, accompanied with other phenotypic changes such as plant height, panicle length, setting rate and so on. Genetic analysis showed that the tiller spreading trait of the mutant is controlled by one single recessive gene. The F2 mapping population was created by crossing tag1 with Minghui63. The mutant gene was mapped between InDel markers AC35795 and M7, on the long arm of chromosome 11, with genetic distances of 0.38 and 0.95 cM respectively. Within this region, there is a cloned gene LAZY1, which controls rice tillering angle. Sequencing analysis reveals a 50 bp deletion at the fourth exon and a 69 bp deletion at the fifth intron, which leads to the loss of the splice site and the remaining segment direct connection between the fourth intron and the fourth exon in mRNA processing. Therefore, TA G1 is an allele of LA ZY1 and is renamed as LA ZY1-2. The different phenotypes of the two mutants may be caused by different mutational sites of genomic sequence.