利用一个F_(2∶3)单基因分离群体精细定位水稻穗顶部退化基因ATS1

Fine Mapping of Rice Panicle Apical Abortion Gene ATS1 Using One F2∶3 Single-gene-segregating Population

水稻穗顶部退化(PAA,panicle apical abortion)是一种典型的数量性状,极容易受环境条件的影响。Ats1是一个来自于秋光和七山占的染色体片段置换系,先前的连锁分析发现,它在第8号染色体上带有一个穗顶部退化基因ATS1(Aborted Top Spikelet 1),与先前定位的qPAA8位置近似。通过比较北京地区2018年与其他年份的气候差异,以及在不同生长环境条件下Ats1的穗顶部退化表型时发现,穗顶部退化表型与生长环境条件高度关联。在2018年的高温生长条件下,Ats1穗顶部退化程度相对减轻,说明高温降低了Ats1穗顶部退化表型的发生率。此外,通过IRAT129和Ats1杂交配置的F_(2)群体的遗传分析,发现穗顶部退化的遗传分离明显偏离单基因显性遗传的3退化∶1正常的分离比例,说明Ats1置换系中可能还存在其他穗顶部退化基因。基于F_(2∶3)家系群的表型分析,筛选出单基因分离家系18C4013,进一步将ATS1基因定位于57 kb区域内,为最终克隆该基因奠定了基础,其表型鉴定及单基因家系分离的方法可以被进一步用于其他受环境条件影响的复杂性状的基因精细定位。

The panicle apical abortion(PAA)of rice is a typical quantitative trait determined by both genotypes that interact with growth environments(i.e.the ambient temperature).A chromosome segment substitution line Ats1(aborted top spikelet 1),which was originated from the cross-combination of Qiuguang×Qishanzhan,was used for map-based cloning of the PAA gene ATS1.Previous linkage analysis suggested that the candidate gene of AST1 was localized on chromosome 8,sharing a long fragment of positioning interval with that of the unidentified gene qPAA8.We compared the climate differences between 2018 and other years in Beijing and the phenotype of Ats1 under different growth conditions.The PAA severity of Ats1 under the high environmental temperature in 2018 was significantly alleviated compared with ordinary years,indicating that high temperature might reduce the incidence of PAA in Ats1.In addition,through the genetic analysis to the F_(2) population of newly created cross-combination IRAT129×Ats1,we further found that the genetic separation of PAA obviously deviated from ratio of the single gene dominant inheritance,i.e.3 PAA to 1 normal,indicating that there are additional PAA genes involved.Here we provided a convenient strategy on developing a single gene segregating population(SGSP),based on the phenotypic analysis in combination with marker-associated selection to individuals of F_(2∶3) lines.Finally,we finally delimited the candidate gene of ATS1 to a 57 kb interval including four potential candidate genes,settling a foundation for the final cloning of the target gene.This method could be helpful using in fine mapping on other complex traits easily affected by environmental conditions.