普通小麦‘Holdfast’条锈病成株抗性QTL定位

QTL mapping of adult-plant resistance to stripe rust in wheat variety holdfast

Holdfast是来自英国的小麦品种,多年来一直保持良好的条锈病持久抗性。本研究目的是发掘Holdfast的条锈病成株抗性基因及其紧密连锁的分子标记,为小麦持久抗性品种选育提供材料和方法。利用铭贤169和Holdfast杂交后代重组自交系(recombinant inbred lines,RIL)群体,于2014—2015和2015—2016年度在甘肃甘谷、甘肃中梁和四川成都进行条锈病成株抗性鉴定,并统计最大严重度(maximum disease severity,MDS)。基于小麦660K SNP芯片和BSA(bulked segregant analysis)技术初步确定抗病基因所在的染色体后,将目标区域的SNP标记转化为KASP(Kompetitive allele specific PCR)标记,检测整个RIL群体,进行基因型分析。最后进行RIL群体条锈病成株抗性的QTL分析,在5AL和7AL染色体上发现了2个成株抗性QTL。5A染色体长臂上1个条锈病成株抗性QTL QYr.gaas-5AL,在所有环境下均存在,可解释6.5%~9.3%的表型变异;QYr.gaas-5AL位于标记Ax-109948955和Ax-108798241之间,连锁距离分别为0.5 cM和1.1 cM。在7A染色体长臂上定位到1个条锈病成株抗性QTL QYr.gaas-7AL,在2015年和2016年甘谷环境中均稳定存在,分别解释6.2%和7.3%的表型变异;QYr.gaas-7AL位于标记Ax-110361069和Ax-108759561之间,连锁距离分别为0.5 cM和0.7 cM。携带QYr.gaas-5AL和QYr.gaas-7AL抗病等位基因家系的MDS显著低于感病等位基因家系的MDS,表明QYr.gaas-5AL和QYr.gaas-7AL可有效降低条锈病严重度,可应用于小麦抗条锈育种。

Holdfast is an elite wheat cultivar from the United Kingdom with well durable resistance to stripe rust for many years.The aim of the present study was to identify adult-plant resistance(APR)genes to stripe rust in Holdfast and closely linked molecular markers to provide materials and methods for breeding wheat cultivars with durable resistance.A recombinant inbred lines(RIL)population,generated from the cross between Mingxian 169(highly susceptible)and Holdfast,was planted in Zhongliang and Gangu of Gansu province,and Chengdu of Sichuan province during 2014?2015 and 2015?2016 cropping seasons for evaluating maximum disease severities(MDS)of stripe rust.The chromosomal locations of QTL were firstly determined based on the wheat 660K SNP array and bulked segregant analysis. Then kompetitive allele specific PCR (KASP) markers were developed to genotype the entire RIL population. Finally, the quantitative trait loci (QTLs) mapping of adult-plant resistance to stripe rust in the RIL population were performed, and two QTLs for APR to stripe rust were mapped on chromosomes 5AL and 7AL, respectively. The QTL on chromosome 5AL, designated QYr.gaas-5AL, was identified in all environments, including Zhongliang 2015, Chengdu 2015, Chengdu 2016, Gangu 2015, Gangu 2016, explaining phenotypic variances ranging from 6.5% to 9.3%. QYr.gaas-5AL was flanked by markers Ax-109948955 and Ax-108798241 with genetic distances of 0.5 cM and 1.1 cM, respectively. The 7AL QTL, designated QYr.gaas-7AL, was detected in two environments Gangu 2015 and Gangu 2016, explaining 6.2% and 7.3% of the phenotypic variances, respectively. QYr.gaas-7AL was mapped between markers Ax-110361069 and Ax-108759561 with genetic distances of 0.5 cM and 0.7 cM, respectively. The RILs containing the resistance allele at QYr.gaas-5AL and QYr.gaas-7AL loci were more resistant to stripe rust and had significantly lower MDS than those without the resistance alleles of QYr.gaas-5AL and QYr.gaas-7AL, indicating that QYr.gaas-5AL and QYr.gaas-7Al can effectively reduce stripe rust severities, thus may be used in wheat breeding for improvement of stripe rust resistance.