甜瓜抗蔓枯病基因Gsb-2的ISSR分子标记

ISSR marker linked to gene Gsb-2 resistant to gummy stem blight in melon(Cucumis melo)

甜瓜蔓枯病(Didymella bryoniae)是危害我国甜瓜的一种主要病害。以抗蔓枯病种质资源PI 157082与感病的甜瓜自交系白皮脆为亲本,建立了抗感F2代群体,对亲本、F1及134个F2代群体进行了苗期抗蔓枯病接种鉴定。利用集团分离分析法(bulked segregant analysis,BSA)在F2代建立抗感基因池,以抗感基因池为模板,对72条ISSR引物进行PCR扩增筛选。共有3条引物在F2代抗感基因池之间扩增出多态性片段,用双亲、F1和F2代抗感单株对这3条引物进一步验证,其中引物ISSR-57扩增出的多态性条带与抗性基因Gsb-2表现连锁关系,该多态性片段大小为560 bp,与Gsb-2的遗传连锁距离为11.3 cM,定名为ISSR-57560。ISSR-PCR扩增体系稳定、重复性好,ISSR-57560可以作为甜瓜抗蔓枯病辅助选择的备选分子标记。

Gummy stem blight（GSB） caused by fungus Didymella bryoniae（Auersw.） Rehm is one of the major diseases of melon,and causes severe losses.Parents,F1 and F2 population derived from the cross of the resistant germplasm PI 157082 and susceptible inbred line Baipicui were identified for their resistance to GSB in seedling stage.Using bulked segregant analysis（BSA）,72 ISSR primers were screened between resistant and susceptible bulks.A 560 bp fragment specifically amplified with ISSR-57 primer was present in the resistant gene bulk but absent in the susceptible one.It was confirmed that the marker ISSR-57560 was linked to the gene Gsb-2,which was resistant to GSB in PI 157082 by screening 134 F2 individuals,and the linkage distance was 11.3 cM.The higher reproducibility of ISSR bands indicated that the marker could be useful for marker-assisted selection in melon breeding for GSB resistance.