甜瓜高代自交系4G21抗蔓枯病基因的分子定位

以甜瓜杂交组合4G21 × 3A832的F1、F3家系、BCs和BCr及其双亲为材料，分析了甜瓜蔓枯病抗源4G21的抗性遗传规律。结果表明：F1抗性水平低于抗病亲本，说明抗病基因在F1表现为不完全显性；BCs抗感分离比为1∶1，F3家系抗感分离比为3∶1，说明抗源4G21对蔓枯病的抗性由一对不完全显性基因控制。将该基因命名为Sb-x，定位于甜瓜基因组分子图谱LG1连锁群上，与其两侧的SRAP标记位点me45em42-4、me45em2-3、me45em2-4和me3em42-4、me3em42-3紧密连锁，其遗传距离分别为2 cM和3 cM。

Molecular Location of Didymella bryoniae Resistant Gene Carried by 4G21 on Cucumis melo L.

Genetic analysis of resistance for anti-source 4G21 to Didymella bryoniae（Auersw.）on Cucumis melo L. was studied，using six generation population F1，F3，BCs、BCr and parents from a cross between a resistant variety 4G21（C. var. chinensis）and a susceptible variety 3A832（C. melo var. saccherinus）. The results showed that：Resistance level of population F1 was slightly lower than that of parent 4G21，it illustrated that disease resistance gene represented as incomplete dominant gene in generation population F1. The segregation ratio of resistant-susceptible was 1:1 in BCs，and 3:1 in F3 genealogy. The results implied that disease resistance was governed by a single incomplete dominant gene，named as Sb-x，it was located on linkage group LG1 of molecular map on melon，and closely linked with both sides of the SRAP marker loci of me45em42-4，me45em2-3，me45em2-4 and me3em42-4，me3em42-3，the genetic distances were 2 cM and 3 cM respectively.