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基于已获得的二倍体西瓜与抗枯萎病基因Fon-1紧密连锁的分子标记,进一步完成了Fon-1基因的精细定位。利用两个四倍体西瓜材料(易感病的NF3为受体,抗病的JH为供体),构建以NF3为轮回亲本的回交群体,使用新开发出的SNP标记对各世代群体进行分子标记辅助选择,及苗期抗病性接种鉴定。结果发现,在分离世代群体中通过接种鉴定获得抗病株比例较分子标记检测值低12.64%~15.34%,这可能是由于基因剂量效应造成的。抗病基因杂合位点对枯萎病抗性依次为:三显体(AAAa)>二显体(AAaa)>单显体(Aaaa)。目前分子标记尚无法检测杂合基因型的剂量效应,容易将感病的单显体(Aaaa)误判为抗病株。在构建的673株BC1F2代自交群体中检测到29株纯合基因型(AAAA)抗病单株,占总检测株数的4.31%,与苗期抗病性接种鉴定结果符合度达到100%。
Based on the molecular markers closely linked to the diploid watermelon and the Fusarium wilt resistance gene Fon-1, the Fon-1 gene was further finely mapped. Using two tetraploid watermelon materials (susceptible NF3 as receptor and disease-resistant JH as donor), a backcross population with NF3 as the recurrent parent was constructed, and the newly developed SNP markers Molecular marker-assisted selection, and seedling disease resistance inoculation identification. The results showed that the proportion of disease-resistant plants obtained by inoculation identification in the isolated population was 12.64% ~ 15.34% lower than the detection value of molecular markers, which may be due to the effect of gene dosage. Resistance to Fusarium wilt disease resistance genes were in order of AAAa> AAaa> Aaaa. At present, the molecular marker can not detect the dose-effect of heterozygous genotypes, and it is easy to misjudge the susceptible monosomy (Aaaa) as the resistant strain. In the constructed 673 BC1F2 selfing population, 29 strains of homozygous genotypes (AAAA) were detected, accounting for 4.31% of the total number of inbred lines, which was 100% consistent with the results of seedling disease resistance inoculation.