辣椒抗PMMoV基因L4连锁标记的验证分析

Test analysis of L4-linked markers for PMMoV resistant gene in pepper

近年来,辣椒轻斑驳病毒(Pepper mild mottle virus,PMMoV)病的发生日趋严重,已严重危害中国辣椒生产。L系列等位基因(L1、L2、L3、L4)是抗烟草花叶病毒属的主要抗性基因,其中L4基因抗性最强且具有广谱性。为加速L4基因的转育应用,本研究对前人报道的3对与L4基因紧密连锁的分子标记进行检验分析。结果显示,标记L4SC340退火温度不稳定,极易造成假阳性,不适用于L4抗性基因的辅助筛选。标记087H3T7和L4-SCAR可以筛选出携带L3和L4抗性基因的辣椒种质,但无法区分携带L3和L4基因的抗性材料,同时087H3T7存在杂合基因型过高的问题。二者比较来说,L4-SCAR标记的筛选准确度高于087H3T7,但是L4-SCAR为显性标记,无法区分杂合基因型。因此上述3对标记均不能用于筛选携带L4抗性基因的种质材料,但是在明确抗性材料基因型的情况下,L4-SCAR标记结合087H3T7可用于L3和L4抗性基因转育后代抗性单株的辅助筛选。本研究结果可为加速辣椒抗PMMoV育种提供更实用的分子标记。

In recent years,disease caused by pepper mild mottle virus(PMMoV)has become more and more serious and has harmed pepper production in China severely.L-series allelic genes(L1,L2,L3,L4)are the main resistant genes against tobamovirus,and L4 gene was reported to show the strongest resistant to tobamovirus with a broad spectrum.In order to accelerate the application of transgenic breeding of the L4 gene,three pairs of reported molecular markers closely linked to L4 gene were examined and analyzed in this study.The results showed that,the annealing temperature of marker L4SC340 was unstable and could easily cause false positives,so L4SC340 was unsuitable for the assisted screening of L4 resistant gene.Markers 087H3T7 and L4-SCAR could be used to screen pepper germplasms carrying L3 and L4 resistant genes,but they could not be used to distinguish resistant materials carrying L3 and L4 genes.Meanwhile,087H3T7 had the problem of excessive heterozygous genotypes.In comparison,the screening accuracy of L4-SCAR marker was higher than that of 087H3T7,but L4-SCAR was a dominant marker that could not distinguish heterozygous genotype.Therefore,none of the three pairs of markers could be used to screen the germplasm material carrying L4 resistant gene.However,through clarifying the genotype of the resistant materials,L4-SCAR marker combined with 087H3T7 could be used for assisted screening of resistant individuals in the breeding of transgenic progeny with L3 and L4 resistant genes.Results of the study can provide more practical molecular markers for accelerated breeding of PMMoV resistant pepper.