烟草骨干亲本主要病毒病抗性鉴定及遗传多样性分析

【目的】评价烟草骨干亲本主要病毒病抗性，分析抗病骨干亲本间的遗传多样性，明确不同抗源间的亲缘关系，为烟草病毒病抗性改良的亲本选择提供理论依据。【方法】在温室条件下采用苗期人工接种方法，对中国烟草育种过程中73份骨干亲本进行CMV、TMV和PVY 3种病毒病抗性鉴定，以CMV高抗、或TMV免疫、或PVY免疫为筛选标准，筛选抗病骨干亲本；并利用条带单一清晰、多态性稳定且分布在烟草24条连锁群上的103对SSR引物，对筛选出的抗病骨干亲本和烟草育种常用的4个主体优质亲本进行遗传多样性、聚类和主坐标分析。【结果】（1）不同供试材料间3种病毒病抗性存在显著性差异。在筛选出的29份病毒病高抗或免疫的烟草种质中，有23份种质对CMV表现为高抗，6份种质对TMV表现为免疫，5份种质对PVY表现为免疫。同时，在29份筛选出的烟草病毒病抗病种质中，龙烟1号和FC8对TMV和PVY都表现为免疫，CV87、T.T.11、抗88、CV91、胎里富1060、革新5号和T.I.245等7份种质对3种病毒病都表现为高抗。（2）对鉴定出的29份抗病骨干亲本以及K326、NC89、Speight G-28和净叶黄等4个烟草育种最常用主体亲本进行基因型分析，共筛选出322个等位位点，每对引物的等位变异为2-6个，平均为3.106个；基因型多样性变化范围是0.059-0.716，平均为0.387；引物多态性信息（PIC）含量为0.057-0.661，平均为0.343。当遗传相似系在0.672取值作切割线时，系统聚类分析将33份供试材料分为7个类群；当遗传相似系数在0.714取值作切割线时，第1类群又被分为4个亚群，其中第1亚群包括了全部供试外引抗病亲本种质和育种最常用外引亲本K326、NC89和Speight G-28，而国内抗病亲本种质分类相对较多。主坐标分析可将33份材料分为6个类群，外引抗病种质被分在第1类群和第2类群中，其中第1类群包括了8份引进抗病亲本种质和3份育种最常用外引亲本K326、NC89和Speight G-28，第2类群有3份外引种质和11份国内种质；而国内抗病亲本种质分类较多。聚类分析结果和主坐标分析结果基本一致，与种质亲缘关系吻合度较高。【结论】苗期人工接种方法对烟草骨干亲本的病毒病抗性鉴定准确，筛选出29份烟草病毒病抗病骨干亲本；外引抗病骨干亲本种质与K326、NC89和Speight G-28的亲缘关系较近，遗传背景狭窄；中国抗病种质地理来源广泛，遗传背景复杂，遗传基础较为丰富。

Identification of Resistance to Main Virus Diseases and Genetic Diversity Study of Tobacco Foundation Parents

【Objective】 This study aims to assess the viral disease resistances of the tobacco foundation parents, and to analyze their genetic diversity and phylogenetic relationship. 【Method】 A total of 73 flue-cured tobacco foundation parents were evaluated for resistances to three kinds of virus diseases by artificial inoculation in the green house. Furthermore, the genetic diversity of 29 resistant foundation parents and additional 4 foundation parents were analyzed using 103 pairs of polymorphism SSR markers distributed on the whole tobacco genome. 【Result】 Different cultivars displayed a wide range of variation for resistances to CMV, TMV and PVY. As for CMV, a total of 23 cultivars exhibited high resistances to CMV, although the cultivars exhibited immunity to CMV were not identified. As for TMV, six cultivars exhibited immunity to TMV. As for PVY, five cultivars exhibited immunity to PVY. In sum, two cultivars, Longyan1 and FC8, exhibited immunity to TMV and PVY, respectively. In addition, seven cultivars including CV87, T.T.11, Kang88, CV91, Tailifu1060, Gexin5 and T.I.245, exhibited resistances to three kinds of virus diseases. The genotypes of 29 resistant foundation parents and additional 4 foundation parents were identified with 103 SSR markers. The total numbers of alleles amplified at the 103 SSR loci were 322 and the mean number of alleles detected for each locus was 3.106, ranging from 2 to 6 alleles. The genetic diversity spanned from 0.059 to 0.716, with an average of 0.387. The PIC value ranged from 0.057 to 0.661, with an average of 0.343. According to UPGMA cluster analysis, the 33 tested cultivars were divided into seven clusters with a cut-off of threshold value as 0.672 and the cultivars belonged to the first group were further subdivided into four clusters with a cut-off of threshold value as 0.714. Principle coordinate analysis (PCoA) showed that the 33 tested cultivars were divided into six clusters, which are in agreement with the results of clustering analysis. The results of molecular clustering largely agreed with the pedigree relationship.【Conclusion】 A total of 29 flue-cured tobacco foundation parents exhibited the resistance to tobacco main virus diseases. The genetic relationships among the groups of genotyped cultivars are in agreement with pedigree relationship. The resistant foundation parents from China showed a relatively higher genetic basis.