SSR marker-based analyses on genetic diversity and relevant variations of agronomic traits and chemical composition of 231 flue-cured tobacco germplasm resources
Zhongguo Yancao Xuebao
The aim of this study was to investigate genetic diversity of flue-cured tobacco (Nicotiana tabacum L.) germplasm and to screen molecular markers for agronomic and chemical traits. A total of 231 flue-cured tobacco germplasms were genotyped with 120 simple sequence repeats (SSRs) markers uniformly distributed on 24 linkage groups. Associations of SSR variation with eight agronomic traits and five chemical components were investigated by two contrasting statistical models, i.e. general linear
... . general linear model (GLM) and mixed linear model (MLM). Overall, 403 alleles were identified in all accessions, ranging from 2 to 21 per locus, with an average of 3.36 alleles per locus. Mean polymorphic information content was 0.408, ranging from 0.036 to 0.785. Genetic distance between varieties ranged from 0.003 to 0.371, with a mean of 0.148. Using unweighted pair-group method with arithmetic mean (UPGMA), all accessions were clustered into four groups at a genetic distance of 0.153. Using population genetic structure analysis, the test materials were divided into three subpopulations. Association analysis by GLM_Q and MLM_Q+K models revealed that seventeen and nine markers were significantly associated with a total of 13 phenotypic traits, respectively. Moreover, nine markers were consistently associated with the same traits at the p < 0.001 level in two years using both models. Specifically, three markers associated with plant height (TM10481, PT54964, and TM20580), two markers with leaf number (TM10846 and PT60728), one marker with stem circumference (TM25276), and one marker with leaf length (TM11215) supported published quantitative trait locus (QTL) mapping results. These seven markers could be used in future molecular marker-assisted selection to improve breeding efficiency.