Genetic diversity and population structure of marigold (Tagetes erecta L.) pre-breeding lines revealed by...

Marigold is an annual flower crop, mainly grown for its ornamental and industrial uses. The existing genetic diversity and phylogenetic relationships among 74 marigold genotypes, predominated with advanced and stable pre-breeding lines, were evaluated using 11 phenotypic traits and 46 polymorphic microsatellite markers. Substantial morphological variations were observed among the genotypes. Multivariate analysis identified the number of branches per plant, weight of ten flowers, and total number of flowers per plant as major contributors to the overall diversity, suggesting their utility as selection indices for future marigold improvement. Two-way Hierarchical Cluster analysis grouped the genotypes into distinct clusters, with each cluster representing pre-breeding lines superior for different morphological traits. The 46 microsatellite markers yielded a total of 123 alleles. The magnitude of polymorphic information content varied between 0.026 and 0.577. The correlation between the morphological and molecular data was also confirmed using the Mantel test.  The weighted neighbor-joining method clustered genotypes into three major groups. Further, model-based Bayesian structure analysis revealed the presence of seven subpopulations, among which one subpopulation was consisted of 14 genetically stable and homozygous genotypes which can be deployed as potential parents for heterosis breeding. The remaining genotypes exhibited shared ancestry and extensive gene flow, representing a diverse admixed gene pool, suitable for specific trait introgression and their potential use for broadening the genetic base of marigold.