Construction of the core germplasm of yellowhorn (Xanthoceras sorbifolium Bunge) using physiological traits and SSR markers

Abstract

Yellowhorn (Xanthoceras sorbifolium Bunge) is an important ecological, economic, and ornamental plant species native to China. However, the physiological diversity, genetic variation, and core germplasms have not been revealed, which hindered the breeding process of yellowhorn. Here, we evaluated the genetic diversity of 155 yellowhorn germplasms using five physiological traits. The content of flavonoids varied significantly in different germplasms, and it was positively correlated with soluble sugar content (P < 0.01). A total of 253, 336 candidate SSR were identified from the whole genome of yellowhorn. A moderate genetic diversity was found in yellowhorn based on the mean values of the number of effective alleles (Ne = 2.307), expected heterozygosity (He = 0.527), and observed heterozygosity (Ho = 0.317) with 30 pairs of polymorphic SSR markers. Population structure, Neighbor-Joining phylogeny, and principal coordinates analyses divided all genotypes into two major groups with few admixtures. Meanwhile, we extracted 34 (21.94 %) core yellowhorn germplasms based on the variation in physiological traits (14 germplasms) and genetic diversity (23 germplasms). After multiple different analyses including genetic diversity parameters, coincidence rate of range, variance difference percentage, and coefficient of variation rate of change, there was no obvious difference between core and original germplasm, which indicated that the core germplasm could represent the original germplasm well. Our study will lay a solid foundation for future conservation and management of yellowhorn germplasms and the core collection will be valuable in molecular breeding programs.