Genetic Diversity Analysis of Cymbidium eburneum Lindl. (Orchidaceae) Based on SSR Markers

Cymbidium eburneum Lindl. is a valuable ornamental orchid and breeding parent, but its genetic background remains unclear due to habitat destruction and germplasm mixing. This study developed specific SSR markers to evaluate the genetic diversity and structure of 96 C. eburneum Lindl. accessions from China and Vietnam. Transcriptome analysis identified 47,248 SSR loci. Sixteen polymorphic core primer pairs detected 150 alleles (mean Na = 9.375) with an average Polymorphism Information Content (PIC) of 0.444. Observed heterozygosity (Ho = 0.290) was noticeably lower than expected (He = 0.478), indicating heterozygote deficiency. UPGMA clustering identified eight groups strongly correlated with geography. Principal Coordinate Analysis (PCoA) revealed a clear geographical differentiation pattern, featuring the most genetically cohesive group from Guangxi and more differentiated geographically marginal populations from Hainan and Vietnam. STRUCTURE analysis (K = 2) indicated two main gene pools with signals of genetic admixture. Geographical isolation was suggested as a potential driver of genetic differentiation. The Guangxi population represents a genetically consistent major reservoir, while marginal populations harbor unique variations. These findings provide a scientific basis for germplasm identification, conservation, and parental selection in C. eburneum Lindl. breeding.