Genetic diversity analysis of main agronomic traits and ISSR markers in 35 ornamental rape germplasm resources

Rape (Brassica napus L.) is a major oil crop in our country, valued for its oil and ornamental uses. This study analyzed 35 ornamental rape germplasm resources from different origins to examine differences in agronomic traits and molecular markers. Nine agronomic traits were assessed in the field for variability, correlation, principal component analysis, and cluster analysis. Genetic diversity was analyzed using microsatellite (ISSR) markers and the unweighted pair group method with arithmetic mean (UPGMA). Our findings revealed a notable average coefficient of variation of 22.59% across the nine agronomic traits, with flower color exhibiting the highest variability and corolla width the least. The observed range of variation spanned from 9.24% to 83.38%, the correlation among these traits was generally low, with a mere 13.9% demonstrating significant correlations. The four principal components accounted for an impressive 84.62% of the cumulative contribution rate, while the genetic similarity, as gauged by eight ISSR primers, varied from 0.675 to 0.980. Most strikingly, we observed that plants from the same geographical region displayed molecular-level differences, underscoring the rich genetic diversity inherent in the 35 ornamental rape resources under study. Employing UPGMA cluster analysis on the primary agronomic traits and ISSR molecular markers, the 35 ornamental rape resources were categorized into seven and four distinct groups, respectively. Although the clustering outcomes from these two methodologies did not align perfectly, they served to complement each other. Collectively, these insights offer a theoretical framework for the innovation of ornamental rape germplasm resources and the cultivation of novel varieties.