Characterization of 15 Asparagus germplasm resources using cladode morphology and trnH-psbA intergenic spacer regions analysis

This study aimed to investigate the morphological traits and chloroplast trnH-psbA intergenic spacer regions of 15 Asparagus germplasm resources in southwest China, aiming to establish a theoretical foundation for resource identification and genetic diversity studies. The morphological analysis indicated a certain correlation among the morphological characteristics of the 15 samples . Principal component analysis reduced all morphological characteristic values into four principal components (eigenvalue > 1), with a cumulative contribution rate of 81.42%. The first principal component reflected the thickness of the cladodes, the second component represented the size of guard cells, and the third and fourth components represented epidermal cell sizes. Cluster analysis, based on these principal components, categorized the samples into three major groups at a genetic distance threshold of 12.5. Group I comprised 11 samples, accounting for 73.33% of the tested samples, and was characterized by linear cladodes. The majority of morphological feature values were distributed between groups II and III. Group II consisted of three species, distinguished by crescent-shaped cladodes that were few in number but large in width. Group III consisted of one sample, accounting for 6.67% of the tested samples, and was characterized by needle-shaped cladodes that were numerous in number but small in length and width, with few stomata, and numerous short epidermal cells. The molecular analysis further revealed that the trnH-psbA sequence of the 15 samples was approximately 750 bp in length, with 591 conserved sites, 124 variable sites, 55 parsimony informative sites, and 41 single mutation sites, indicating significant genetic differences among the species. The evolutionary tree demonstrated that the 15 Asparagus germplasm resources were all in independent branches, and the trnH-psbA sequence could distinguish and identify all except A. taliensis. This studysuccessfully in analyzed the 15 species of Asparagus using both morphological and molecular biology approaches. These findings can provide the theoretical and practical foundations necessary for further protection and utilization of the germplasm resources of Asparagus.