Correlation analysis between the karyotypes and phenotypic traits of Chinese cymbidium cultivars

摘要

Chinese cymbidium are a group of valuable ornamental plants that is formed by genetically distinct species. Currently, a robust Chinese cymbidium classification system, such as that based on cytotaxonomy, is lacking. To investigate the genetic variation within Chinese cymbidium, we selected 28 individual Chinese cymbidium cultivars as experimental material to perform karyotype analysis. The results showed that chromosome number among these 28 cultivars was constant and diploid (i.e., 2n = 40). In addition, no satellite chromosomes were observed. The karyotypes were more symmetrical and consisted mainly of 1B and 2B types with a small number of 2A and 2C types. Based on principal component analysis, the five karyotype parameters with the highest classification values were screened, which revealed that the mean of long to short arm ratio, the mean relative length of long arms, and the asymmetry coefficient of karyotypes (As.K.) were reliable parameters for use in Chinese cymbidium cytotaxonomy. Cluster analysis of karyotype parameters successfully identified cultivars of the bamboo petal, narcissus petal, and plum petal types, thus confirming the accuracy of the cytological classification system. Furthermore, flower traits of Chinese cymbidium were strongly correlated with karyotype parameters. Overall, we conclude that karyotype parameters can provide valuable information for studies on the classification, identification, and genetic diversity of Chinese cymbidium.