关键词: 映山红亚属, 品种群, 数量分类, 全基因组重测序, SNP, 聚类分析

Abstract:

Based on numerical taxonomy and whole genome resequencing，varietal groups among 108 Rhododendron subgenus Tsutsusi cultivars in this study. Using 102 Rhododendron subgenus Tsutsusi cultivars as experimental materials，the results of a numerical taxonomy study based on 37 phenotypic traits showed that the Summer azalea group can be differentiated from other groups by flowering period，while sepal petaloidy and hose-in-hose corolla type served as key traits for distinguishing the East azalea group from others. However，due to the high similarity in phenotypic traits，the classification boundary between the West azalea and Hairy azalea groups remained unclear. 57 commercially representative cultivars of Rhododendron subgenus Tsutsusi were selected for whole genome resequencing. Clustering analysis，PCA，and population structure analysis based on the detected SNPs indicated that the 57 cultivars of Rhododendron subgenus Tsutsusi could be divided into four groups，supporting the existing classification system comprising four major cultivar groups. Furthermore，the analysis about genetic background revealed that the Hairy and East azalea groups are independent，thereby refuting the proposal to merge them under the term“Spring azalea”. Integrating morphological and genomic evidences support the classification of Rhododendron subgenus Tsutsusi cultivars into four variety groups：Hairy azalea，East azalea，West azalea，and Summer azalea. However，outlier individuals were identified within the East azalea，Hairy azalea，and West azalea groups. This study recommends reclassifying the East azalea cultivar R.‘Yudaizhirong’into the West azalea group，and proposes treating the Hairy azalea cultivar R. ‘Shuangjitaohong’as a synonym of the East azalea cultivar R.‘Zhuangyuanhong’.

Key words: Rhododendron subgenus Tsutsusi, cultivar groups, numerical taxonomy, whole genome resequencing, SNP, clustering analysis