结合分子手段和形态分析验证大白杜鹃与马缨杜鹃的自然杂交

Molecular and morphological evidence for natural hybridization between Rhododendron decorum and R. delavayi(Ericaceae)

中国西南地区是世界杜鹃属(Rhododendron)植物的分布和分化中心,开展杜鹃属自然杂交研究可为分类修订和新品种选育提供依据。本文以贵州百里杜鹃自然保护区(百里保护区)和云南石宝山分布的大白杜鹃(Rhododendron decorum)、马缨杜鹃(R.delavayi)及两种间疑似自然杂交后代和人工杂交后代个体为研究材料,通过形态特征比较、核基因间隔序列ITS以及叶绿体基因片段trnL-trn F、rbcL和trnH-psb A测序特征分析,发现疑似自然杂交后代与人工杂交后代形态特征介于大白杜鹃与马缨杜鹃之间;4个DNA片段序列均能区分大白杜鹃和马缨杜鹃,同一物种的不同居群在叶绿体基因片段rbcL、trnH-psb A序列存在差异位点;所有人工杂交后代个体和1个石宝山疑似杂交个体均以大白杜鹃为母本,所有百里保护区疑似杂交个体和6个石宝山疑似杂交个体以马缨杜鹃为母本。本研究证实了大白杜鹃与马缨杜鹃在百里保护区和云南石宝山存在自然杂交现象,杂交为双向且自然杂交后代绝大多数以马缨杜鹃为母本。

The southwestern region of China is the center of differentiation for the genus Rhododendron. Studies on the natural hybridization of Rhododendron provide solutions for taxonomic problems and enhance the ability to breed new cultivars faster. In this paper, we compared the morphological features and sequenced nuclear internal transcribed spacer （ITS） and chloroplast trnL-trnF, rbcL, trnH-psbA for Rhododendron de- corum, R. delavayi, and the putative hybrid offspring of these two species. All samples in this study were collected from Baili Rhododendron Nature Reserve in Guizhou Province, the Shibao Mountain of Yuunan Province and Kunming Botanical Garden. Results showed that all putative hybrids （natural and artificial） produced an intermediate morphology. Sequencing results revealed that all artificial hybrids and one col- lected from the Shibao Mountain inherited cpDNA from R. decorum, and all putative hybrids collected from Baili Rhododendron Nature Reserve and six from Shibao Mountain inherited cpDNA from R. delavayi. In this study, we have confirmed that natural hybridization between R. decorum and R. delavayi exists in the Guizhou and Yunnan sites. Hybridization was bilateral, and most of the hybrids were derived from maternal parent R. delavayi.