单 位：
Guiyang Institute of Humanities and Technology, Guiyang, Guizhou 550025, China;University of Chinese Academy of Sciences, Beijing 100049, China;West China Subalpine Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Chengdu, Sichuan 611834, China;Beijing Genomics of Institute, Shenzhen, Guangdong 518120, China;State Forestry and Grassland Administration Key Laboratory of Silviculture in Downstream Areas of the Yellow River, College of Forestry, Shandong Agricultural University, Tai’an, Shandong 271018, China;The Southwest China of Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China; Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China;Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China;Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, Chin
摘 要：
Rhododendron is the most species rich plant genus in China and is famous for its extremely high ornamental value. However, the genus is taxonomically difficult and the relationships within Rhododendron remain unresolved. In addition, the origin of some key morphological characters particularly with high important horticulture value need to be explored. Both problems largely hinder effective utilization of its germplasm resources. Most previous studies have attempted to disentangle the phylogeny of Rhododendron, but only used a few genomic markers and lacked large-scale sampling, resulting in low clade support and contradictory phylogenetic signals. Here, we used restriction-site associated DNA sequencing (RAD-seq) data and morphological traits for 144 species of Rhododendron, representing all subgenera and most sections and subsections of this species-rich genus, to decipher its intricate evolutionary history and reconstruct ancestral state of Rhododendron. Our results revealed high resolutions at subgenera and section levels of Rhododendron based on RAD-seq data. Both optimal phylogenetic tree and split tree recovered five lineages among Rhododendron. Subg. Therorhodion (clade I) formed the basal lineage. Subg. Tsutsusi and Azaleastrum formed clade II and had sister relationships. Clade III included all scaly rhododendron species. Subg. Pentanthera (clade IV) formed a sister group to Subg. Hymenanthes (clade V). The results of ancestral state reconstruction showed that Rhododendron ancestor was a deciduous woody plant with terminal inflorescence, ten stamens, leaf blade without scales and broadly funnelform corolla with pink or purple color. This study shows significant distinguishability to resolve the evolutionary history of Rhododendron based on high clade support of phylogenetic tree constructed by RAD-seq data. It also provides an example to resolve discordant signals in phylogenetic trees and demonstrates the application feasibility of RAD-seq with large amounts of missing data in deciphering intricate evolutionary relationships. Additionally, the reconstructed ancestral state of six important characters provides insights into the innovation of key characters in Rhododendron.
