J Syst Evol

• Research Articles •    

Origins of cultivars of Chrysanthemum - evidence from the chloroplast genome and nuclear LFY gene

Yueping Ma 1, Liang Zhao 2, Wenjie Zhang1, Yinghua Zhang1, Xia Xing1, Xiaxia Duan1, Jing Hu1, AJ Harris3, Peiliang Liu4, Silan Dai5, and Jun Wen6*   

  1. 1College of Life and Health Sciences, Northeastern University, Shenyang 110004, China
    2College of Life Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
    3Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou510650, China
    4College of Life Sciences, Northwest University, Xi'an710069, China
    5Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture and College of Landscape Architecture, Beijing Forestry University, Beijing 100083, China
    6Department of Botany, National Museum of Natural History, MRC 166, Smithsonian Institution, Washington, DC, 20013-7012, USA
  • Received:2020-08-07 Accepted:2020-08-31

Abstract:

The origins of cultivated chrysanthemums have attracted considerable attention but remain poorly known. Here, we reconstructed the phylogeny of representative well-known cultivars and wild species of the genus Chrysanthemum using chloroplast genomes and the nuclear LFY gene. Our results suggest that geographic and ecological factors may determine the opportunities for wild species to be involved in the origin of the cultivars. The wild species, C. indicum, C. zawadskii, C. dichrum, C. nankingense, C. argyrophyllum, and C. vestitum were likely directly or indirectly involved as paternal species of most of the chrysanthemum cultivars that we examined. Yet the maternal species is supported to be a lineage of an extinct wild Chrysanthemum species and its subsequent cultivars, as all accessions of chrysanthemum cultivars sampled formed a strongly supported clade distinct from all other species of Chrysanthemum in the plastome tree. Thus, the cultivated chrysanthemums originated from multiple hybridizations involving several paternal species rather than only two or a few wild species, with an extinct species and its subsequent cultivars serving as the maternal parents. This finding is consistent with Chrysanthemum having high rates of hybridization and gene flow, which has been demonstrated within previous studies, yet it is significant to unravel the role of an extinct wild Chrysanthemum species as the ultimate maternal parent species for all the chrysanthemum cultivars. Our results also suggest that C. vestitum from Tianzhu and Funiu Mountains in Anhui and Henan Provinces of China represent two distinct cryptic species.

Key words: NGS, low copy nuclear gene, phylogenetic relationship, Chrysanthemum