Arid Zone Research ›› 2024, Vol. 41 ›› Issue (12): 2110-2119.doi: 10.13866/j.azr.2024.12.12

• Plant Ecology • Previous Articles     Next Articles

Characteristics and evolutionary history of the chloroplast genome in Malus sieversii

ZHANG Jian1,2(), ZHANG Hongxiang1,3,4()   

  1. 1. State Key Laboratory of Desert and Oasis Ecology, Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, Xinjiang, China
    2. University of Chinese Academy of Science, Beijing 100093, China
    3. Xinjiang Key Lab of Conservation and Utilization of Gene Resources, Urumqi 830011, Xinjiang, China
    4. Specimen Museum of Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, Xinjiang, China
  • Received:2024-01-04 Revised:2024-10-06 Online:2024-12-15 Published:2024-12-20
  • Contact: ZHANG Hongxiang E-mail:zj13201654032@163.com;zhanghx561@ms.xjb.ac.cn

Abstract:

Malus sieversii, a state-protected species and the progenitor of cultivated apples, is an important germplasm resource within the genus Malus. In this study, we aimed to compare the structural characteristics of chloroplast genomes across various populations of M. sieversii, clarify the lineage divergence pattern, and trace the evolutionary history of this species. We used the Illumina NovaSeq platform to conduct whole-genome sequencing of individuals from 16 different populations, with one sample representing each population. After conducting quality control on the sequencing data, we conducted genome assembly and functional annotation. Subsequently, we conducted a comprehensive structural analysis and lineage differentiation studies on the assembled genomes. The chloroplast genome length in M. sieversii ranged from 160195 to 160279 base pairs (bp), exhibiting a typical tetrad structure. In total, 131 genes were identified within the chloroplast genome, along with 48-58 long repeats and 93-101 simple sequence repeats. Notably, variations in the IR region between M. sieversii and other species in the genus were minimal, predominantly occurring in noncoding regions. Phylogenetic analysis revealed that M. sieversii clusters into three distinct lineages: lineage I, primarily occupying the eastern part of the distribution range, and lineages II and III, predominantly found in the west. The divergence time between lineages I and II was approximately 1.74 million years ago (Ma), while the divergence between lineages I, II, and III was around 2.28 Ma. These findings indicate that the lineage divergences of M. sieversii were significantly influenced by climate changes during the Quaternary period. Compared to internationally distributed populations, M. sieversii in China shows relatively low genetic diversity. Therefore, tailored conservation strategies should be implemented for M. sieversii across different regions, with particular emphasis on protecting genetically diverse populations in the Tacheng area.

Key words: Malus sieversii, chloroplast genome, phylogeny, divergence time, conservation genetics