Biotechnology Bulletin ›› 2026, Vol. 42 ›› Issue (8): 239-250.doi: 10.13560/j.cnki.biotech.bull.1985.2025-1432

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Comparative Analysis of Chloroplast Genome Characteristics among Three Cultivated Types of Chrysanthemum Varieties

LIU Rou-zhi, WU Jia-qi, WU Hui-ye, YUAN Jing-yi, CHENG Tang-ren, ZHANG Qi-xiang, YUAN Cun-quan()   

  1. 1.Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, Beijing 100083
    2.National Engineering Research Center for Floriculture, Beijing 100083
    3.Beijing Laboratory of Urban and Rural Ecological Environment, Beijing 100083
    4.Engineering Research Center of Landscape Environment of Ministry of Education, Beijing 100083
    5.School of Landscape Architecture, Beijing Forestry University, Beijing 100083
  • Received:2025-12-28 Online:2026-08-26 Published:2026-08-17
  • Contact: YUAN Cun-quan E-mail:yuancunquan@bjfu.edu.cn

Abstract:

Objective To explore the chloroplast genome characteristics and phylogenetic relationships of Chrysanthemum cultivars of different cultivation types, providing a theoretical basis for research on the phylogeny, species identification and germplasm conservation of the genus Chrysanthemum. Method Chloroplast genome sequencing, assembly and annotation were performed on the groundcover Chrysanthemum × morifolium ‘Bei Lin Qiu Yun’, the single-headed cut flower C. morifolium ‘Sheng Xue’, and the traditional large-flowered C. morifolium ‘Fen Shi Ba’. Analysis of genomic structure, simple sequence repeats (SSRs), codon usage bias, inverted repeat (IR) boundary regions and collinearity characteristics was conducted. For phylogenetic analysis, nine chloroplast genome sequences, including eight from Chrysanthemum species and one outgroup from the Asteraceae family, were downloaded from GenBank. Result The chloroplast genomes of the three cultivars all exhibited a typical double-stranded circular quadripartite structure, ranging in length from 151 060 to 151 073 bp, with a GC content of 37.5%. A total of 131 genes were annotated in each genome, including 86 protein-coding genes, 37 transfer RNA (tRNA) genes, and 8 ribosomal RNA (rRNA) genes. Whole-genome alignment revealed high overall conservation of the chloroplast genomes: the IR regions showed higher conservation than the single-copy (SC) regions, and the non-coding regions had a higher mutation frequency than the coding regions, with no large-scale gene rearrangements detected. Boundary gene types were consistent across all samples. C. morifolium ‘Sheng Xue’ and C. morifolium ‘Fen Shi Ba’ each contained 68 SSRs, whereas C. morifolium ‘Bei Lin Qiu Yun’ contained 70 SSRs. Mononucleotide repeats (A/T-type) dominated the SSRs in all three cultivars, with no hexanucleotide repeats detected. Codon usage bias was weak (CAI: 0.168‒0.169; ENC: 49.127‒49.420), with a preference for A/U-ending codons. Selection pressure was identified as the key factor influencing codon usage bias. Phylogenetic analysis showed that C. morifolium ‘Sheng Xue’ and C. morifolium ‘Fen Shi Ba’ were closely related to cultivated C. morifolium, while C. morifolium ‘Bei Lin Qiu Yun’ was closely related to wild Chrysanthemum species. Conclusion The three Chrysanthemum cultivars of different cultivation types have a conserved chloroplast genomic structure and gene content. The groundcover C. morifolium is more closely related to wild species, whereas the traditional large-flowered C. morifolium and single-headed cut C. morifolium are more closely related to cultivated varieties.

Key words: Chrysanthemum, Chrysanthemum × morifolium, chloroplast genome, phylogenetic analysis, sequence characteristics, codon usage bias, SSR