Characterization of the complete chloroplast genome of Brassica oleracea var. italica and phylogenetic relationships in Brassicaceae

PLoS One. 2022 Feb 24;17(2):e0263310. doi: 10.1371/journal.pone.0263310. eCollection 2022.

Abstract

Broccoli (Brassica oleracea var. italica) is an important B. oleracea cultivar, with high economic and agronomic value. However, comparative genome analyses are still needed to clarify variation among cultivars and phylogenetic relationships within the family Brassicaceae. Herein, the complete chloroplast (cp) genome of broccoli was generated by Illumina sequencing platform to provide basic information for genetic studies and to establish phylogenetic relationships within Brassicaceae. The whole genome was 153,364 bp, including two inverted repeat (IR) regions of 26,197 bp each, separated by a small single copy (SSC) region of 17,834 bp and a large single copy (LSC) region of 83,136 bp. The total GC content of the entire chloroplast genome accounts for 36%, while the GC content in each region of SSC,LSC, and IR accounts for 29.1%, 34.15% and 42.35%, respectively. The genome harbored 133 genes, including 88 protein-coding genes, 37 tRNAs, and 8 rRNAs, with 17 duplicates in IRs. The most abundant amino acid was leucine and the least abundant was cysteine. Codon usage analyses revealed a bias for A/T-ending codons. A total of 35 repeat sequences and 92 simple sequence repeats were detected, and the SC-IR boundary regions were variable between the seven cp genomes. A phylogenetic analysis suggested that broccoli is closely related to Brassica oleracea var. italica MH388764.1, Brassica oleracea var. italica MH388765.1, and Brassica oleracea NC_0441167.1. Our results are expected to be useful for further species identification, population genetics analyses, and biological research on broccoli.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Composition / genetics
  • Brassicaceae / classification
  • Brassicaceae / genetics*
  • Chloroplasts / genetics
  • Codon / genetics
  • Evolution, Molecular
  • Genome, Chloroplast / genetics*
  • High-Throughput Nucleotide Sequencing
  • Microsatellite Repeats / genetics
  • Molecular Sequence Annotation
  • Phylogeny*
  • RNA, Ribosomal / genetics
  • RNA, Transfer / genetics
  • Sequence Analysis, DNA
  • Whole Genome Sequencing*

Substances

  • Codon
  • RNA, Ribosomal
  • RNA, Transfer

Grants and funding

The new statement below is suitable for my publication:This study was funded by the National Natural Science Foundation of China (NSFC) in the form of a grant to ZCZ [31401871], the Jiangsu Agriculture Science and Technology Innovation Fund in the form of funds to LXS [CX (18)3068], the Project for Nature Sciences in Zhejiang in the form of funds to ZGJ [LY18C150006], the Project for Fundamental Research of Local Undergraduate Universities (Partial) in Yunnan Province in the form of funds to ZGJ [2018FH001-044], and the Jurong Science and Technology Innovation Fund Project in the form of funds to ZCZ [NY2019001]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.