Genome-wide identification and gene expression pattern of ABC transporter gene family in Capsicum spp

PLoS One. 2019 Apr 30;14(4):e0215901. doi: 10.1371/journal.pone.0215901. eCollection 2019.

Abstract

ATP-binding cassette (ABC) transporter genes act as transporters for different molecules across biological membranes and are involved in a diverse range of biological processes. In this study, we performed a genome-wide identification and expression analysis of genes encoding ABC transporter proteins in three Capsicum species, i.e., Capsicum annuum, Capsicum baccatum and Capsicum chinense. Capsicum is a valuable horticultural crop worldwide as an important constituent of many foods while containing several medicinal compounds including capsaicin and dihydrocapsaicin. Our results identified the presence of a total of 200, 185 and 187 ABC transporter genes in C. annuum, C. baccatum and C. chinense genomes, respectively. Capsaicin and dihydrocapsaicin content were determined in green pepper fruits (16 dpa). Additionally, we conducted different bioinformatics analyses including ABC genes classification, gene chromosomal location, Cis elements, conserved motifs identification and gene ontology classification, as well as profile expression of selected genes. Based on phylogenetic analysis and domain organization, the Capsicum ABC gene family was grouped into eight subfamilies. Among them, members within the ABCG, ABCB and ABCC subfamilies were the most abundant, while ABCD and ABCE subfamilies were less abundant throughout all species. ABC members within the same subfamily showed similar motif composition. Furthermore, common cis-elements involved in the transcriptional regulation were also identified in the promoter regions of all Capsicum ABC genes. Gene expression data from RNAseq and reverse transcription-semi-quantitative PCR analysis revealed development-specific stage expression profiles in placenta tissues. It suggests that ABC transporters, specifically the ABCC and ABCG subfamilies, may be playing important roles in the transport of secondary metabolites such as capsaicin and dihydrocapsaicin to the placenta vacuoles, effecting on their content in pepper fruits. Our results provide a more comprehensive understanding of ABC transporter gene family in different Capsicum species while allowing the identification of important candidate genes related to capsaicin content for subsequent functional validation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • ATP-Binding Cassette Transporters / chemistry
  • ATP-Binding Cassette Transporters / genetics*
  • ATP-Binding Cassette Transporters / metabolism
  • Alleles
  • Amino Acid Motifs
  • Capsaicin / analogs & derivatives
  • Capsaicin / analysis
  • Capsicum / genetics*
  • Chromosomes, Plant / genetics
  • Gene Expression Profiling*
  • Gene Expression Regulation, Plant*
  • Gene Ontology
  • Genes, Plant
  • Genetic Markers
  • Genome, Plant*
  • Molecular Sequence Annotation
  • Phylogeny
  • Plant Proteins / chemistry
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Polymorphism, Single Nucleotide / genetics
  • Promoter Regions, Genetic / genetics

Substances

  • ATP-Binding Cassette Transporters
  • Genetic Markers
  • Plant Proteins
  • Capsaicin
  • dihydrocapsaicin

Grants and funding

This study was supported by the National Institute of Food and Agriculture (USDA-NIFA) (grant no. 2016-06616 to PN). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.