Research Article

Genome-wide comparison of AP2/ERF superfamily genes between Gossypium arboreum and G. raimondii

Published: July 29, 2016
Genet. Mol. Res. 15(3): gmr8211 DOI: https://doi.org/10.4238/gmr.15038211
Cite this Article:
Z.P. Lei, D.H. He, H.Y. Xing, B.S. Tang, B.X. Lu, Z.P. Lei, D.H. He, H.Y. Xing, B.S. Tang, B.X. Lu (2016). Genome-wide comparison of AP2/ERF superfamily genes between Gossypium arboreum and G. raimondii. Genet. Mol. Res. 15(3): gmr8211. https://doi.org/10.4238/gmr.15038211
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Abstract

The APETALA2/ethylene response factor (AP2/ERF) transcription factor superfamily is known to regulate diverse processes of plant development and stress responses. We conducted a genome-wide analysis of the AP2/ERF gene in Gossypium arboreum and G. raimondii. Using RPSBLAST and HMMsearch, a total of 271 and 269 AP2/ERF genes were identified in the G. arboreum and G. raimondii genomes, respectively. A phylogenetic analysis classified diploid Gossypium spp AP2/ERF genes into 4 families and 16 subfamilies. Orthologous genes predominated the terminal branch of the phylogenetic tree. Physical mapping showed at least 30% of AP2/ERF genes clustered together. A high level of intra- and inter-species collinearity involving AP2/ERF genes was observed, indicating common (before species divergence) or parallel (after species divergence) segmental duplications, along with tandem duplications, resulting in the species-specific expansion of AP2/ERF genes in diploid Gossypium species. Motif analyses of the AP2/ERF proteins revealed that motif arrangements were highly diverse among subfamilies, but shared by orthologous gene pairs. An examination of nucleotide divergence of AP2/ERF coding regions identified small and non-significant sequence differences among orthologs. Expression profiling of AP2/ERF orthologous gene pairs showed similar abundance levels of orthologous copies between G. arboreum and G. raimondii. Thus, cotton species possess abundant and diverse AP2/ERF genes, resulting from tandem and segmental duplications. Protein and nucleotide sequence and mRNA expression analyses revealed symmetrical evolution, indicating that most AP2/ ERF genes may not have undergone significant biochemical and morphological divergence between sister species. Our study provides detailed insights into the evolutionary characteristics and functional importance of AP2/ERF genes, and could aid in the genetic improvement of agriculturally significant crops in this genus.

The APETALA2/ethylene response factor (AP2/ERF) transcription factor superfamily is known to regulate diverse processes of plant development and stress responses. We conducted a genome-wide analysis of the AP2/ERF gene in Gossypium arboreum and G. raimondii. Using RPSBLAST and HMMsearch, a total of 271 and 269 AP2/ERF genes were identified in the G. arboreum and G. raimondii genomes, respectively. A phylogenetic analysis classified diploid Gossypium spp AP2/ERF genes into 4 families and 16 subfamilies. Orthologous genes predominated the terminal branch of the phylogenetic tree. Physical mapping showed at least 30% of AP2/ERF genes clustered together. A high level of intra- and inter-species collinearity involving AP2/ERF genes was observed, indicating common (before species divergence) or parallel (after species divergence) segmental duplications, along with tandem duplications, resulting in the species-specific expansion of AP2/ERF genes in diploid Gossypium species. Motif analyses of the AP2/ERF proteins revealed that motif arrangements were highly diverse among subfamilies, but shared by orthologous gene pairs. An examination of nucleotide divergence of AP2/ERF coding regions identified small and non-significant sequence differences among orthologs. Expression profiling of AP2/ERF orthologous gene pairs showed similar abundance levels of orthologous copies between G. arboreum and G. raimondii. Thus, cotton species possess abundant and diverse AP2/ERF genes, resulting from tandem and segmental duplications. Protein and nucleotide sequence and mRNA expression analyses revealed symmetrical evolution, indicating that most AP2/ ERF genes may not have undergone significant biochemical and morphological divergence between sister species. Our study provides detailed insights into the evolutionary characteristics and functional importance of AP2/ERF genes, and could aid in the genetic improvement of agriculturally significant crops in this genus.