Molecular Evolution and Expression Analysis of Subfamily ABCB Transporter Genes in Rice
With the accomplishment of genome sequencing projects, over 130 ABCs were identified separately from the model plants of monocots and dicots, rice and Arabidopsis, but the functions of most of the members remain elusive. Therefore, 27 and 29 subfamily B of ABC genes (ABCB) in rice and Arabidopsis were systematically characterized, respectively. The exon number, length and molecular weight of proteins encoded by these genes varied greatly between the two plants. Albeit the isoelectric point was less diverse. Proteins of this subfamily were divided into 4 subgroups accordingpar to phylogenetic analysis, suggesting that divergence probably occurred among them; 6 and 9 pairs of paralogous genes were identified from rice and Arabidopsis, respectively, indicating that species-specific expansion contributed to the evolution of this subfamily in rice and Arabidopsis after the split of monocots and dicots. Segmental and tandem duplication contributed to the amplification of ABC family in rice. Multiple sequence alignment revealed that the Walker A, Walker B, and ABC signature motifs of nucleotide-binding domain (NBD) are highly conserved, but less the Q and H loops; no significant conservatism could be pointed out as to TMD domain within a single ABC protein and among different proteins. Expression of rice ABCB genes is highly tissue-specific, and divergence has occurred among the expression profiles of different genes. Expression analysis of rice ABCB genes under abiotic stress suggested that most of the genes are responsive to at least 1 type of stress factors. Ka/Ks calculation indicated that purifying selection is essential to the functional maintenance of genes after duplication.
国家科技期刊平台
NSTL
万方数据
维普
