Sequence Characterization,Expression,and Evolutionary Analysis of Heat Shock Transcription Factors in Apple
To extensively understand the sequence feature and evolution of heat shock transcription factors(Hsf)in the genome of apple,fifty MdHsf genes were identified using bioinformatics methods at the whole-genome level of apple,and a series of analysis including sequence characterization,phylogenetic relationship,gene expression and selective pressure of MdHsf genes were further performed.Phylogenetic relationship and sequence characterization analysis showed that,like the model species Arabidopsis and rice,50 MdHsf genes were divided into three subfamilies A,B and C.Additionally,at least two genes were found in the same end clades in the phylogenetic tree,indicating that the lineage-specific amplification had happened during evolutionary processes of apple Hsf gene family.Although the intron numbers and sizes of MdHsf genes were relatively divergent,the conserved motifs and domains of MdHsf proteins were highly conserved because of functional constraints.Based on EST data,72% of the 50 genes(except 14 genes such as MdHsfA2a and MdHsfA3a/b/c)had transcription activities.Selective pressure signatures demonstrated that no positive selection site was identified in the cleaned codon alignments for 36 MdHsf genes based on site-specific model,suggesting that this protein family was controlled by purifying selection.However,branch-site model had identified a total of five positively selected sites in the d and e clade of the phylogenetic tree,i.e.28R,30L,35D,51M and 67V.28R and 30L were included in the Hsf domains,while 35D,51M and 67V were not mapped on the region of Hsf domains,suggesting that purifying selection was the main evolutionary dynamics of functional conservation Hsf domains except for 28R and 30L.In conclusion,various Hsfs existed in apple genome,and the conserved motifs and functional domains were conserved.The majority of them had transcription activity,and the evolution of this family was dominated by purifying selection.
国家科技期刊平台
NSTL
万方数据
维普
