Duplication of the class I cytosolic small heat shock protein gene and potential functional divergence revealed by sequence variations flanking the α-crystallin domain in the genus Rhododendron (Ericaceae)

摘要: †Background and Aims Positive selection in the a-crystallin domain (ACD) of chloroplast small heat shock protein (CPsHSP) gene was found a previous study suggested to be related ecological adaptation Rhododendron species subgenus Hymenanthes. Consequently, it interest examine whether duplication subsequent divergence have occurred other sHSP genes, for example class I cytosolic genes (CT1sHSPs )i nRhododendron Taiwan, where many endemic evolved as result habitat differentiation. †Methods A phylogeny CT1sHSP amino acid sequences built from Rhododendron, Arabidopsis thaliana, Oryza sativa, Populus trichocarpa, Vitis vinifera elucidation phylogenetic relationships among CT1sHSPs. Phylogenies nucleotide were generated positive functional analysis, respectively. Positively selected sites differences between types CT1sHSPs mapped onto wheat sHSP16.9 structure. Average genetic distance (Dxy) dN/dS ratios analysed using sliding window analysis. Gene conversion also assessed †Key Results Two identified. high level similarity diversity within flanking ACD, respectively, found. Main two were: (1) increased hydrophobicity by positively seven-amino-acid insertion N-terminal arm; (2) structural flexibility solubility arm one site C-terminal extension. †Conclusions Functional conservation ACD inferred because strong purifying selection. However, sequence variations inRhododendronCT1sHSP duplicates may resulted played important roles chaperon function enhancement.