Protein disulphide isomerase family in bread wheat (Triticum aestivum L.): genomic structure, synteny conservation and phylogenetic analysis

Abstract

Eight genes encoding protein disulphide isomerase (PDI)-like proteins in bread wheat were cloned and characterized and their genomic structure was compared with that of homoeologous genes isolated from other plant species. Fourteen wheat cDNA sequences of PDI-like genes were amplified and cloned; eight of them were relative to distinct PDI-like genes, whereas six corresponded to homoeologous sequences. Also, the genomic sequences of the eight non-homoeologous genes were amplified and cloned. Phylogenetic analysis, which included eight genes encoding PDI-like proteins and the gene encoding the typical PDI, assigned at least one of them to each of the eight major clades identified in the phylogenetic tree of the PDI gene family of plants. The close chromosome synteny between wheat and rice was confirmed by the location of the homoeologous genes of the PDI family in syntenic regions of the two species. Within the same phylogenetic group, a high level of conservation, in terms of sequence homology, genomic structure and domain organization, was detected between wheat and the other plant species. The high level of conservation of sequence and genomic organization within the PDI gene family, even between distant plant species, might be ascribed to the key metabolic roles of their protein products.