Wheat Protein Disulfide Isomerase (PDI) Promoter Sequence Analysis in Triticum aestivum cv Chinese Spring and its Wild Relatives

Protein disulphide isomerase (PDI) is an oxidoreductase enzyme abundant in the endoplasmic reticulum (ER). Plant PDIs has been shown to be involved in the folding and deposition of seed storage proteins, which makes this enzyme particularly interesting in wheat, as flour quality is strongly affected by composition and structure of seed storage proteins. Promoter sequences of three homoeologous genes encoding typical PDI, located on chromosome group four of bread wheat, and PDI promoter sequence analysis of Triticum urartu, Aegilops speltoides and Aegilops tauschii had also been reported previously. In this study, we report the isolation, cloning and sequencing of a ~1450 bp region, comprising ~1350 bp of the putative promoter region and 88 bp of the first exon of the typical PDI gene, from Triticum urartu (AA), Aegilops speltoides (BB) and Aegilops tauschii (DD). Sequence analysis indicated close similarity was found within each species and with the corresponding homoeologous PDI sequences of Triticum aestivum cv. CS (AABBDD) resulting in an overall high conservation of the sequence in proximal region then distal region of promoter conferring endosperm-specific expression.