Abstract: Bioinformatics methods were used for the genome-wide identification of the wheat (Triticum aestivum) protein disulfide isomerase-like (TaPDIL) gene family. A total of 21 members of the TaPDIL gene family were identified and named TaPDIL1A to TaPDIL8D according to their chromosomal positions, and the length of their coding sequences, the physicochemical properties and secondary structure of the encoded proteins and their subcellular localization were evaluated as well as their expression patterns during grain development in high-gluten (Yaomai 36) and all-purpose (Pinyu 8155) wheat cultivars. Phylogenetic analysis categorized these genes into six subfamilies. The analysis of gene structure and conserved motifs showed high conservation within each subfamily. The prediction of protein secondary structure showed that the amino acid sequences of all TaPDIL proteins were predominantly composed of α-helix and random coil. RNA sequencing (RNA-Seq) data showed that TaPDIL3B, TaPDIL4B, TaPDIL4D, TaPDIL5A, TaPDIL6A, TaPDIL6B, TaPDIL7A-1, TaPDIL7B, TaPDIL7D-1 and TaPDIL7D-2 during the grain filling period were significantly differentially expressed between the two cultivars. Significant differences were observed in the contents of disulfide bonds and glutenin macropolymers (GMP), and gluten index between these cultivars. ‘Yaomai 36’ gluten had the largest proportion of random coil (42.04%), lacked α-helix structure, and showed a more continuous and denser microstructure, which imparted strong elasticity and toughness to the dough. In contrast, ‘Pinyu 8155’ gluten had the highest proportion of α-helix (49.34%) and did not contain random coil. Numerous network structures were observed on the gluten cross-section, which contributed to a loose gluten structure. This study provides important basic information regarding the physiological function of PDIL family proteins during wheat grain development.

Key words: wheat; TaPDIL; bioinformatics; gluten; microstructure