LAUSR

Protein kinases (PKs) belonging to a large superfamily play vital roles in plant development and stress tolerance, whereas only a small number of PKs have been functionally studied in wheat. Genome-wide survey and characterization of wheat PK genes (TaPKs) will be valuable in future genetic improvement program. In this study, we performed genome-wide identification of PK in wheat, containing phylogenetic evolution, gene expression pattern, and functional prediction analysis, and to explore structure–function relationship, the secondary and tertiary structures of wheat OST1 were visualized. Totally, 4479 TaPKs composed of 4446 Ser/Thr/Tyr (TaPK1 to TaPK4446) and 33 His PKs (TaHPK1 to TaHPK33) were identified in the TGACv1 assembly. According to phylogenetic analysis, wheat Ser/Thr/Tyr PKs were categorized into eight groups with 57 families and 64 subfamilies, and His PKs were classified into three families. The genes contained on average 5.07 introns, ranging from 0 to 31, and about 54.68% TaPKs exhibited relatively simpler exon–intron organization (0–4 introns). RNA-seq analysis showed 324 TaPKs were significantly differentially expressed after exposure to drought, 372 TaPKs were significantly differentially expressed after inoculation with Puccinia striiformis f. sp. tritici (Pst) and Blumeria graminis f. sp. tritici (Bgt), and a large number of TaPKs exhibited stage- or organ-specific expression patterns. Co-expression analysis showed that 1388 TaPKs were distributed in 19 modules, while 9 modules with 511 TaPKs had the most obvious tissue- or stress-specific expression trends. A suite of sexual reproduction related genes were identified in magenta module where TaPK960, TaPK707–3708, TaPK4243, and TaPK4249 were related to polarized pollen tube growth, TaPK627 and TaPK629 to pollen tube guidance, and TaPK4226–4228 to flowering time regulation. Finally, 12 TaPKs were selected to validate their expression level through qRT-PCR. Our findings obtained will offer a clue to elaborate the roles of PKs in wheat growth and stress resistance for agricultural improvement.