Genome-wide study of OsWRKY gene in Oryza sativa subsp. japonica

WRKY transcription factor (TF) family is well known to govern essential physiological functioning as well as regulate plant response to biotic and abiotic stress. In this study, we have identified 108 OsWRKY genes in the genome of Oryza sativa subsp. japonica, using the updated genomic data from the Rice Annotation Project Database and Oryzabase, which were further used to conduct the phylogenetic study, motif analysis, gene structure analysis, chromosomal mapping, and prediction of sub-cellular localization. The multiple sequence alignment OsWRKY proteins revealed the presence of nine different types of alterations in the conserved heptapeptide sequence WRKYGQK associated with 19 OsWRKY genes. Physiochemical analysis discloses the hydrophobic amino acid-rich, thermally stable, and polar nature of OsWRKY proteins. These genes were noted as highly conserved between the two cultivated sub-species of Oryza sativa, that is Indica and japonica type. Additionally, from motif analysis, we have found a new motif, which was categorized as hAT family C-terminal dimerization region associated with four members of group IIc. We have identified 21 stress-responsive OsWRKY genes, and their significance to the different biotic and abiotic stress-mediated cascades was further evaluated by analysing 1500 kb upstream sequences and this disclosed the presence of important phytohormone-responsive cis-elements in the OsWRKY gene, suggesting its direct involvement in defence against a wide range of external stressors and these 21 OsWRKY genes are tentatively listed as possible candidates for more study.