Expression profile and characterization of respiratory burst oxidase homolog genes in rice under MeJA, SA and Xoo treatments

Respiratory burst oxidase homologs (Rboh) genes is essential for synthesizing reactive oxygen species, which play a crucial role in environmental stress response. The Rboh gene family has been studied in model plants such as Arabidopsis. Nevertheless, Rboh remained largely unexplored in Rice (Oryza sativa L.). Here, we performed characterization of the Rboh genes family in rice (OsRboh) under Xanthomonas oryzae pv. oryzae (Xoo), salicylic acid (SA), and methyl jasmonate (MeJA) treatments. Nine OsRboh genes were retrieved distributed across six chromosomes (1, 5, 8, 9, 11, 12).These genes vary in amino acid sequence length (728-1034), isoelectric point (9.05-9.84), and molecular weight (8.341-115.014 kDa). Analysis of gene structure, motifs and conserved domains showed that OsRboh genes have similar protein sequences and functions. The promoter region of OsRboh genes was found to contain mainly cis-acting elements associated with light, jasmonic acid (JA), abscisic acid (ABA), and SA responsiveness. Predictions of functional protein-protein interaction showed that OsRboh genes were associated with MAPK signaling, plant-pathogen interaction, and other mRNA surveillance pathways. Prediction of miRNA targets and post-translational modification sites indicated that OsRboh genes may be regulated by miRNA and protein phosphorylation. Phylogenetic analysis showed that OsRboh genes were distributed into 7 clusters. Furthermore, 9 OsRboh genes were differentially expressed in different tissues (roots, stems, and leaves). OsRbohA, OsRbohB, and OsRbohD are significant genes in rice defense responses, showing unique and increased expression profiles under (Xoo-PXO99), (MeJA), and (SA) treatments. These genes important function in triggering defense mechanisms is further stressed by the high (> 20-fold) changes in expression they exhibit under these treatments. These findings enhance our understanding of rice OsRboh genes functions and contribute to stress tolerance improvement strategies.