Genome-Wide Identification of Ascorbate Peroxidase Gene Family in Two Contrasting Barley (Hordeum vulgare L.) Cultivars: Essential Roles in Various Abiotic Stress Tolerance

Abstract

Abstract Plants with their antioxidant defense systems evolved under stress conditions and detoxify and remove the levels of reactive oxygen species (ROS). The survey of ascorbate peroxidase (APX) gene families in barley identified eight APX genes. The comprehensive analysis of HvAPX genes in barley has not yet been described. In this study, 8 members of the barley APX family were characterized for phylogenetic tree, conserved motifs, gene ontology, correlation between traits and gene expression, prediction of cis-elements, and gene expression in APX under abiotic stress conditions. In addition, analysis of physiological traits was performed on two contrasting Iranian barley cultivars namely Sahra (drought tolerant) and Nobahar (drought susceptible) under abiotic stress (PEG, heat, ABA, and salt) conditions. Gene expression analysis revealed that 8 HvAPX genes were accumulated in the leaf and root tissues at 24 and 48 hours after abiotic stresses. Furthermore, the gene expression analysis of the HvAPX genes revealed genes increase and decrease in response to PEG, ABA, salt, and heat stresses in the leaf and root tissues. The phylogenetic analysis of the HvAPX proteins sequences in barley were grouped into three clusters. The HvAPX7 and HvAPX8 genes had the highest number of cis-elements in their promoter regions, indicating that they might be stimulated by a plethora of environmental stresses. The HvAPX genes had GT1-motif, STRE, CAAT-box, MYB, and MYC in their promoter regions, playing a key role in response to abiotic stresses. Our findings provide new insights into APX genes and provide a basis for next investigations of APX genes in plant improvement (breeding) programs.