Genome-Wide Characterization of Ascorbate Peroxidase Gene Family in Peanut ( L.) Revealed Their Crucial Role in Growth and Multiple Stress Tolerance.

Ascorbate peroxidase (APX), an important antioxidant enzyme, plays a significant role in ROS scavenging by catalyzing the decrease of hydrogen peroxide under various environmental stresses. Nevertheless, information about the gene family and their evolutionary and functional attributes in peanut ( L.) was not reported. Therefore, a comprehensive genome-wide study was performed to discover the genes in cultivated peanut genome. This study identified 166 genes in the peanut genome, classified into 11 main groups. The gene duplication analysis showed that genes had experienced segmental duplications and purifying selection pressure. Gene structure and motif investigation indicated that most of the genes exhibited a comparatively well-preserved exon-intron pattern and motif configuration contained by the identical group. We discovered five phytohormones-, six abiotic stress-, and five growth and development-related -elements in the promoter regions of . Fourteen putative ah-miRNAs from 12 families were identified, targeting 33 genes. Furthermore, we identified 3,257 transcription factors from 38 families (including AP2, ARF, B3, bHLH, bZIP, ERF, MYB, NAC, WRKY, etc.) in 162 genes. Gene ontology and KEGG enrichment analysis confirm the role of genes in oxidoreductase activity, catalytic activity, cell junction, cellular response to stimulus and detoxification, biosynthesis of metabolites, and phenylpropanoid metabolism. Based on transcriptome datasets, some genes such as and showed significantly higher expression in diverse tissues/organs, i.e., flower, leaf, stem, roots, peg, testa, and cotyledon. Likewise, only a few genes, including and , were significantly upregulated under abiotic (drought and cold), and phytohormones (ethylene, abscisic acid, paclobutrazol, brassinolide, and salicylic acid) treatments. qRT-PCR-based expression profiling presented the parallel expression trends as generated from transcriptome datasets. Our discoveries gave new visions into the evolution of genes and provided a base for further functional examinations of the genes in peanut breeding programs.