AUTHOR=Raza Ali , Sharif Yasir , Chen Kun , Wang Lihui , Fu Huiwen , Zhuang Yuhui , Chitikineni Annapurna , Chen Hua , Zhang Chong , Varshney Rajeev K. , Zhuang Weijian 

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

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.962182

DOI=10.3389/fpls.2022.962182

ISSN=1664-462X

ABSTRACT=<p>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 <italic>APX</italic> gene family and their evolutionary and functional attributes in peanut (<italic>Arachis hypogea</italic> L.) was not reported. Therefore, a comprehensive genome-wide study was performed to discover the <italic>APX</italic> genes in cultivated peanut genome. This study identified 166 <italic>AhAPX</italic> genes in the peanut genome, classified into 11 main groups. The gene duplication analysis showed that <italic>AhAPX</italic> genes had experienced segmental duplications and purifying selection pressure. Gene structure and motif investigation indicated that most of the <italic>AhAPX</italic> 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 <italic>cis</italic>-elements in the promoter regions of <italic>AhAPX</italic>. Fourteen putative ah-miRNAs from 12 families were identified, targeting 33 <italic>AhAPX</italic> genes. Furthermore, we identified 3,257 transcription factors from 38 families (including AP2, ARF, B3, bHLH, bZIP, ERF, MYB, NAC, WRKY, etc.) in 162 <italic>AhAPX</italic> genes. Gene ontology and KEGG enrichment analysis confirm the role of <italic>AhAPX</italic> 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 <italic>AhAPX4/7/17/77/82/86/130/133</italic> and <italic>AhAPX160</italic> showed significantly higher expression in diverse tissues/organs, i.e., flower, leaf, stem, roots, peg, testa, and cotyledon. Likewise, only a few genes, including <italic>AhAPX4/17/19/55/59/82/101/102/137</italic> and <italic>AhAPX140</italic>, 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 <italic>APX</italic> genes and provided a base for further functional examinations of the <italic>AhAPX</italic> genes in peanut breeding programs.</p>