Novel Ascorbate Peroxidase from Common Vetch (Vicia sativa)

Ascorbate peroxidase (APX) is a heme containing enzyme that acts as a key scavenging enzyme in the Ascorbate-Glutathione (AsA-GSH) cycle to scavenge hydrogen peroxide (H ₂ O ₂ ). APX expression in plants can enhance their tolerance to environmental stresses, potentially increasing crop yield. In this study, the full-length genomic DNA and cDNA of the APX gene were successfully cloned and characterized from Vicia sativa . The full-length gDNA- APX was 2425 bp with 10 exons that is enterspaced by nine introns. The first intron is located within the 5’-untranslated region (5’UTR). The transcribed cDNA (1010 bp) covers 5’UTR (61 bp), 3’UTR (196 bp) and open reading frame (ORF) (753 bp). It encodes the cytosolic APX protein (250 amino acids) with a molecular weight of 27.1 kDa and a theoretical isoelectric point (pI) of 5.60. Bioinformatic analysis of the deduced VsAPX1 amino acid sequence displays a high similarity with other plant species cytosolic APX. The main conserved domains were also determined, and the phylogenetic analysis showed that VsAPX1 clustered with the cytosolic APX clade. The expression pattern of VsAPX1 was determined using qRT-PCR in response to different stresses. Compared to the control, the level of VsAPX1 transcript showed an early increase after 2 h in response to heat stress (42 ^o C), abscisic acid, and salicylic acid, while being upregulated after 4 h of jasmonic acid treatment. While hydrogen peroxide treatment, caused a downregulation of VsAPX1 expression over time. The overall results suggest that VsAPX1 plays a role major in common vetch response to heat and plant bioregulators.