Stilbene synthase is an important enzyme of the phenylpropanoid pathway, regulating the production of several biologically active stilbenoids. These compounds have antioxidant, anti-inflammatory, and anti-cancer properties. However, the detailed characterization of stilbene synthase genes in Arachis hypogaea has not yet been performed. In this study, the comprehensive characterization of stilbene synthase genes in A. hypogaea was conducted, commencing with identification, phylogenetic analysis, and study of their expression in response to exogenous hormonal treatment. We identified and isolated five AhSTSs genes and recorded their expression pattern in peanut (BARD-479) in response to methyl jasmonate (MeJA) and salicylic acid (SA) treatment. The presence of Chal_sti_synt, ACP_syn_III, and FAE1_CUT1_rppA domains in all AhSTSs indicated their role in the biosynthesis of stilbene and lipid metabolism. Cis-regulatory element analysis indicated their role in light responsiveness, defense responses, regulation of seed development, plant growth, and development. Despite close structural and functional similarities, expression and correlational analysis suggested that these genes may have a specific role in peanut, as individual AhSTS exhibited differential expression upon hormonal treatment in a genotype dependent manner. Further studies on functional characterization involving the transcriptional regulation of AhSTSs can clearly explain the differential expression of stilbene synthase genes to hormonal treatment.

Nitric oxide is a gaseous signalling molecule produced by plants. Slight changes in endogenous NO levels have significant biochemical and physiological consequences. We investigated the structural and functional properties of NO-responsive antiporter genes in Arabidopsis thaliana. Phylogenetic analysis of 50 antiporter genes classified them into four subgroups based on the presence of NHX and CPA domains and the evolutionary similarity of the protein sequences. Antiporters were found scattered across the five chromosomes with unique physico-chemical properties and subcellular localisation in the plasma membrane, nucleus, chloroplasts, and vacuole. Furthermore, we performed QPCR analysis of eight different antiporter genes after infiltrating the plants with 1 mM CySNO (S-nitroso-L-cysteine), a nitric oxide donor, in WT and the loss-of-function atgsnor1-3 (disruptive S-nitrosoglutathione reductase 1 activity) plants. The AT1G79400 (CHX2), AT2G38170 (RCI4), and AT5G17400 (ER-ANT1) showed a significant increase in their expression in response to CySNO infiltration. However, their expression in atgsnor1-3 plants was found to be lower than in the WT plants, indicating a significant redundancy in the response of these genes to 1 mM levels of CySNO and physiological levels of SNOs in atgsnor1-3. On the other hand, a significant reduction in the expression of AT1G16380 (CHX1), AT2G47600 (MHX1), AT3G13320 (CAX2), and AT5G11800 (KEA6) was observed in WT plants after CySNO infiltration as well as in the leaves of atgsnor1-3 plants. Our study identified three NO-responsive antiporter genes in Arabidopsis, indicating their roles in stress responsiveness and ion homeostasis that could be used for further validation of their roles in NO signalling in plants.