Combining elicitor treatment of chitosan, methyl jasmonate, and cyclodextrin to induce the generation of immune response bioactive peptides in peanut hairy root culture.

The endogenous peptides from peanut hairy root culture were induced upon elicitor treatment with chitosan (CHT), methyl jasmonate (MeJA), and cyclodextrin (CD): CHT+MeJA+CD. The peptides secreted into the liquid culture medium play an important role in plant signaling and stress responses. By performing gene ontology (GO) analysis, a number of plant proteins involved in biotic and abiotic defense responses were identified, such as endochitinase, defensin, antifungal protein, cationic peroxidase and Bowman-Birk type protease inhibitor A-II. The bioactivity of 14 peptides synthesized from secretome analysis was determined. Peptide BBP1-4, derived from the diverse region of Bowman-Birk type protease inhibitor, displayed high antioxidant activity and mimicked the property of chitinase and ß-1,3-glucanase enzymes. The antimicrobial activity against S. aureus, S. typhimurium, and E. coli was evidenced with different peptide concentrations. Additionally, peptide BBP1-4 has the potential to be a useful candidate for an immune response property, as it was found to increase the expression of some pathogenesis-related (PR) proteins and stilbene biosynthesis genes in peanut hairy root tissues. The findings indicate that secreted peptides may play a role in plant responses to both abiotic and biotic stresses. These peptides, which possess bioactive properties, could be considered as potential candidates for use in the pharmaceutical, agricultural, and food industries.

Effect of light and mechanical stress in combination with chemical elicitors on the production of stilbene compounds and defensive responses in peanut hairy root culture.

Plants encounter diverse stressors simultaneously with changing environmental factors. The combined effect of different types of stresses can have a wide range of effects on plants. The present study demonstrated that various stress factors such as the combination of chemical elicitors, namely paraquat (PQ), methyl jasmonate (MeJA) and methyl-ß-cyclodextrin (CD), light exposure versus darkness, and mechanical shearing stress affected the defence response in peanut hairy root culture. The antioxidant activities were dramatically increased at all time points after hairy roots were subjected to elicitation with PQ + MeJA + CD under root cutting in both light and dark conditions. The stilbene compounds were highly increased in the culture medium after elicitor treatment of uncut hairy roots under dark conditions. In contrast to the high stilbene contents detected in culture medium under dark conditions, the transcription of the stilbene biosynthesis genes PAL, RS and RS3 was enhanced by the effect of light in uncut hairy root tissues. The antioxidant enzyme genes APX, GPX and CuZn-SOD of uncut and cut hairy roots were more highly expressed in light conditions than in dark conditions. The pathogenesis-related protein (PR)-encoding genes chitinase, PR4A, PR5 and PR10 of uncut hairy roots were highly expressed in response to light conditions compared to dark conditions at all time points. Recent evidence of the production of antioxidant stilbene compounds and defence response genes has implicated plant protective functions through defence responses under different stress challenges. Plant responses might therefore be regulated by the coordination of different signal responses through dynamic pathways.