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.

Enhancement of adaptive response in peanut hairy root by exogenous signalling molecules under cadmium stress.

Plants counteract Cd toxicity by activating cellular stress responses. The simultaneous exogenous application of methyl jasmonate (MeJA) and methyl-ß-cyclodextrin (CD) before Cd exposure improved the response of Arachis hypogaea hairy root culture to the unfavourable effects of Cd toxicity. At 24 h after elicitation, genes that encode key enzymes in the phenylpropanoid biosynthesis pathway (i.e., PAL and RS3) were up-regulated to 3.2- and 5.4-fold changes respectively, thereby inducing stilbene production. The up-regulation of genes that encode transcription factors (i.e., ERF1 and ERF6) significantly increased the expression of several genes (PR4A, PR5, PR10, and chitinase) that encode the pathogenesis-related (PR) proteins to 25.8-, 45-, 5- and 12.6-fold changes, respectively. The more dramatic up-regulation of PR protein-encoding genes demonstrated the significant role of defence proteins in plant protective mechanisms. The prolonged (i.e., 72-h) treatment with MeJA + CD_Cd triggered adaptive responses by substantially increasing the levels of antioxidants, stilbenes, and other phenolic substances. These findings suggest that the interaction between signalling elicitors (MeJA and CD) and Cd modulates a complex signalling network for plant defence system.