Modulation of plant defenses by Jasmonic acid and salicylic acid in Capsicum annuum L. against Fusarium wilt in response to Fusarium oxysporum pathogen

Wilt disease in chilli caused by Fusarium oxysporum is a serious and global issue in chilli production, necessitating greater knowledge of plant defense systems for overall disease protection and management. In an eco-friendly integrated agricultural protection system, the introduction of chemical elicitors like jasmonic acid (JA) and salicylic acid (SA) represents an attractive new prospect means of controlling bacterial and fungal diseases. In the present study effectiveness of JA and SA as elicitors in disease progression was investigated in Capsicum annuum L. c.v., Kashmiri longum (chilli) plants against Fusarium wilt caused by pathogen Fusarium oxysporum. The experiment had eight sets of plants as control (untreated, uninfected), infected (untreated, infected), and one set of plants for each concentration of JA treatment (50 µM, 100 µM, 150 µM) + pathogen, and SA treatment (50 µM, 100 µM, 150 µM) + pathogen. Pre-treatment of JA and SA elicitors to F.oxysorum-infected chilli plants showed significant decrease in disease severity index as well as in disease symptoms compared to pathogen-infected and control plants. There was a substantial increase in the activities of antioxidant and defense enzymes in elicitor treated samples post pathogen inoculation. Exogenous application of JA and SA enhanced the growth of morphological parameters (shoot length, root length, number of leaves, leaf area, and plant height). Moreover, the statistical analysis using two-way ANOVA and Tukey test revealed significant differences between treatments, and days post infection in comparison to control. The study found that each elicitor treatment significantly differs in the type of enzymes activated and their amounts post-inoculation, indicating distinct host reaction patterns. Overall, the current study highlights the induced defense resistance role of JA and SA in chilli plants in response to F.oxysporum and JA was found most effective concerning disease protection followed by SA.