Antioxidant Responses of Three Pepper (Capsicum annuum) Varieties against Pepper veinal mottle virus

Aims: This study aimed to investigate the changes in antioxidant activity and protein content between non-infected and infected leaves of three Capsicum annuum varieties against Pepper veinal mottle virus. Materials and Methods: Pepper veinal mottle virus isolated from infected pepper plants was inoculated to three healthy varieties of pepper (Pepper Narval, Yolo Wonder and Chili pepper) by gently rubbing on the leaves of 14-day-old seedlings. Control peppers of each variety were treated in the same way with distilled water. The infection of inoculated plants was confirmed by the enzyme-linked immunosorbent assay method. Control and infected leaves were collected 21 days after inoculation (when symptoms manifested) and used for biochemical analyses. Change in different biochemical parameters (catalase, superoxide dismutase, malondialdehyde and protein) in infected pepper plant was observed compared to control non-infected ones. Results: Catalase and superoxide dismutase activities were increased in Pepper Narval and Pepper Yolo Wonder infected leaves compared to non-infected, while a significant decrease was observed in infected Chili pepper compared to control. Higher malondialdehyde content was found in Pepper Yolo Wonder and Chili pepper infected leaves (P < 0.05) than control while a non-significant difference was shown between the infected and non-infected of Pepper Narval variety (P > 0.05). Infected Chili pepper showed high protein content compared to control (P < 0.05). An opposite trend was observed in pepper Narval and Yolo Wonder varieties (P < 0.05). Conclusion: The results of this study showed that Pepper veinal mottle virus infection induces changes in antioxidant enzymes activities, malondialdehyde and total protein levels. These biochemical components were greatly expressed differentially between Pepper veinal mottle virus infected and non-infected in Pepper Yolo Wonder variety. Further studies with more biochemical parameters may contribute to improve the pepper tolerance mechanism to Pepper veinal mottle virus in a breeding program.