EXPRESSION OF DEFENSE-RELATED ENZYMES IN WILT RESISTANT AND SUSCEPTIBLE VARIETIES OF CHRYSANTHEMUM MORIFOLIUM RAMAT

Abstract

Wilt induced by Fusarium sp. is among the most devastating diseases that restrict the productivity and commercial production of chrysanthemum (Chrysanthemum morifolium Ramat.). Comprehending the biochemical pathways that govern host resistance is crucial for the development of resistant varieties and the formulation of efficient disease management methods. This study aimed to examine the biochemical responses linked to wilt resistance in two distinct chrysanthemum varieties, Cent Yellow and Champagne Orange, after inoculation with a virulent Fusarium sp. isolate. Total protein content, peroxidase (POX), catalase (CAT), polyphenol oxidase (PPO) activities, and total phenol content were assessed at 0, 24, 48, 72, and 96 hours post inoculation (hpi), in conjunction with their corresponding uninoculated controls. The resistant variety demonstrated a gradual increase in total protein content during the trial period, while the susceptible variety exhibited a consistent decrease. The activities of POX and CAT markedly rose in both varieties post-inoculation; however, the induction was more pronounced, prolonged, and elevated in the resistant variety. Polyphenol oxidase activity was constantly high in the resistant variety, but it exhibited only a temporary increase followed by a decrease in the susceptible variety. The total phenol content increased upon pathogen exposure, with the resistant variety consistently exhibiting significantly greater phenolic levels than the susceptible variety over the observation period. The findings indicate that augmented antioxidant enzyme activities, heightened protein accumulation, and higher phenolic content jointly foster resistance to Fusarium wilt in chrysanthemum. Consequently, POX, CAT, PPO, total protein, and total phenol content may function as dependable biochemical indicators for evaluating chrysanthemum germplasm for wilt resistance and facilitate future resistance breeding initiatives.