Enzymatic profiling and phenolic response of leaf spot pathogen from Punica granatum under controlled nutritional condition

The current study investigates the enzymatic profiling and phenolic response of Alternaria alternata, a leaf spot pathogen isolated from Punica granatum (pomegranate), under varied nutritional conditions. This research aims to understand how distinct carbon and nitrogen sources influence the production of cellulolytic enzymes and phenolic compounds, which are pivotal for fungal pathogenicity and host-pathogen interaction. The fungus was cultured in modified Czapek-Dox liquid medium, incorporating different carbon (glucose, dextrose, lactose, fructose) and nitrogen (KNO?, Ni(NO?)?, Ba(NO?)?, Co(NO?)?) sources. Enzymatic activity was assessed using the loss of coherence method on filter paper discs, while total phenol content was estimated through a colorimetric assay using Folin-Ciocalteu reagent. Results indicated that lactose and fructose as carbon sources showed maximum cellulolytic activity (M.A. = 67.57), while KNO? and Ni(NO?)? among nitrogen sources exhibited comparatively reduced macerating activities. Phenolic production was highest with dextrose (4.425 mg/L) and Ni(NO?)? (3.753 mg/L), suggesting enhanced oxidative stress response in nutrient-rich media. The findings underscore the nutritional modulation of fungal virulence traits, emphasizing how altered nutrient regimes can influence the biochemical arsenal of pathogenic fungi.