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Abstract

Mango is an economically important fruit tree widely cultivated in tropical and subtropical countries. Anthracnose is one of the most destructive pre- and postharvest diseases of mango, particularly during ripening. Induction of resistance in plants through the pre-harvest application of fluorescent pseudomonad strains is a promising strategy for disease management. In the present investigation, fifty fluorescent pseudomonad strains were isolated from various mango-growing regions of Tamil Nadu, India, and evaluated for their ability to inhibit the growth of the anthracnose pathogen (Colletotrichum gloeosporioides) in vitro. The isolate KFP1 exhibited the maximum inhibition (66%) of C. gloeosporioides mycelial growth, followed by FP7 (60%). Further, the efficacy of the elite fluorescent pseudomonad strains (KFP1 and FP7), applied individually, in combination, and in combination with or without chitin, was evaluated for their ability to suppress anthracnose and induce defense enzymes in mango trees under field conditions. The results showed that the talc-based formulation of the KFP1 + FP7 + chitin mixture was the most effective treatment for reducing anthracnose incidence. It also improved yield parameters, including flower number, fruit number, and total yield, as well as fruit quality parameters such as free acidity, total soluble solids, ascorbic acid, and total, non-reducing, and reducing sugar contents. A delay in the expression of latent symptoms of up to 15 consecutive days was recorded in fruits maintained at room temperature (28 ± 2°C) following treatment with KFP1 + FP7 + chitin. This treatment also resulted in greater accumulation of phenolics and defense enzymes, including peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL), β-1,3-glucanase, and chitinase, in mango compared with the other treatments. Our findings demonstrate that induced systemic resistance (ISR) triggered by the KFP1 + FP7 + chitin mixture can significantly reduce the incidence of anthracnose, thereby extending the shelf life of mango fruits and improving several fruit quality characteristics.