Comparative study of salicylic acid-induced resistance in moderately resistant and susceptible mango varieties to Colletotrichum asianum

Anthracnose of mango caused by Colletotrichum spp. results in quality loss, reduced shelf life, and diminished market value. Despite its economic impact, the molecular basis of mango–Colletotrichum asianum interactions remains largely unclear. This study assessed the antifungal activity of salicylic acid (SA) against C. asianum and explored its potential mechanisms. SA inhibited mycelial growth in a concentration-dependent manner, with complete arrest of spore germination at concentrations ≥ 2 mM. Postharvest application of 2 mM SA significantly suppressed lesion development in the fruits of ‘Alphonso’ and ‘Banganapalli’ cultivars, compared with untreated controls. Gene expression profiling at 2 mM SA was conducted in ‘Gomavu’ (moderately resistant) and ‘Banganapalli’ (susceptible) cultivars. In ‘Gomavu’, MRNBS-11 transcripts were markedly elevated at 6 and 12 h post-inoculation, indicating early pathogen recognition and activation of defence signalling. Additionally, SA treatment induced the expression of pathogenesis-related (PR) proteins (PR4, PR1A) and defence-related enzymes (Phenylalanine ammonia-lyase, Peroxidase), highlighting their role in restricting C. asianum infection. These findings demonstrate the potential of SA as a postharvest treatment for managing mango anthracnose and provide novel insights into the genetic basis of resistance. Further validation through field trials, and exploration of genetic improvements is recommended to strengthen disease management strategies.