Emerging Dynamics of Blast Disease in Cereals and Millets: Biology, Pathotypes and Management Strategies

Résumé fourni par la source

Blast disease, caused by the filamentous ascomycete Magnaporthe spp. (anamorph: Pyricularia spp.), represents one of the most devastating threats to global cereal and millet production. Originally recognized as a rice pathogen, Magnaporthe oryzae has since adapted to infect several other major crops, including wheat, finger millet, foxtail millet and pearl millet, resulting in significant yield and economic losses worldwide. Globally, yield loss due to blast disease ranges from 70–100% under severe outbreaks, while in India, losses average 28–36%, reaching up to 90% in endemic regions. Ranked among the top ten fungal pathogens due to its scientific and agricultural impact, M. oryzae exhibits high genetic variability, host adaptability and environmental resilience, making it particularly difficult to manage. Historical records trace the earliest descriptions of blast disease to 17th-century in Asia and it is now prevalent across more than 85 rice-growing nations, with expanding incidence in other cereals and millets. The pathogen’s capacity for long-distance dissemination via infected seed and airborne spores, coupled with favourable climatic conditions particularly high humidity and moderate temperatures causes frequent epidemic outbreaks. The emergence of multiple pathotypes, including the Triticum lineage responsible for wheat blast, highlights ongoing evolutionary diversification within the M. oryzae species complex. Several hosts including rice, wheat, finger millet, and pearl millet are being extensively reviewed to understand host–pathogen interactions and mechanisms of resistance. Recent advances in molecular breeding, marker-assisted selection and CRISPR-based genome editing have accelerated the development of resistant cultivars. Additionally, biocontrol agents such as Trichoderma spp., Pseudomonas fluorescens and Bacillus spp. show promise as sustainable alternatives to chemical fungicides. Effective management involves quarantine enforcement, deployment of resistant cultivars, integrated cultural, biological, and chemical control measures, supported by continuous pathogen surveillance, AI-based forecasting and resistance monitoring to safeguard global food security.

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