Rice Blast Disease in India: Present Status and Future Challenges

Abstract

Rice (Oryza sativa L.) is the staple food of the majority of Indians, and India is both the major producer and consumer of rice. Rice cultivation in India is confronted with diverse agro-climatic conditions, varying soil types, and several biotic and abiotic constraints. Among major fungal diseases of Rice in India, the blast caused by Magnaporthe oryzae is the most devastating disease, with the neck blast being the most destructive form. Most of the blast epidemic areas in India have been identified with a mixture of races blast fungus resulting in the resistance breakdown in a short period. At present, a more significant number of the rice varieties cultivated in India were bred by conventional breeding methods with blast resistance conferred by a single resistance gene. Therefore, the blast disease in India is predominantly addressed by the use of ecologically toxic fungicides. In line with the rest of the world, the Indian scientific community has proven its role by identifying several blast resistance genes and successfully pyramiding multiple blast resistance genes. Despite the wealth of information on resistance genes and the availability of biotechnology tools, not a great number of rice varieties in India harbor multiple resistance genes. In the recent past, a shift in the management of blast disease in India has been witnessed with a greater focus on basic research and modern breeding tools such as marker-assisted selection, marker-assisted backcross breeding, and gene pyramiding.

The link between changing in host carbon allocation and resistance to Magnaporthe oryzae : a possible tactic for mitigating the rice blast fungus

“… 1 Rapid and extensive lesions on leaves, stems, and grains are the hallmarks of this destructive disease, which causes large yield losses and negative economic effects. 1 , 2 Rice blast is a calamitous disease that spreads quickly and has the potential to cause significant yield losses. As a result, it poses a threat to global food production.…”

Marker Assisted Introgression of Resistance Genes and Phenotypic Evaluation Enabled Identification of Durable and Broad-Spectrum Blast Resistance in Elite Rice Cultivar, CO 51

“…In addition to this, the frequent emergence of new virulent races also leads to the loss of resistance, even in resistant varieties within a span of 3–4 years. Hence, such resistant lines become susceptible to infection [ 13 ]. Therefore, it is necessary to combine broad-spectrum and durable resistance genes into a single elite rice cultivar.…”

Introgression of genes associated with yield enhancement and resistance against bacterial leaf blight and blast diseases into an elite rice variety, ‘Jaya’ through marker assisted backcrossing

“…As on date 109 signi cant genes for leaf blast resistance have been discovered, of which 25 genes have been molecularly characterized with Pi9 being the rst cloned R gene. The vast majorities of these genes are allelic or closely linked genes that encode disease-resistant NBS-LRR proteins and Zinc nger domains (Annegowda et al 2021). The 'Pi54' locus confers broad-spectrum resistance to various M. oryzae isolates.…”