Defence Responses in Rice against Bipolaris oryzae, the Causal Agent of Brown Spot Disease: A Comprehensive Review

Abstract

Brown spot disease caused by Bipolaris oryzae remains a persistent threat to global rice production, with potential yield losses of up to 90%. This review consolidates current knowledge on the pathogen’s biology, epidemiology and host-pathogen interactions, with particular emphasis on structural, biochemical, hormonal and genetic defence mechanisms in rice. Both pre-existing and induced defence responses are discussed, including callose deposition, accumulation of phytoalexins and phenolic compounds, activation of antioxidant enzymes, detoxification of pathogen toxins, hormone mediated resistance and R gene-mediated resistance. This review was prepared through a comprehensive analysis of research articles retrieved from databases such as PubMed, Scopus and Google Scholar, covering vast number of studies. Recent advances in molecular studies, including gene expression profiling and quantitative trait loci (QTL) identification have further elucidated resistance mechanisms against brown spot disease. A comprehensive understanding of these defence pathways is essential for developing durable resistance strategies through breeding and biotechnological approaches. Insights into these mechanisms can guide future breeding and biotechnological approaches for durable resistance.