Rice-Magnaporthe oryzae arms race: From effector diversification and NLR-mediated immunity to CRISPR-driven durable resistance

Abstract

Rice blast is a significant threat to global food security and is caused by the virulent fungal pathogen Magnaporthe oryzae, resulting in a loss of about 30 % of the annual yield. This review will present a synthesis of the molecular processes involved in the interaction between rice and M. oryzae, highlighting the evolutionary arms race between the host and the pathogen. The pathogen exploits the genomic plasticity and diversification of the effectors, to avoid being recognized by the host. In contrast, the host immune system operates through two interconnected defense layers: Pattern-triggered immunity (PTI), which serves as the first line of defense, and the effector-triggered immunity (ETI). ETI is mediated by specialized NLR (nucleotide-binding site–leucine-rich repeat) proteins that initiate rapid hypersensitive responses to restrict pathogen invasion. Although more than 146 resistance (R) genes have been described, the review mentions that single-gene resistance is often unsuccessful because of the rapid evolution of pathogens. The transition to gene pyramiding and altering susceptibility (S genes, such as pi21 and bsr-d1, is necessary. Elaborate breeding techniques have also come to depend on the CRISPR/Cas9 system to perform precise multi-locus stacking and disruption of negative regulators, so as to obtain a more durable and broad-spectrum resistance without loss of any yield. Moreover, predictive receptor-effector structure prediction with the aid of artificial intelligence applications like AlphaFold3, combined with pangenomics to harness the lost genetic diversity, is making rice enhancement a predictive, data-oriented science. The review eventually recommends an integrative model that combines multiomics, digital phenotyping, and computational intelligence, to protect the world's rice production under the pressure of the changed environment and pathogens.