Although some lesion mimic mutants (LMMs) confer broad-spectrum disease resistance, their constitutive autoimmunity often penalizes plant growth and yield, limiting their application in crop breeding. Here, we report a novel strategy to overcome this trade-off in rice (Oryza sativa) by introducing a pathogen-inducible LMM gene variant, LRD6-6^E315Q. We first found that constitutive expression of LRD6-6^E315Q, a dominant-negative (DN) variant of the AAA-type ATPase gene LRD6-6, enhanced broad-spectrum resistance but inhibited plant growth, resembling the phenotype of the lrd6-6 mutant. To resolve this trade-off between disease resistance and growth, we screened a rice transcriptome and identified a rare inducible promoter, MIG6P that was specifically activated during early pathogen attack but maintained low activity under normal conditions, and was not inducible by abiotic stresses. We constructed a MIG6P:LRD6-6^E315Q cassette, introduced it into rice cultivar TP309, and developed rice lines with enhanced resistance to multiple diseases, including bacterial blight and fungal diseases rice blast and sheath blight without affecting growth or yield. Since promoters analogous to MIG6P and protein homologs of AAA-type ATPase LRD6-6 carrying potential DN effects occur in diverse plant species, this strategy may be widely applicable to improve disease resistance in other crop species.

Global food security is threatened by rice blast disease caused by the filamentous fungus Magnaporthe oryzae. An understanding of rice resistance mechanisms is fundamental to developing strategies for disease control. In this review, we summarize recent advances in pathogen-associated molecular pattern-triggered immunity, effector-triggered immunity, defense regulator-mediated immunity, and effects of nutrient elements on rice blast resistance. We outline strategies used for breeding rice cultivars with improved disease resistance. We also present the major research challenges for rice blast disease resistance and propose approaches for future investigation.