A research team led by Dr. Xuewei Chen from Sichuan Agricultural University has developed a genetic strategy to enhance broad-spectrum disease resistance in rice without compromising plant growth and yield, a major challenge in crop breeding. The findings are published in The Crop Journal.
Rice, a staple food for half of the global population, is constantly threatened by diseases such as rice blast, bacterial blight, and sheath blight. While lesion mimic mutant (LMM) genes are known to confer broad-spectrum disease resistance, their constitutive activation often triggers autoimmunity that stunts plant growth and reduces yield. Additionally, traditional resistance genes (e.g., NLRs) provide only race-specific protection that is overcome by rapidly evolving pathogens, and many defense regulators exhibit pleiotropic effects on growth.
To address these issues, the research team targeted the AAA-type ATPase gene LRD6-6, a rice LMM gene that suppresses plant immunity via the multivesicular body (MVB)-mediated vesicle trafficking pathway. They first identified a dominant-negative (DN) variant of this gene, LRD6-6E315Q, whose constitutive expression strongly enhanced resistance to multiple rice pathogens but significantly impaired agronomic trait.
The main finding was the identification of a rare pathogen-inducible promoter, MIG6P, through a genome-wide expression screen of early-stage rice-blast fungus interactions. MIG6P exhibits three properties: extremely low basal activity under normal growing conditions, rapid and specific activation within 6 hours of pathogen infection, and no induction by abiotic stresses (high temperature, drought, salt) — an advantage over previously reported inducible promoters that are either pathogen-specific or responsive to environmental stress.
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