Blocking miR439 enhances rice disease resistance and yield

Improving disease resistance in plants often incurs a growth and yield penalty. Therefore, identifying and utilizing genetic resources that enhance resistance without compromising yield is an urgent need in crop breeding. In this study, we identified miR439 as a key regulator of both fungal disease resistance and yield-related traits in rice. Blocking or knockout of miR439 enhances grain yield and resistance to blast and sheath blight, whereas its overexpression compromises both traits. miR439 targets and suppresses Wall-associated receptor kinase-like protein 14 (WAKL14) and Subtilisin-like protease 20 (Sub20). Overexpression of these two targets simultaneously enhances disease resistance and yield. WAKL14 and Sub20 function as major downstream mediators contributing to miR439-regulated immunity, basal defense responses, and panicle number. Time-course expression analysis revealed that the accumulation of miR439 and the transcript levels of WAKL14 and Sub20 in leaves and tiller buds are dynamically and inversely correlated throughout the growth period, orchestrating normal development and resistance in rice. Our findings establish a model in which miR439 coordinately regulates rice yield and immunity via two target genes, and demonstrate that MIR439a represents a promising genetic target for breeding rice varieties with improved disease resistance and yield.