Osa-miR162a fine-tunes rice resistance toMagnaporthe oryzaeand Yield

MicroRNAs (miRNAs) play essential roles in rice immunity againstMagnaporthe oryzae, the causative agent of rice blast disease. Here we demonstrate that Osa-miR162a fine-tunes rice immunity againstM. oryzaeand yield traits. Overexpression of Osa-miR162a enhances rice resistance toM. oryzaeaccompanying enhanced induction of defense-related genes and accumulation of hydrogen peroxide (H2O2). In contrast, blocking Osa-miR162 by overexpressing a target mimic of Osa-miR162a enhances susceptibility to blast fungus associating with compromised induction of defense-related gene expression and H(2)O(2)accumulation. Moreover, the transgenic lines overexpressing Osa-miR162a display decreased seed setting rate resulting in slight reduced yield per plant, whereas the transgenic lines blocking Osa-miR162 show an increased number of grains per panicle, resulting in increased yield per plant. Altered accumulation of Osa-miR162 had a limited impact on the expression of riceDicer-like 1(OsDCL1) in these transgenic lines showing normal gross morphology, and silencing ofOsDCL1led to enhanced resistance to blast fungus similar to that caused by overexpression of Osa-miR162a, suggesting the involvement ofOsDCL1in Osa-miR162a-regulated resistance. Together, our results indicate that Osa-miR162a is involved in rice immunity againstM. oryzaeand fine-tunes resistance and yield.