P-210 - miR169f, dampened by LASSO, is a master regulator of rice root immunity

Root immunity is crucial for plant survival, defending against belowground pathogens and ensuring food security. Emerging evidence highlights the role of non-coding RNAs in regulating plant immune responses to various stresses. In a transcriptomic analysis of root-knot nematode (RKN)-infected rice roots at 3 days post-inoculation (dpi), we identified significant differential expression of microRNA miR169f and its predicted target genes. Integrative network analysis predicted a long antisense non-coding RNA (LASSO) that acts as a molecular sponge, suppressing miR169f activity. qRT-PCR validated increased transcript levels of LASSO and NF-YA1, while miR169f levels decreased upon RKN infection. Functional characterization in Nicotiana benthamiana confirmed miR169f targets NF-YA1 and LASSO sequesters miR169f, forming a competing endogenous RNA regulatory module. Consistently, transgenic miR169f overexpression conferred resistance to RKN, whereas LASSO and NF-YA1 overexpression increased susceptibility. Further functional analysis of these transgenic lines demonstrated that miR169f is a key regulator of the JA-dependent immune response in rice roots. Moreover, root exogenous application of synthetic miR169f enhanced plant resistance to RKN, introducing a non-transgenic strategy for plant protection. These findings reveal a critical role for the LASSO/miR169f/NF-YA1 module in root immunity and highlight the potential of RNA-based approaches for crop protection.