Fungal lncRNA Translocates into Rice Cells and Suppresses Host Immunity

Researchers identified a 1,589-nucleotide fungal long non-coding RNA, lnc117761, that is highly expressed during the appressorium and invasive hypha stages of Magnaporthe oryzae infection of rice. Deletion of the lncRNA gene in multiple fungal strains reduced pathogenicity, producing shorter lesions and lower fungal biomass on infected leaves.

Transgenic rice lines engineered to express the fungal lncRNA showed longer disease lesions and higher fungal biomass than wild-type plants. The lncRNA contains a sequence that pairs with rice miR5827, and electrophoretic mobility shift assays confirmed direct binding between the two RNAs.

Rice miR5827 normally represses PKR1, a gene encoding a negative regulator of immunity. Sequestration of miR5827 by the fungal lncRNA derepresses PKR1, lowering expression of defense marker genes PR1 and PR10 and weakening the plant response. The study reports that the regulatory DNA region encoding lnc117761 is conserved across 150 M.

oryzae strains and appears in diverse species, suggesting a broader role in pathogen-host RNA interactions.

The authors propose that miRNAs derived from the identified DNA region could be used to develop new strategies for controlling rice blast disease.