Osa-miR169 Negatively Regulates Rice Immunity against the Blast Fungus Magnaporthe oryzae

Abstract

miR169 is a conserved microRNA (miRNA) family involved in plant development and stress-induced responses. However, how miR169 functions in rice immunity remains unclear. Here, we show that miR169 acts as a negative regulator in rice immunity against the blast fungus Magnaporthe oryzae by repressing the expression of nuclear factor Y-A (NF-YA) genes. The accumulation of miR169 was significantly increased in a susceptible accession but slightly fluctuated in a resistant accession upon M. oryzae infection. Consistently, the transgenic lines overexpressing miR169a became hyper-susceptible to different M. oryzae strains associated with reduced expression of defense-related genes and lack of hydrogen peroxide accumulation at the infection site. Consequently, the expression of its target genes, the NF-YA family members, was down-regulated by the overexpression of miR169a at either transcriptional or translational level. On the contrary, overexpression of a target mimicry that acts as a sponge to trap miR169a led to enhanced resistance to M. oryzae. In addition, three of miR169’s target genes were also differentially up-regulated in the resistant accession upon M. oryzae infection. Taken together, our data indicate that miR169 negatively regulates rice immunity against M. oryzae by differentially repressing its target genes and provide the potential to engineer rice blast resistance via a miRNA.

A novel fungal effector from Puccinia graminis suppressing RNA silencing and plant defense responses

“…The miR169-NF-YA modules play crucial roles in plant growth, plant development, nutrition and abiotic stresses (Misson et al, 2005;Nelson et al, 2007;Pant et al, 2009;Liu & Howell, 2010). Most recently, miR169a has been implicated as a negative regulator in rice immunity against the blast fungus M. oryzae by repressing the expression of NF-YA genes (Li et al, 2017). MiR164 and two NAC and WRKY2 transcription factor targets that were affected by PgtSR1s are also known to play important roles in response to abiotic and biotic stresses (Pandey & Somssich, 2009;Nuruzzaman et al, 2013).…”

Osa‐miR398b boosts H2O2 production and rice blast disease‐resistance via multiple superoxide dismutases

“…YFP detection and accumulation was assayed as reported previously (Li et al ., ,b). In order to generate miR398 target‐site reporter fusions, we fused yellow fluorescent protein (YFP) with either the target site of Superoxide DismutaseX ( SODX ) at its N‐terminus ( 35S:SODX ts ‐YFP ) or with a mutated target site ( 35S:SODX mts ‐YFP ) that could not be recognized by miR398b.…”

A combined microRNA and transcriptome analyses illuminates the resistance response of rice against brown planthopper

“…2a), many of which belonged to known miRNA families including miR156, miRNA160, miR166, miR169, miR1846, miR1861 and miR319 (Additional file 3: Table S2). Members of the miRNA families were reported to be involved not only in growth, development, grain size and hormone signaling, but also in response to biotic and abiotic stress [21][22][23][24][25][26][27][28][29][30][31]. These BPH6 responsive DEMs might be involved in response to BPH.…”

“…miRNAs specifically regulate target gene expression through binding complementary sequences to degrade mRNA or inhibit translation [19]. Plant miRNAs are involved in many development processes, including hormone signal transduction, and leaf, floral, shoot, root and vascular development [20][21][22], and play significant roles in abiotic and biotic stress responses [23][24][25][26][27][28]. miR160 is associated with local defense and systemic acquired resistance to potato late blight [24].…”

“…miR160 is associated with local defense and systemic acquired resistance to potato late blight [24]. miR166, miR169 and miR319 participate in the regulation of rice immunity against the blast fungus Magnaporthe oryzae [25][26][27][28]. However, few miRNAs have been revealed functioning in insect response.…”