Identification of a novel microRNA (miRNA) from rice that targets an alternatively spliced transcript of the Nramp6 (Natural resistance-associated macrophage protein 6) gene involved in pathogen resistance

• Published in: The New phytologist Vol. 199; no. 1; pp. 212 - 227
• Main Authors: Campo, Sonia, Peris-Peris, Cristina, Siré, Christelle, Moreno, Ana Beatriz, Donaire, Livia, Zytnicki, Matthias, Notredame, Cedric, Llave, César, San Segundo, Blanca
• Format: Journal Article
• Language: English
• Published: England New Phytologist Trust 01.07.2013; Wiley Subscription Services, Inc; Wiley
• Subjects: Alternative Splicing; Blasts; Defence mechanisms; Disease resistance; DNA microarrays; Domestication; elicitors; Evolution; Fungi; Gene expression; Gene Expression Regulation, Plant; Gene regulation; Genomes; Genomics; Identification; Immunity; Life Sciences; Macrophages; Magnaporthe oryzae; Medical treatment; metal transporter; MicroRNA; MicroRNAs; MicroRNAs - genetics; MicroRNAs - metabolism; miRNA; mRNA processing; Nicotiana - genetics; Nramp; Nucleotide sequences; Oryza; Oryza - genetics; Oryza - microbiology; Oryza sativa; Pathogens; Plant Diseases - genetics; Plant Diseases - microbiology; Plant immunity; Plant Leaves - genetics; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - genetics; Plants; Plants, Genetically Modified; Proteins; Reproducibility of Results; Reverse transcriptase polymerase chain reaction; Ribonucleic acid; Rice; rice (Oryza sativa); Rice blast; RNA; RNA, Plant - genetics; Species Specificity; Transcription; Vegetal Biology; Nramp; Alternative splicing; Elicitors; Magnaporthe oryzae; microRNA; Evolution; Metal transporter; Rice (oryza sativa)
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.12292

Plants have evolved efficient defence mechanisms to defend themselves from pathogen attack. Although many studies have focused on the transcriptional regulation of defence responses, less is known about the involvement of microRNAs (miRNAs) as post-transcriptional regulators of gene expression in plant immunity. This work investigates miRNAs that are regulated by elicitors from the blast fungus Magnaporthe oryzae in rice (Oryza sativa). Small RNA libraries were constructed from rice tissues and subjected to high-throughput sequencing for the identification of elicitor-responsive miRNAs. Target gene expression was examined by microarray analysis. Transgenic lines were used for the analysis of miRNA functioning in disease resistance. Elicitor treatment is accompanied by dynamic alterations in the expression of a significant number of miRNAs, including new members of annotated miRNAs. Novel miRNAs from rice are proposed. We report a new rice miRNA, osa-miR7695, which negatively regulates an alternatively spliced transcript of OsNramp6 (Natural resistance-associated macrophage protein 6). This novel miRNA experienced natural and domestication selection events during evolution, and its overexpression in rice confers pathogen resistance. This study highlights an miRNA-mediated regulation of OsNramp6 in disease resistance, whilst illustrating the existence of a novel regulatory network that integrates miRNA function and mRNA processing in plant immunity.