What's happening at IRRI
Friday, October 14, 2016, 02:00pm - 03:00pm
PB & GB Special Joint Division Seminar
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MicroRNAs (miRNAs) in rice innate immunity
Blanca San Segundo
Professor of Research
Spanish Research Council (CSIC)
Center for Research in Agricultural Genomics
1400-1500H, Friday, 14 October 2016
PBGB Conference Room 1
NC Brady Laboratory Bldg.
MicroRNAs (miRNAs) are short regulatory non-coding RNAs that guide gene silencing by triggering sequence-specific cleavage or translational repression of target transcripts. Plant miRNAs are known to play important roles in a wide range of developmental processes and adaptive responses to abiotic stress (drought, cold, salinity and nutrient deficiency) and biotic stress (e.g. antibacterial resistance). During the last years, the adoption of high-throughput sequencing technologies has significantly contributed to uncover multiple miRNAs while allowing miRNA profiling in rice. Although a substantial fraction of the rice miRNA transcriptome has been shown to be responsive to infection by the rice blast fungus Magnaporthe oryzae, the exact role of most of these pathogen-regulated miRNAs in rice immunity remains elusive.
To obtain a genome-wide survey of miRNAs in rice and their responsiveness to M. oryzae, we constructed small RNA libraries from rice leaves that have been treated, or not, with M. oryzae elicitors. This study allowed us to identify not only known miRNAs, but also previously unknown miRNAs (novel miRNAs) from rice whose expression is affected by treatment with fungal elicitors. The contribution of several elicitor-regulated miRNAs in resistance to blast disease has been confirmed in transgenic rice, including miRNAs controlling the expression of genes involved in nutrient homeostasis. Pathogen-regulated miRNAs can function as positive or negative regulators of the rice defense response to M. oryzae. Combined small RNA and degradome analyses revealed regulatory networks enriched in elicitor-regulated miRNAs supported by the identification of their corresponding target genes. Specifically, we identified an important number of miRNA/target gene pairs involved in small RNA pathways, hormone signaling and crosstalk among hormone pathways having great potential in regulating rice immunity. These findings support that miRNAs, and their corresponding target genes, represent an integral part of the rice response to infection by the blast fungus M. oryzae.
PBGB Conference Room 1