Abstract
Rhizoctonia solani, the causal agent of rice sheath blight disease, causes significant losses worldwide as there are no cultivars providing absolute resistance to this fungal pathogen. We have used Host Delivered RNA Interference (HD-RNAi) technology to target two PATHOGENICITY MAP KINASE 1 (PMK1) homologues, RPMK1-1 and RPMK1-2, from R. solani using a hybrid RNAi construct. PMK1 homologues in other fungal pathogens are essential for the formation of appressorium, the fungal infection structures required for penetration of the plant cuticle, as well as invasive growth once inside the plant tissues and overall viability of the pathogen within the plant. Evaluation of transgenic rice lines revealed a significant decrease in fungal infection levels compared to non-transformed controls and the observed delay in disease symptoms was further confirmed through microscopic studies. Relative expression levels of the targeted genes, RPMK1-1 and RPMK1-2, were determined in R. solani infecting either transgenic or control lines with significantly lower levels observed in R. solani infecting transgenic lines carrying the HD-RNAi constructs. This is the first report demonstrating the effectiveness of HD-RNAi against sheath blight and offers new opportunities for durable control of the disease as it does not rely on resistance conferred by major resistance genes.
Highlights
Rice is one of the most important cereal crops and a source of staple food for nearly half of the global population
Pathogenic MAP Kinase 1 (PMK1) was chosen for our study as it plays an important role in several pathogenic fungi including Magnaporthe grisea, Colletotrichum lagenarium, Cochliobolus heterostrophus and Pyrenophora teres[40]
The effect that climate change will have on rice production is unknown and it could have an important impact on the ever increasing food demand to feed the growing world population
Summary
Rice is one of the most important cereal crops and a source of staple food for nearly half of the global population. Artificial selection during rice domestication, has resulted in a significant reduction of genetic diversity in the gene pool among the present day rice cultivars[20]. This process has largely contributed to the genetic vulnerability of modern rice lines to various biotic and abiotic stresses. In this context, transgenic approaches offer new opportunities to www.nature.com/scientificreports/. Genetic engineering is a promising strategy to generate crops with resistance against economically important plant diseases like rice ShB. We observed increased ShB resistance in the transgenic lines accompanied by a concomitant decrease in fungal expression levels for the targeted genes, compared to controls
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