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A myosin5 dsRNA that reduces the fungicide resistance and pathogenicity of Fusarium asiaticum

Xiu-Shi Song: Nanjing agricultural university

<div>Fungal resistance to fungicides is a serious challenge in crop protection. Although strategies have been found to prevent the development of fungicide resistance, no strategy has been found to reduce such resistance once it has occurred. We demonstrate that the application of a <em>Myo5</em> dsRNA, which interferes with the target gene of the fungicide phenamacril in <em>Fusarium</em>, decreased <em>F.</em> <em>asiaticum</em> resistance to phenamacril as well as plant resistance to <em>F. </em><em>asiaticum</em> infection. The silencing of <em>Myo5</em> also resulted in cell wall defects, life cycle disruption, and virulence reduction. Unexpectedly, the silencing lasted for only a short time in <em>F. </em><em>asiaticum</em> unless the dsRNA was continuously supplied. After being treated with a mixture of Myo5-8 dsRNA and phenamacril, plants highly resisted phenamacril resistance strain infection. Myo5-8 dsRNA was found to be highly conserved among <em>F. asiaticum</em>, <em>F. grammearum</em>, <em>F. tricinctum</em>, and <em>F. oxysporum</em>, and induced sequence-specific RNAi activity in these <em>Fusarium</em> species but not in other fungi. Our findings suggest a new strategy for reducing fungicide resistance and for designing new fungicides, which is significant in controlling of pathogens which easily develop fungicide resistance or are lack of natural resistance and specific fungicide.</div>