AUTHOR=Hu Zongli , Parekh Urvi , Maruta Natsumi , Trusov Yuri , Botella Jose R. 

TITLE=Down-regulation of Fusarium oxysporum endogenous genes by Host-Delivered RNA interference enhances disease resistance

JOURNAL=Frontiers in Chemistry

VOLUME=3

YEAR=2015

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2015.00001

DOI=10.3389/fchem.2015.00001

ISSN=2296-2646

ABSTRACT=<p><italic>Fusarium oxysporum</italic> is a devastating pathogen causing extensive yield losses in a variety of crops and development of sustainable, environmentally friendly methods to improve crop resistance is crucial. We have used Host-Delivered RNA interference (HD-RNAi) technology to partially silence three different genes (<italic>FOW2, FRP1</italic>, and <italic>OPR</italic>) in the hemi-biotrophic fungus <italic>F. oxysporum</italic> f. sp. <italic>conglutinans</italic>. Expression of double stranded RNA (dsRNA) molecules targeting fungal pathogen genes was achieved in a number of transgenic Arabidopsis lines. <italic>F. oxysporum</italic> infecting the transgenic lines displayed substantially reduced mRNA levels on all three targeted genes, with an average of 75, 83, and 72% reduction for <italic>FOW2, FRP1</italic>, and <italic>OPR</italic>, respectively. The silencing of pathogen genes had a clear positive effect on the ability of the transgenic lines to fight infection. All transgenic lines displayed enhanced resistance to <italic>F. oxysporum</italic> with delayed disease symptom development, especially <italic>FRP1</italic> and <italic>OPR</italic> lines. Survival rates after fungal infection were higher in the transgenic lines compared to control wild type plants which consistently showed survival rates of 10%, with <italic>FOW2</italic> lines showing 25% survival; <italic>FRP1</italic> lines 30–50% survival and <italic>OPR</italic> between 45 and 70% survival. The down-regulation effect was specific for the targeted genes without unintended effects in related genes. In addition to producing resistant crops, HD-RNAi can provide a useful tool to rapidly screen candidate fungal pathogenicity genes without the need to produce fungal knockout mutants.</p>