Successful Silencing of the Mycotoxin Synthesis Gene TRI5 in Fusarium culmorum and Observation of Reduced Virulence in VIGS and SIGS Experiments

Abstract

Crops constantly experience various biotic stresses during their life cycle, and <i>Fusarium</i> spp. remain one of the most serious groups of pathogens affecting plants. The ability to manipulate the expression of certain microorganism genes via RNAi creates the opportunity for new-generation dsRNA-based preparations to control a large number of diseases. In this study, we applied virus-induced gene silencing (VIGS), and spray-induced gene silencing (SIGS) to silence the trichothecene-producing gene <i>TRI5</i> in <i>F. culmorum</i> as a means to reduce its aggressiveness on spring wheat. Treatment of the fungus with dsTRI5RNA in vitro reduced deoxynivalenol (DON) and 3-acetyldeoxynivalenol (3-A-DON) accumulations by 53-85% and 61-87%, respectively, and reduced <i>TRI5</i> expression by 84-97%. VIGS decreased the proportion of infected wheat spikelets by 73%, but upregulation was observed for <i>TRI5</i>. SIGS on wheat leaves and ears using certain dsTRI5RNA amounts negatively impacted <i>F. culmorum</i> growth. However, when performing in vivo analyses of <i>TRI5</i> mRNA levels, the upregulation of the gene was determined in the variants where fungal colonization was restricted, suggesting a compensatory reaction of the pathogen to RNAi.