Effect of Carbendazim Resistance on Trichothecene Production and Aggressiveness of Fusarium graminearum

Abstract

Fusarium graminearum (teleomorph, Gibberella zeae) causes head blight of cereals and contaminates grains with trichothecene mycotoxins that are harmful to humans and domesticated animals. Control of Fusarium head blight relies on carbendazim (MBC) in China, but resistance to MBC in F. graminearum is now widespread. Sixty-seven strains were evaluated for trichothecene production in shake culture or in the field. The strains included 60 wild-type strains (30 MBC-resistant and 30 MBC-sensitive), three MBC-resistant site-directed mutants at codon 167 in beta(2)-tubulin, three MBC-sensitive site-directed mutants at codon 240 in beta(2)-tubulin, and their MBC-sensitive wild-type progenitor strain ZF21. The incidence of infected spikelets and the amount of F. graminearum DNA in field grain (AFgDNA) also were evaluated for all strains. MBC resistance increased trichothecene production in shake culture or in the field. Although MBC resistance did not change the incidence of infected spikelets, it did increase AFgDNA. Tri5 gene expression increased in MBC-resistant strains grown in shake culture. We found a significant exponential relationship between trichothecene production and Tri5 gene expression in shake culture and a linear relationship between the incidence of infected spikelets or AFgDNA and trichothecene production in field grain.

Deoxynivalenol Biosynthesis-Related Gene Expression During Wheat Kernel Colonization by Fusarium graminearum

“…Stephens and colleagues (41) used Affymetrix GeneChips to examine Fusarium gene expression during crown rot of wheat, and reported significant upregulation of Tri5 and Tri14 in planta (compared with mycelial culture). Zhang and colleagues (48) compared Tri5 expression between carbendazin-resistant and -sensitive F. graminearum in shake culture and found higher expression levels in the resistant strain. Gardiner et al (14) showed that Tri5 is strongly expressed in the rachis tissue of wheat, implicating DON in the early spread through the head.…”

Multiple facets of response to fungicides – the influence of azole treatment on expression of key mycotoxin biosynthetic genes and candidate resistance factors in the control of resistant Fusarium strains

“…2). However, there are past reports of resistant strains found in the field (Chen et al 2008;Chen and Zhou 2009) or artificially created via sitedirected mutagenesis of codon 167 in beta-tubulin (Zhang et al 2009b).…”

Impact of Fungicide Timing on the Composition of the Fusarium Head Blight Disease Complex and the Presence of Deoxynivalenol (DON) in Wheat

“…Finally, the presence of DON was also associated with the higher disease classes. Nevertheless, although this link was apparent, no clear linear correlation was observed between quantitative DON presence and disease symptoms (Audenaert et al, 2009 Some exceptions notwithstanding no real contradictory reports are mentioned although Zhang et al (2009b) and Pirgozliev et al (2002) obtained different results on the effect of azoxystrobin to control F. graminearum and F. culmorum. Possibly, these differences originate from different environmental conditions under which experiments were carried out.…”

“…In addition, a benzimidazole binding site on the β-tubulin gene was suggested to be mutated conferring strains resistant to benzimidazole fungicides such as carbendazim (Qiu et al 2011). An even more interesting observation in carbendazim resistant F. graminearum strains was that a proliferated production of DON was observed (Zhang et al 2009b). …”