Transcriptomic and Exometabolomic Profiling Reveals Antagonistic and Defensive Modes of Clonostachys rosea Action Against Fusarium graminearum

Abstract

The mycoparasite Clonostachys rosea ACM941 is under development as a biocontrol organism against Fusarium graminearum, the causative agent of Fusarium head blight in cereals. To identify molecular factors associated with this interaction, the transcriptomic and exometabolomic profiles of C. rosea and F. graminearum GZ3639 were compared during coculture. Prior to physical contact, the antagonistic activity of C. rosea correlated with a response heavily dominated by upregulation of polyketide synthase gene clusters, consistent with the detected accumulation of corresponding secondary metabolite products. Similarly, prior to contact, trichothecene gene clusters were upregulated in F. graminearum, while those responsible for fusarielin and fusarin biosynthesis were downregulated, correlating with an accumulation of trichothecene products in the interaction zone over time. A concomitant increase in 15-acetyl deoxynivalenol-3-glucoside in the interaction zone was also detected, with C. rosea established as the source of this detoxified mycotoxin. After hyphal contact, C. rosea was found to predominantly transcribe genes encoding cell wall–degradation enzymes, major facilitator superfamily sugar transporters, anion:cation symporters, as well as alternative carbon source utilization pathways, together indicative of a transition to necrotropism at this stage. F. graminearum notably activated the transcription of phosphate starvation pathway signature genes at this time. Overall, a number of signature molecular mechanisms likely contributing to antagonistic activity by C. rosea against F. graminearum, as well as its mycotoxin tolerance, are identified in this report, yielding several new testable hypotheses toward understanding the basis of C. rosea as a biocontrol agent for continued agronomic development and application.

The role of Dicer-dependent RNA interference in regulating cross-species communication during fungus-fungus interactions

“…The sorbicillin BGC, responsible for the yellow coloration of WT C. rosea colonies [50], is downregulated in Δdcl2, and both sorbicillin and sorbicillinol were underproduced in Δdcl2 and had their biosynthesis restored in the complementation mutant in the in vitro trials, explaining the difference in pigmentation of the Δdcl2 mutant. This gene cluster was also induced during the interaction of C. rosea strain ACM941 with F. graminearum in the study of Demissie et al [48]. However, it is interesting to notice how the positive regulator of the cluster, YPR1 (CRV2G00015416), is not differentially expressed in our study, while the transcription factor YPR2 (CRV2G00015419) is down-regulated and hence coregulated with the other genes in the gene cluster in Δdcl2.…”

“…Among these were three GH18 chitinases (ech37, ech42 and chiA5) and one GH20 N-acetylhexosaminidase (CRV2G00012950), which were downregulated during interaction with both mycohosts. Furthermore, four genes putatively involved in cell wall degradation of F. graminearum [48] were found to be downregulated in the Δdcl2 mutant: these were two glycoside hydrolases of classes GH2 (CRV2G00016896) and GH114 (CRV2G00003509), as well as two metallopeptidases (CRV2G00010851 and CRV2G00011092). Interestingly, the gene chiC1, predicted to encode a killer toxin-like chitinase that permeabilizes the cell wall of antagonistic species to facilitate entry of toxic metabolites [121,122], is upregulated in the Δdcl2 mutant.…”

“…C. rosea efficiently overgrows and kills its mycohosts such as Botrytis cinerea and Fusarium graminearum [41][42][43]. During mycoparasitic interactions or exposure to the secreted factors from mycohosts, C. rosea induces expression of genes associated with the production of secondary metabolites, hydrolytic enzymes and other secreted proteins [43][44][45][46][47][48][49][50]. Furthermore, C. rosea induces expression of genes coding for membrane transporters to efflux the endogenous toxic compounds and exogenous metabolites that may come from interacting organisms during the interspecific interactions [49,51,52].…”

Role of Dicer-Dependent RNA Interference in Regulating Mycoparasitic Interactions

“…The sorbicillin BGC, responsible for the yellow coloration of WT C. rosea colonies ( 50 ), is downregulated in the Δ dcl2 mutant, and both sorbicillin and sorbicillinol were underproduced in the Δ dcl2 mutant and had their biosynthesis restored in the complementation mutant in the in vitro trials, explaining the difference in pigmentation of the Δ dcl2 mutant. This gene cluster was also induced during the interaction of C. rosea strain ACM941 with F. graminearum in the study of Demissie et al ( 48 ). However, it is interesting that the positive regulator of the cluster, YPR1 (CRV2G00015416), is not differentially expressed in our study, whereas the transcription factor YPR2 (CRV2G00015419) is downregulated and hence coregulated with the other genes in the gene cluster in the Δ dcl2 mutant.…”

Antifungal activity of epecific plant essential oils against fusarium graminearum

“…These agents prevent the natural compounds from binding their natural targets and inhibit biochemical processes. These important processes are composed of nucleic acid metabolism, cytoskeleton, respiration, signal transduction and sterol biosynthesis [9][10][11][12][13]. Currently, the high use of these fungicides, the increased use of aromatic hydrocarbons, and use in common of various fungicides worldwide, led to an increase in the levels of fungicide resistance in fungus [14][15][16].…”