AUTHOR=Demissie Zerihun A. , Foote Simon J. , Tan Yifang , Loewen Michele C. 

TITLE=Profiling of the Transcriptomic Responses of Clonostachys rosea Upon Treatment With Fusarium graminearum Secretome

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.01061

DOI=10.3389/fmicb.2018.01061

ISSN=1664-302X

ABSTRACT=<p><italic>Clonostachys rosea</italic> strain ACM941 is a fungal bio-control agent patented against the causative agent of Fusarium Head Blight, <italic>Fusarium graminearum</italic>. Although the molecular details remain enigmatic, previous studies have suggested that <italic>C. rosea</italic> may secrete <italic>F. graminearum</italic> growth inhibitors. Further toward this, experiments described herein show that induction of <italic>C. rosea</italic> cultures by the addition of an aliquot of <italic>F. graminearum(Fg)</italic>-spent media (including macroconidia), yield <italic>C. rosea (Cr)</italic>-spent media that elicited higher anti-<italic>F. graminearum</italic> activity than either control or deoxynivalenol (DON)-induced <italic>Cr</italic>-spent media. To gain additional insight into the genetic and metabolic factors modulating this interaction, transcriptomic (RNAseq) profiles of <italic>C. rosea</italic> in response to DON and <italic>Fg-</italic>spent media treatment, were developed. This analysis revealed 24,112 <italic>C. rosea</italic> unigenes, of which 5,605 and 6,285 were differentially regulated by DON and <italic>F-</italic>spent media, respectively. More than half of these unigenes were up-regulated, with annotations, most notably in the <italic>Fg</italic>-spent media treatment data, suggesting enhancement of polyketide (PK) and non-ribosomal peptide (NRP) secondary metabolite precursor synthesis, and PK/NRP-like synthases. Four ABC transporters were also up-regulated in response to <italic>Fg-</italic>spent media. Further analysis showed that the PK and NRP-like synthases belong to three gene clusters that also include ABC transporters, and other genes known to tailor secondary metabolite biosynthesis. The RNAseq data was further validated using quantitative RT-qPCR. Taken together, these results show that <italic>C. rosea</italic> responds to the presence of <italic>Fg</italic>-spent media (and to a lesser extent, DON-alone) by up-regulating unique aspects of its secondary metabolism-related genetic repertoire. The identities and roles of <italic>C. rosea</italic> secondary metabolites produced by the targeted gene clusters are now under investigation.</p>