AUTHOR=Tan Jiang , De Zutter Noémie , De Saeger Sarah , De Boevre Marthe , Tran Trang Minh , van der Lee Theo , Waalwijk Cees , Willems Anne , Vandamme Peter , Ameye Maarten , Audenaert Kris 

TITLE=Presence of the Weakly Pathogenic Fusarium poae in the Fusarium Head Blight Disease Complex Hampers Biocontrol and Chemical Control of the Virulent Fusarium graminearum Pathogen

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.641890

DOI=10.3389/fpls.2021.641890

ISSN=1664-462X

ABSTRACT=<p>Fusarium head blight (FHB) in wheat (<italic>Triticum aestivum</italic> L.) is caused by a consortium of mutually interacting Fusarium species. In the field, the weakly pathogenic <italic>F. poae</italic> often thrives on the infection sites of the virulent <italic>F. graminearum</italic>. In this ecological context, we investigated the efficacy of chemical and biocontrol agents against <italic>F. graminearum</italic> in wheat ears. For this purpose, one fungicide comprising prothioconazole + spiroxamine and two bacterial biocontrol strains, <italic>Streptomyces rimosus</italic> LMG 19352 and <italic>Rhodococcus</italic> sp. R-43120 were tested for their efficacy to reduce FHB symptoms and mycotoxin (deoxynivalenol, DON) production by <italic>F. graminearum</italic> in presence or absence of <italic>F. poae</italic>. Results showed that the fungicide and both actinobacterial strains reduced FHB symptoms and concomitant DON levels in wheat ears inoculated with <italic>F. graminearum</italic>. Where <italic>Streptomyces rimosus</italic> appeared to have direct antagonistic effects, <italic>Rhodococcus</italic> and the fungicide mediated suppression of <italic>F. graminearum</italic> was linked to the archetypal salicylic acid and jasmonic acid defense pathways that involve the activation of <italic>LOX1</italic>, <italic>LOX2</italic> and <italic>ICS</italic>. Remarkably, this chemical- and biocontrol efficacy was significantly reduced when <italic>F. poae</italic> was co-inoculated with <italic>F. graminearum</italic>. This reduced efficacy was linked to a suppression of the plant’s intrinsic defense system and increased levels of DON. In conclusion, our study shows that control strategies against the virulent <italic>F. graminearum</italic> in the disease complex causing FHB are hampered by the presence of the weakly pathogenic <italic>F. poae</italic>. This study provides generic insights in the complexity of control strategies against plant diseases caused by multiple pathogens.</p>