An ATP-Binding Cassette Pleiotropic Drug Transporter Protein Is Required for Xenobiotic Tolerance and Antagonism in the Fungal Biocontrol Agent Clonostachys rosea

Abstract

ATP-binding cassette (ABC) transporters mediate active efflux of natural and synthetic toxicants and are considered to be important for drug tolerance in microorganisms. In biological control agents (BCA), ABC transporters can play important roles in antagonism by providing protection against toxins derived from the fungal prey and by mediating the secretion of endogenous toxins. In the present study, we generated deletion and complementation strains of the ABC transporter abcG5 in the fungal BCA Clonostachys rosea to study its role in xenobiotic tolerance and antagonism. Gene expression analysis shows induced expression of abcG5 in the presence of the Fusarium mycotoxin zearalenone (ZEA), secreted metabolites of F. graminearum, and different classes of fungicides. Phenotypic analysis of abcG5 deletion and complementation strains showed that the deletion strains were more sensitive towards F. graminearum culture filtrates, ZEA, and iprodione- and mefenoxam-based fungicides, thus suggesting the involvement of abcG5 in cell protection. The ΔabcG5 strains displayed reduced antagonism towards F. graminearum in a plate confrontation assay. Furthermore, the ΔabcG5 strains failed to protect barley seedlings from F. graminearium foot rot disease. These data show that the abcG5 ABC transporter is important for xenobiotic tolerance and biocontrol traits in C. rosea.

The mycoparasitic fungus Clonostachys rosea responds with both common and specific gene expression during interspecific interactions with fungal prey

“…Putative transformants were selected on a plate containing hygromycin (200 μg/ml). Validation of homologous integration of the deletion cassettes in putative transformants was performed using a PCR screening approach with primer combinations targeting the hph gene (Hyg F/Hyg R) and sequences flanking the deletion cassettes (Appendices and ) as described previously (Dubey, Jensen, & Karlsson, ; Dubey et al., ). RT‐PCR analysis was conducted on WT and gene deletion strains using RevertAid premium reverse transcriptase (Fermentas, St. Leon‐Rot, Germany) and primer pairs specific for the respective genes (Appendix ).…”

“…Several biocontrol mechanisms are reported in C. rosea , including direct parasitism of pathogenic fungi (Li, Huang, Kokko, & Acharya, ; Yu & Sutton, ), antibiosis (Pachenari & Dix, ; Rodriguez et al., ), production of fungal cell wall degrading enzymes (Chatterton & Punja, ; Mamarabadi, Jensen, & Lubeck, ), induction of plant defence reactions (Lahlali & Peng, ; Roberti et al., ) and plant growth promotion (Roberti et al., ). Tolerance towards, and detoxification of, toxic metabolites produced by the fungal prey is also reported to be an important biocontrol trait in C. rosea (Dubey, Jensen, & Karlsson, ; Kosawang, Karlsson, Velez et al., ).…”

Identifying glycoside hydrolase family 18 genes in the mycoparasitic fungal species Clonostachys rosea

“…S2e). Previous studies have showed that expression of hygB in C. rosea does not result in any detectable growth-or biocontrol-related phenotypes (Dubey et al, 2014b;Lübeck et al, 2002).…”

Translating biosynthetic gene clusters into fungal armor and weaponry

“…As ABC transporters are known to display some promiscuity in their substrates, it is likely that many transporters protect from SMs produced by other fungi 35 . This can be illustrated in Neurospora crassa , a fungus sensitive to cer-cosporin that possesses a transporter conferring some resistance to the toxin 36 , or in the biocontrol fungus Clonostachys rosea , which contains an ABC transporter protective against the Fusarium mycotoxin zearalenone as well as several fungicides 37 .…”