@masterthesis{Coort, type = {Bachelor Thesis}, author = {Coort, Katharina}, title = {Rhizosphere and endophytic colonization of cover crops by entomopathogenic fungus Metarhizium brunneum}, school = {Hochschule Rhein-Waal}, abstract = {Species of the entomopathogenic fungal genus Metarhizium (Ascomycota: Hypocreales) are pathogenic to many arthropods, a trait that is utilized in agricultural pest control. Next to their pathogenic lifestyle, many Metarhizium species show plant root association. Due to the potential to improve efficiency in pest management by increasing abundance and persistence in the soil, and positively influence plant development by facilitating nutrient uptake as well as biotic and abiotic stress tolerance (e.g., droughts and diseases), interactions of EPF with plant roots represent valuable characteristics. EPF species Metarhizium brunneum is known for its virulence against wireworms, a major insect pest for example in potato farming, and has shown its root associating abilities before. To investigate its potential in cover crop applications, a recent approach to improve field efficiency in wireworm control, this experiment studied its root associations with seven different cover crop species. In a greenhouse pot trial, one-week-old seedlings were inoculated with M. brunneum isolate Cb 15-ǀǀǀ followed by bulk soil, rhizosphere, and root sampling 8 weeks later, and plating them onto semi selective nutrient agar. Bulk soil and rhizosphere populations were assessed by CFU counting while endophytic root colonization was determined by identification of colonies growing from root cut surfaces. Rhizosphere populations were on average 54 \% higher than bulk soil ii populations, indicating a substantial root association. Endophytic root colonization was observed with 4 out of 7 species. Amongst them were the two Brassicaceae species Raphanus sativus and Sinapis alba as well as grass species Lolium multiflorum which showed the overall highest root associations with M. brunneum. Rhizosphere populations of S. alba were noticeably lower than for all other species while still showing one of the highest internal root colonization rates which potentially originates from species-specific allelochemicals in the rhizosphere. There was a significant negative correlation between Metarhizium populations in the bulk soil and endophytic root colonization, which was interpreted with care considering some analytical constraints. Results from this experiment give insight into root associations of M. brunneum with cover crops and suggest suitable species for further investigation. Deeper understanding of complex interactions which influence plant-fungus relationships (e.g., competition with other soil microbes or the impact of agricultural practices), could improve the efficiency of corresponding products and facilitate additional applications and benefits (e.g. improved nutrient uptake and disease resistance) by utilizing EPF root associations.}, language = {en} }