The fungal root-endophyte Trichoderma virens: Combinations with rhizosphere competent Bacilli to achieve synergistic effects in rapeseed systemic resistance induction

Fatema Binte Hafiz, Jörg Geistlinger, Ingo Schellenberg

Anhalt University of Applied Sciences, Institute of Bioanalytical Sciences (IBAS)

Combinations of different root-endophytic T. virens strains and supporting Bacillus species will be tested for beneficial influences on plant performance by using an in-vitro system of sterile rapeseed plants. Root and plant development will be recorded. Fungal root colonization densities will be monitored by qPCR and molecular markers and be correlated to the utilized mycorrhiza helper bacteria. Favorable combinations leading to enhanced root colonization with the fungal endophytes will be identified and systemic plant responses be analyzed at the gene expression level. Marker genes for SAR and ISR pathways will be applied to dissect plant responses at the systemic level. In the final step rapeseed plantlets will be inoculated with the most promising combinations of beneficial microbes and subsequently being challenged with fungal pathogens. Effectiveness of elevated systemic resistance levels on the inhibition of fungal plant pathogens will be evaluated. The main research questions are: • Can the synergistic effects demonstrated for T. harzianum and B. amyloliquefaciens concerning enhanced root colonization densities of the fungus in maize be successfully transferred to the combination T. virens and Bacillus sp. in a rapeseed bioassay? • Is root colonization density with beneficial root-endophytic fungi directly correlated to enhanced root growth and improved plant performance? • Are genes involved in SAR and ISR pathways significantly up-regulated in plants with roots well colonized by T. virens (priming effect)? • Do elevated expression levels of such genes directly reflect improved tolerance of crop plants to fungal pathogens?