Location: Sustainable Perennial Crops
Title: Establishing fungal entomopathogens as endophytes: towards endophytic biological control Authors
Submitted to: Journal of Visualized Experiments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 15, 2013
Publication Date: April 11, 2013
Citation: Parsa, S., Ortiz, V., Vega, F.E. 2013. Establishing fungal entomopathogens as endophytes: towards endophytic biological control. Journal of Visualized Experiments. 74:e50360. Interpretive Summary: The common bean (Phaseolus vulgaris), can be affected by more than 400 pests and 200 pathogens, whose attack is thought to be the most limiting bean production factor across many regions. Accordingly, the common bean may be an excellent candidate crop to examine the full spectrum of endophytic biological control by the fungal insect pathogen Beauveria bassiana. As a first step in this direction, this article describes two inoculation methods (foliar spray or soil drench) effective in introducing Beauveria bassiana as an endophyte in the common bean. This information will be of use to mycologists, entomologists, microbiologists, and practitioners of biological control of insect pests.
Technical Abstract: Beauveria basssiana is a fungal entomopathogen with the ability to colonize plants endophytically. As an endophyte, B. bassiana may play a role in protecting plants from herbivory and disease. This protocol demonstrates two inoculation methods to establish B. bassiana endophytically in the common bean (Phaseolus vulgaris), in preparation for subsequent evaluations of endophytic biological control. Plants are grown from surface-sterilized seeds for two weeks before receiving a B. bassiana treatment (or water) applied either as a foliar spray or a soil drench. Two weeks later, the plants are harvested and their leaves, stems and roots are sampled to evaluate endophytic fungal colonization. For this, samples are individually surface sterilized, cut into multiple sections, and incubated in potato dextrose agar media for 20 days. The media is inspected every 2-3 days to observe fungal growth associated with plant sections and record the occurrence of B. bassiana to estimate the extent of its endophytic colonization. Both inoculation methods resulted in endophytic colonization by B. basssiana in over 80% of treated plants. However, the extent of colonization depended on the plant part evaluated and the inoculation method used. Leaves responded best to spray inoculations. Roots, on the other hand, only responded to drench inoculations. Finally, stems responded similarly to both inoculation methods. Beauveria bassiana was not detected in any of the control plants sections.