Volatile Compounds and the Pest-Deterrent Phenotype of Endophyte-Inoculated Cotton

Fungal endophytes are microscopic fungi that live asymptomatically within plant tissues. All plants are believed to harbor endophytes. Certain fungal endophytes can confer benefits to the plant hosting them through disease, drought, or pest resistance. Our lab has been working with fungal endophytes isolated from nature, coating cotton seeds with either spores or biomass of the fungi, and examining phenotypic responses of these inoculated plants to insect pests and field conditions. No-choice behavioral assays with Hemipteran pests reveal that the pests tend to avoid the leaf tissues of inoculated plants. These data suggest that volatile compounds may be mediating the deterrent response. I am using solid-phase micro-extraction to gas chromatography and mass spectrometry (SPME-GC-MS) to identify volatile compounds released from the cultured fungi of interest, inoculated cotton plants, and control cotton plants. I am developing volatile-compound profiles for each of these in order to identify which compounds make inoculated plants distinct from control plants. Follow-up experiments will include olfaction and behavioral assays of the pest species and these compounds.