Sampling Volatile Organic Compounds From Individual Cotton Leaves To Test Effects Of Fungal Endophyte Treatments

Facultative fungal endophytes are unspecialized plant-associated fungi capable of colonizing plant tissues without causing symptoms of disease. Studies suggest facultative fungal endophytes enhance cotton (Gossypium hirsutum L.) plant defense against insect herbivores and might alter emissions of volatile organic compounds. We tested for changes in emissions of volatile organic compounds using cotton plants treated with facultative fungal endophtytes Beauveria bassiana (Balsamo-Crivelli) Vuillemin strain GHA and Phialemonium inflatum (Burnside) strain TAMU490 in the presence and absence of herbivory. Solid-phase micro-extraction was used to sample static headspace of individual leaves in collection chambers designed specifically for the experiment. Relative abundance of volatile organic compounds was significantly affected by herbivory, but differences caused by treatment with B. bassiana or P. inflatum were not significant. Findings showed our sampling method can be used to assess constitutive and herbivore-induced volatile organic compound profiles from individual leaves, but further studies need to investigate mechanisms underlying facultative fungal endophyte-mediated herbivore resistance in cotton.