Evaluating the effects of drought stress on cotton plant volatile emissions

Climate change is expected to have critical impact on precipitation patterns, which may ultimately lead to a dramatic increase in the frequency and duration of drought in the North American cotton belt and other agriculturally relevant areas around the world. Plants are known to respond to biotic and abiotic stress by emitting volatile organic compounds (VOCs). The emitted VOCs could either be constitutive or induced.  Emitted VOCs have important ramifications in plant-insect and tritrophic interactions. Little is known about the effect of drought stress on emission of VOC by plants. This study was conducted to evaluate the effect of drought stress on VOCs emission in cotton plants. Cotton plants were grown under greenhouse conditions and headspace volatiles were collected from drought-free (control) plants and plants that were drought-stressed. Volatiles were collected for 4 days, allowing us to document changes in VOCs from day 1 to day 4 of drought.  The identity of the VOCs was determined using gas chromatography-mass spectrometry (GC-MS). Noticeable differences in VOCs emissions were recorded between drought-free (controls) versus drought-stressed cotton plants. Moreover, there were noticeable differences in the identity of VOCs emitted as drought progressed. These results demonstrate that drought stress in cotton plants elicits changes in cotton VOCs with potential ramifications for plant-insect and tritrophic interactions.