Field-based metabolomic reveals alteration of the volatiles organic compounds produced by Lavandula species in the context of yellow decline disease

Introduction: Fine lavender and lavandin are perfume and medicinal plants widely cultivated in Provence (south-east of France) for their essential oil and for the production of honey. The lavender monocultures are affected by a severe decline in France, due to the propagation of the yellow decline disease. This disease is caused by the Stolbur phytoplasma, a bacterium transmitted by a sap-sucking insect, Hyalesthes obsoletus . Objectives: Main objective was to develop an untargeted metabolomic approach to highlight changes in the volatiles organic compounds produced by asymptomatic (“healthy”) and symptomatic (“infected”) plants. Methods: Samples from fine lavender and lavandin aerial parts were collected in the field, then stored volatile compounds were extracted in the laboratory by ultrasound assisted extraction and analyzed by gas chromatography–mass spectrometry. Afterwards, multivariate statistical analysis has been performed using principal component analysis and partial least square regression as well as a multiblock statistical analysis by orthogonal partial least squares discriminant analysis to compare VOCs from fine lavender (variety 7713 ) and lavandin (variety abrial ). Results: Fifty stored VOCs, mainly oxygenated monoterpenes, from lavender and lavandin leaves and blooming head of the inflorescences were identified. Metabolism of several compounds were found to be altered by yellow decline such as β-farnesene overexpressed by symptomatic plants. Conclusion: The developed metabolomic approach allowed the identification of specific volatile compounds produced by asymptomatic and symptomatic plants in a complex field environment.