The nonvolatile metabolome of sunflower linear glandular trichomes

Uniseriate linear glandular trichomes occur on stems, leaves and flowering parts of Helianthus species and related taxa. Their metabolic activity and biological function are still poorly understood. A phytochemical study documented the accumulation of bisabolene type sesquiterpenes and flavonoids as the major constituents of the non-volatile metabolome of linear glandular trichomes in the common sunflower, Helianthus annuus. Besides known sesquiterpenes of the glandulone, helibisabonol and heliannuol type, four previously undescribed sesquiterpenes named glandulone D, E, F and helibisabonol C were identified by spectroscopic analysis. In addition, four known nevadensin type flavonoids varying in O-methoxy substitutions were found. None of them has previously been reported from Helianthus annuus.