Volatiles and Nonvolatiles in Flourensia campestris Griseb. (Asteraceae), How Much Do Capitate Glandular Trichomes Matter?

Abstract

The distribution and ultrastructure of capitate glandular trichomes (GTs) in Flourensia species (Asteraceae) have been recently elucidated, but their metabolic activity and potential biological function remain unexplored. Selective nonvolatile metabolites from isolated GTs were strikingly similar to those found on leaf surfaces. The phytotoxic allelochemical sesquiterpene (-)-hamanasic acid A ((-)-HAA) was the major constituent (ca. 40%) in GTs. Although GTs are quaternary ammonium compounds (QACs)-accumulating species, glycine betaine was not found in GTs; it was only present in the leaf mesophyll. Two (-)-HAA accompanying surface secreted products: compounds 4-hydroxyacetophenone (piceol; 1) and 2-hydroxy-5-methoxyacetophenone (2), which were isolated and fully characterized (GC/MS, NMR), were present in the volatiles found in GTs. The essential oils of fresh leaves revealed ca. 33% monoterpenes, 26% hydrocarbon- and 30% oxygenated sesquiterpenes, most of them related to cadinene and bisabolene derivatives. Present results suggest a main role of GTs in determining the volatile and nonvolatile composition of F. campestris leaves. Based on the known activities of the compounds identified, it can be suggested that GTs in F. campestris would play key ecological functions in plant-pathogen and plant-plant interactions. In addition, the strikingly high contribution of compounds derived from cadinene and bisabolene pathways, highlights the potential of this species as a source of high-valued bioproducts.

Foliar behaviour of biogenic semi-volatiles: potential applications in sustainable pest management

“…SQTs are also found in GTs of the plant families Asteraceae (Bezerra et al 2018), Solanaceae (McDowell et al 2011 and Geraniaceae (Kremer et al 2013). Oxidised SQTs can be found in GTs of the families Asteraceae (Piazza et al 2018), Rosaceae (Hashidoko et al 1994) and Ericaceae (Mofikoya et al 2018a). GTs in some species of the Solanaceae family may have, in addition to MTs and SQTs, a highly diverse set of non-volatile metabolites including flavonoids and other phenylpropanoids, alkaloids, fatty acids and acyl sugars (McDowell et al 2011;Glas et al 2012).…”