Temporal relationship between emitted and endogenous floral scent volatiles in summer- and winter-blooming Jasminum species.

Jasminum spp. is cultivated for their fragrant flowers used in essential oil production and cosmetic uses. An attempt was made to study the temporal variations in floral scent volatiles composition including emitted, free endogenous and glycosyl-linked volatile compounds from two summer-blooming species namely, Jasminum auriculatum and Jasminum grandiflorum as well as from two winter-blooming species namely, Jasminum multiflorum and Jasminum malabaricum. The overall emitted volatile organic compounds (VOCs) were found to be highest when the matrix Porapak Q 80/100 was used with dichloromethane (DCM) as elution solvent. The floral volatile emission from bud to senescence exhibited nocturnal maxima pattern for both the summer-blooming species. Both the winter-blooming species emitted its highest concentration at noon. The free endogenous concentrations of all VOCs were low when corresponding emitted concentrations were high. Enzymatic treatment of petal extract revealed that several aromatic volatiles including aromatic alcohols and monoterpenols are synthesized and stored in the flowers as water-soluble glycosides; these compounds were shown to accumulate in higher amounts in flowers at late bud stage. These findings indicate the utilization of the precursors, i.e. the volatile-conjugates, through hydrolysis followed by their release as free-volatiles at flower opening stage. The outcome as a whole suggests a linkage among the temporal pattern of emitted volatiles, free-endogenous volatiles and glycoside-bound volatile compounds in all above studied Jasminum spp. and provided an overview of their floral volatilome.