Floral scent

[1][2] The primary functions of floral scent are to deter herbivores and especially folivorous insects (see Plant defense against herbivory), and to attract pollinators.

Floral scent is one of the most important communication channels mediating plant-pollinator interactions, along with visual cues (flower color, shape, etc.).

A good characterization of floral scent, both qualitative and quantitative, is necessary to understand and potentially predict flower visitors' behavior.

[10] A primary function of floral scent is to attract pollinators and ensure the reproduction of animal-pollinated plants.

[19] The second chemical class is composed of the fatty acid derivatives synthesized from acetyl-CoA, most of which are known as green leaf volatiles, because they are also emitted by vegetative parts (i.e.: leaves and stems) of plants, and sometimes higher in abundance than from floral tissue.

Floral scent emissions of most flowering plants vary predictably throughout the day, following a circadian rhythm.

[23] In tropical orchids, floral scent emission is terminated immediately following pollination, reducing the expenditure of energy on fragrance production.

[24] In petunia flowers, ethylene is released to stop the synthesis of benzenoid floral volatiles after successful pollination.

[25] Abiotic factors, such as temperature, atmospheric CO2 concentration, hydric stress, and soil nutrient status also impact the regulation of floral scent.

This is more adapted to the study of heavier organic compounds, and/or VOCs that are stored in floral tissue before being emitted into air.

Gas chromatography (GC) is ideal to separate volatilized VOCs due to their low molecular weight.

VOCs are carried by a gas vector (helium) through a chromatographic column (the solid phase) on which they have different affinities, which allows to separate them.

Separation systems are coupled with a detector, that allows the detection and identification of VOCs based on their molecular weight and chemical properties.

The most used system for the analysis of floral scent samples is GC-MS (gas chromatography coupled with mass spectrometry).

Floral scent may also be composed of very similar molecules, such as isomers and especially enantiomers, which tend to co-elute and then to be very hardly separated.