Flower fragrances depend on type of bacteria and fungi covering them

A new research conducted by CREAF and the UAB, led by Josep Peñuelas, research lecturer at CREAF and at the Spanish National Research Council, verifies that the elimination of bacteria and fungi living on flowers would cause a great variation in the amount and composition of its fragrance.

03/12/2014

The soft fragrance of lavender is easy to recall. Its characteristic perfume is produced by chemical compounds known as volatile organic compounds (VOCs). Until now, it was known that plants with flowers used different biochemical means to produce a wide range of volatile organic compounds which gave the flowers a specific aroma. Now, a research conducted by CREAF and the UAB has discovered that flowers smell of something more than just flowers. According to a study published in the journal Scientific Reports, belonging to Nature, the perfumers of the world, the stars in creating the most delicate floral aromas are not only the flowers, by also the microorganisms and fungi that cover them.

Researchers conducted a series of experiments in which they sprayed elderflowers with a wide range of antibiotics. In the plants treated with the antibiotics the internal content of volatile compounds and the respiration showed to remain stable, which demonstrated that the antibiotics caused no damage or stress to the plants. However, the amount of aromatic compounds emitted by the flowers, which provide their fragrance, reduced drastically in the ones sprayed with antibiotics. The spray had also modified the type of compounds emitted by the flower: some of the compounds ceased to be emitted. Therefore, in general the elderflowers' bouquet was completely different up to seven days after being sprayed with the antibiotics.

“With the antibiotics the elders, although they continued to have healthy flowers, did not smell like elders. That is because the antibiotics hadn't affected the plant, but they did eliminate the microorganisms and fungi living in the flowers. This demonstrates the main role played by fungi and bacteria in the smells and perfumes we notice when we are given flowers", Josep Peñuelas comments.

The authors of the article confirm that both bacteria and fungi have the ability to produce aromatic compounds such as linalool. It must be taken into consideration that the same plant responds to these microorganisms by also emitting special chemical compounds. According to Jaume Terradas, founder of CREAF and emeritus professor of Ecology at Universitat Autònoma de Barcelona who also participated in the study, the microbes in the flower seem to have a crucial role in its final fragrance, and that entails relevant implications.

An element to take into consideration when pollinating

The fact that volatile organic compounds are fragrances allows plants to communicate chemically with other organisms. Different plant fibres, such as the flowers, emit these compounds with the aim of catching the attention of, for example, pollinators. Given the current “pollination crisis”, produced largely by the fall in insects but also by the alterations in floral smells, studies such as this one offer highly valuable knowledge which can serve to make improvements in such a vital area. “If the smells guiding pollinators are largely produced by fungi and microorganisms, we will need to reconsider the use of antifungals in cultivation, because they could be altering the fragrances and future pollination of these plantations”, professor Peñuelas concludes.