The fragrance of the flowers depends on the bacteria and fungi that cover them

We all remember the gentle scent of lavender. Its characteristic perfume is caused by chemical compounds called volatile organic compounds (VOCs). Until now it was known that flowering plants used various biochemical pathways to produce a wide range of volatile organic compounds that give flowers their own aroma. Now, a CREAF study, in collaboration with the UAB, has discovered that flowers smell more than just flowers. According to a study published in the journal Scientific Reports, of the Nature group, the perfumers of the planet, the protagonists when it comes to elaborating the most delicate floral aromas, are not only the flowers, but also the microorganisms and fungi that cover them.

Researchers have conducted a series of experiments in which they sprayed elderberry flowers with broad-spectrum antibiotics. In plants treated with antibiotics, the internal floral content of volatile compounds and respiration were stable, showing that the antibiotics did not cause damage or stress to the plants. However, the amount of the aromatic compounds emitted by the flowers, which provide the scent, decreased dramatically in cases where it was sprayed with antibiotics. On the other hand, antibiotics had also modified the types of compounds emitted by the flower: they had stopped generating some compounds. Thus, in general, the bouquet of elderflowers was completely different up to seven days after spraying with antibiotics.

"With antibiotics, the elderberries, despite still having healthy flowers, did not smell like elderberry. And the fact is that the antibiotics had not affected the plant, but they had eliminated the microorganisms and fungi that live in the flowers. The role is thus demonstrated key to fungi and bacteria in the smells and perfumes that flowers give us ", says Josep Peñuelas.

The authors of the article confirm that bacteria such as fungi have the ability to produce aromatic compounds such as linalool. It must be taken into account that the same plant responds to some of these microorganisms by also emitting special chemical compounds. According to Jaume Terradas, founder of CREAF and emeritus professor of Ecology at the Autonomous University of Barcelona who also participated in the study, the microbiota of flowers seems to play a key role in the final fragrance, and this would have relevant implications.

An element to consider during pollination

Indeed, volatile organic compounds, being fragrant, allow chemical communication of plants with other organisms. Various plant tissues, such as flowers, emit these compounds to attract the attention of, for example, pollinators. Faced with the current "pollination crisis", produced largely by the decline in pollinating insects but also by the alteration of floral aromas, studies like this provide very valuable knowledge that can contribute to improvements in this vital issue. "If the odors that these insects guide are largely produced by fungi and microorganisms, we will have to review, for example, the effects of the use of some antifungals in crops, because they could alter the fragrances and future pollination of the plantations themselves" ,