Smelling trouble: plant hormones and cosmetics

“Women cannot do plant science.”

A plant scientist once told me about an urban legend at his old lab. Apparently, all results went haywire whenever a female scientist had worked with the plants or entered the greenhouse. The problem was not intelligence, work ethics or dedication. Only the sheer fact that women’s presence in the lab ruined the results. And no one knew why.

Surely, plants have no concept of gender so the fact that there were women in the room should not bother them. Then what was going on?

This specific lab was researching how plants respond to insects. Plants are often eaten by herbivores and they have developed a wide arrange of defense mechanisms. Plants have spikes; tough leaves which are difficult to digest; and can produce toxins to ward off insects. These insect-repelling toxins cost a lot of energy to produce so they are only made by the plant when they are being eaten. This process requires some regulation: plants ‘recognize’ leaf damage after which they can respond. This response occurs via hormones, among which Jasmonic Acid. After leaf damage, plants produce Jasmonic Acid, which can regulate the expression of genes to turn on a stress response. In the case of leaf damage, the stress response involves the production of insect-repelling chemicals. So the hormone Jasmonic Acid pushes the PANIC button – causing the plant to make insect-repelling chemicals. (Katsir, L., et al(2008). Current opinion in plant biology, 11(4), 428–435. doi:10.1016/j.pbi.2008.05.004)

Now, why is the hormone Jasmonic Acid relevant? This hormone was originally found in essential oils from the Jasmin plant (Jasminun grandiflorum) and is considered an important component of perfume. This plant hormone attributes to a flowery, complex scent and is popular in high-class cosmetics. (Dhandhukia PC, and Thakkar VR. (2007) J Appl Microbiol 105:636-643.)

Looking back at the urban legend at the beginning of this story: What happened here was that the Jasmonic Acid in perfume would trigger the plant’s stress pathway. Because of this, the results were constantly off and drove the (male) scientists crazy.

There are a few conclusions to be drawn from this story. The first one being the obvious question whether the men in the lab spent any time on personal grooming. Men, really now?

The second conclusion is that we honestly don’t know in which ways we influence our experiments without knowing it. Do my microbes recognize the soap I use? Are they sensitive to light? Is the radio channel interfering with secondary metabolite production? Do they smell my fear and respond by ruining my experiments? (I bet they do)