Green thumbs

In October, I started prep work for a field experiment that was planned to take place this field (spring and summer) season. It was supposed to be something small, merely to help out a new PhD candidate that we had selected, so she could arrange contractual stuff, and she would not experience delays because of those. There were delays, many delays, due to the pandemic on the contractual side. But none in our greenhouses!

This project is part of a consortium on phytochemical diversity and its role in mediating plant interactions. One of the consortium’s – and our sub-project’s core model species is the asteraceous plant Tansy, or Tanacetum vulgare for people that like it fancy. Tansy is a wonderful plant. It is easy to propagate, and grows fast. It has pretty yellow flowers which produce tonnes of seeds. It is no surprise that it has the tendency to become very invasive outside its native range. Well, that’s not where I live, so not really a problem for me. Its abundant flowers attract a lot of pollinating insects, and as some pollination experts in the consortium have claimed, it is probably the plant that has the highest diversity of flower visitors in this part of the world. A strong claim, but it would not surprise me. This high diversity can probably be explained in part because it is an highly aromatic plant species that boasts an impressive bouquet of chemical and partly volatile compounds that remind me of the smell of flower shops. Other people apparently are less appreciative of it, as on the web it is often described as a plant that smells very strongly, and some even go as far as to say it smells nasty. I simply disagree, and so do the pollinating insects, it seems.

On the level of shoot herbivory, the story seems to be a bit different. There, the plant seems to be the preferred host plant for a number of aphid species that are mono- or oligophagous on Tansy and some closely related asters. Furthermore, there are some ants to like to hang around the plants, but this is, of course, mostly because they like to hang around the aphids, to sip on their honeydew. Some of these aphids indeed even rely on this ant-mutualism for their survival. It seems that more polyphagous insect species may take a nibble here and there, but don’t go for the all-you-can-eat menu. I expect that this is also largely driven by these chemical compounds inside the plants. I have yet to make my own observations in the field, of course, as this model system is relatively new to me.

Now, we want to see how these chemical compounds, and variation in their blends, may influence the associated community. So, as we do when we’re curious – we experiment. And this time, we do that in the field, because I wanted to be a field biologist… Or maybe more because it is probably the most relevant place to test such hypothesis. Or maybe both. Doesn’t matter. What matters is that we needed plants. A lot of plants.

I started off with thousands of seeds from different lineages, and from each of these lineages, I selected a cohort of seedlings that I would grow into proper plants. That left me with 120 plants. A manageable bunch. These plants were kindly chemotyped by our friends and collaborators at Bielefeld University. Then we selected a subset of plants, based on their chemotypes, and these I had to turn into 30 clones. Somehow. Now I’m probably not exaggerating when I say that I have cloned a million plants in my life. It was my job for many years. So in a way I was super excited to do that again, and anything that needs my green thumbs is like meditation to me, so that is a huge plus. So two weeks ago I started cloning my babies. It felt strange though to clone a species that I had never worked with before. Should I be so confident? It’s a bloody weed, they should root somehow, right? We’ll see in a few weeks.

Lina, the PhD candidate that will be working with me on this project, will soon arrive in Freising, so we hopefully can start in the field soon after. What started off as something on the side to help prepare Lina, has turned into something quite massive, but also into something very rewarding already. I’m quite excited to see this take off!

Stay tuned for more updates once we get these tansies to the field!

Published by Robin Heinen

Father of two | Husband | Entomologist and Ecologist | Postdoctoral Researcher @ TUM | Traveler | Coffee Addict

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