Photo: Oliver Staša

What were your interests in elementary school?

I have always enjoyed nature. I was interested in the universe, Grygar’s shows and animals, but I wasn’t really “into” plants at that time. I enjoyed taking part in biological olympiads. 

Were you attracted to botany while studying at grammar school?

Yes, because we had an excellent biology teacher with a great teaching style. He didn't need to interpret according to textbooks, he just knew the material and could pass it on. He taught us to think and know why. In the first year, our task was to create an herbarium, and that was it, I was hooked. That small impulse was enough to trigger my collecting passion. My collection started to run into hundreds of items and I started learning to determine types. In the third year, I participated in the Secondary School Professional Activity (SOČ) and fought my way up to the state round, where I won the winner’s diploma, though there were perhaps more people awarded with the same diploma if I remember well. When I presented my herbarium, which included nine hundred items and about six hundred species, it took the commission. I also used the herbarium of the Museum of Vysočina in Třebíč, where I often went to consult. This is where my initial idea of ​​a profession in botany began to emerge; the peace and quiet of the herbarium collection embodied what I wanted to do. I would stay in the herbarium, rummage through the collection, go out in the field, collect plants and know everything about what grows where. 

Was botany a clear choice for you when choosing your field of university studies?

Because I still saw myself professionally in the Třebíč herbarium, Systematic Botany was a clear choice. But I was most interested in field practice in the first year. I think this is the best place to "catch" prospective students. I focused on fescue, specifically the taxonomy of Festuca pallens (blue fescue) in southern Moravia. Gradually, my research topic expanded to the whole country, and eventually over its whole range, from Belgium to Ukraine. 

In botany, what does it mean when you deal with taxonomic topics, as in the case of your Bachelor's thesis?

Usually, there is a problem at the beginning. It is quite typical, for example, that a single species will have a different name in each country, meaning that it is necessary to unify the names somehow. Conversely, within one species there may be slightly different looking populations and it is necessary to check whether it is not something else, like a separate species. With the blue fescue, I counted the numbers of chromosomes in different individuals and populations. If plants have different numbers of chromosomes, they may not communicate well genetically; they may also have differently sized cells and organs. I wanted to clarify if there were two types, and it turned out that they were. 

Was possible to recognise that these were two species under a microscope? Is it very difficult to determine the differences between grasses when they are indistinguishable at first glance?

Fescues are very similar to each other and the distinguishing features can only be found in their anatomy, most often observed in cross sections of leaves. And when you "cut" a few thousand leaves, you will learn to determine the species according to the external signs. I spent days and weeks on my Bachelor’s thesis counting chromosomes from the roots of fescue and optimising the method for counting them, which was often frustrating. I learnt how to stain the specimens, I planted the plants, removed the roots, stained them, looked in the microscope all day and couldn’t see anything to count. Over time, I found that, in order for the chromosomes to be visible, the plants being studied must be in the "right mood" when the roots begin to grow. When I came to understand this, after some time, my research progressed much better. I had to take account of the fact that blue fescue is a drought-tolerant species and somehow senses the weather. Therefore, it primarily minimizes the risk of any desiccation. Its roots so start to grow only when there is absolutely no risk of desiccation. 

Is it just a certain time of day or is it more complicated?

I noticed that the tips of the root tips began to divide when the air pressure was low for two to three days and it was raining. The next day, when the pressure rose and the sun came up, the plant reacted. The is humidity high, it’s lasted a while and it will probably go on, now it's morning, the sun is shining, but not too much - I can start. I saw that the leaves were outstretched in the morning and the plant knew that it had a few hours of rest, when it could transpire, photosynthesise and work on root growth with impunity. When the roots were removed at this point, the chances of finding countable chromosomes increased considerably. This was the first thing I had to figure out. Later, I moved to Olomouc, where they were beginning to use flow cytometry, which is much more convenient and effective for the purposes of my research. While I counted a maximum of eight plants a day when conditions were suitable for counting from the roots, one could now measure a hundred plants in a morning, regardless of the weather. That was a significant step forward. 

So, you got into laboratory research. Has your professional vision of being an herbarium employee changed over time?

Yes, it probably started when I discovered scientific problems. I was fortunate to learn that when we started with flow cytometry in fescues, they turned out to have different genome sizes, even though they had the same number of chromosomes. We hypothesised that there was a connection with the evolutionary processes of plant genomes. In plants, it is known that a single species has a relatively stable genome size. But how is it that when a new species emerges, its genome is different in size than the parent species, and what happens in between? The measurement of intraspecific variability in genome size is methodologically quite demanding, however, and the results of many earlier works devoted to this topic were later refuted by newer methods. Our results are among the few where intraspecific variability is documented particularly thoroughly. Over the course of further experiments we managed to turn Festuca pallens into a model plant for research into this phenomenon. Success in measuring genome size by flow cytometry then motivated me to look for other scientific problems, and I slowly became an independent scientist. Grant money, and the support of colleagues who helped implement my ideas, contributed a lot to this. When I found out that I enjoyed making scientific discoveries, the vision of working in an herbarium gradually disappeared. Of course, I still enjoy discovering plants that no one has found, but I increasingly feel that what attracts me the most in science is discovering processes and how and why things actually work. One asks more and more general questions, such as how to explain the course of vegetation over the geological history of the Earth. Even then, one often gets involved in quite banal questions such as why does this plant grow on this hill? 

In addition to taxonomy, you focus on biosystematics. Can you explain this botanical science?

It is the study of the processes that lead to the emergence of species, or how plant evolution takes place, and the taxonomy describes the existing diversity. The biosystematic group in our department is investigating how genome size is evolving and what it means for plants, what they can and cannot do with a large genome, and how this may have affected their chances of survival in the current geological age. With its equipment and technical background, our workplace, and the Czech Republic in general, are among the world leaders in this field. 

What motivates you in your study and scientific work?

During my studies, I was lucky with my classmates. Above us was a very strong botanical year, which we wanted to emulate. In addition, my zoological classmates were people who won national rounds of biological olympiads, they were all people interested in research who had mostly been working in their fields for some time. I am also lucky with my boss, Associate Professor Petr Bureš, leader of the Plant Biosystematics group, who supports critical thinking and the discovery of new ideas and gives me a lot of space for my own work. This is crucial for a scientific career. When you have the space to think, ask questions and you have the opportunity to connect knowledge from different fields, new ideas come almost on their own. 

How does your current botanical research relate to the study of plant genomes?

We are interested in the "letters" that make up plant genomes and DNA. Our laboratory is the only one in the world where research into the guanine-cytosine (GC) content of plants is being studied on a larger scale. As botanists, however, we have a huge advantage over classical laboratory scientists because we know how to recognise plants and know where to look for them. I benefit from my taxonomic and herbarium education here and I can do my research on a large number of species. I started with the grasses again. Coincidentally, they appear to have the highest concentration of GC base pairs in their DNA, making it the most suitable group for such a study. In addition, grasses are highly successful evolutionarily. It is a very young group, only 30-40 million years old, but during this time it has become the dominant feature on a third of the Earth’s surface. Our research has shown that increased GC content and related changes in grass genomes are in some way directly related to this success. We are also currently measuring the GC content of other terrestrial plants, starting with mosses and ending with flowering plants. Our goal is to develop a worldwide overview of GC content across all plants. We are also preparing an overview of genome sizes for the complete Czech flora and monitoring how species in different habitats and in different types of vegetation differ in genome size. Based on this, we should then know how much the environment affects the evolution of plant genome size. I have gone back a bit to herbarium science and am working again on what I always wanted, i.e. to have all Czech flowers in my herbarium. 

Tell me about your new research on global climate change? How does such a topic relate to botany?

Alongside calculating genome size, I got to study the stomata and the physiology of the plants. The larger the genome, the larger the cell must be, and the larger the vent through which plants receive carbon dioxide and evaporate water, which then affects their overall physiology. A plant with larger and slower vents cannot afford everything, e.g. it cannot grow in a dry environment without further adaptations, as it would lose an excessive amount of water through these vents. I am currently considering an overview of the size of plant vents around the world and finding out how the size of vents is related to the ecology of individual species and their worldwide distribution. The size of vents could then be related to the risk of extinction and the success of some groups during global climate change. We know, for example, that the concentration of carbon dioxide in the atmosphere has been declining since the Mesozoic and is currently more than ten times lower. Plants had to adapt to this, and it can be assumed that those with large genomes and vents would do worse. Such species are likely to become extinct much more often than plants with small genomes. It is also possible that, thanks to a description of the mechanism of vent adaptation, the reactions of individual species to current global climate change and the anthropogenic increase in the concentration of carbon dioxide could be predicted. Although many scientific teams are trying to do this, it is possible that it could all be discovered using simpler, botanical methods rather than those being considered in multi-million dollar, long-term projects. 

Thank you for the interview.
Zuzana Jayasundera 

Translated by Kevin F. Roche