An Interview with Liana Acevedo Siaca: Measuring Photosynthesis Under Real World Conditions

Dr. Liana Acevedo-Siaca (X: @Liana_Ace) is currently a post-doctoral researcher in the Plant Research Laboratory at Michigan State University. She obtained her PhD from the University of Illinois at Urbana-Champaign, under the supervision of Prof. Stephen P. Long, within the framework of the Realizing Increased Photosynthetic Efficiency (RIPE) Project. After a brief postdoc at the same university, she moved to the International Maize and Wheat Improvement Center (CIMMYT) as an associate scientist for almost two years, before obtaining her current position. Recently, she has been appointed as an assistant professor at Wageningen University, where she will start in April 2024.

Liana is a plant physiologist with a strong interest in plant breeding and throughout her career she has worked with a variety of plant species, including rice, wheat, soy, and Arabidopsis. Her research is focused on understanding the rapid changes in leaf photosynthesis under fluctuating light environments, also in combination with other stresses, such as temperature. Through this work, she aims to understand how different environmental conditions can limit processes related to photosynthesis. These fluctuating conditions better reflect the challenges faced by crops in the field and indeed field work is an essential part of her research, establishing a connection between her expertise in plant physiology and interest in plant breeding. The ultimate goal of her research is to identify photosynthetic traits to be utilized in the breeding of more resilient crops that can contribute to a food-secure future.


Carlo Pasini: Liana, what motivated you to do research in your field in the first place?

Liana Acevedo Siaca: I initially became interested in the plant sciences through the field of plant breeding and the mission of working towards a world with more resilient and sustainable agriculture. However, during graduate school I had the great luck to work in a lab focused on plant physiology and photosynthesis, where I began to truly understand how plants respond to their surrounding environment. I think as a society we collectively think of plants as inert organisms at the mercy of their environment; however, plants are constantly responding to changes in their surroundings. Under fluctuating light for example, even if the stimulus is a few seconds long, we can already observe changes in their photosynthetic activity, and I find this fascinating. Beside this, I have always felt the need to translate findings in plant physiology into something that can hopefully make an impact on food security, for example by providing plant breeders with new desirable phenotypes or traits of interest.


Carlo: In which ways do you think your research could contribute to achieving these ambitious goals?

Liana: During graduate school my work focused on characterizing natural genetic variation for traits related to photosynthetic induction in diverse rice accessions as well as understanding what limitations to photosynthesis may be present during fluctuating light environments. This work led to the identification of some traits that could be beneficial to plant productivity, such as the speed of photosynthetic induction. While at CIMMYT, I measured photosynthetic traits in diverse wheat panels and populations to help identify genotypes to incorporate into pre-breeding programs that are focused on improving crop physiology, especially within the context of heat and drought tolerance. Currently, my work is focusing on how limitations to photosynthesis may change during short light fluctuations and how these limitations are affected by environmental factors such as ambient light intensity and temperature. I believe this work is important and helps work toward these goals as we are generating a more representative understanding of how photosynthesis operates in our agricultural and natural environments. To be able to improve something, we must first understand it. I am also cognizant that my work is only a very small part of the larger puzzle to solving issues in our agricultural systems and I do not pretend that my work will single-handedly solve these issues. However, I strongly believe in the power of collaboration and the cumulative power of scientific discovery.


Carlo: Is there any specific plant-related fact that influenced the direction of your research?

Liana: Most of our knowledge on photosynthesis is derived from experiments under steady-state conditions, with a constant light supply, but the natural environment in which plants live is very dynamic. For a long time now, I have been wondering what the things are that we might be overlooking because of these intrinsic limitations in the ways we have previously measured photosynthesis, and how can we design experiments and collect data that are more representative of the way photosynthesis works in non-steady state conditions.


Carlo: Which research directions would you personally like to pursue going forward?

Liana: Throughout the years, while utilizing the same infra-red gas analysis and chlorophyll fluorescence techniques, I have shifted my focus from measurements on longer timescales to shorter ones. During my PhD, I would measure plants for 30 minutes under ambient light, followed by 15 minutes under high light, and then back to ambient light, focusing on the process of photosynthetic induction. Now I have reduced the duration of these treatments to a few seconds or 1 minute. By doing so, I am trying to recreate the effects of sunflecks on leaves and characterize the response of plants to such stimuli. This is the research direction I want to follow for the foreseeable future. In the longer term, I would also like to couple the high throughput phenotyping of these fluctuations with -omic techniques, to understand the underlying molecular factors for these responses.


Carlo: Where do you see your field heading in the future?

Liana: The field of photosynthesis under fluctuating light gained significant interest during the 1980s and 1990s and it has seen a resurgence in attention in the last few years. As we continue to collect new data under fluctuating light, I think that we will have to reconsider some of our assumptions on how photosynthesis works and how the assumptions learned under steady-state conditions can be applied to fluctuating, dynamic environments. Part of this is trying to design experiments that more accurately represent these quick changes. Take NPQ relaxation (non-photochemical quenching) as an example: a lot of the studies out there, including mine, observe the decay in NPQ after the light is turned-off on the scale of roughly 30 minutes or longer; but there might be immediate changes, as soon as the light is turned off, that we may not be capturing in the “typical” way we do measurements. These results could substantially improve the models we currently use to simulate plant growth and primary productivity at the field- and ecosystem-level. Right now, these models are based on steady-state assumptions about photosynthesis and sometimes perform poorly when trying to account for dynamic conditions.

Furthermore, we have a new generation of instruments for measuring chlorophyll fluorescence and gas exchange, that allow us to measure more plants in the same amount of time and at a higher data density. I do believe this will be essential to bringing photosynthesis research into more applied contexts.


Carlo: If you were not limited by funding and resources, what other scientific topics would you like to investigate?

Liana: I would love to team up with ecologists and other ecophysiologists to expand my work to diverse, non-cultivated plants in their natural environments. I’ve always enjoyed spending time outdoors and it would be wonderful to combine these two interests. These plants do not enjoy the often “cushy” environments of modern agriculture and require a much higher degree of resilience to survive their habitats compared to modern crops. If there is a high degree of phenotypic variability and lessons to be learned from accessions of the same crop species, I can only imagine what we could learn from plants in diverse and dynamic ecosystems.


Carlo: Which parts of your job do you like the most and which ones the least?

Liana: I have a few favorite things and the first one is collaborating with other scientists, which makes the whole scientific process much more enjoyable to me. I’ve been extremely lucky in that I’ve had the opportunity to work with people that are not just excellent scientists, but phenomenal people. I also love field work, which I find extremely gratifying. I often say that I am happiest when I am outside in the field. The third thing I really enjoy is writing, especially the creative process of writing papers, where you get to finally see all your hard work coming together. On the other hand, writing is at times also my least favorite activity. There is a huge pressure to constantly publish papers in academia and it can take away the joys of the writing process.


Carlo: Is there any important lesson you have learnt throughout your career that you would like to share with younger scientists and students?

Liana: Find good mentorship because it is essential to overcoming obstacles in academia. Personally, I have been lucky to find amazing mentors throughout my career. These people have advocated for me, they have helped me in finding new opportunities, and in building my own network of collaborators.

Also, communication and expectation setting is key. In certain situations, the instructions we receive, especially at the beginning, might sound unidirectional but it is important to keep the dialogue flowing both ways. Do not wait too long to address issues and give your feedback whenever is needed, because solvable problems might end up becoming irreconcilable if not tackled in a timely manner. Finally, science is a profession based on ideas, so you need to learn to advocate for your ideas and to defend them in front of others, while also being willing to update them when new findings call for it.


Carlo: If you could change one thing about academia, what would that be?

Liana: I do wish people were kinder to one another. There are a lot of things that we cannot control in our professional lives, like paper and grant rejections. But one thing that is always under our control is the way in which we choose to treat others and the professional environments that we elect to construct.



About the Author

Carlo Pasini is a PhD student at ETH Zurich, and a 2024 Plantae Fellow. He studies the links between carbon metabolism and abiotic stresses, primarily focusing on guard cells. In his free time, Carlo enjoys reading, playing ice hockey and any kind of snow-related activity. You can find him on X: @Crl_Psn.