Lancaster University's new Professor of Crop Physiology leads the Photosynthesis Team, focussed on how to feed more people with less by improving the efficiency of how plants turn the sun’s energy into food.

Despite growing up in rural Portugal surrounded by plants, Elizabete Carmo-Silva was bored by photosynthesis and plant science at school – “I just didn’t see the point of it” says Elizabete, who was recently appointed Professor of Crop Physiology at the Lancaster Environment Centre.

Studying biology at Lisbon University changed all that. “During a field trip, an 80-year-old professor told us all these amazing stories about plants: I realised plants are so fascinating, I was hooked.

“Plants are so diverse and flexible. If an animal gets cold it will seek shelter, but plants have to put up with it. I became curious to understand plant physiology, how they respond and adapt to different environments.”

Researching the interplay between plant stresses

Two decades later, Elizabete is heading up the 15-strong Photosynthesis Team, continuing to explore her fascination with plants. Her focus is on the interplay between the environment and photosynthesis – the process by which plants assimilate carbon dioxide from the atmosphere and use it to grow. In particular she researches Rubisco, the enzyme which initiates both photosynthesis and photorespiration.

“Rubisco is the most common enzyme on the planet, but it has its shortcomings,” Elizabete explains.

Her work and that of the Photosynthesis Team explores how these shortcomings might be minimised through plant selection and breeding, and so help to increase crop production and reduce use of resources like water and fertiliser.

Her first research in this area was as a PhD student, studying the drought response of three C₄ grasses, which use a more efficient type of photosynthesis. “These plants use a combination of metabolic and anatomical adaptations to cope with water deficit. One of three species I was studying had many more inhibitors of Rubisco activity compared to the other two.”

Her next move was to Arizona, working for the US Department of Agriculture: she was researching Rubisco activase, the protein that activates Rubisco, looking at how it responds to a combination of water deficit and heat stress and so how it might be impacted by a warming planet.

For the first time she was working with a crop – cotton – and researching in the field as well as at a molecular level in the laboratory.

“There weren’t many studies at time looking at the interaction between heat and drought stress in plants because it gets quite complex. What I learnt was that cotton plants are able to cool their leaves by about 10 degrees if well-watered, by opening their stomata. As I walked through the field, I could feel my legs were being cooled by the cotton. It gave me an even higher admiration for plants.”

But if the plants were not watered, this mechanism failed, meaning they took in less CO₂ and their Rubisco activase was less active – reducing photosynthesis and plant growth.

Coming to the UK – Rothamsted Research

In 2012, Elizabete moved to England to join Rothamsted Research, the world’s first agricultural field research station, working on carbon assimilation and Rubisco activity in 64 cultivars of wheat.

“At Rothamsted I started to interact with breeders to understand what would be useful for them to integrate into breeding programmes, which gave me a better understanding of their context, so the research could be impactful.”

She also had her first experience of leading a team and supervising students – something she had initially been reluctant to do.

“When I first decided I wanted to focus on plants, I thought people were too difficult, I would just deal with plants. I then realised that you can’t separate plants from people, we are all connected. I had grown to understand that diversity enables a team to address challenges from different perspectives and come up with more creative solutions.”

Diversity is also useful in crop physiology. “Some cultivars were more efficient at photosynthesis than others, so I gained an appreciation that you can improve photosynthesis through breeding.”

“I also discovered that the cultivars response to light was one of the traits most related to productivity. In the field, leaves are exposed to ever changing levels of light. I realised that we need to understand the regulation of carbon assimilation in dynamic conditions.”

Moving to Lancaster - building the Photosynthesis Team

Then in 2015, Elizabete moved to Lancaster University, along with other Rothamsted photosynthesis specialists. They started to put together a specialised biochemistry lab to work on Rubisco, and to expand the Photosynthesis Team. It was Elizabete’s first opportunity to teach the younger generation, and to work on a campus encompassing lots of different disciplines.

The Rothamsted group brought with them two major international collaborations, with the RIPE project – Realizing Increased Photosynthetic Efficiency – and with the International Wheat Yield Partnership.

Elizabete, and the researchers she supervises, continued to focus on Rubisco activase.

“One of our key findings has been that, in wheat, there are three different forms of Rubisco activase, which respond differently to changes in light and temperature. This offers the possibility that by adjusting how much of these forms are available in a wheat plant, we can make that plant more suitable for different temperatures and where light is changing dynamically.”

They are now looking at similar research in cowpea, wanting to understand how fast Rubisco gets activated when the light level goes up. They are collaborating with breeders in Sub-Saharan Africa, where cowpea is a major crop, to ensure that their findings get used in the field.

Her work uses both traditional breeding and gene editing techniques, which can cause controversy.

“With the challenges ahead, especially a warmer climate, how are we going to feed everyone in a sustainable manner? We have to produce more crops with less resources. This needs multiple solutions, and we don’t yet know which crop improvement approach will offer the best solutions.

“I fully understand that people are scared about new technologies, especially involving food, which is why we as scientists have to take time to have conversations about this.”

Photosynthesis team

Becoming a professor

Elizabete has come a long way from the teenager who wasn’t interested in plants, and the young researcher who wasn’t interested in people. Becoming a professor has made her more confident in her approach to leadership.

“I believe we need to be collaborative, supportive and inclusive, and inspire and mentor others. It’s possible to deliver research in a positive and inclusive way.”

She remains in awe of plants and fascinated by the mechanisms that control how they respond to the environment.

“There are still an amazing number of questions to be answered in photosynthesis, for example what makes some forms of Rubisco activase tolerate high temperatures.”