Berkley Walker's Plan: Overhauling Photosynthesis for an Evolving Climate

Despite initially aspiring to be an entrepreneur, Berkley Walker veered towards the field of science. As a high school student in Portland, Oregon, he established a granola bar business that funded his undergraduate studies in microbiology.

After graduating, Walker took on the role of a product manager at an instruments company in Washington state. His plan was to attend business school and subsequently delve into the biotech industry. However, an environmental biophysics course at Washington State University in 2009 altered his career path.

The course focused on using maths to model physical systems in nature. According to Walker, comprehending the interaction of energy and matter in the environment through mathematical models sparked his interest in plant science. He decided to follow this path with a desire to offer some valuable contribution to the world.

Walker now researches at Michigan State University, aiming to understand the intricacies of photosynthesis with a goal of optimizing it.

Walker holds a profound fascination for plants, describing their ability to take sunlight and carbon dioxide to produce the food, clothes, the air we breathe, and energy, in "miraculous" terms.

However, he acknowledges that photosynthesis isn't as efficient as it seems. According to him, a leaf only manages to convert around 1 percent of sunlight into usable energy. This inefficiency is partly due to errors in the first stage of photosynthesis. An enzyme meant to capture CO2 molecules often ends up seizing oxygen instead, which results in a compound that inhibits photosynthesis and necessitates a high-energy process called photorespiration for its removal.

Walker postulated that in the American Midwest, the energy lost due to this recycling process across an average wheat and soybean growing season could be equivalent to roughly 148 trillion dietary calories. An increase in efficiency could significantly impact agricultural productivity, thus necessitating a deeper understanding of photorespiration.

For this purpose, Walker developed an innovative method to trace carbon molecules in leaves, as described in a 2022 study published in Nature Plants. The study reports the use of flux analysis to unveil the movement of molecules within plants' metabolic network.

In order to freeze the metabolism of a plant, they needed a more efficient way than spraying liquid nitrogen onto the instrument chamber holding the leaf. This led Walker to drill a hole in the chamber to rapidly administer liquid nitrogen onto the leaf’s surface. As postdoc Xinyu Fu points out, this is significant as factors can change within just 10 seconds that it would take to open the chamber and remove the leaf.

Their research found that around 40 percent of the carbon-bearing amino acid serine, produced during photorespiration might be used for something else possibly protein synthesis, instead of undergoing the entire recycling process. Therefore, enhancing photorespiration in response to climate change might lead to a yield of protein-rich crops. However, Walker stresses the importance of understanding potential trade-offs.

Walker is recognized for his readiness to collaborate and generous nature. His former postdoc advisor, Don Ort, praised Walker for his passion for teaching and his enthusiasm.

Walker views plant science as a community working towards addressing two major complications: increasing crop productivity to serve a growing population, and adapting to a changing climate that presents various agricultural challenges. He projects that these problems will start seeing solutions in the forthcoming decades, whether from his lab or elsewhere.

“Whoever comes up with those, and if they’re shown to work and work repeatedly in a lot of crops, then that’s a really big deal,” he says. “That’s the kind of idea that we’re chasing.”

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