Engineered enzymes may help plants adapt to higher temperatures

As global temperatures rise, it's imperative that plants can adapt to new and changing conditions. Michigan State University researchers from the Walker lab are looking at ways to give plants an assist. More specifically, their research aims to help plants adapt to changing temperatures by introducing engineered enzymes that will increase plants' heat tolerance.

Their recent paper is published in the Plant Biotechnology Journal.

"I would say that the main goal of our research is to prepare plants for elevated temperatures because, with climate change, temperatures rise," said Ludmila Roze, senior research scientist in the Michigan State University-Department of Energy Plant Research Laboratory (PRL). "How can we help agriculture be prepared to sustain yield in this changing environment?"

The lab is looking to increase the thermotolerance of plants, or their ability to survive at high temperatures. These temperatures can wreak havoc on plants, down to the cellular machinery that keeps them alive. The plant's ability to maintain its physical and chemical structures while under these temperature conditions is known as thermostability.

The lab's recent paper looks at increasing thermostability of an enzyme known as glycerate 3-kinase, or GLYK, in the plant Arabidopsis thaliana, commonly known as thale cress. This enzyme is the final step of a vital plant process known as photorespiration, which is expected to become even more important as temperatures increase.

To develop a repertoire of enzymes with different thermostabilities, the Walker lab looks at a variety of photosynthetic organisms, including the alga Cyanidioschyzon merolae, which lives in acidic volcanic hot springs. When compared to many plants, C. merolae has much better thermostability.

"By understanding the 'why' of how [C. merolae enzymes] operate at higher temperatures, we can reengineer plant enzymes to be better prepared for a world with higher temperatures," said Berkley Walker, associate professor in the PRL and the MSU Department of Plant Biology.

Combining artificial intelligence-assisted enzyme folding models with molecular dynamics from the PRL Vermaas lab, the researchers were able to identify parts of the C. merolae enzyme, referred to colloquially as loops, which were responsible for thermostability. These loops were introduced to the Arabidopsis GLYK enzyme.

The researchers found that with the loops introduced, the Arabidopsis enzyme had increased thermotolerance, which would allow it to better adapt to a changing climate.

"There is very intensive research into how temperature affects plant growth, physiology and yield," Roze said. "Elevated temperature affects many agricultural plant species in a dramatic way; they reduce their yield."

For example, in some plants such as Brassica rapa, or field mustard, from which turnips and bok choy were cultivated, elevated temperatures can stall photosynthesis, putting the plant at risk.

The next step is to introduce these engineered, more thermotolerant enzymes into the model plant Arabidopsis to see how the plant reacts.

"Understanding how we can learn from nature and improve enzymes for a warmer future is critical since plants are faced with temperatures that they have not historically been exposed to," Walker said. "Some enzymes are going to be just fine, but others may not be able to take the heat. With this knowledge, we have a strategy we can try on any enzyme to increase its ability to operate under warmer conditions."