In plant stress response, one protein lures, binds its own killer

In response to drought, cold, lack of sunlight and other stress, cellular proteins interact in different ways to help a plant survive. A primary protective act is the destruction and recycling of some of the plant's own cellular materials into what is needed for others.

A Purdue University-led research team has identified proteins involved in this protective process and discovered how they act upon each other. A better understanding of these mechanisms could lead to ways to help plants withstand severe conditions.

Normal growth condition (top) and carbon starvation stress condition (bottom). Unlike wild type, the SINAT mutant did not survive carbon starvation stress. Purdue University professor Gyeong Mee Yoon discovered a mechanism involved in plants' response to stress.

"We identified three proteins involved in this process and discovered a surprising co-regulation mechanism," said Gyeong Mee Yoon, associate professor of botany and plant pathology at Purdue, who led the study. "One protein, called ACC synthases (ACS), an enzyme regulating ethylene biosynthesis, recruits the two other proteins and acts like a scaffold, or glue holding them together. Interestingly, the two proteins are ones that under normal growth conditions break down ACS. It lures its own killers into a bind that causes them to degrade each other instead."

Yoon also found that a byproduct of the process is an increase in the plant hormone ethylene. The role of ethylene in ripening produce in a fruit bowl or refrigerator may be familiar, but it also influences plant growth, development and plant stress responses. It has been a key target of research, she says.

"We know that ethylene is somehow involved in the stress response and autophagy, or the destruction and recycling of cellular materials, but we don't know exactly how it is involved," said Yoon, who also is a member of Purdue's Center for Plant Biology and part of Purdue's Next Moves plant sciences initiative. "This is one clue as we seek to solve the mystery and to understand ethylene biosynthesis and signaling in autophagy regulation."

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Image of HarrietP via Pixabay 

Source: Greenhouse Management