Pathway to understanding plant stress

Exploring how plants and crops cope with stress in a changing environment

Nearly 15 years of research has culminated in a new framework for understanding how plants respond to stress and could be made more resilient to climate change.

A new Nature Communications paper, by a team from the ARC Centre of Excellence in Synthetic Biology, suggest a new role for a biochemical pathway known as the MEP (methylerythritol phosphate) pathway in detecting, signalling and responding to environmental stress – for example, when plants get too much sunlight or not enough water. Stress causes accumulation of damaging reactive oxygen species (ROS) molecules, an indicator that plants are struggling.

The researchers, who include Jordi Perez-Gil, James Behrendorff, Andrew Douw and Claudia Vickers, suggest the stress-sensing response is likely triggered by iron-sulfur cluster enzymes in the pathway. These enzymes are particularly sensitive to ROS molecules. The ROS damage these enzymes, causing accumulation of intermediate molecules in the pathway.

These intermediates act as signals to tell the plant that it’s in trouble and help it respond. These signals travel from the chloroplasts (where photosynthesis happens) to the nucleus (the cell’s control centre). The signals tell the nucleus to make proteins that help the plant deal with the stress in the chloroplasts, rather like sending a distress message and getting help in return.

‘Getting a better understanding of this pathway is important for us to understand how plants and crops respond to stress in a changing environment, especially under climate change conditions where stress happens more frequently,’ says Claudia Vickers, Adjunct Professor at Queensland University of Technology. ‘This could help us engineer plants to better respond to environmental stress.’

Lead author Dr Jordi Perez-Gil says the signalling molecules are also produced by some bacterial pathogens during the infection processes. ‘Human beings and animals don’t have the MEP pathway so it’s a great target for antimicrobials as it’s less likely there will be side effects,’ says Dr Perez-Gil.

Prof Vickers says the paper provides an important new direction for science to further explore the roles of the MEP pathway. Key questions include how the MEP pathway evolved, its function in different organisms and its mechanisms in pathogen infection.
Further investigation is needed to understand the pathway’s oxygen response mechanisms and the role of the iron-sulfur cluster enzymes.

Addressing these questions, the researchers say, will require significant investment but promises to yield fascinating insights and potential biotechnological applications. These could include the production of valuable industrially useful isoprenoids, which are also produced by the MEP pathway.

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