Agricultural crops often face harsh environmental conditions. Instead of using energy for growth, factors such as disease, extreme temperatures and salty soils force plants to use it to respond to the resulting stress. This phenomenon is called "the trade-off between the response to growth and stress."
A team of researchers from Nagoya University has discovered a previously unknown pathway to regulate whether a plant uses its resources for growth or to cope with stress. Phys.org portal. This discovery could allow for the control of the stress response in agricultural conditions, increasing their yield. The scientists published their results in the journal Science.
The research team, led by Professor Yoshikatsu Matsubayashi and Associate Professor Mari Ohnishi from the Nagoya University Graduate School of Life Sciences in Japan, studied the role of hormones and their receptors in plant responses to stress.
They focused on three receptors for which the corresponding hormone had not yet been identified. Using Arabidopsis thaliana, a small flowering plant, they discovered the PSY family that functions as a hormone, binding to these receptors and switching the stress response to growth and vice versa.
Normally, receptors and hormones function as locks and keys, with the hormone (in this case, the peptide PSY) acting as the key needed to start the biological process. However, in this study, plant cells that did not produce PSY nevertheless had an active stress response. Therefore, this suggests that instead of activating the stress response, the presence of a PSY "key" in the receptor "lock" keeps it off.
To test the nature of stress responses, the researchers grew plants under extremely stressful conditions using heat, salt, and infected them with bacteria. Plants that were either deficient in PSY receptors or constantly receiving the PSY hormone failed to adequately respond to stress, resulting in reduced survival. The scientists concluded that stressed plants stop producing PSY, the absence of which causes stress responses.
To explain this phenomenon, the researchers proposed a mechanism whereby damaged cells reduce the concentration of PSY hormones in cell layers adjacent to the damaged areas. This lack of PSY triggers the stress response. Importantly, this may explain why even damaged plants can send messages.
Instead of using its limited resources to create a new signal, the damaged plant cell can instead stop the release of the PSY hormone, activating the stress response. Such a mechanism would make it possible to balance stress resistance with the associated energy costs. As a result, even under the most stressful environmental conditions, plants can still grow by managing their limited resources.
Most of the mechanisms found in Arabidopsis are found in other plants as well. Therefore, these results are applicable to all crops.