Image: PSY receptor mutant (right) and wild type (left). PSY receptor mutants are less able to withstand stress but grow more easily.
Source: Dr. Yoshikatsu Matsubayashi
Crops often face harsh growing conditions. Factors such as disease, extreme temperatures and saline soils force plants to use energy to cope with the resulting stress, rather than using energy for growth. This is known as the “growth-stress response trade-off”. Now, a team of researchers from Nagoya University has discovered a previously unknown pathway that regulates whether plants use their resources to grow or their ability to withstand stress. The discovery could enable the control of stress responses under agricultural conditions, increasing crop yields. They published their findings in the journalscience．
A research team led by Professor Yoshikatsu Matsubayashi and Assistant Professor Mari Ohnishi at the Graduate School of Science, Nagoya University, Japan, investigated the role of hormones and their receptors in plant stress responses. They focused on three receptors whose corresponding hormones have not yet been identified. Using the small flowering plant Arabidopsis thaliana (thale cress), they discovered the PSY family, which acts as a hormone that binds to these receptors and regulates the switch between stress response and growth.
When the researchers investigated related pathways, they made an unexpected discovery. Often, receptors and hormones act like locks and keys, and hormones (in this case, a peptide PSY hormone) act like the keys necessary to unlock a biological process. In this study, however, those plant cells that did not produce PSY had a positive stress response. Thus, this suggests that the presence of the PSY ‘key’ in the receptor ‘lock’ does not activate the stress response, but keeps it closed.
To test the nature of the stress response, the researchers grew plants under extreme stress conditions, such as heat and salt, and infected them with bacteria. Plants lacking PSY receptors or continuously fed the PSY hormone fail to respond adequately to stress, resulting in reduced survival. The scientists concluded that stressed plants stop releasing PSY, and that loss of PSY triggers stress-responsive genes.
To explain this phenomenon, the researchers proposed a mechanism whereby damaged cells reduce the concentration of the PSY hormone in the cell layer near the damaged site. This loss of PSY triggers a stress response. Importantly, this may explain why even damaged plants can send messages. Rather than using their limited resources to create new signals, damaged plant cells may stop the release of the PSY hormone, which activates the stress response. This mechanism will balance stress resilience and associated energy costs. Thus, even under the most stressful environmental conditions, plants can still grow by managing their limited resources.
“Most of the mechanisms found in Arabidopsis are also found in other plants. Therefore, our findings are applicable to all crops.” “This mechanism makes it possible to artificially control the balance between stress tolerance and yielding, which It’s a trade-off. In recent years, more and more crops have been grown in plant factories. When crops are grown indoors, it’s a low-stress environment, versus the stress-responsive systems needed to withstand the fluctuating natural outdoor environment. Not always necessary. Breeding varieties with low PSY receptor activity in plant factories may yield higher yields in these controlled environments.”
文章标题Peptide ligand-mediated trade-off between plant growth and stress response