A plant scientist has discovered a new way of measuring stress in plants, which comes at a time when plants are experiencing multiple stressors from heat, drought and flooding because of extreme weather events.

The discovery involves a once maligned collection of molecules called reactive oxygen species (ROS), which are produced by anything that uses oxygen, like animals, people and plants. But the author has uncovered a redeeming quality of ROS — their role as a communication signal that can indicate whether plants are stressed out.

“When stressors from heat and drought are added together, plants don't have ground water to draw from, so they close the stomata [leaf pores], and this makes the leaves become really hot,” said the author. “This is why the combination of drought and heat is really dangerous, because the leaf temperature is much higher than with a plant subjected to just heat. The change can be anywhere between two and four degrees, and that can make the difference between life and death.”

Plant stress is also tied to crop loss, but existing analytical research on the subject has typically focused on how crops react to just one stressor. However, the author said a plant’s survival rate will dramatically decrease as the number of stressors continues to increase to three to six different stressors. The key, the author said, is to keep ROS levels in check. Either too much or too little can be damaging, but an optimum level of ROS can be considered safe for life.

Recent advances in the study of ROS signalling in plants include the identification of ROS receptors and key regulatory hubs that connect ROS signalling with other important stress-response signal transduction pathways and hormones, as well as new roles for ROS in organelle-to-organelle and cell-to-cell signalling.

Our understanding of how ROS are regulated in cells by balancing production, scavenging and transport has also increased.

https://www.nature.com/articles/s41580-022-00499-2