New research indicates that when plant leaves make physical contact, they establish a biological signaling network that enhances their resilience to environmental stressors, particularly intense light. This finding, which is yet to undergo peer review, suggests that plants communicate with one another to prepare for challenges, thereby boosting their ability to endure excess light without incurring severe damage.
In the study, resilience is defined as a plant’s capacity to withstand high light levels without developing significant issues, such as leaf lesions. Researchers evaluated damage by measuring ion leakage from the leaves. A plant exhibiting greater resilience demonstrates lower ion leakage in response to excess light, while one that is more sensitive shows higher levels of leakage.
Ron Mittler, a phytologist at the University of Missouri in Columbia, explained, “We demonstrated that if plants touch each other, they are more resilient to light stress by comparing groups of plants that touch each other with groups that do not.” This research builds upon earlier work conducted in 2022, where scientists revealed that plants in physical contact could transmit electrical signals. Mittler and his team aimed to investigate if the act of touching itself could enhance plants’ tolerance to stress.
Using the small weed-like plant, Arabidopsis thaliana, researchers arranged two groups: one where the plants maintained leaf-to-leaf contact and another that did not. After establishing this physical connection, they subjected both groups to bright, intense light akin to harsh sunlight. Following exposure, the team assessed damage by measuring ion leakage from the affected tissues and the accumulation of a pigment known as anthocyanin, which signifies stress in plants.
Results showed that plants in contact experienced lower leaf damage and reduced anthocyanin accumulation compared to those grown in isolation. Mittler noted, “If you stimulate or stress one plant, it will send a signal to all the other plants that it touches, and they all become more tolerant.”
To deepen their understanding of the underlying mechanisms, the team employed genetically modified plants incapable of transferring chemical signals. Their experimental setup involved three plants: a transmitter, a mediator, and a receiver. When the mediator was replaced with mutant plants, the receiver plants did not receive protection from stress, indicating that hydrogen peroxide secretion plays a vital role in enhancing resilience.
This study sheds light on the cooperative behaviors of plants, which typically compete for resources such as space, light, and nutrients. Mittler asserts that this phenomenon represents an evolutionary trade-off: “If you grow under harsh conditions, you better grow in a group. If you grow under really ideal conditions with no predators, with no stressors, then you better grow individually.”
Piyush Jain, a plant biologist at Cornell University and a contributor to the study, commended the research design, stating, “The authors propose a thoughtful and clever experimental design to better understand the still underexplored pathways of aboveground plant-to-plant communication.” Jain emphasized that the study addresses a longstanding question regarding whether chemical and electrical signaling contribute to increased resilience against excessive light stress.
While the findings are promising, it is essential to note that the study has not yet been peer-reviewed and is currently available on BioRxiv. As research continues to explore the complexities of plant interactions, these insights could pave the way for advancements in agricultural practices and environmental management.
