How Plantago asiatica plants communicate with each other to respond to salt stress

Plants exchange adaptive information, helping them to adjust to environmental challenges. Salt stress in plants, caused by soil salinity, often results in water loss. Plants often cope with this situation by closing the stomatal aperture. In this study, the scientists wanted to understand how Plantago asiatica plants utilize both above- and below-ground communication to differentially respond to salt stress cues perceived from neighbors with variable genetic identities.

Interplant cueing or communication is a fascinating method through which neighboring plants exchange adaptive information. Plants can send and receive information through both aboveground and belowground pathways: via the shoot system (involving stems and leaves) and the root system, respectively.

Communication usually relies on volatile organic compounds aboveground and fungal networks in the soil for the root system. This exchange of information helps plants to respond quickly to certain stress situations and enhance their resistance by activating adaptive mechanisms. Plants exchange information regarding altered nutrient availability, impending competition, neighbor proximity, drought stress, and salt stress. Plant stomata refer to microscopic pores on leaf surfaces that control gas exchange and transpiration. Closure of stomata due to salt stress was previously recorded as a stress response in many plants. Some studies also reported that unstressed plants show this adaptive mechanism, which is a result of communication with stressed plants.

Many studies to date have focused on above- and below-ground communications separately. However, how and if these two networks interact with one another and work as a whole is still unidentified. This study, led by Professor Akira Yamawo from Kyoto University, decided to focus on the combined effect of interplant cueing in both above- and belowground systems. “I am fascinated by how plants communicate with each other and adapt to their environment. We also wanted to understand the effect of genetic relatedness in these communications” mentioned Dr. Yamawo, while talking about the motivation behind the study. The study was published on August 12, 2025, in Volume 20 of the Plant Signaling & Behavior journal.

The study was conducted on Japanese plantain (Plantago asiatica). As these plants have limited seed dispersal, sibling plants often grow in clumped patches, and thus plant populations from different locations have reduced genetic relatedness. For the study, two plant populations were collected from Aomori city (Aomori city A and Aomori city B), which were genetically related, and one was collected from Fukuoka city, which showed a distinct genetic difference from the other two. For the experiment, each set consisted of three plants, including one stress-induced (IND) plant. The other two were the recipient plants that shared either their rooting space or aerial space with an IND plant. Half of the roots of the IND plants were either left untreated, treated with distilled water (DW), or treated with saline water solution to induce salt stress. (The DW served as an unstressed control). The effect of salt stress on the stomatal opening on the IND and the recipient plants, as well as how the genetic backgrounds affect this mechanism, was observed and compared.

The plants were classified as having three different genetic backgrounds based on location of seed collection. Plants from the same population were termed Half-Sibling (SB). Plants obtained from seeds collected from Aomori city A and B were termed as near population (NP), and those from seeds collected from Fukuoka were termed as far population (FP).

Regardless of genetic background, all IND plants showed decreased proportion of open stomata, compared to untreated or DW treated plants, indicating stress-response. The study suggested interesting effects of genetic background on the aboveground and belowground cues. While aboveground cues conveyed information related to salt stress regardless of genetic background, the proportion of open stomata of belowground recipient plants was lower in SB and NP group, compared to FP group, suggesting that belowground cueing was more effective between closely related neighbors.

The study points to the interplant communication of salt stress involving both above- and below-ground cueing in Japanese plantain. The difference in below-ground cueing based on genetic relatedness suggests the involvement of genetically specific root-metabolites, which requires further investigation. “If crops also have the ability to transmit stress information, then understanding and utilizing this mechanism in the future may help us achieve more stable food production.”, mentioned Dr. Haruna Ohsaki from Meijo University, another researcher involved in this study. Further related research and investigation can help to improve modern agriculture by ensuring resilience to stress-related challenges and improving crop yields.

About Akira Yamawo from Kyoto University

Professor Akira Yamawo is a faculty member at the Center for Ecological Research, Kyoto University. He graduated from Okayama University of Science High School. His field of expertise includes Evolutionary Biology, Community ecology, Plant Ecology, Forest Ecology, and others. His current research focuses on the evolution of intelligence and inter-organism communication. He is a member of multiple societies including The Botanical Society of Japan and The Ecological Society of Japan. He has more than 50 published research articles. He is also the recipient of multiple awards, including the Konosuke Matsushita Memorial Encouragement Award from the Konosuke Matsushita Memorial Foundation.

Website: https://akira-yamawo.jimdofree.com/

About Haruna Ohsaki from Meijo University

Haruna Ohsaki is associated with the Faculty of Agriculture, Meijo University, Nagoya, Japan. She was a JSPS Research Fellow and was previously associated with the Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University. In January 2023, she received the 13th Ikushi Prize from the Japan Society for the Promotion of Science. Her research interest focuses on plant science and ecology. She has contributed to more than 15 research articles to date.

Website: https://mric3706hrn.wixsite.com/website

Funding information: This study was supported by the Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research [KAKENHI; grant numbers 18K19353, 19H03295, 22K19337, 23H02558, and 23H04970 to AY].