They discover how bacteria help trees survive drought.

*This content was produced by experts from the Weizmann Institute of Science, one of the world’s leading centers for multidisciplinary basic research in the natural and exact sciences, located in Rehovot, Israel.

When things get tough, we all need a helping hand, and Trees They are not the exception. Researchers from The Department of Plant Sciences at the Weizmann Institute of Science has discovered that under drought conditions, the Cypress Get help from bacteria Beneficial to the soil in a kind of cooperation that allows them to survive and even thrive.

“our Studying He could have provided the best evidence yet of this. Trees and bacteria can live in symbiosis.“, He says Dr. Tamir Klein, Head of the Research Team“This has tremendous environmental significance,” he adds.

In many places in the world, The summer of 2022 was one of the driest seasons on record.Parts of China, Europe, the Middle East, the Horn of Africa and North America have suffered. severe droughtThese extreme weather conditions are expected to increase as a result of climate change.

According to Klein, the increasing prevalence of drought creates an urgent need to understand the underground mechanisms that keep trees alive in harsh climate conditions, in order to mitigate the increasing mortality rate of trees in the region. Israel And other places.

“If we lose the forests, we will lose everything because Trees produce our oxygen.And absorb carbon dioxide, clean the air, and regulate temperature. So we need to support our forests. “If bacteria can support trees, and we can understand how they do it, that’s a great starting point,” he explains.

Klein’s journey to uncover the collaboration between trees and other organisms in forests began years ago. In his previous studies, he investigated how trees share resources with other trees to stay healthy and how they maintain symbiotic relationships with others. mushroom.

The latest study, led by Dr. Yara Oppenheimer-Shananlaboratory microbiologist KleinFocus on the interactions between Cypress And beneficial bacteria found in forest soil.

For a month, the researchers grew seedlings. Cypress In custom-made boxes filled with forest soil, which were placed in a greenhouse in Weizmann Institute of Science. the Cypress They were divided into two groups: one was watered regularly and the other was deprived of water. In each group, half of the cypress trees were exposed to soil bacteria collected from the soil. Harel Forest.

The research team examined the interactions between tree roots and bacteria using several methods, including measuring the trees’ physiological responses to drought, conducting bacterial counts, imaging bacterial colonies in root zones using fluorescent markers, analyzing compounds released by seedlings through the roots, and assessing the mineral composition of plant leaves. Cypress.

Through this multidisciplinary approach, combining microbiology, plant physiology and organic chemistry, the researchers have identified the amazing collaboration that occurs underground between trees and soil bacteria: Bacteria help trees overcome water shortages and in return benefit from tree root secretions..

For example, Root exudate rates were more than doubled in trees exposed to the bacteria.Compared to trees that were not irrigated, whether in the irrigated cypress group or in the group grown under irrigated conditions. drought.

In addition, the scientists identified about 100 compounds in the exudates, including phenolic and organic acids, and the concentration of about half of these compounds differed significantly between irrigated and water-starved trees.”When we added nine compounds to the bacteria as sources of carbon and nitrogen, eight of them stimulated bacterial growth.“This is evidence that the secretions are a food source for bacteria,” says Oppenheimer Shanan.

Overall, the study results suggest that tree health improved as a result of interactions with bacteria. Furthermore, during drought, the cooperation between trees and bacteria offset the negative impact of water shortages.

Phosphorus availability in the soil was maintained only for cypress trees exposed to the bacteria, and this availability compensated for the decrease in phosphorus and iron levels measured in the leaves of cypress trees grown under drought conditions.

Klein hopes that the results of this research will advance our knowledge on the subject. forest environment And the realization that trees engage in much broader cooperation than previously thought.

At the applied level, the findings could have important implications for improving soil health and learning how to support plants that are stressed by lack of resources. For example, recruiting specific bacteria could help improve the health of trees and forests and create greater resilience and ecological stability.

“The next step is to determine the exact contribution of each bacterium or group of bacteria, and which bacteria benefit which trees.“Oppenheimer Shannan says.

“This is just the beginning. The more we learn about these interactions, the more we can formulate a complete and accurate dictionary, which will allow us to achieve the desired results, or prevent undesirable results, in the future. Taking care of our forests“Klein concludes,”

* The research team consists of Gilad Jacoby and Maya Starr from the Klein Group; doctors Maxim Itkin and Sergey Maletsky from the Weizmann Life Sciences Core Facilities Department; and two high school students, Rommel Karliner and Gal Eilon, who were selected through the Alpha Program, which integrates outstanding high school students into the world of scientific research.