Researchers at the Karlsruhe Institute of Technology (KIT) have found how plant cells respond to stress. If their energy supply is disrupted by heat, drought or saline soils, chloroplasts—the cells' powerhouses—send an intracellular distress signal by forming tiny, finger-like projections. This signal specifically activates protection programs that help limit damage. The study, published in Plant Physiology, reveals the function of these previously mysterious structures and presents an approach for making crops more resilient to climate stress.

Each plant cell contains chloroplasts, which work like little solar power stations. The tiny structures are the green energy centers of plant cells. Absorbing sunlight and extracting carbon dioxide from the air, they produce sugar—the energy source every plant needs for growth and survival. Without these solar power stations, plants would not be able to produce energy and thus could not serve as a food resource for other living beings. Another effect would be that less oxygen would be released into the atmosphere.

Protection against heat, drought, or salt
If plants are under stress because of, for example, a lack of water, high temperatures such as those Germany and Central Europe are currently experiencing, or saline soils, this delicate energy system gets out of balance. Aggressive substances develop that can affect and damage important parts of the cell. To survive, the plant needs to respond quickly and activate protective measures.

In this stress situation, chloroplasts react by forming the "fingers" that were recently investigated. The researchers revealed that these structures send a signal to the central control of the cell. "Particular genes are enabled or disabled, which triggers protection programs that support the damaged areas," said Professor Peter Nick from KIT's Botanical Institute.