Researchers identify drought-resistance mechanism in plants

A team of Spanish researchers has identified a double mechanism that regulates how plants respond to drought. The mechanism of inhibition and degradation was identified by researchers from the Institute for Plant Molecular and Cell Biology (IBMCP), Polytechnic University of Valencia (UPV) and the Spanish National Research Council (CSIC), providing a window into how plants respond to environmental stress. The results of this research have been published in the Proceedings of the National Academy of Sciences.

To respond to environmental conditions, plants have different signalling paths that are blocked by repressors as they wait for the appropriate stimulus. The removal of these repressors makes it possible to signal several hormone paths, including the one that is activated during times of drought. The stress hormone abscisic acid (ABA) acts as a regulator, enabling plants to adapt to drought stress. Levels of ABA increase during periods of drought, initiating a plant’s adaptation to drought stress via stomatal closure and reduced plant growth.

Pedro Luís Rodríguez, research professor of the CSIC at the IBMCP, explained that “until now, we knew that hormone ABA, after being perceived by its receptors, triggered the inhibition of the repressors of the answer to drought, which are the 2C phosphatase proteins. In this work, we have discovered a supplementary mechanism based on BPM proteins, which regulate the degradation of these repressors,” he explained.

The IBMCP researchers have discovered that BPM proteins facilitate the tagging of 2C phosphatase proteins for degradation and recycling. This process takes place in a regulated manner, as the hormone itself facilitates the degradation of the phosphatases.

“The BPM proteins recognise 2C-type phosphatases and facilitate their marking with ubiquitin, which leads to the degradation of these repressors,” Rodríguez explained.

“This makes it possible, for example, for the perspiration of the plant to decrease in a situation of drought, which represents a key adaptation. If the degradation of 2C-type phosphatases was accelerated, plants with better resistance to drought could be obtained,” he added.

“In general, plants have a vast arsenal of proteins that degrade the repressors of their adaptive responses, so that the mechanism only triggers when necessary.

“In nature, plants suffer environmental stress in a transient or continued manner, and the existence of a double mechanism of inhibition and degradation to remove the hindrance of the adaptative answer provides greater versatility,” Rodríguez concluded.

Image caption: Plants subjected to drought with a greater degradation of 2C-type phosphatase proteins from left to right.