Loss of oleic acid indicates water deficit in plants

Are there markers that show that plants are starting to suffer from water deficit? The answer to this question has been discovered by researchers from CATRIN in cooperation with colleagues from Poland, Germany and Belgium. They identified specific metabolites that are related to the response of plants to water deficit. One of them – oleic acid – has not yet been described in this context. The description of identification features is important for basic research or could be used for screening methods. The results of approximately two years of research were published in The Plant Journal.

The researchers studied pea plants, which they examined during their growth for three weeks. The plants that received reduced watering were compared to those with enough water.

“During the experiment, we monitored the phenotype with our modern non-invasive methods. We analyzed the morphology of the plants, i. e. whether they change shape, leaf size and total biomass. At the same time, we monitored their physiological state, studied all the essential parameters of photosynthesis, and determined by thermal analysis how the plant manages water. Another part of the research was the collection of phloem juice to determine the content of metabolites from phloem pathways, which are used to distribute nutrients. By statistical analysis, we determined those metabolites that correlated the most with the physiological changes in plants signaling a lack of water,” explained of one of the authors Lukáš Spíchal.

Under mild drought stress, the researchers described 30 statistically significant metabolomites in plants. Many of them are already known to be linked to plant defense mechanisms against drought. However, they were the first to describe oleic acid in this context. Its decrease in the phloem juice, which has occurred after several hours, can be used as a marker for detecting early monitoring that the plant is exposed to water deficit.

“We also tried to compare the contents of metabolites with the phenotype of plants. The phenotype was not very distinct, because the plants did not show significant changes at first glance. For example, we used thermal imaging in order to find out what the temperature of the leaf of the plants is. Changes in temperature indicate how plants open or close vents while losing water. This process therefore shows how the plants are able to cool themselves and manage water,” said a member of the author team Nuria De Diego.

Blicharz S., Beemster G.T.S., Ragni L., De Diego N., Spíchal L., Hernándiz A.E., Marczak L., Olszak M., Perlikowski D., Kosmala A., Malinowski R.: Phloem exudate metabolic content reflects the response to water-deficit stress in pea plants (Pisum sativum L.). Plant J. 2021, in press; DOI: 10.1111/tpj.15240

Martina Šaradínová
June 9, 2021