Humans have been using salicylic acid for centuries to treat pain and inflammation. Plants also seem to use it for their own benefit, in times of stress when they feel threatened. A new study published in Science Advances looks at this self-defense mechanism, as well as how plants regulate the production of salicylic acid.
Plants produce salicylic acid through chloroplasts, those tiny green organelles where photosynthesis takes place. They do it in response to stress. Salicylic acid produced by plants is critical for signaling, regulation, and defense against pathogens. “It ‘s as if plants use a pain reliever , just like us,” says plant biologist Wilhelmina van de Ven of the University of California at Riverside (UCR).
To better understand the series of reactions that occur in plants when they are subjected to stress, the team of researchers carried out biochemical analyzes on mutated plants to block the effects of stress signaling pathways.
Environmental stress produces reactive oxygen species (ROS) in all living organisms. A good example of this is when we burn our skin after spending too much time in the sun without putting on protection. For plants, stressors include unfriendly insects, drought, and excessive heat . While high levels of ROS in plants can be lethal, smaller amounts serve a safety function. Regulating these levels is, therefore, of vital importance for them.
The researchers used thale cress ( Arabidopsis thaliana ) as a model plant to conduct the experiments. They focused on an early warning molecule called MEcPP , which has also been observed in bacteria and malaria parasites. Apparently, when MEcPP accumulates in a plant, it triggers a chemical reaction and response that includes salicylic acid. “At non-lethal levels, ROS are like an emergency call to action, allowing the production of protective hormones such as salicylic acid,” says plant geneticist Jin-Zheng Wang, from UCR. “ROS are a double-edged sword.”
The findings could be used to produce modified plants that are more resistant to future environmental hazards . “We would like to be able to use the knowledge gained to improve crop resistance. That will be crucial for the food supply in our increasingly hot and bright world.”
There is work ahead to find out more about the MEcPP molecule and how it works. Knowing its mechanism of action would help scientists to produce plants that are more resistant to stress. As is happening with animals, plants are under increasing pressure due to global warming. It is not known how many species will be able to survive if temperatures continue to rise.
In the study, the plants have been subjected to different pressures such as high heat, constant sunlight and lack of water, all stresses that plants around the world are already facing. And if the plants already have problems, we do too .
“These impacts go beyond our diet”, says the molecular biochemist Katayoon Dehesh, from the UCR. “Plants clean our air by sequestering carbon dioxide, they offer us shade and are the habitat of numerous animals. The benefits of enhancing their survival are exponential.”
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Referencia: Wang, J., Van de Ven, W. et al. 2022. Reciprocity between a retrograde signal and a putative metalloprotease reconfigures plastidial metabolic and structural states. Science Advances. DOI: 10.1126/sciadv.abo0724
