A recent study conducted on melon plants has revealed a defense mechanism that certain plants activate to deal with insect pests. It is a system of signaling molecules that, distributed through extracellular vesicles - including exosomes - allow plants to adapt their defenses according to the level of stress they are under. The results obtained and published in the Journal of Extracellular Vesicles open new avenues for the development of sustainable methods of crop protection.
Led by the University of Valencia, the research team has identified, in the phloem of plants -plant tissue for nutrient transport-, extracellular vesicles capable of carrying signaling molecules that allow plants to adapt and dose their defenses depending on the level of stress to which they are subjected.
Recent research has shown that, in addition to transporting nutrients, the phloem is a pathway for the transmission of signaling macromolecules, such as proteins and nucleic acids, which change under stress. Until recently, the role of vesicles in this communication was little studied and was the subject of debate in the scientific community.
In the present study, the team analyzed sap samples from melon plants free and infested by the aphid Aphis gossypii, an important pest in melon cultivation and a recognized vector of plant viruses. The results revealed that phloem extracellular vesicles (PhlEVs) contain not only defense proteins, but also proteasome-active complexes, i.e., they degrade any foreign material detected in plants infested by these insect virus vectors.
"This increased activity in response to aphid infestation suggests that plants adapt their defenses depending on threats to biotic stresses, i.e. caused by living organisms," says Antonio Marcilla, Professor of Parasitology at the University of Valencia and principal investigator of the paper recently published in the Journal of Extracellular Vesicles.
The article confirms that plants use extracellular vesicles as part of an early warning system to defend themselves against infectious agents and phytophagous insects, a breakthrough for agricultural biotechnology, since, according to the team, taking advantage of these natural mechanisms could contribute to the protection of crops against pests and diseases, reducing the use of pesticides and promoting a more sustainable agriculture.
"We hope to better understand in the future the role of these vesicles in stress response, defense mechanisms and physiological processes in plants," explains Antonio Marcilla. "Advancing the study on the transport of small RNAs by extracellular vesicles could allow the development of innovative methods for disease control against pathogens and pests in agriculture," adds the scientist.
The phloem sap used for the study was collected through incisions in the plant stem, and the vesicles were isolated by molecular exclusion chromatography. These vesicles were characterized by advanced transmission electron microscopy and proteomic techniques carried out at the Central Support Service for Experimental Research (SCSIE) of the University of Valencia.
The Universitat de Valčncia team is formed by Antonio Marcilla, Christian M. Sánchez-López, Carla Soler and Pedro Pérez-Bermůdez, all members of a Prometeo Excellence Group of the Generalitat Valenciana (CIPROM23-054). The work has been carried out in collaboration with researchers Elisa Garzo and Alberto Fereres from the Instituto de Ciencias Agrarias-CSIC in Madrid.
This research has been funded by the R&D projects PID2019-105713GB-I00 and PID2023-146116NB-I00 financed by MICIU/AEI/10.13039/501100011033 and "FEDER/UE", and by a CSIC intramural project (Ref. 201440E0169) .
Reference :
Phloem sap from melon plants contains extracellular vesicles that carry active proteasomes which increase in response to aphid infestation . Christian M. Sánchez-López , Carla Soler , Elisa Garzo , Alberto Fereres , Pedro Pérez-Bermůdez , Antonio Marcilla. Journal of Extracellular Vesicles 2024. https://doi.org/10.1002/jev2.12517
