Plant extracellular vesicles are incorporated by a fungal pathogen and inhibit its growth.

Extracellular vesicles (EV) are membrane particles released by cells into their environment and are considered to be key players in intercellular communication. EV are produced by all domains of life but limited knowledge about EV in plants is available, although their implication in plant defense has been suggested. We have characterized sunflower EV and tested whether they could interact with fungal cells. EV were isolated from extracellular fluids of seedlings and characterized by transmission electron microscopy and proteomic analysis. These nanovesicles appeared to be enriched in cell wall remodeling enzymes and defense proteins. Membrane-labeled EV were prepared and their uptake by the phytopathogenic fungus Sclerotinia sclerotiorum was verified. Functional tests further evaluated the ability of EV to affect fungal growth. Spores treated with plant EV showed growth inhibition, morphological changes, and cell death. Conclusive evidence on the existence of plant EV is presented and we demonstrate their ability to interact with and kill fungal cells. Our results introduce the concept of cell-to-cell communication through EV in plants.

Cell wall proteome of sugarcane stems: comparison of a destructive and a non-destructive extraction method showed differences in glycoside hydrolases and peroxidases.

BACKGROUND: Sugarcane has been used as the main crop for ethanol production for more than 40 years in Brazil. Recently, the production of bioethanol from bagasse and straw, also called second generation (2G) ethanol, became a reality with the first commercial plants started in the USA and Brazil. However, the industrial processes still need to be improved to generate a low cost fuel. One possibility is the remodeling of cell walls, by means of genetic improvement or transgenesis, in order to make the bagasse more accessible to hydrolytic enzymes. We aimed at characterizing the cell wall proteome of young sugarcane culms, to identify proteins involved in cell wall biogenesis. Proteins were extracted from the cell walls of 2-month-old culms using two protocols, non-destructive by vacuum infiltration vs destructive. The proteins were identified by mass spectrometry and bioinformatics. RESULTS: A predicted signal peptide was found in 84 different proteins, called cell wall proteins (CWPs). As expected, the non-destructive method showed a lower percentage of proteins predicted to be intracellular than the destructive one (33% vs 44%). About 19% of CWPs were identified with both methods, whilst the infiltration protocol could lead to the identification of 75% more CWPs. In both cases, the most populated protein functional classes were those of proteins related to lipid metabolism and oxido-reductases. Curiously, a single glycoside hydrolase (GH) was identified using the non-destructive method whereas 10 GHs were found with the destructive one. Quantitative data analysis allowed the identification of the most abundant proteins. CONCLUSIONS: The results highlighted the importance of using different protocols to extract proteins from cell walls to expand the coverage of the cell wall proteome. Ten GHs were indicated as possible targets for further studies in order to obtain cell walls less recalcitrant to deconstruction. Therefore, this work contributed to two goals: enlarge the coverage of the sugarcane cell wall proteome, and provide target proteins that could be used in future research to facilitate 2G ethanol production.