Exploring the Plant–Microbe Interface by Profiling the Surface-Associated Proteins of Barley Grains

• Published in: Journal of proteome research 2016-04, Vol.15 (4), p.1151-1167
• Main Authors: Sultan, Abida, Andersen, Birgit, Svensson, Birte, Finnie, Christine
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - analysis; Bacterial Proteins - metabolism; Edible Grain - metabolism; Edible Grain - microbiology; Electrophoresis, Gel, Two-Dimensional; Endo-1,4-beta Xylanases - analysis; Endo-1,4-beta Xylanases - metabolism; Enzyme Inhibitors - analysis; Enzyme Inhibitors - metabolism; Fungal Proteins - analysis; Fungal Proteins - metabolism; Hordeum - metabolism; Hordeum - microbiology; Metabolome; Microbial Consortia - physiology; Microbiota - physiology; Plant Proteins - analysis; Plant Proteins - metabolism; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Surface Properties
• ISSN: 1535-3893; 1535-3907
• DOI: 10.1021/acs.jproteome.5b01042

Cereal grains are colonized by a microbial community that actively interacts with the plant via secretion of various enzymes, hormones, and metabolites. Microorganisms decompose plant tissues by a collection of depolymerizing enzymes, including β-1,4-xylanases, that are in turn inhibited by plant xylanase inhibitors. To gain insight into the importance of the microbial consortia and their interaction with barley grains, we used a combined gel-based (2-DE coupled to MALDI-TOF-TOF MS) and gel-free (LC–MS/MS) proteomics approach complemented with enzyme activity assays to profile the surface-associated proteins and xylanolytic activities of two barley cultivars. The surface-associated proteome was dominated by plant proteins with roles in defense and stress-responses, while the relatively less abundant microbial (bacterial and fungal) proteins were involved in cell-wall and polysaccharide degradation and included xylanases. The surface-associated proteomes showed elevated xylanolytic activity and contained several xylanases. Integration of proteomics with enzyme assays is a powerful tool for analysis and characterization of the interaction between microbial consortia and plants in their natural environment.