The assessment of enriched apoplastic extracts using proteomic approaches |
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Authors: | R P HASLAM A L DOWNIE M RAVETON K GALLARDO D JOB K E PALLETT P JOHN M A J PARRY J O D COLEMAN |
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Institution: | Crop Performance and Improvement, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK;UniversitéJoseph Fourier, UFR de Biologie, Centre de Biologie Alpine –Bâtiment D, Laboratoire ECE, BP53, 38041 Grenoble Cedex 9, France;Laboratoire Mixte Centre National de la Recherche Scientifique-Institut National de la Recherche Agronomique-Bayer, Bayer CropScience, Lyon, France;Bayer CropScience GmbH, D-65926 Frankfurt am Main, Germany;School of Plant Sciences, The University of Reading, Plant Science Laboratories, Reading RG6 6AS, UK;School of Biological &Molecular Sciences, Oxford Brookes University, Oxford OX3 0BP, UK |
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Abstract: | In plant tissues the extracellular environment or apoplast, incorporating the cell wall, is a highly dynamic compartment with a role in many important plant processes including defence, development, signalling and assimilate partitioning. Soluble apoplast proteins from Arabidopsis thaliana, Triticum aestivum and Oryza sativa were separated by two‐dimensional electrophoresis. The molecular weights and isoelectric points for the dominant proteins were established prior to excision, sequencing and identification by matrix‐assisted laser‐desorption ionisation time of flight mass spectrometry (MALDI ‐ TOF MS). From the selected spots, 23 proteins from O. sativa and 25 proteins from A. thaliana were sequenced, of which nine identifications were made in O. sativa (39%) and 14 in A. thaliana (56%). This analysis revealed that: (i) patterns of proteins revealed by two‐dimensional electrophoresis were different for each species indicating that speciation could occur at the level of the apoplast, (ii) of the proteins characterised many belonged to diverse families reflecting the multiple functions of the apoplast and (iii), a large number of the apoplast proteins could not be identified indicating that the majority of extracellular proteins are yet to be assigned. The principal proteins identified in the aqueous matrix of the apoplast were involved in defence, i.e. germin‐like proteins or glucanases, and cell expansion, i.e. β‐D‐glucan glucohydrolases. This study has demonstrated that proteomic analysis can be used to resolve the apoplastic protein complement and to identify adaptive changes induced by environmental effectors. |
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Keywords: | Apoplast proteomics extracellular cell wall Arabidopsis thaliana Triticum aestivum Orzya sativa |
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