Ascorbate deficiency influences the leaf cell wall glycoproteome in Arabidopsis thaliana

作者：Sultana Nighat; Florance Hannah V; Johns Alex; Smirnoff Nicholas^*

来源：Plant, Cell and Environment, 2015, 38(2): 375-384.

DOI：10.1111/pce.12267

• Arabinogalactan
• cell wall proteome
• glycoproteins
• hydrogen peroxide
• pathogen response
• peroxidase
• reactive oxygen
• vitamin C
• vtc mutants

The cell wall forms the first line of interaction between the plant and the external environment. Based on the observation that ascorbate-deficient vtc mutants of Arabidopsis thaliana have increased cell wall peroxidase activity, the cell wall glycoproteome of vtc2-2 was investigated. Glycoproteins were purified from fully expanded leaves by Concanavalin A affinity chromatography and analysed by liquid chromatography quadrupole time-of-flight mass spectrometry. This procedure identified 63 proteins with predicted glycosylation sites and cell wall localization. Of these, 11 proteins were differentially expressed between vtc2-2 and wild type. In particular, PRX33/34 were identified as contributing to increased peroxidase activity in response to ascorbate deficiency. This is the same peroxidase previously shown to contribute to hydrogen peroxide generation and pathogen resistance. Three fasciclin-like arabinogalactan proteins (FLA1, 2 and 8) had lower abundance in vtc2-2. Inspection of published microarray data shows that these also have lower gene expression in vtc1 and vtc2-1 and are decreased in expression by pathogen challenge and oxidative stresses. Ascorbate deficiency therefore impacts expression of cell wall proteins involved in pathogen responses and these presumably contribute to the increased resistance of vtc mutants to biotrophic pathogens.
Ascorbate deficient vtc mutants of Arabidopsis thaliana have increased cell wall peroxidase activity and higher resistance to biotrophic pathogens compared to wild type. To discover which peroxidase isoforms are affected, cell glycoproteins were isolated and subjected to label free quantitative proteomics analysis. This approach revealed that peroxidases 33 and 34 (PRX33/34) were more abundant in vtc2-2 while three fasciclin-like arabinogalactan proteins (FLA1, 2 and 8) had lower abundance in vtc2-2. Inspection of previously published transcriptome data showed that expression of these genes is affected in vtc mutants and that they are responsive to pathogen challenge. The results suggest a role for both classes of proteins in the increased pathogen resistance of vtc mutants.

• 出版日期2015-2