An epidermis/papilla-specific oxalate oxidase-like protein in the defence response of barley attacked by the powdery mildew fungus

Plant Mol Biol. 1998 Jan;36(1):101-12. doi: 10.1023/a:1005955119326.

Abstract

A cDNA clone of a defence response transcript was isolated from a library prepared from barley leaves expressing papilla resistance towards the powdery mildew fungus, Blumeria (syn. Erysiphe) graminis f.sp. hordei (Bgh). The 904 bp sequence encodes a 229 amino acid polypeptide with a putative signal peptide of 23 amino acids. After cleavage, the protein has a mass of 22.3 kDa and exhibits up to 60% amino acid identity to certain dicot proteins, and 46% amino acid identity to barley oxalate oxidase; therefore we designated it HvOxOLP (for Hordeum vulgare oxalate oxidase-like protein). Single-base substitutions among several cDNA and RACE clones demonstrate a gene of many copies. Both the transcript and protein accumulate from 3 h after inoculation with Bgh. The transcript level peaks at 18-24 h and subsequently decreases, whereas the protein level is stable from 24 h after inoculation. The accumulation patterns are independent of the outcome of the barley/powdery mildew interaction, unlike that of PR proteins, for example. The transcript accumulates specifically in the inoculated epidermal tissue. This temporal and spatial expression pattern suggests a very close relationship to papilla formation. Immunoblot analyses have facilitated a demonstration that HvOxOLP, like oxalate oxidase, is a water-soluble 100 kDa oligomeric protein. The oligomer is heat-stable and SDS-tolerant, and it can be denatured into a 25 kDa monomer. Attempts to demonstrate oxalate oxidase activity for this protein have failed. However, the relationships to oxalate oxidase suggests that HvOxOLP may be involved in H2O2 generation necessary for, for example, cross-linking of cell wall components during formation of papillae.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Ascomycota / pathogenicity*
  • Base Sequence
  • Gene Expression Regulation, Enzymologic
  • Gene Expression Regulation, Plant*
  • Gene Library
  • Hordeum / enzymology*
  • Hordeum / microbiology*
  • Hordeum / physiology
  • Molecular Sequence Data
  • Oxidoreductases / biosynthesis*
  • Oxidoreductases / chemistry
  • Plant Epidermis
  • Plant Leaves
  • Polymerase Chain Reaction
  • Protein Sorting Signals
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Sequence Homology, Nucleic Acid
  • Time Factors
  • Transcription, Genetic

Substances

  • Protein Sorting Signals
  • Recombinant Proteins
  • Oxidoreductases
  • oxalate oxidase

Associated data

  • GENBANK/X93171