A novel protein associated with citrus blight has sequence similarities to expansin

摘要: A protein associated with citrus blight (CB), a disease of unknown cause, was partially characterized. The 12 kDa protein, designated p12, is diagnostic CB and present in leaves xylem fluid from roots stems CB-affected trees. up to six other CB-specific proteins, are readily detected by SDS-PAGE partial N-terminal amino acid sequence p12 found be unique based on database searches. cDNA library root cambium screened 60 bp fragment, obtained PCR amplification degenerate primers designed using the two clones were selected. These sequenced revealing 674 nucleotide 393 nt ORF which included predicted p12. 49% similar 31% identical expansins. Bacterial expression cloned ORF, encodes an 11.8 plus hydrophobic signal peptide, produced immunoreactive expected size. By northern blot analysis, it determined that transcripts stem cambium, but not trees, suggesting transport leaves. Southern hybridization analysis genomic DNA indicated encoded protein.p>