Open AccessThe molecular characterization of two barley proteins establishes the novel PR‐17 family of pathogenesis‐related proteins
Author(s) -
Christensen Anders B.,
Cho Baik HO,
Næsby Michael,
Gregersen Per L.,
Brandt Jakob,
MadrizOrdeñana Kenneth,
Collinge David B.,
ThordalChristensen Hans
Publication year - 2002
Publication title -
molecular plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.945
H-Index - 103
eISSN - 1364-3703
pISSN - 1464-6722
DOI - 10.1046/j.1364-3703.2002.00105.x
Subject(s) - biology , hordeum vulgare , aminopeptidase , pathogenesis related protein , complementary dna , cdna library , signal peptide , microbiology and biotechnology , botany , gene , peptide sequence , genetics , gene expression , amino acid , leucine , poaceae
Summary Two barley ( Hordeum vulgare L.) cDNA clones (pBH6‐12 and pBH6‐17) were isolated from a cDNA library prepared from leaves 6 h after inoculation with Blumeria graminis f.sp. hordei ( Bgh ). The two transcripts accumulate strongly in response to Bgh , peaking around 6, 15–24 and 48–96 h after inoculation, concomitant with fungal penetration attempts, hypersensitive response and fungal growth. The encoded proteins, Hv PR‐17a and Hv PR‐17b, belong to a new family of plant pathogenesis‐related proteins, designated ‘PR‐17’. The family also include NtPRp27 from tobacco (Okushima et al ., 2000, Plant Mol. Biol. 42 , 479–488) and WCI‐5 from wheat (Görlach et al ., 1996, Plant Cell 8 , 629–643), responsive to viral and fungal infection, respectively. Antisera were raised to Hv PR‐17a and Hv PR‐17b, and the proteins exhibit apparent molecular weights of 26 and 24 kDa, respectively. They accumulate in the mesophyll apoplast following Bgh ‐inoculation, as well as in the leaf epidermis, the only tissue to be invaded by the fungus. Several homologous plant proteins exist, and a highly conserved part of the members of this new protein family show similarity to the active site and to the peptide‐binding groove of the exopeptidase ‘aminopeptidase N’ from eukaryotes and the endopeptidase ‘thermolysin’ from bacteria.