Defence-related gene activation during an incompatible interaction between Stagonospora (Septoria) nodorum and barley (Hordeum vulgare L.) coleoptile cells

Abstract

Two previously unidentified cDNA clones (bsi1 and bpr1-1) were isolated by differential hybridization from a cDNA library of Stagonospora (Septoria) nodorum (Berk) Castellani & E.G. Germano (teleomorph Phaeosphaeria (Leptosphaeria) nodorum (E. Muller) Hedjaroude-challenged barley (Hordeum vulgare L.) coleoptiles. bsi1 encoded a cysteine-rich protein containing 89 amino acids (aa) with a relative molecular mass (M(r)) of 9405. Protein sequence homologies showed that Bsi1 was very similar to an aluminium-induced protein from wheat and indicated that it was related to the Bowman-Birk-type proteinase inhibitors (BB-PIs). The predicted aa sequence of Bsi1 contained an N-terminal secretory signal sequence which implied that the protein was exported. The other clone, bprl-1, which was truncated at the 5' end, encoded a type-1 pathogenesis-related (PR-1) protein. The complete sequence of bpr1-1 was obtained after cloning a barley genomic DNA fragment and was shown to encode a basic protein containing 174 aa with a M(r) of 18 859. The deduced aa sequence of bpr1-1 contained both an N-terminal secretory signal sequence and a charged C-terminal extension. This latter sequence may represent a vacuolar targeting signal. bsil and bpr1-1 and four other defence-related genes (encoding 1,3-beta-glucanase, 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, a homologue of a putative wheat peroxidase, and barley leaf-specific thionin), showed increased transcription levels in S. nodorum-challenged coleoptiles, although their pattern of accumulation varied after inoculation (a.i.). The potential role of these induced genes in defence against fungal attack is discussed.

Monitoring of gene expression profiles and identification of candidate genes involved in drought responses in Festuca mairei

“…The farnesylated protein encoded by SSBI-B9 has been found in Hordeum vulgare to be a nuclear protein involved in stress response and leaf senescence (Barth et al 2004). SSBI-D4, SSBI-D9, SSBII-A3, and SSBI-A4 encoded a Wber protein Fb19 (Chow et al, unpublished), a dehydration-responsive family protein (Albertini et al 2004), a type-1 pathogenesis-related protein (Stevens et al 1996), and a DNAJ heat shock N-terminal domain-containing protein (Chow et al, unpublished), respectively, which have been widely studied in association with stress response. SSBI-E2 encoded a 34 kD Wbrillin-like protein, the major constituent of elastin-associated extracellular microWbrils, and has been recently identiWed in a network of rice genes associated with stress response (Cooper et al 2003).…”

Plant thionins – the structural perspective

“…In most species in which careful genetic characterization has been made, thionins appear to be expressed as non-toxic propeptides activated upon pathogenic attack [32][33][34]. Analysis of thionin cDNA showed that thionins have a common gene structure with an approximately 20-amino acid-long leader peptide and an approximately 60-amino acid-long trailing acidic peptide, which neutralizes the basic toxin [15].…”

Bacteria associated with Stagonospora (Septoria) nodorum increase pathogenicity of the fungus

“…The original laboratory isolate of S. nodorum, coded SG, which was pathogenic on wheat but not barley, was obtained from Institute of Arable Crop Research (IACR), Long Ashton, UK and was the same as that used by Stevens et al (1996). Other isolates of S. nodorum used in this study were freshly isolated from field material using the following techniques : infected wheat leaves with Staganospora-like lesions were placed on damp filter paper in a sealed polythene box and incubated at 18mC for 3-5 d under continuous near UV light (Sylvania F15TB\BL8 15W).…”