Molecular cloning and gene transcription analyses of barwin-type PR-4 genes from Phellinus sulphurascens-infected Douglas-fir seedlings

• Published in: Forest pathology = Journal de pathologie forestière = Zeitschrift für Forstpathologie 2012-08, Vol.42 (4), p.279-288
• Main Authors: Islam, M. A., Sturrock, R. N., Ekramoddoullah, A. K. M.
• Format: Article
• Language: English
• Subjects: Hordeum vulgare; Phellinus; Pseudotsuga menziesii
• ISSN: 1437-4781; 1439-0329
• DOI: 10.1111/j.1439-0329.2011.00752.x

Summary To better understand the molecular basis of interactions between the laminated root rot pathogen Phellinus sulphurascens Pilát and its principal host, Douglas‐fir [DF; Pseudotsuga menziesii (Mirb.) Franco.], we constructed a cDNA library from roots of P. sulphurascens‐infected DF seedlings. From a total of 3600 random cDNA clones, we identified 56 clones that matched with barley wound induced (barwin)‐type pathogenesis‐related 4 (PR4) genes that have been reported in planta. At least three PR4 genes comprising 426‐ to 444‐bp full‐length open reading frames, Pm PR4a1, Pm PR4a2, and Pm PR4b1, were identified from DF seedlings. Deduced amino acid sequences for the proteins encoded by these genes confirmed that two of them are acidic (Mr, 12.8–13.0 kDa; pI, 4.12–4.53) and one is a basic (Mr, 13.0 kDa; pI, 8.53) PR4 protein. Quantitative reverse transcriptase‐PCR analyses of these transcripts showed significantly higher transcription in P. sulphurascens‐infected vs. control DF tissues. Upregulation of the transcripts in roots of a P. sulphurascens‐resistant DF family was significant. Our results suggest that DF PR4 genes play an important role in the defence mechanism of DF against P. sulphurascens infection and thus could be useful in DF breeding.