Canadian Forest Service Publications

Gene cloning of a thaumatin-like (PR-5) protein of western white pine (Pinus monticola D. Don) and expression studies of members of the PR-5 group. 2004. Piggott, N.; Ekramoddoullah, A.K.M.; Liu, J.-J.; Yu, X. Physiological and Molecular Plant Pathology 64: 1-8.

Year: 2004

Issued by: Pacific Forestry Centre

Catalog ID: 24971

Language: English

Availability: Order paper copy (free)

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To understand the molecular defence response of western white pine to the blister rust pathogen Cronartium ribicola, we have endeavoured to isolate and characterise pathogenesis-related (PR) proteins from western white pine. A full-length cDNA (Pin mTLP) was isolated from a cDNA library constructed from inoculated foliage. BLASTX search results indicated that the sequence shared a high degree of identity with the thaumatin-like proteins (TLPs) of the PR-5 family, and in particular with those of the ‘small-TLP’ subgroup mainly identified in monocots. The mature protein predicted from the cDNA sequence has a molecular mass of 16 kDa and pI of 4.1. Southern blot analysis showed that Pin mTLP is a single-copy gene member of a multi-gene family.

Two-dimensional Western blot analysis of total western white pine protein extracts probed with a Douglas-fir anti-TLP antibody detected a major and a minor protein spot of 23 and 17 kDa, respectively. Both 23 and 17-kDa proteins were identified as TLPs by Nanospray MS/MS analysis. The 23-kDa protein was shown to accumulate in canker margins in the bark of infected seedlings indicating that it is locally induced in response to fungal invasion. Both local wounding and methyl jasmonate treatments induced expression of the protein, whereas salicylic acid treatment did not. These results suggest that the 23-kDa TLP plays a role in the molecular defence response of western white pine to wounding and pathogen attack.