Scots pine (Pinus sylvestris) secretes a number of small, highly-related, disulfide-rich proteins (Sp-AMPs) in response to challenges with fungal pathogens such as Heterobasidion annosum, although their biological role has been unknown. Here, we examined the expression patterns of these genes, as well as the structure and function of the encoded proteins. Northern blots and quantitative real time PCR showed increased levels of expression that are sustained during the interactions of host trees with pathogens, but not non-pathogens, consistent with a function in conifer tree defenses. Furthermore, the genes were up-regulated after treatment with salicylic acid and an ethylene precursor, 1-aminocyclopropane-1-carboxylic-acid, but neither methyl jasmonate nor H2O2 induced expression, indicating that Sp-AMP gene expression is independent of the jasmonic acid signaling pathways. The cDNA encoding one of the proteins was cloned and expressed in Pichia pastoris. The purified protein had antifungal activity against H. annosum, and caused morphological changes in its hyphae and spores. It was directly shown to bind soluble and insoluble β-(1,3)-glucans, specifically and with high affinity. Furthermore, addition of exogenous glucan is linked to higher levels of Sp-AMP expression in the conifer. Homology modeling and sequence comparisons suggest that a conserved patch on the surface of the globular Sp-AMP is a carbohydrate-binding site that can accommodate approximately four sugar units. We conclude that these proteins belong to a new family of antimicrobial proteins (PR-19) that are likely to act by binding the glucans that are a major component of fungal cell walls.
Plant Molecular Biology – Springer Journals
Published: May 17, 2011
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera