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Nitrogen and carbon dynamics of a foliar biotrophic fungal parasite in fertilized Douglas‐fir
Author(s) -
ElHajj Zeina,
Kavanagh Kathleen,
Rose Cathy,
KanaanAtallah Zahi
Publication year - 2004
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2004.01102.x
Subject(s) - biology , fungus , botany , nutrient , host (biology) , nitrogen , δ13c , fertilizer , human fertilization , isotopes of carbon , douglas fir , stable isotope ratio , horticulture , agronomy , ecology , total organic carbon , chemistry , physics , organic chemistry , quantum mechanics
Summary• We investigated the nutritional dynamics of Phaeocryptopus gaeumannii and the impact of nitrogen (N) fertilization of Douglas‐fir ( Pseudotsuga menziesii ) on the production of P. gaeumannii fungal fruiting bodies. Emergence of P. gaeumannii fungal fruiting bodies (pseudothecia) in Douglas‐fir stomata has been directly linked to premature needle loss, a symptom of Swiss needle cast disease. • Douglas‐fir trees (10‐yr‐old) naturally infected with P. gaeumannii were treated with soil applications of N fertilizer isotopically enriched with 15 N to increase foliar N and track the movement of N from the host to the fungus. Foliar N, free amino acids, percent of stomata occluded by pseudothecia, N isotope and carbon (C) isotope levels were assessed on treated and control trees. • Higher foliar N resulted in increased %N and %C in P. gaeumannii , as well as increased fungal fruiting and thus disease severity. Comparisons of δ 15 N levels between P. gaeumannii pseudothecia and associated needles indicated an increase in δ 15 N of needles and a simultaneous decline in δ 15 N of pseudothecia coupled with increased levels of foliar and fungal percentage N. • These findings confirm that P. gaeumannii responds to host nutrient status and that increased N availability inside Douglas‐fir needles is linked to increased severity of Swiss needle cast disease.