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191243 
Journal Article 
Beech leaf colonization by the endophyte Apiognomonia errabunda dramatically depends on light exposure and climatic conditions 
Bahnweg, G; Heller, W; Stich, S; Knappe, C; Betz, G; Heerdt, C; Kehr, RD; Ernst, D; Langebartels, C; Nunn, AJ; Rothenburger, J; Schubert, R; Wallis, P; Muller-Starck, G; Werner, H; Matyssek, R; Sandermann, H 
2005 
1 
Plant Biology
ISSN: 1435-8603
EISSN: 1438-8677 
7 
6 
659-669 
WOS:000234280600011 
Ozone and light effects on endophytic colonization by Apiognomonia errabunda of adult beech trees (Fagus sylvatica) and their putative mediation by internal defence compounds were studied at the Kranzberg Forest free-air ozone fumigation site. A. errabunda colonization was quantified by "real-time PCR" (QPCR). A. errabunda-specific primers allowed detection without interference by DNA from European beech and several species of common genera of plant pathogenic fungi, such as Mycosphaerella, Alternaria, Botrytis, and Fusarium. Colonization levels of sun and shade leaves of European beech trees exposed either to ambient or twice ambient ozone regimes were determined. Colonization was significantly higher in shade compared to sun leaves. Ozone exhibited a marginally inhibitory effect on fungal colonization only in young leaves in 2002. The hot and dry summer of 2003 reduced fungal colonization dramatically, being more pronounced than ozone treatment or sun exposure. Levels of soluble and cell wall-bound phenolic compounds were approximately twice as high in sun than in shade leaves. Acylated flavonol 3-O-glycosides with putatively high UV-B shielding effect were very low in shade canopy leaves. Ozone had only a minor influence on secondary metabolites in sun leaves. It slightly increased kaempferol 3-O-glucoside levels exclusively in shade leaves. The frequently prominent hydroxycinnamic acid derivative, chlorogenic acid, was tested for its growth inhibiting activity against Apiognomonia and showed an IC50 of approximately 8 mM. Appearance of Apiognomonia-related necroses strongly correlated with the occurrence of the stress metabolite, 3,3',4,4'-tetramethoxybiphenyl. Infection success of Apiognomonia was highly dependent on light exposure, presumably affected by the endogenous levels of constitutive phenolic compounds. Ozone exerted only minor modulating effects, whereas climatic factors, such as pronounced heat periods and drought, were dramatically overriding. 
European beech (Fagus sylvatica); Apiognomonia errabunda; endophyte; "real-time PCR"; plant phenolics; sun and shade leaves; light; ozone; climate; precipitation 
NAAQS
• ISA-Ozone (2013 Final Project Page)
     Considered
     Eco/Welfare