Flavonoids in roots of white clover: interaction of arbuscular mycorrhizal fungi and a pathogenic fungus

• Published in: Plant and soil Vol. 302; no. 1-2; pp. 33 - 43
• Main Authors: Carlsen, S. C. K, Understrup, A, Fomsgaard, I. S, Mortensen, A. G, Ravnskov, S
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 2008; Springer; Springer Netherlands; Springer Nature B.V
• Subjects: Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Arbuscular mycorrhizal fungi (AMF); Biological and medical sciences; Biomass; Biomedical and Life Sciences; Clover; Cultivars; Ecology; Flavonoids; Fundamental and applied biological sciences. Psychology; Fungi; Glomus mosseae; Infections; Legumes; Life Sciences; Metabolites; Mosses; Mycorrhizal fungi; Pathogens; Plant pathology; Plant Physiology; Plant roots; Plant Sciences; Plants; Pythium ultimum; Regular Article; Roots; Soil Science & Conservation; Symbiosis; Trifolium repens; Trifolium repens (white clover); Arbuscular mycorrhizal fungi (AMF); Flavonoids; Roots; white clover; Pythium ultimum; Trifolium repens (white clover); Soil plant relation
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-007-9452-9

The effects of two arbuscular mycorrhizal fungi (AMF) (Glomus mosseae and G. claroideum) and a pathogenic fungus (Pythium ultimum) on the production of eight flavonoids in roots of two white clover (Trifolium repens L.) cultivars were evaluated. Quantification of AM and pathogenic fungi in the roots showed that the AM symbiosis significantly reduced P. ultimum biomass and in some cases prevented infection. The flavonoid productions in clover roots varied depending on the presence of beneficial and/or pathogenic fungi, fungal isolate or plant cultivar. Only plants colonized with G. claroideum showed detectable concentrations of either coumestrol or kaempferol (cultivar-dependant). In addition, inoculation with G. claroideum resulted in significantly higher concentrations of coumestrol in cv. Sonja and medicarpin in cv. Milo. A low production of coumestrol and kaempferol in mycorrhizal plants may be G. mosseae-specific. Only the concentrations of formononetin and daidzein increased in clover roots in response to infection with P. ultimum. These flavonoids are supposedly stress metabolites, synthesized or produced from glycosides in response to pathogen infection. However, the presence of one or both AMF significantly lowered the formononetin and daidzein concentrations, and overruled the inductive effect of P. ultimum. Therefore the antagonistic action of AM against the pathogen must take place through another mechanism.