Flavonoid exudation

Dorr, E., Rozefelds, A. C., Mincbin, P. and Eorster, P. I. 2000. Variation in flavonoid exudates in Eucryphia species from Australia and South America. Phytochemistry 28 111-118. 

Flavonoids exuded from plants play an important role in the symbiosis between legumes and leguminous bacteria. At the same time, they attract zoospores and induce spore germination of phytopathogenic fungi. 

Table 2.4 Flavonoid variation in leaf exudates of Achillea aspleniifolia (from Valant-Vetschera and Wollenweber, 1988)...

See D. M. Smith, 1980, for a study of flavonoid profiles of the varieties.) The overall flavonoid profile of P. triangularis is fully in accord with the uifique status of the species. A detailed discussion of the chemistry of this system, which is beyond the scope of the present treatment, can be found in a paper by Wollenweber and Dietz (1980). An example of the complexity of flavonoid biosynthesis in this species can be found in a description of biflavonoids present in the farinose exudate (linuma et al., 1994). 

Additional information on chemical variation within this species came from studies of exudate and internal (vacuolar) pigments based on broader collections of the fern (Star et al., 1975a, b). Exudate flavonoids, identified from specimens representing the range of the species, were identified as ceroptene [221], the C-methylflavonol pityrogrammin [222], and two derivatives of kaempferol, the 4 -methyl ether [223] and the 7,4 -dimethyl ether [224] (see Fig. 2.69 for stmctures 221-224). 

Major exudate flavonoids of Dubautia arborea (Asteraceae). Biochem. Syst. Ecol. 

Star, A. E., Rosier, H., Mabry, T. J. and Smith, D. 1975a. Flavonoid and ceroptin pigments from frond exudates of Pityrogramma triangularis. Phytochemistry 14 2275-2278. 

Valant-Vetschera, K. M. and Wollenweber, E. 1988. Leaf flavonoids of the Achillea millefolium group. 11. Distribution patterns of free aglycones in leaf exudates. Biochem. Syst. Ecol. 16 605-614. 

Flavonoids from seed exudation Flavonoids from root exudation... 

Figure 2 Structures of flavonoids present in root exudates of host plants and inducing nod gene expression in rhizobia (1) as 3,5,7,3 -tetrahydroxy-4 -methoxyflavanone, inducer in Rhizohium legiiminosarum bv. viciae (2) as 3, 4, 5, 7-tetrahydroxy-flavone, inducer in Rhizohium melilotr, (3) as 4, 7-dihydroxyisoflavone, inducer in Bradyrhizohium japonicum (4) as couinestrol, intermediate in phenylpropane metabolism, weak inducer. (From Ref. 64.)...

A detailed analysis of the root exudate of Phaseolus vulgaris found six flavonoids daidzein, coumestrol, naringenin, genistein, liquiritigenin, and isoli-... 

M. C. Bolanos-Vasquez and D. Werner, Effects of Rhizohium tropici, R. etii, and R. leguminosarum bv. phaseoU on nod gene-inducing flavonoids in root exudates of Phaseohis vulgaris. Molec. Plant Microbe Interact. 10 229 (1997). 

P. Scheidemann and A. Wetzel, Identification and characterization of flavonoids in the root exudate of Rohinia pseudoacacia. Trees 11 3 6 (1997). 

The effect of flavonoids on spore germination and hyphal growth of ecto-mycorrhizal fungi is poorly known. However, several metabolites relea.sed by the plant roots trigger events leading to their infection (44,55). In the saprotrophic phase, spores of several ectomycorrhizal fungi respond to stimulation by abietic acid, the diterpene resin acid, in root exudates (56). 

V. Gianinazzi-Pearson, B. Branzanti, and S. Gianinazzi, In vitro enhancement of spore germination and early hyphal growth of a vesicular-arbuscular mycorrhizal fungus by host root exudates and plant flavonoids. Symbiosis 7 243 (1989). 

As the separation characteristics of liquid chromatographic and electrophoretic techniques markedly differ from each other, combined methods using the advantages of both procedures have been successfully used for the analysis of flavonoids. Thus, the use of CZE-UV, HPTLC-UV and GC-MS for the measurement of flavonoids in seeds and root exudates of Lotus pedunculatus has been reported. The rooting solution and seed exudate were passed through cellulose acetate filters to bind the flavonoids. After extraction,... 

H.L. Steele, D. Werner and J.E. Cooper, Flavonoids in seeds and root exudates of Lotus pedun-culatus and their biotransformation by Mesorhisobium loti. Physiol. Plant. 107 (1999) 251-258. 

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