title: Distribution of isoflavones in lupin hypocotyls. Possible control of cell wall peroxidase activity involved in lignification.
abstract: The distribution of 4 key isoflavones (luteone, genistein, 2'-hydroxygenistein and wighteone) in lupin (Lupinus albus L. cv. multolupa) hypocotyls shows a gradient that diminishes from young to old tissues. A spatial gradient occurs within the hypocotyl, and a temporal gradient in both the outermost vascular and epidermal tissues. Not only does a gradient exist in respect to the quantity of isoflavones, but there is also a gradient in respect to the type of isoflavone. Thus, wighteone is mainly associated with the non-meristematic zones of the lupin hypocotyl. A close relationship was found between the distribution and the localization in the walls of phloem cells of both peroxidase (EC 1.11.1.7) and isoflavones. This observation suggests an in vivo peroxidase-isoflavone interconnection. In fact, lupin isoflavones are able to inhibit the peroxidase-catalyzed oxidation of the lignin precursor coniferyl alcohol, probably due to the co-oxidation of isoflavones in the reaction media. The results are discussed on the basis of a possible role for isoflavones in controlling cell wallperoxidase activity involved in the lignification of phloem cells.
authors.affiliation: Depto de Biologia Vegetal (Fisiologia Vegetal), Universidad de Murcia, Campus de Espinardo, E-30071 Murcia, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Ferrer
authors.forename: M A
authors.initials: MA
authors.lastname: Pedreño
authors.forename: A A
authors.initials: AA
authors.lastname: Calderón
authors.forename: R
authors.initials: R
authors.lastname: Muñoz
authors.forename: A
authors.initials: A
authors.lastname: Barceló