title: Incorporation of atmospheric15NO2-nitrogen into free amino acids by Norway spruce Picea abies (L.) Karst.
abstract: During spring and autumn 1991, potted 6-yearold spruce trees (Picea abies (L.) Karst.) were fumigated with 60 nl·1-115NO2for 4 days under controlled conditions in constant light. Current and previous flush needles, the bark and the fine roots were analysed for total15N content and incorporation of15N into the α-amino nitrogen of free amino acids. In addition, in vitro nitrate reductase activity and stomatal conductance of the needles were measured. Nitrate reductase activity was significantly higher in the needles of fumigated trees compared to control trees exposed to filtered air. With an average of 9.1%15N, free glutamate was the pool with the most label. Taking into account the time-course of the labelling of this pool, this figure can be taken as an estimate of the minimum contribution of NO2to the N nutrition of the needles.15N-labelled amino acids were also detected in the bark and the roots, indicating export from the needles.
authors.affiliation: Pflanzenphysiologisches Institut der Universität Bern, 3013, Bern, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Nussbaum
authors.affiliation: Pflanzenphysiologisches Institut der Universität Bern, 3013, Bern, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: von Ballmoos
authors.affiliation: Institut für Organische Chemie der Universität Bern, 3012, Bern, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Gfeller
authors.affiliation: Institut für Organische Chemie der Universität Bern, 3012, Bern, Switzerland.
authors.forename: U P
authors.initials: UP
authors.lastname: Schlunegger
authors.affiliation: Eidgenössische Anstalt für Agrikulturchemie und Umwelthygiene, 3097, Liebefeld, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Fuhrer
authors.affiliation: Department of Horticulture, Purdue University, 47907, West Lafayette, IN, USA.
authors.forename: D
authors.initials: D
authors.lastname: Rhodes
authors.affiliation: Pflanzenphysiologisches Institut der Universität Bern, 3013, Bern, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Brunold
keywords: 15N incorporation; Amino acids; Nitrate reductase activity; Nitrogen dioxide; Picea abies