Quantification of ozone influx and apoplastic ascorbate content in needles of Norway spruce trees (Picea abies L., Karst) at high altitude

Abstract

The objective of the present study was to investigate whether peak concentrations of ozone can deplete the apoplastic ascorbate pool of needles from Norway spruce trees (Picea abies L. Karst.) and, thereby, contribute to damage to forest trees. Twigs of forest trees grown at high altitude (1950m above sea level; Mt Patscherkofel, Austria) were enclosed in situ in chambers and fumigated for 5‐5 or 17 h with ozone concentrations ranging from 60 to 798 nmol mol−1. Adjacent branches were fumigated with filtered air. Ozone influx into the foliage ranging from 1‐7 to 17nmolm−2s−1 had little effect on whole‐needle ascorbate or glutathione contents. However, apoplastic ascorbate decreased by about 30% when the needles were exposed to environmentally relevant ozone concentrations and increased about 3‐fold at higher ozone concentrations. This response suggests the induction of ascorbate as a protective system and may also be important under field conditions. Needles of spruce trees from high altitude that were exposed to chronically increased ozone concentrations contained significantly higher apoplastic ascorbate concentrations than needles from spruce trees from lower altitudes with lower mean atmospheric ozone concentrations. The results show that peak concentrations of ozone do not act in spruce via a depletion of the apoplastic ascorbate pool.

Impacts of ozone on forests: a European perspective

“…Site-specific differences in chlorophyll, starch, proline and acid phosphatase and peroxidase activity between healthy and damaged Norway spruce have been identified in northern Germany (Godbold et al, 1993), although no pattern common to all sites was found. Ascorbate, which is thought to provide substantial protection from oxidative injury, occurred in significantly higher concentrations in needles from spruce trees growing at high altitudes than in trees growing at lower altitudes at lower O $ concentrations (Polle, Wieser & Havranek, 1995). However, because these chemicals are produced non-specifically in response to stress it is difficult to use them to quantify the impact of O $ .…”

Impacts of ozone on Plantago major: apoplastic and symplastic antioxidant status

“…APX (Castillo & Greppin, 1986 ;Peters et al, 1989 ;Ranieri et al, 1996), POD (Castillo et al, 1984 ;Takahama & Oniki, 1992 ;Polle et al, 1994), SOD (Castillo et al, 1987 ;Streller & Wingsle, 1994 ;Ogawa et al, 1996), ascorbate (Polle et al, 1990 ;Takahama & Oniki, 1992 ;Luwe & Heber, 1995) and small quantities of glutathione (Polle et al, 1990 ;Jamaı$ et al, 1996), although the enzymes required for the recycling of ascorbate and glutathione appear to be absent (Castillo & Greppin, 1988 ;Polle et al, 1990 ;Luwe et al, 1993). There is, therefore, the potential that O $ and\or its reactive products are scavenged before reaching the plasmalemma (Heath, 1988), and thus antioxidants located in the aqueous matrix of leaf cell walls might constitute an important first line of defence against the pollutant (Polle et al, 1995 ;Conklin et al, 1996 ;Dietz, 1997 ;Lyons et al, 1999).…”

“…Apoplastic reduction of MDHA by plasmalemma-bound MDHAR (Navas et al, 1994 ;Asard et al, 1995 ;Be! rczi & Mo$ ller, 1998) might be of minor importance during O $ exposure as the oxidation of ascorbate by O $ under acidic conditions does not produce MDHA (Giamalva et al, 1985 ;Polle et al, 1995). Based on measurements indicating that the volume of the apoplast in leaves of mesomorphic species commonly represents c. 10% of leaf f. wt (Speer & Kaiser, 1991 ;Pfanz, 1995 ;Dietz, 1997), the concentration of ASCjDHA in the apoplast of leaves of P. major was estimated to be c. 200 µM.…”

NH3 and NO2 fluxes between beech trees and the atmosphere – correlation with climatic and physiological parameters

“…Since disproportionation of NO # in water is thought to be slow at atmospheric NO # concentrations (Lee & Schwartz, 1981 ;Norby et al, 1989 ;Ramge et al, 1993), the reaction with apoplastic ascorbate might be of particular significance for maintaining a high flux of NO # into the leaves, and might prevent internal resistances. The apoplastic ascorbate concentration, however, is supposed to vary considerably between species (Polle et al, 1990Luwe, 1996 ;Schwanz et al, 1996a) and might depend on environmental factors (Polle & Rennenberg, 1992 ;Polle et al 1995 ;Schnug et al, 1995 ;Schwanz et al, 1996a, b) and\or stage of development (Luwe, 1996). Further experiments are required to correlate differences in internal resistances with apoplastic ascorbate concentrations.…”