Effects of long-term open-field ozone exposure on leaf phenolics of European silver birch (Betula pendula Roth)

Citation
A. Saleem et al., Effects of long-term open-field ozone exposure on leaf phenolics of European silver birch (Betula pendula Roth), J CHEM ECOL, 27(5), 2001, pp. 1049-1062
Citations number
36
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF CHEMICAL ECOLOGY
ISSN journal
0098-0331 → ACNP
Volume
27
Issue
5
Year of publication
2001
Pages
1049 - 1062
Database
ISI
SICI code
0098-0331(200105)27:5<1049:EOLOOE>2.0.ZU;2-R
Abstract
The response of phenolic compounds as a result of long-term low open-field ozone exposure was studied in ozone-sensitive and ozone-tolerant clones of European silver birch (Betula pendula Roth). The saplings were exposed to 1 .5-1.6 times the ambient (elevated) ozone and ambient air (as control) over three growing seasons from May 1996 until August 1998. Quantification by m odified Folin-Ciocalteau assay showed a 16.2% increase in total phenolics i n elevated ozone plants as compared to that in controls and a corresponding 9.9% increase of 10 phenolic compounds quantified by HPLC. Five nonflavono ids and five flavonoids showed 8.4% and 11.4% increases, respectively. The phenolic results indicated slightly higher ozone sensitivity of clone 5 as compared to clone 2. The most ozone-responsive phenolic compounds in clone 2 and clone 5 were (+)-catechin (CT), chlorogenic acid (CGA), 5-p-coumaroyl quinic acid (5CQA), 3-p-coumaroylquinic acid (3CQA), myricetin galactopyran oside (MG), quercetin-3-O-glucuronopyranoside (QGR), and quercetin-3-O-arab inofuranoside (QA). Increased phenolic content in ozone-exposed plants was related to impaired growth and accelerated leaf senescence, indicated by en hanced autumn leaf yellowing and lower chlorophyll and Mg content. The chan ge in carbon allocation towards defensive phenolics at the expense of growt h was greater in the ozone-sensitive clone as compared to tolerant clone.