Phenol metabolism is differentially affected by ozone in two cell lines from grape (Vitis vinifera L.) leaf

Two differentially ozone-sensitive cell lines obtained from Vitis vinifera leaf explants, one richer in polyphenols and brown pigmented (Ph+) and the other phenol-poorer and pale (Ph-), were used as experimental tool for analyzing ozone (O-3) stress response. The study deals with the phenylpropanoid and flavonoid pathway induction by ozone stress. Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5), stilbene synthase (STS, EC 2.3.1.95), chalcone synthase (CHS, EC 2.3.1.74) activities in particular were assayed in order to obtain additional information on the biochemical parameters involved in the early ozone response. A pool of phenolics was also examined in Ph+ and Ph - callus. These compounds appeared to decrease and only Ph+ callus seemed able to recover the metabolites considered. PAL activity increased in both cell lines during ozone fumigation, reaching the highest increase in Ph+. Ph - cell line seemed to be able to synthesize stilbene phytoalexin, measured as resveratrol, which showed maximum value at 24 h after ozone treatment. No evidence of involvement of CHS in the ozone response was recorded in either of the cell lines selected. (C) 2003 Published by Elsevier Ireland Ltd.