PHENOLIC PATTERN OF BEAN (PHASEOLUS-VULGARIS L.) AS AN INDICATOR OF CHRONIC OZONE STRESS

From sowing till emergence of the fourth trifoliolate leaf, beans were exposed for seven hr a day to four ozone concentrations in open-top c hambers: filtered air (FA), non-filtered air (NF), non-filtered air pl us 30 ppb ozone (NF+) and non-filtered air plus 60 ppb ozone (NF++). C ontrols in ambient air of open plots (AA) were also available. The fre e polyphenolic pool of the first trifoliolate leaf was systematically investigated using HPLC. The groups of phenolics to which the three ma in chromatographic signals belonged were identified as hydroxycinnamic acid derivative for peak No 1 and flavonoids for peaks Nos 4 and 6. T he metabolic regulation of phenolic accumulation could be recognized a s different clusters based on specific phenolic patterns that reflecte d some of the tested atmospheric conditions. The comparison of AA and NF conditions revealed a 'chamber effect'. FA and NF atmospheres gave rise to almost the same phenolic equilibriums dominated by a hydroxyci nnamic acid derivative (about 53% of the total phenolics). Ozone addit ion was associated with a regular reduction of the percentage of peak No 1: about 40% for NF+ and 19% for NF++. Therefore, the significant d ecrease of the vacuolar storage of this phenolic compound (from 23 mg g(-1) dry weight for NF to about 3 mg g(-1) dry weight for NF++) can b e regarded as a useful tool for monitoring long-term exposure to eleva ted ozone concentrations.