Ascorbic Acid and Chlorophyll Content in Cell Cultures of Spruce (Picea abies): Changes by Cell Culture Conditions and Air Pollutants

Conifers contain ascorbic acid which is probably a protective against oxidative attacks. In yellow needles of damaged conifers the ascorbic acid content is increased, this suggests an in­ duction by air pollutants and/or photooxidants of a protection mechanism in trees. To study this mechanism in more detail, a green cell suspension culture of spruce (Picea abies) has been established. These cells contain chlorophyll and have a photosynthetic capacity, but they need carbohydrates (sucrose) for growth and are thus photoheterotrophic. Their ascorbic acid con­ tent and its regulation depends on carbohydrates, the cells resemble healthy green needles in this respect; they appear to be qualified for studies on the induction of a defense mechanism. Treatment of these cells with S0 2 (20 ppm, 4 days) ozone (1 ppm, 14 days) and vaporous H 20 2 revealed a decrease of the ascorbic acid content and (to a lesser extent) also of chloro­ phyll. It is concluded that (photo-)oxidants obviously do not play such a dominant role in bleaching of needles as it is assumed. The increased ascorbic acid content found in needles of damaged conifers is probably not an induced protection mechanism against oxidants.