Treatment of young spruce shoots with SO2 and H2S: Effects on fine root chromosomes in relation to changes in the thiol content and redox state

Three year old spruce trees (Picea omorika) were exposed to 100 and 225 nl l(-1) SO2 and H2S for three weeks. The number of chromosomal aberrations an d the mitotic index in the root tip meristems, and glutathione and cysteine contents in fine roots were determined twice weekly. An increase in glutat hione content in fine roots of H2S exposed plants was only detectable after 13 days of fumigation. The number of chromosomal aberrations increased sig nificantly after 9 days of exposure to 225 nl l(-1) H2S and after 13 days o f exposure to 225 nl l(-1) SO2 or 100 nl l(-1) H2S. This increase in chromo somal damage persisted up to the end of the 3 week treatment. Neither SO2 n or H2S exposure affected the cysteine content or the redox state of glutath ione in fine roots. These results suggest that the development of chromosom al aberrations during SO2 and H2S exposures does not directly reflect chang es in thiol/glutathione content or redox state in the fine roots.