CU(2-SYNTHESIS OF PEA-PLANTS() EFFECT UPON PHOTOSYNTHESIS, CHLOROPLAST STRUCTURE, RNA AND PROTEIN)

Ten day old pea plants (Pisum sativum L., cv. Ran) were used to analyz e the effects of Cu2+ ions on the dry mass, chlorophyll, carotenoid an d proline contents, rates of photosynthesis (P(N)) and transpiration ( E), stomatal resistance (r(s)), carboxylation enzymes activities (RuBP C, PEPC), RNA and protein syntheses and changes in chloroplast structu re. Cu2+ treated plants showed lower chlorophyll a and carotenoids con tents, and higher r(s) than controls. P(N), E and protein synthesis we re significantly reduced. Four days after metal treatment P(N) was 5-7 % at 500 and 1000 muM Cu2+ from the controls, r(s) was reduced and E w as increased by all used metal concentrations. The lower RuBPC activit y after the 4 d treatment by 1000 muM Cu2+ could be due to the inhibit ion of de novo protein synthesis. The higher proline content was proba bly due to the same reason. Cu2+ ions did not change RNA synthesis in pea leaves. We found complete disintegration of chloroplast lamellar s ystem 4 d after 1000 muM Cu2+ treatment, which confirmed the observed functional changes.