PIGMENTS AND PIGMENT-PROTEIN COMPLEXES IN CHLOROPLASTS FROM SOYBEAN MIXOTROPHIC CALLUS - EFFECTS OF AMMONIUM AND DIURON

The effect of ammonium on the composition of pigments and pigment-prot ein complexes in chloroplasts of the mixotrophic callus culture of soy bean (Glycine max L.) was studied. In the presence of exogenous ammoni um, the relative amounts of chlorophylls and beta-carotene in soybean chloroplasts were similar to those in photosystem II-enriched particle s from spinach chloroplasts. The presence of photosystem II in photoch emically active or inactive states had little effect on the pigment pr oportions or the contents of pheophytin and beta-carotene. These data suggest that, even after inhibition of photosynthesis by diuron, compl exes of at least two types can be synthesized and assembled: the light -harvesting chlorophyll a/b-protein complex and the complex of photosy stem I. The composition of xanthophylls remained unaffected by the act ion of diuron and ammonium, although the proportions of these pigments varied within a wide range. It was found that the addition of ammoniu m to the growth medium activates processes related to chlorophyll synt hesis in soybean callus but has no discernible effect on the compositi on of chlorophyll-protein complexes in chloroplasts.