Regulation of the Phosphorylation of Chromatin-associated Proteins in Lemna and Hordeum

This paper represents attempts to observe alterations in the pattern of chromatin protein phosphorylation in Lemna and barley ( Hordeum vulgare ). As judged by in vitro labeling the phosphorylation profile is substantially altered during germination. This may not be the result of specific tissue differentiation, however, because phosphorylation does not differ markedly between the embryonic root and shoot. Treatment of nuclei from germinating embryos with low concentrations of sodium or potassium chloride produced phosphorylation patterns similar but not identical to those found in nuclei from ungerminated embryos. Treatment of Lemna with abscisic acid in vivo causes substantial alterations in the labeling of three protein bands and part of this may be duplicated by labeling isolated nuclei from treated tissue with γ 32 P-ATP. Some effects of light/dark transition on Lemna chromatin protein phosphorylation are also described.