Nuclease sensitivity of storage-protein genes in isolated nuclei of pea seeds.

The chromatin structure of legumin genes in nuclei isolated from leaves and cytyledons of pea (Pisum sativum L.) was investigated. Digestions with micrococcal nuclease (EC 3.1.31.1.) showed that the nucleosomal repeat length of total chromatin (171±25 base pairs) was similar in nuclei from both tissues. The sensitivity to pancreatic deoxyribonuclease (DNase I; EC 3.1.21.1.) of the legumin genes in cotyledon nuclei was greater than that in leaf nuclei; this increase in sensitivity correlated with transcriptional activity of the genes. No DNase-I-hypersensitive sites were detected in these genes in either tissue.