Gene Number Estimates in Plant Tissues and Cells

Two methods are described to measure numbers of active genes. The one uses 3H-unique DNA saturation and the other the kinetics of hybridization of 3H-cDNA with its complementary RNA to estimate mRNA complexities (informational lengths) and hence gene numbers. We used both approaches to measure numbers of active genes in plants. The data obtained were 11,500–13,300 in parsley root callus and 9,200–10,000 in parsley leaf, 14,200 m barley young leaves. In barley and in parsley a close correspondence between complexity of poly(A)-mRNA and poly(A)+mRNA was found.