Аннотация:Summary The somatic and germinal activity of the maize transposable element, Ac , has been analysed in progeny of 43 transformants of A. thaliana using a streptomycin resistance assay to monitor Ac excision. The ability to assay somatic activity enabled, for the first time, a detailed analysis of Ac activity in individual A. thaliana seedlings to be made. The effects of T‐DNA copy number, generation, dosage at each locus, flanking sequences and orientation of the element were compared. The most striking observation was the variability in Ac activity in genotypically identical individuals and the poor penetrance of the variegated phenotype. In general, increasing Ac dosage increased both somatic and germinal excision frequencies. The majority of families from individuals selected as inheriting an excision event carried transposed Ac elements re‐integrated in different positions in the genome.
