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Doubly transformed tobacco plants were obtained following sequential transformation steps using two T‐DNAs encoding different selection and screening markers: T‐DNA‐I encoded kanamycin resistance and nopaline synthase; T‐DNA‐II encoded hygromycin resistance and octopine synthase. A genetic analysis of the inheritance of the selection and screening marker genes in progeny of the doubly tranformed plants revealed that the expression of T‐DNA‐I genes was often suppressed. This suppression could be correlated with methylation in the promoters of these genes. Surprisingly, both the methylation and inactivation of T‐DNA‐I genes occurred only in plants containing both T‐DNAs: when self‐fertilization or backcrossing produced progeny containing only T‐DNA‐I, expression of the genes on this T‐DNA was restored and the corresponding promoters were partially or completely demethylated. These …