Inheritance and expression of transgenes in white clover

when a plant is initially transformed, the transgene is present in a heterozygous form. Since white clover is outcrossing and predominantly self incompatible it is necessary to cross primary transgenic plants to produce an BC1 population, then intercross BC1 transgenic plants to produce an F2 population. The F2 population will have a highly heterogeneous genetic background and a variable allelic copy number (0 to 2) for the transgene. Therefore, it is essential to establish the effects of both allelic composition at individual loci and differing genetic backgrounds on transgene expression. Multiple copies of a transgene within a plant can result in increased levels of expression, however, there are also examples where expression is reduced or silenced (Hobbs et al. 1993). It is therefore necessary to check the expression level of each transgene before they are incorporated into a breeding programme. This paper reports an evaluation of the inheritance and expression of an introduced uidA reporter gene in transgenic white clover plants.