Transgene sites in 3D interphase nuclei of wheat (A), rice (B) and tobacco (C) root tissue sections. The wheat line (A) is homozygous and carries two transgene copies per homologue at a single site in the metaphase chromosome , each homologue is indicated by arrows. The rice line (B) was labeled with the plasmids SCM11, K1, H28, J1 , which were all co-bombarded. The tobacco line (C) contains 7 copies of the GUS gene and is a double haploid . Confocal image stacks were recorded with a section spacing of 1 μm and a projection of two confocal sections is shown. Hybridization signals are indicated by arrows and show two single dots one for each homologue. Each dot can include multiple copies of the transgene. Bars, 10 μm.