Alteration of Petunia plant form through the introduction of the rolC genefrom Agrobacterium rhizogenes

Mitchell Petunia (Petunia axillaris x (P. axillaris x P. hybrida) plants we re transformed with the rolC gene from Agrobacterium rhizogenes under contr ol of the cauliflower mosaic virus 35S promoter. Regenerated Petunia plants were confirmed as transgenic by Southern and northern blot analyses. Five transgenic lines expressing differing levels of rolC transcript were charac terised in detail. The following phenotypic alterations were found to incre ase in severity with increasing rolC transcript abundance: reductions in pl ant height, leaf and flower size, a break in apical dominance leading to in creased branching, and decreased male and female fertility. Time to floweri ng was also reduced in the rolC transgenic plants. The rolC gene appears to be a useful tool for the development of cultivars of ornamental crops with alterations in several commercially important traits.