Alteration of Petunia plant form through the introduction of the rolC gene from Agrobacterium rhizogenes

Mitchell Petunia (Petunia axillaris x (P. axillaris x P. hybrida) plants were transformed with the rolC gene from Agrobacterium rhizogenes under control 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 characterised in detail. The following phenotypic alterations were found to increase in severity with increasing rolC transcript abundance: reductions in plant height, leaf and flower size, a break in apical dominance leading to increased branching, and decreased male and female fertility. Time to flowering 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.