Transformation of Kalanchoë and oilseed rape with ORFs 11-15 from Agrobacterium rhizogenes

Infection by naturally occurring Agrobacterium rhizogenes gives rise to hairy root disease in many host plants. Moreover, plants transformed with this bacterium exhibit compact growth and frequently wrinkled leaves that often are reduced in size. The phenotypes are caused by the bacterial T-DNA integration in the plant host genome. The T-DNA includes several genes of which the best characterized are the root oncogenic loci (rol) genes: rolA, rolB, rolC and rolD, corresponding to open reading frames (ORFs) 10, 11, 12 and 15, respectively. Understanding how the rol-genes confer compact growth traits in plants is relevant given the potential to reduce the use of chemical growth retardants, thus providing environmentally friendly produced compact ornamental plants. Few studies have investigated the association of genotypes with phenotypic traits caused by the individual rol-genes and selected ORFs from A. rhizogenes. The current study aims to investigate this association in Kalanchoë spp. and oilseed rape by producing plant lines with a selection of single gene constructs comprising rol-genes and ORFs. Hence, transformation and tissue culture methods are currently being developed. The aim is implementing a transformation platform to facilitate the regeneration of transgenic lines to study the individual genes. Callus formation of 100% and 80-100% was observed in K. blossfeldiana 'Molly' and K. pinnata leaf explants, respectively. Whereas in Brassica napus 'Elan' cotyledons, the callus formation ranged from 50 to 75% a month after inoculation. Shoot formation in the studied Kalanchoë species was between 0 to 10% of the initial number of inoculated explants; whereas in B. napus 'Elan' it ranged from 2 to 9%.