Transformation of Diploid and Tetraploid Potato Clones with the rol C Gene of Agrobacterium rhizogenes and Characterization of Transgenic Plants

Diploid and tetraploid potato clones were transformed with the rol C gene from Agrobacterium rhizogenes under the control of the cauliflower‐35‐S promoter. Parameters proper to the sink and source attributes and hormone treatments have been considered to study the effect of the gene on yield physiology of the potato plant. The expression of the rol C gene in diploid and tetraploid potato lines induced drastic developmental abnormalities like dwarfism and increased tillering. Hormonal treatments revealed a different behavior of rol C transformams and controls. This supports the conclusion that the gene product of the ml C gene interacts with the hormonal status of the plant. Grafting experiments showed the non‐ditfusable nature of rol C gene product. Tuberization was studied in‐vitro and in‐planta. Relevant differences in tuber shape and eye number were noted between rol C transfonnams and controls. Tuber yields in‐planta in greenhouse or in growth chamber resulted higher in the controls; a significant increased number of tubers per plant was found, however, in both diploid and tetraploid rol C transformants. The effect of the rol C gene was apparently too drastic for diploid and tetraploid potatoes; weaker and tissue specific promoters may be necessary to induce only those modifications which are wanted for this crop. The experiments nevertheless proved that one single gene was capable in potato to affect substantially the manifestation of vieldmg attributes.