FACTORS INFLUENCING THE AGROBACTERIUM-TUMEFACIENS-MEDIATED TRANSFORMATION OF CARROT (DAUCUS-CAROTA L)

To develop an efficient procedure for Agrobacterium tumefaciens-mediated genetic transformation of carrot (Daucus carota L.) the effects of several factors were studied. Parameters which significantly affected the transformation frequency were the variety. the explant type, and the co-cultivation period. Under optimal conditions, using the A. tumefaciens C58C1 containing either pGSTRN943 or pGSGluc1 and 3 days of co-cultivation, the frequency of transformation of petiole explants of the variety Nanco was greater than 45%. This procedure does not require acetosyringone or prolonged precultivation period. Using kanamycin (100 mg l-1) for selection, a large number of transgenic plantlets developed from the embryogenic calli within 8-10 weeks of culture on hormone-free medium. Transformation was confirmed by histochemical detection of beta-glucuronidase activity in the transformed cells, by the ability of petiole segments to produce embryogenic calli in presence of kanamycin, and by Southern hybridization analyses.