The influence of plant growth regulators on callus induction in pumpkin (Cucurbita pepo L.) hairy roots.

Following in vitro infection with Agrobacterium rhizogenes wild strain (mannopine, 8196) and two A. tumefaciens transconjugant strains (C58C1 pArA4abc and C58C1 pArA4b) transformed (hairy) roots were induced in pumpkin (C. pepo L.) cotyledons. The presence of pRi T-DNA in pumpkin long-term hairy root cultures was determined by Southern hybridization. The influence of plant growth regulators on callus induction in root explants from hairy root lines, which differed mutually in morphology and growth rate, was tested by the addition of growth regulators to basal nutrient medium; while 2.4-D inhibited root proliferation in all hairy root lines tested, callus induction depended both on plant growth regulators and the root line.