Induction of cucumber hairy roots and effect of cytokinin 6-BA on its growth and morphology / 生物工程学报

ABSTRACT

Hairy roots of Cucumis sativus L. could be incited directly from the cut edges of 10-day-old cotyledon explants after infection with the strain Agrobacterium rhizogenes ATCC15834 harboring agropine-type plasmid, pRiA4b for 5 days. It was observed that the percentage of rooting cotyledon explants was more than 90 % 10 days after infection. Hairy roots could grow rapidly and highly branched on solid plant growth regulator-free MS medium. The PCR amplification of rol B genes and vir C gene showed that T-DNA of Ri plasmid of A. rhizogenes was integrated and expressed into the genome of transformed cucumber hairy roots. A bacterium-free transformed cucumber hairy root line was selected to culture on solid MS medium to examine influence of exogenous cytokinin 6-BA on growth and morphology alteration of cucumber hairy roots. The results showed that cytokinin 6-BA can influence the growth and altered the morphology of hairy roots. With increasing of 6-BA concentrations, Cucumber hairy roots become shorter and thicker and less branched. 6-BA at the concentration of 0.1 to approximately 3.0 mg/L could delay the appearance of maximum growth peak by 5 days and decreased the content of soluble protein, enhanced the activities of SOD and POD and decreased the levels of endogenous ethylene evolution in cucumber hairy roots. Our results also indicated that cytokinin 6-BA in the medium could influence growth and morphology alternation of cucumber hairy roots and delay its senescence of hairy roots by acting through ethylene.