Objective: To establish an effective system for genetic transformation of autotetraploid Isatis indigotica by Agrobacterium rhizogenes.
Method: Agrobacterium rhizogenes strains R1601, ATCC15834 and A4 were employed to induce hairy roots from autotetraploid Isatis indigotica, and the obtained hairy roots were developed into regenerated plants on solid MS media with different Kinds of plant growth regulators.
Result: Root induction differed obviously. By three Agrobacterium strains. Hairy roots grew rapidly on solid MS medium without plant growth regulators and showed the typical hairy root phenotype: profuse branching, high density of root hairs and plagiotropism. And the transformation of Ri T-DNA was confirmed by opine analysis. The biomass of hairy roots increased nearly 35 times regulator-free MS after suspended in plant growth two weeks. On solid MS medium with BA, adventitious buds were differentiated directly from hairy roots without callus formation. All of the adventitious buds were rooted on root induction medium and developed into regenerated plants. Opine analysis indicated the integration of Ri T-DNA in the transformed plants.
Conclusion: Agrobacterium rhizogene can induce hairy roots from autotetraploid Isatis indigotica, and the obtained hairy roots can develop into regenerated plants.