ABSTRACT
Hairy roots are formed by genetic transformation of plant cells using Agrobacterium rhizogenes. Integration into the plant genome of T-DNA from the bacterial root-inducing (Ri) plasmid results in differentiation and growth of hairy roots at the infection site. Hairy roots can be excised, cleared of excess bacteria using antibiotics, and grown indefinitely in vitro by subculture of root tips in liquid medium. Practical techniques for initiation, culture, genetic manipulation, and molecular analysis of hairy roots are summarized in Hamill and Lidgett (1). Hundreds of plant species have been successfully transformed to hairy roots; lists of amenable species are provided in several publications (2-5).
