Horseradish (Armoracia rusticana) hairy roots generated by the integration of a part of Ri plasmid in Agrobacterium rhizogenes were excised and encapsulated in alginate beads to produce individual artificial seeds. Root fragments with an apical meristem or a branch efficiently regenerated to whole plants, and those more than 5 mm in length possessed a high shoot-formation ability. We found that naphthaleneacetic acid (NAA) or indole-3-butyric acid treatment stimulated branch emergence and shoot formation on the roots. These results indicated that root fragment with a branch induced by auxin was the most reactive portion. After two-step liquid culture (14 d without NAA and 10 d with NAA), root fragments with high shoot-formation frequency could be selected as material for artificial seeds. Development to a plantlet after encapsulation was inhibited by NAA, and auxin was not required for encapsulation. When encapsulated root fragments were placed under light conditions, addition of 3% of sucrose in the beads was sufficient for regeneration. The results showed the high potential of hairy root for propagation in combination with the formation of artificial seeds.
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology