Production of dwarf potted gentian using wild-type Agrobacterium rhizogenes

We successfully produced dwarf potted gentian using wild-type Agrobacterium rhizogenes A4 strain (ATCC43057) harboring an agropine type plasmid (pRiA4). A number of hairy roots were induced by direct inoculation with A. rhizogenes to the stem and leaf tissues in vitro. Adventitious shoots were regenerated from the hairy roots on Murashige and Skoog medium containing 10 mg l � 1 N-phenyl-N� -(1,2,3-thiadiazol-5-yl) urea, 0.1 or 1.0 mg l � 1 1-naphthaleneacetic acid, and 3 g l � 1 gellan gum. Regenerated plants were then cultured in vitro for at least six months and tested for the absence of viable A. rhizogenes within their tissues. After receiving authorization from the Ministry of Agriculture, Forestry and Fisheries, Japan, the plants were acclimated and grown in a greenhouse and/or field. Opine synthesis and rolC gene expression were analyzed to demonstrate successful introduction and expression of the transferred DNA. In total, 122 lines of variant types of dwarf plants with blue, white, and pink flowers were obtained, which might be useful for molecular breeding of a series of dwarf potted gentian cultivars.