Improved shoot organogenesis from hypocotyl segments of lingonberry (Vaccinium vitis-idaea L.)

An improved protocol for shoot regeneration from hypocotyl segments of seedlings from open-pollinated seeds of lingonberry (Vaccinium vitis-idaea L.) cultivars, 'Ida', 'Splendor', and 'Erntesegen', and a native clone from Newfoundland was developed. The effect of thidiazuron (TDZ) on adventitious bud and shoot formation from apical, central, and basal segments of the hypocotyl was tested. Highly regenerative callus was obtained from hypocotyl segments on modified Murashige and Skoog (MMS) medium containing 5-10 muM TDZ. A maximum of 10 buds and 12 shoots per apical segment for seedlings of cultivar 'Ida' regenerated on MMS containing 10 muM TDZ. Callus and bud regeneration frequency, callus growth, and number of buds and shoots per regenerating explant depended not only on the specific segment of the hypocotyl, but also on parental genotype. Inhibition of shoot elongation by TDZ was overcome by transferring shoot cultures to a shoot proliferation medium containing 1-2 muM zeatin. The optimal concentration of sucrose for shoot elongation was 20 g l(-1). Shoots were rooted ex vitro on a 2 peat : 1 perlite (v/v) medium after dipping in 0.8% indole-3-butyric acid, and rooted plants acclimatized readily under greenhouse conditions.