MINIBEET INITIATION FROM DEROOTED SUGAR-BEET (BETA-VULGARIS L) SEEDLINGS IN-VITRO

An in vitro method for the initiation of minibeet development from derooted sugarbeet seedlings was developed. The surface sterilized seeds were germinated for 25 days on sugar-free Murashige and Skoog medium containing half-strength nutritive elements, 10 mg 1(-1) thiamine, 0.1 mg 1(-1) gibberellic acid and 7.0 g 1(-1) agar. After germination, seedlings of six different genotypes were derooted at the root neck and incubated for 90-120 days on minibeet initiation medium containing double-strength Murashige and Skoog elements, B-5 vitamins, 100 mg 1(-1) activated charcoal, 30 g 1(-1) D-glucose, 6-benzylaminopurine (0.2 mg 1(-1)) and abscisic acid (0.2 mg 1(-1)). Without subculturing, minibeets developed on 20-40% of five different genotypes of seedlings. The developed minibeets were characterized structurally and functionally by means of a histological study and relative sucrose accumulation. Minibeets were compared to tuber-like formations which showed neither polycambial structure nor relative sucrose accumulation. Minibeets gave rise to plants after potting in the greenhouse.