SHOOT ORGANOGENESIS IN CALLUS INDUCED FROM PEDICEL EXPLANTS OF COMMON BEAN (PHASEOLUS-VULGARIS L)

Plant regeneration has been achieved in two common bean lines from pedicel-derived callus that was separated from the explant and maintained through successive subcultures. Callus was induced either on B5 or MS medium containing 2% sucrose and enriched with 0.5 or 1.0 mg thidiazuron/liter alone or plus various concentrations of indoleacetic acid. The presence of 0.07 or 0.14 g ascorbic acid/liter in the maintenance media prolonged the maintenance time. Up to 40 shoot primordia were observed in 4-week-old cultures obtained from 40 to 50 mg callus tissues on shoot-induction medium containing 1-mg benzyladenine/liter. These shoot primordia developed two to five excisable shoots (>0.5 cm) on medium with 0.1-mg BA/liter. A histological study confirmed the organogenic nature of regeneration from the callus tissues. The R2 line from a selected variant plant showed stable expression of increased plant height and earlier maturity. Chemical names used: ascorbic acid, N-(phenylmethyl)-1H-purin-6-amine [benzyladenine, BA], 1H-indole-3-acetic acid (IAA), N-phenyl-N'-1,2,3-thiadiazol-5-ylurea [thidiazuron, TDZ].