摘要 : Somatic embryogenesis in American ginseng (P. quinquefolium [P. quinquefolius]) was investigated using 3 explant sources (root, leaf and epicotyl) with Murashige and Skoog (MS) medium containing different growth regulators. Mature... 展开 Somatic embryogenesis in American ginseng (P. quinquefolium [P. quinquefolius]) was investigated using 3 explant sources (root, leaf and epicotyl) with Murashige and Skoog (MS) medium containing different growth regulators. Mature roots and leaves obtained from 3- to 5-yr-old field-grown plants, and seedling leaves and epicotyls from plantlets grown in vitro, were evaluated. From root and epicotyl explants, callus development was optimal with 3,6-dichloro-o-anisic acid (dicamba; 9.0 鍹) and kinetin(KN; 5.0 鍹) as the growth regulators. When these calluses were transferred after 3 months to dicamba alone (9.0 鍹), somatic embryo formation was observed at an average frequency of 15.6% in root explants after an additional 3 months, and 2% in epicotyl explants after an additional 6 months. No plantlets were recovered because the embryos germinated to form shoots with no roots. From leaf explants, callus growth was optimal with NAA at 10.0 鍹 and 2,4-D at 9.0 鍹. Somatic embryos developed on this medium, with the highest frequency (40%) obtained after 3 months from seedling-leaf explants. Calluses on mature leaves formed somatic embryos after 7 months with NAA/2,4-D at an average frequency of 30%. Transfer of these somatic embryos to 6-benzyladenine/gibberellic acid (4.4/2.9 鍹) promoted shoot development but no roots were observed. Up to 100% of germination was observed within 6 wk on half-strength MS salts containing activated charcoal (1%) and on NAA/2,4-D (5.0/4.5 鍹) with charcoal (1%). On thelatter medium, somatic embryos enlarged and frequently gave rise to new somatic embryos after a brief callusing phase. The embryos germinated through a 2-stage process, involving the elongation of the root followed by the formation of a shoot. The highest recovery of ginseng plantlets from germinated embryos was 61.0%. Following transfer to potting medium and maintenance under conditions of high humidity and low light intensity, the plantlets elongated and developed new leaves. A high percentage (50%)of these plants was acclimatized to soil. 收起