We used unfertilized ovules of the pumpkin cultivar 'Experiment 1' as explants to examine the effect of combinations and concentrations of growth regulators, different developmental periods, high-temperature pretreatment, and AgNO3 concentrations on embryoid induction. The combination of 2,4-D, NAA, and 6-BA favoured embryoid induction; the medium with the best effect was Murishige and Skoog (MS)+1.0 mg·L-12,4-D+0.25 mg·L-1NAA+0.5 mg·L-1 6-BA, for 31.1% embryoid induction. The flowering ovules for the day showed the highest frequency of embryoid induction (26.7%) and the lowest frequency of callus formation (<5%). The explants treated with darkness and high temperature (35℃) for 5 days showed the best embryoid induction, 32.2%. However, the addition of AgNO3 remarkably inhibited embryoid induction. Transfer of embryoids to plant-regeneration medium led to the highest regeneration frequency, 64.3%. Plant regeneration expressed a typical pathway as for embryogenesis. Cytologic observations revealed that embryoids probably derived from cells close to the micropyle (i.e., ovums or synergids).%以南瓜(Cucurbita moschata)品种试验1号为材料,以未受精胚珠为外植体,研究了激素种类、外植体发育时期、高温预处理时间和AgNO3浓度对胚状体诱导的影响.结果表明,2,4-D、NAA和6-BA组合有利于胚状体的形成,出胚效果最好的培养基为MS+1.0 mg·L-12,4-D+0.25 mg·L-1NAA+0.5 mg·L-16-BA,出胚率达31.1％；雌花开放当天的胚珠出胚率最高(26.7％),且愈伤组织形成频率低(＜5％)；外植体在黑暗、高温(35℃)条件下处理5天有利于胚状体的形成,出胚率为32.2％.培养基中添加AgNO3对胚状体形成的抑制作用明显.胚状体转移至成苗培养基后可形成正常小苗,出苗率最高可达64.3％,植株再生过程经历了典型的胚胎发育途径.细胞学观察结果表明,胚状体极有可能起源于胚囊珠孔端的细胞,即卵细胞或助细胞.
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