南瓜未受精胚珠的离体培养及植株再生

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°C)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。

In Vitro Culture of Pumpkin Unfertilized Ovules and Plant Regeneration

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°C) 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).