The two most commonly used plant growth regulator regimes (PGR) are the IK and DK treatments for somatic embryogenesis. Segments from hypocotyls of Gossypium hirsutum cv. YZ-1 were cultured on callus induction medium for 4 weeks, and sub-cultured on differentiation medium for somatic embryogenesis. The results demonstrated that somatic embryogenesis occurred in the two treatments. In the IK treatment, somatic embryos appeared on day 33 after inoculation, the ratio of differentiation was 97.6%, and somatic embryos commonly appeared prior to an obvious embryogenic callus. One the other hand, somatic embryogenesis was represented at a late stage in the DK treatment, somatic embryos developed from obvious embryogenic calli, and the ratio of callus differentiation was distinctly lower than that with IK treatment, being only 28.6%. Furthermore, adventitious roots almost appeared on the surface of all explants in the IK treatment, but none were found in the DK treatment. Therefore, two distinct patterns of somatic embryogenesis occurred in the two treatments, with histological observation suggesting that the majority of somatic embryos originated from primary meristem and cortex in the DK and the IK treatments, respectively.%MSB培养基添加两种常用植物激素组合,Indole-3-butyric acid (IBA)+ kinetin (KT)和2,4-dichlorophenoxyacetic acid(2,4-D)+ KT,分别命名为IK和DK处理用来诱导陆地棉体细胞胚胎发生.陆地棉品系YZ1下胚轴切段作为外植体在诱导培养基上培养4周后,继代到分化培养基上促进体细胞胚胎发生.结果表明,两种处理均有体细胞胚胎发生,其中IK处理上外植体嫁接33 d后就可见体细胞胚出现,分化率高达97.6％,大多数外植体表现为体细胞胚较胚性愈伤早出现.DK处理中体细胞胚胎发生慢,体细胞胚都是经过明显的胚性愈伤发育而来,胚性愈伤分化率明显低于IK处理,仅为28.6％.此外,IK处理中的外植体在培养过程中大部分都出现了须根,而DK处理中则没有.两种处理中出现了两种不同的体细胞胚胎发生过程,组织学观察结果表明DK和IK处理中的体细胞胚分别主要起源于初生形成层和皮层.
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