Xie D Y, Hong Y
Institute of Molecular Agrobiology, 1 Research Link, The National University of Singapore, Singapore 117604 e-mail:
Plant Cell Rep. 2001 Jan;20(1):34-40. doi: 10.1007/s002990000288.
Somatic embryogenesis and whole plant regeneration were achieved in callus cultures derived from immature zygotic embryos of Acacia mangium. Embryogenic callus was induced on MS medium containing combinations of TDZ (1-2 mg/l), IAA (0.25-2 mg/l) and a mixture of amino acids. Globular embryos developed on embryogenic callus cultured on the induction medium. Nearly 42% of embryogenic cultures with globular embryos produced torpedo- and cotyledonary-stage embryos by a two-step maturation phase. The first stage occurred on 1/2-strength MS basal medium containing 30 g/l sucrose and 5 mg/l GA followed by the second stage on 1/2-strength MS basal medium containing 50 g/l sucrose. Of the cotyledonary-stage somatic embryos, 11% germinated into seedlings that could be successfully transferred to pots. Light- and scanning electron microscopy showed that the somatic embryos originated from single cells of the embryogenic callus. Further, a single cell layer could be detected beneath the developing somatic embryos that appeared to be a demarcation layer isolating the somatic proembryonic structure from the rest of the maternal callus. A suspensor-like structure connected the globular embryos to the demarcation layer. This is the first successful report of plant regeneration through somatic embryogenesis for this economically important tropical forest species.
从马占相思未成熟合子胚诱导的愈伤组织培养中实现了体细胞胚胎发生和完整植株再生。在含有噻二唑（TDZ，1 - 2毫克/升）、吲哚乙酸（IAA，0.25 - 2毫克/升）和氨基酸混合物的MS培养基上诱导出胚性愈伤组织。在诱导培养基上培养的胚性愈伤组织上形成了球形胚。近42%带有球形胚的胚性培养物通过两步成熟阶段产生了鱼雷形和子叶形阶段的胚。第一阶段在含有30克/升蔗糖和5毫克/升赤霉素（GA）的1/2强度MS基本培养基上进行，随后第二阶段在含有50克/升蔗糖的1/2强度MS基本培养基上进行。子叶形阶段的体细胞胚中有11%萌发成幼苗，并能成功移栽到花盆中。光学显微镜和扫描电子显微镜显示，体细胞胚起源于胚性愈伤组织的单个细胞。此外，在发育中的体细胞胚下方可以检测到一层单细胞，这似乎是一个将体细胞原胚结构与母体愈伤组织其余部分隔开的分界层。一个类似胚柄的结构将球形胚与分界层相连。这是关于这种具有重要经济价值的热带森林树种通过体细胞胚胎发生实现植株再生的首次成功报道。
