A Simple Method of Inducing Somatic Embryogenesis in Brassica juncea (L.) Czern & Coss.

A single-step method for the induction and development of somatic embryoids from hypocotyls explains of Brassica juncea is reported. On modified MS medium containing 2 % sucrose, 0.25 mgl ¹ 2,4-D, 0.5 mgl ¹ each of NAA and BaP-R, each explant calluses at both of and at its best, 31% of explants produce embryoids. In the variety RLM-198, the number of embryoids ranges from 8–21 per culture. Each embryoid, upon proliferation, developed up to the 25 shoots. The method is rapid; the time La ken from inoculation to the development of intact plantlets is 8–10 weeks. Regenerated plants have flowered normally and have set seed. The system can profitably be used for in vitro mutant selection and early bulking in mustard.     

The Effect of Carbohydrate Composition and Concentration on Anther Culture Response in Barley (Hordeum vulgare L.)

Culture medium composition is critical for the successful induction of microspore division in vitro. The present experiments have focused on a relatively neglected area of cell and tissue culture research, namely the carbohydrate component used in the medium. Three spring barley genotypes were cultured on a medium which was modified by replacing sucrose with the following carbohydrates (6 % w/v): maltose, fructose, malt extract, galactose and a glucose (3 % w/v)/fructose (3 % w/v) mixture. Both maltose and malt extract were superior to sucrose in their capacity to induce green plantlet differentiation from microspores. The concentrations of both sucrose and maltose were also varied. Overall the response of anthers on maltose based media was higher than on sucrose based media. Furthermore, a concentration of maltose m the range 6—12 % w/v produced a higher frequency of green plants than a low concentration (1—3 % w/v). The effect of maltose based media on germplasm of direct relevance to barley breeders was also tested. The cultivar ‘Blenheim’ was shown to be very responsive and this genetic factor was transmitted to the F₁ hybrid. The frequency of haploid to diploid regenerants was not consistent over genotypes, but in general there were more haploid than diploid regenerants. The implications of these results for barley breeding are discussed.     

云杉属树种体细胞胚胎发生研究进展

云杉属树种具有适应性强、抗逆性强、生长迅速等特性,是园林绿化的重要树种。体细胞胚胎发生技术在云杉属树种中的应用,为其品种改良和规模化、产业化繁殖提供了可能。文中综述云杉属树种体细胞胚胎发生的过程及主要影响因素,提出在云杉属树种体细胞胚胎诱导过程中存在的问题和研究展望,以期为云杉属树种体细胞胚产量和质量的提高以及建立高效再生体系提供借鉴。     

Cryopreservation of yellow-poplar and sweetgum embryogenic cultures

Cryopreservation has become anessential tool for operational application offorest tree embryogenic cultures, due to thelong evaluation periods needed for treesregenerated from these cultures. Fiveyellow-poplar (Liriodendron tulipifera)and seven sweetgum (Liquidambar spp.)embryogenic culture lines werestored in liquid nitrogen for 48 hours, afterwhich they were thawed and tested for regrowthand ability to produce somatic seedlings.Combinations of two sorbitol pretreatments andthree dimethylsulfoxide (DMSO) cryoprotectantlevels were evaluated for their impact onrecovery following cryogenic storage. The bestresults were obtained with 0.4 M sorbitol and5% DMSO, which provided 100% recovery.Somatic seedlings were regenerated from allculture lines and treatments, except for atransgenic sweetgum line.     

花楸树体细胞胚与合子胚的发生发育

利用花楸树人工控制授粉后的未成熟合子胚进行体细胞胚的诱导培养,通过石蜡切片、扫描电镜和透射电镜对合子胚和体细胞胚的发生发育过程进行组织、细胞观察。结果表明:1)体细胞胚发生进程与合子胚相似,均经历了球形期、心形期、鱼雷形期,最终发育成成熟胚;2)直接发生和间接发生在愈伤组织表面的体细胞胚均为单细胞起源,间接发生在愈伤组织内部的体细胞胚存在单细胞起源,同时还存在可能的多细胞起源;3)子叶和愈伤组织表面发生的体细胞胚在发育早期均具明显的胚柄,鱼雷形胚期胚柄退化;4)愈伤组织内部发生的体细胞胚没有胚柄;5)与合子不同,胚性细胞的第1次分裂为均等分裂;6)多细胞原胚周围降解的细胞具有细胞程序性死亡的形态特征。     

红豆杉及南方红豆杉体细胞胚胎发生的研究

利用江西的红豆杉（Ｔａｘｕｓｃｈｉｎｅｎｓｉｓ）、福建的南方红豆杉（Ｔａｘｕｓｃｈｉｎｅｎｓｉｓｖａｒ．ｍａｉｒｅｉ）以及四川的南方红豆杉（Ｔａｘｕｓｃｈｉｎｅｎｓｉｓｖａｒｍａｉｒｅｉ）的成熟胚为试验材料,成功地诱导出大量的愈伤组织。这３种材料愈伤组织的最高诱导频率分别为９５７％、９８４％、９１７％。细胞学和形态学的观察结果表明：在适当的条件下经过一段时间的培养,这些愈伤组织能够产生处在不同发育阶段的体细胞胚。上述３种植物材料每１００块愈伤组织平均最多分别可产生１２７、９１和３３个体细胞胚。     

核桃体细胞胚发生与转基因研究进展

总结了核桃体细胞胚发生的研究进展,列表统计已报道的核桃５个种和３个杂种体细胞胚发生的外植体与诱导条件,重点论述了影响核桃体细胞胚发生与次生胚发生的因素,介绍了核桃体细胞胚萌发与转化的方法。还总结核桃转基因研究的进展,提出了用核桃体细胞胚发生系统进行外源基因转移的操作模式。     

栓皮栎体胚的增殖、成熟和萌发

以栓皮栎实生苗叶片为外植体诱导体细胞胚胎发生,调查碳水化合物、渗透剂和植物生长调节剂对体胚增殖、成熟和萌发的影响,建立体胚增殖、成熟和萌发的培养基方案.叶片外植体在附加1.0 mg·L-1NAA和0.5mg·L-1BA的起始培养基上诱导形成前胚性团块.这些胚性团块在增殖培养基上培养6周,在附加1 mg·L-1BA、0.25 mg·L-1NAA和3%蔗糖的MS培养基上增殖效果最好.将单个体胚转接到成熟培养基上进行培养,蔗糖浓度对栓皮栎体胚成熟以及后续的萌发有显著影响.成熟培养基中附加5%的蔗糖,体胚成熟率和萌发率分别达到63.5%和33.8%.虽然在成熟培养基中附加ABA有利于体胚成熟,但对体胚的进一步萌发没有促进作用.为了提高萌发率,成熟体胚在附加植物生长调节剂的萌发培养基上进行培养,以及进行预冷处理.成熟体胚4℃冷处理没有促进胚根和上胚轴的发育萌发.在附加0.5 mg·L-1BA和0.25 mg·L-1 IBA的1/2 MS萌发培养基上,体胚萌发率达到65.9%,再生植株转化率达到9.4%.     

Somatic embryo culture for propagation,artificial seed production,and conservation of sawara cypress (<Emphasis Type="Italic">Chamaecyparis pisifera</Emphasis> Sieb. et Zucc.)

 Somatic embryogenesis in Chamaecyparis pisifera Sieb. et Zucc. was initiated from immature seeds collected from the end of June to early July. Mass propagation through adventitious shoot bud production from somatic embryo culture on Woody Plant (WP) medium and artificial seed production using sodium alginate was achieved. A high bud forming index value (25.8) was obtained on medium supplemented with 1 μM 6-benzylaminopurine. The conversion rates from artificial seeds under aseptic and nonaseptic conditions were 60%–100% and 10%–12%, respectively. For germplasm conservation, somatic embryos and embryogenic cells were successfully stored at 4°C (medium-term storage) and in liquid nitrogen for long-term storage. Received: December 21, 2001 / Accepted: August 1, 2002 Acknowledgments This work was supported in part by the Japan Science and Technology Corporation and in part by a Grant for Research for the Future Program from the Japan Society for the Promotion of Science. Correspondence to:E. Maruyama     

Thidiazuron-induced somatic embryos,their multiplication,maturation, and conversion in <Emphasis Type="Italic">Cinnamomum pauciflorum</Emphasis> Nees (Lauraceae)

Thidiazuron (TDZ) induced somatic embryogenesis from immature zygotic embryos in Cinnamomum pauciflorum Nees while 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzylaminopurine (BA) or picloram only induced callus and/or adventitious buds. The highest induction frequency for somatic embryogenesis was achieved with MS medium (Murashige and Skoog in Physiol Plant 15:473–497 1962) supplemented with 2.5 μM TDZ using torpedo-shaped embryos (3–5 mm in length) as explants. In addition, induction medium was supplemented with 0.8 g l⁻¹ casein, 0.4 g l⁻¹ glutamine, and 10 g l⁻¹ sucrose. Somatic embryos (SEs) initiated from root tips or hypocotyls without callus formation. SEs were maintained and multiplied via secondary somatic embryogenesis. Embryo maintenance medium was similar to induction medium except that TDZ was reduced to 0.5 μM. Secondary embryogenesis was enhanced by supplementation of 5 g l⁻¹ activated charcoal in the culture. The best medium for embryo maturation was MS medium containing 30 g l⁻¹ sucrose and 5 g l⁻¹ Phytagel without plant growth regulators. A typical mature SE consisted of two large cotyledons and a short embryo proper. Approximately 82% of selected mature SEs were able to germinate and 63% could convert into plantlets on germination medium that was composed of half strength MS medium salts, 10 g l⁻¹ sucrose, 3 g l⁻¹ Phytagel, and 5 g l⁻¹ activated charcoal.