植物体细胞胚发生与作物育种

评述了植物体细胞胚发生在作物育种中的研究与应用,内容包含有：胚性细胞系的建立与原生质体培养;体细胞胚的形成与人工种子制作;胚性细胞与遗传转化;胚性细胞系与优良种质保存和体细胞无性系变异与突变体筛选等,并讨论了有关机理。     

细胞信号转导与植物体细胞胚发生

细胞信号转导主要是指胞间通讯的激素以及外界环境因子等作用于细胞表面（或胞内受体）后,如何跨膜传递形成胞内第二信使,以及其后的信息分子级联传递、诱导基因表达和引起生理反应的过程。植物体细胞胚发生的本质是基因的判别表达,因此细胞信号转导在此起关键作用。在植物组织培养过程中,外加的激素等因子通过细胞信号转导诱导基因差别表达,使体细胞转入胚胎发生过程,最终生长发育成完整植株。     

植物体细胞胚同步化发生的控制

体细胞胚发生的不同步是植物胚状体发生过程中的问题之一。控制体细胞胚同步发生的方法主要有物理方法和化学方法,文章就此作简要介绍。     

植物生长素与体细胞胚发生

简要介绍了植物生长素对体细胞胚发育的作用及其调控机制的研究进展。     

植物体细胞胚发生过程中基因表达的研究进展

植物体细胞胚胎发生是一个复杂的发育过程,研究者们通过分析植物体细胞胚发生过程中的基因表达或胚性组织和非胚性组织中基因的差异表达,获得了在体细胞胚发生过程不同时期表达的基因,并分析了这些基因在胚胎发生途径中可能的作用。综述了在植物体细胞胚发生过程中细胞周期相关基因、胁迫和激素应答相关基因、信号转导相关基因、晚期胚胎丰富蛋白基因及与体细胞胚发生相关的胞外蛋白基因表达的研究进展。     

植物体细胞胚发生中抗氧化系统代谢动态和程序性细胞死亡

在胚性细胞分化过程中ＳＯＤ活性明显高于对照，同时ＳＯＤ活性与胚性细胞分化密切相关，表明胚性细胞具有较强的抗氧化能力。低浓度的Ｈ２Ｏ２对胚性细胞的分化有促进作用，并认为Ｈ２Ｏ２可能是作为一种细胞信号物，通过细胞信号系统调节相关基因表达，或通过提高细胞内Ｃａ＾２＋浓度而促进细胞分化。在胚性细胞分化和发育过程中存在程序性细胞死亡（ｐｒｏｇｒａｍｍｅｄ ｃｅｌｌ ｄｅａｔｈ，ＰＣＤ）。活性氧在诱发植物ＰＣ     

刺五加体细胞胚发生研究进展

综述了国内外对刺五加体细胞胚发生研究的现状。分别对刺五加体细胞胚发生方式、体细胞胚发育相关生理生化变化（包括生长素极性运输、DNA甲基化和代谢途径调控）、体细胞胚生物反应器培养的研究现状进行了评述。     

Plant regeneration via somatic embryogenesis in cotton

An efficient in vitro plant regeneration system characterized by rapid and continuous production of somatic embryos using leaf and stem explants of abnormal seedling as an explant have been developed in Gossypium hirsutum L. Embryogenic callus and somatic embryos have been obtained directly from the explants of cotton abnormal seedlings. Plant growth regulators influenced the induction of cotton somatic embryogenesis. The optimal medium for direct somatic embryogenesis was modified MS medium supplemented with 0.1 mg l^-1 ZT and 2 g l^-1 activated carbon. On this medium, an average of 28.0 and 28.1 matured somatic embryos formed from per leaf and stem explants respectively. The highest frequency of somatic embryogenesis was 100%. The somatic embryos were converted into normal plantlets when cultured on modified MS medium supplemented with 0.1 mg l^-1 ZT. Upon transfer to soil, plants grew well and appeared normal. Plants could be regenerated within 60–80 days. The system of cotton somatic embryogenesis and plant regeneration described here will facilitate the application of plant tissue culture and genetic engineering on cotton genetic improvement. This revised version was published online in June 2006 with corrections to the Cover Date.     

Plant regeneration through somatic embryogenesis in Quercus suber

Cork oak ( Quercus suber L.) zygotic embryos, endosperm and ovules were treated with different concentrations of 2,4-D for induction of somatic embryos. Plant material was collected during the embryo development season, from June to September. Immature embryos proved to be the most reactive initial explant. Callus and somatic embryos developed a few weeks after the beginning of the 2,4-D treatment. For embryo development experiments, different growth regulators and cold and desiccation treatments were tested. Cold storage of somatic embryos matured in vitro at 5°C was the best treatment for breaking dormancy.     

Noninvasive evaluation of somatic embryogenesis

Callus Suspension Cultures of Ipomea batates Poir. cv. White Star were grown in an airlift bioreactor. A machine vision system was used to monitor nondestructively callus growth during a 10 day culture period. Growth data obtained with this system included the overall reactor population and population estimates for the 200-1200-mum fractions at 200-mum intervals. A model of callus growth was developed to explain the mechanics of callus enlargement. The model was based on the assumptions that (1) the calli could not subdivide or shrink, (2) there was a fixed percentage of the initial population for each fraction that was nonviable, and (3) growth rates did not vary with time during the culture period. It was determined that the growth rates and nonviable ratios decreased as fraction size increased.     

Plant regeneration from protoplasts of immature Vigna sinensis cotyledons via somatic embryogenesis

Summary Protoplasts were isolated from immature cotyledons of Vigna sinensis and cultured in a modified MS Liquid medium containing 0. 2 mg/l 2, 4-dichlorophenoxyacetic acid (2, 4-D), 1 mg/l naphthaleneacetic acid (NAA) and 0. 5 mg/l 6-benzylaminopurine (BAP) in the dark at a density of 1 × 10⁵/ml. The protoplasts began to divide in 3–5 days. Sustained cell division resulted in formation of cell clusters and small calli, with the cell division frequency and plating efficiency of cell colonies reaching 27. 7% and 1. 7% respectively. When calli of 2 mm in size were transferred onto MSB medium (MS salts and B5 vitamins) containing 500mg/l NaCl, 500 mg/ 1 casein hydrolysate (CH), 2 mg/l 2,4-D and 0. 5 mg/l BAP for further growth, approximately 5% of the calli developed embryogenically. The embryogenic calli were selected and subcultured on the same composition of MSB medium and were able to maintain somatic embryogenesis capacity in subculture for a long time. When the calli were moved to MSB medium with 0. 1 mg/l indole-3-acetic acid (IAA), 0. 5mg/l kinetin(KT), 3–5% mannitol and 2% sucrose in the light, many somatic embryos formed from the calli. Only part of the embryoids developed further to the cotyledonary stage, and the others died at the globular, heart-shaped or torpedo stages. Finally, some cotyledonary embryoids germinated and developed into plants or shoots. The shoots were readily rooted on 1/2 strength MS medium with 0. 1–0.3 mg/l indole-3-butyric acid (IBA). The plants grew well in soil and were fertile.Abbreviations 2, 4-D dichlorophenoxyacetic acid - NAA naphthaleneacetic acid - BAP 6-benzylaminopurine - IAA indole-3-acetic acid - KT kinetin - IBA indole-3-butyric acid - CH casein hydrolysate - CM coconut milk - ZT zeatin     

In vitro plant regeneration of Aster scaber via somatic embryogenesis

We established an in vitro plant regeneration system via somatic embryogenesis of Aster scaber, an important source of various biologically active phytochemicals. We examined the callus induction and embryogenic capacities of three explants, including leaves, petioles, and roots, on 25 different media containing different combinations of α-naphthalene acetic acid (NAA) and 6-benzyladenine (BA). The optimum concentrations of NAA and BA for the production of embryogenic calli were 5.0 μM and 0.05 μM, respectively. Media containing higher concentrations of auxin and cytokinin (such as 25 μM NAA and 25 μM BA) were suitable for shoot regeneration, especially for leaf-derived calli, which are the most readily available calli and are highly competent. For root induction from regenerated shoots, supplemental auxin and/or cytokinin did not improve rooting, but instead caused unwanted callus induction or retarded growth of regenerated plants. Therefore, plant growth regulator-free medium was preferable for root induction. Normal plants were successfully obtained from calli under the optimized conditions described above. This is the first report of the complete process of in vitro plant regeneration of A. scaber via somatic embryogenesis.     

Enhancer-trapping system for somatic embryogenesis in carrot

Somatic embryogenesis in the carrot was used to model zygotic embryogenesis because the spatial and temporal changes in somatic and zygotic embryogenesis are quite similar. To establish an enhancer-trapping system for somatic embryogenesis in the carrot, we constructed 2 enhancer-trap vectors (pETVs) using the GUS reporter gene with a minimal promoter. We also constructed several positive control vectors (pPCVs) using the CaMV 35S promoter. These are models in which pETVs are inserted near a native enhancer region in correct or reverse orientation. First, we tested whether these vectors could be used as enhancer-trap vectors using transgenic hairy root of tobacco. Histochemical GUS assays revealed that pETVs could be used as enhancer-trap vectors, even when the reporter gene in the pETVs was inserted near the native enhancer. Subsequently, we examined the availability of pETVs in somatic embryogenesis in the carrot. The constructed vector was activated in transgenic carrot embryogenic cells at high frequency (64%). This suggests that the enhancer-trapping vector is suitable as a carrot somatic embryogenesis system.     

植物激素对棉花体细胞胚胎发生的诱导及调节作用

选用11种激素研究了外源激素对棉花胚性愈伤组织增殖、胚胎发生和发育的调控作用。结果表明不同激素对棉花胚性愈伤组织增殖、胚胎发生与发育的影响不同。除2,4-D和BA对棉花胚性愈伤组织的增殖影响不大外,其他激素对棉花胚性愈伤组织的增殖均具有抑制作用,且具有一定的时间效应,同时还受基因型的影响。激素对棉花体细胞胚的形成和发育的影响极大,2,4-D既抑制了体细胞胚的形成,又抑制了体细胞胚的发育;TDZ的作用与2,4-D相似,显抑制了体细胞胚的形成,且诱导获得的体细胞胚均停留在球形胚阶段;GA也抑制了体细胞胚的形成,且不利于体细胞的成熟与萌发;BU-30对棉花体细胞胚形成与发育的影响不大。其他7类生长素类物质和细胞分裂素类物质对棉花体细胞胚的形成均具有促进作用,且依IBA、ABA、IAA、BA、KT、ZT、2iP序增强,其总胚数为对照的1．193—3．852倍;其中2iP的促进作用最大,可使产生的体细胞胚数提高2．852倍。     

Protocols for efficient repetitive and secondary somatic embryogenesis in Helianthus maximiliani (Schrader)

 Indirect somatic embryogenesis was induced on leaf explants of greenhouse-grown Helianthus maximiliani plants. Leaves of the regenerated plants were used as starting explants for the induction of direct somatic embryogenesis. Another cycle of somatic embryogenesis was induced on the leaves of regenerated plants. In both cases, leaf explants were cultured on media containing different auxin/cytokinin ratios. The auxin/cytokinin ratio had an influence on the intensity of embryo formation, germination and the capability to regenerate plants. Somatic embryogenesis was generally more intensive on the medium with lower concentrations of 6-benzylamino-purine. Further, the percentage of regenerated plants was higher when embryos were induced on high-cytokinin, low-auxin medium. Secondary somatic embryogenesis was induced on embryos by culture in liquid hormone-free medium. Similar to direct embryogenesis the efficiency of secondary embryogenesis depended on the medium used for the induction of the primary embryos. In contrast to the mostly low frequencies of conversion of secondary embryos into plants that has been observed in other species, the percentage of regenerated plants from secondary embryos of H. maximiliani was quite high, although slightly lower than that obtained in primary embryos. Received: 28 March 2000 / Revision received: 1 September 2000 / Accepted: 2 October 2000