Somatic Embryogenesis and Cytological Variation in Protoplast Culture of Levisticum officinale Koch

Protoplasts were isolated from spongy calli in a well growing state. Protoplasts were induced to undergo sustained divisions and to form colonies in the liquid C81V medium supplemented with 2,4-D and kinetin. When protoplast derived colonies were transferred onto agarsolidified medium, the spongy, white calli developed. After being subcultured on N6 medium plus 6BA and IBA, the light-yellow, granular embryogenic calli emerged on the protoplast regenerated callus surface. A large number of plantlets were obtained on MS medium with NAA and IBA via somatic embryogenesis Cytological observation on the donor calli used for protoplast isolation and plantlets regenerated from protoplasts were carried out. Remarkable variation of nucleus morphology and chromosome numbers were observed in donor calli. However, the cytological abnormalities in plantlets regenerated from protoplasts were comparatively less seen. The reason are discussed.     

Somatic Embryogenesis in Asparagus densiflorus (Kunth) Jessop cv Sprengeri

An efficient protocol has been developed for plant regeneration in Asparagus densiflorus (Kunth) Jessop cv Sprengeri (Asparagaceae) through somatic embryogenesis from spear sections. Callus culture was initiated on Murashige and Skoog (MS) medium formulation containing α-naphthaleneacetic acid (5.37 μM), indole-3-acetic acid (5.71 μM) and 6-benzylaminopurine (2.22 μM). The callus became embryogenic by transferring to 2, 4-dichlorophenoxyacetic acid (4.52 μM) containing MS medium. Somatic embryos developed and matured vigorously on MS medium with NAA (1.07 μM), 6-γ-γ- dimethylaminopurine (9.84 μM) and abscisic acid (1.89 μM). Mature bipolar embryos were converted efficiently into plants on MS medium in the presence of low level of kinetin (2.32 μM). Regenerated plants showed 80% survival after transfer to field. These plants were all diploid (2n=60). Peroxidase activity was maximum in the embryogenic callus as documented from the gel as well as spectrophotometric analysis.     

Developmental Aspects of Soybean (Glycine max) Somatic Embryogenesis

A detailed study of the developmental aspects for soybean somaticembryogenesis was undertaken with emphasis on biochemical andhistological markers. The various stages of somatic embryo developmentin callus cultures have been identified and characterized. Germinatingembryos could be converted to fertile plants at a high frequency(90%). Dicamba (3, 6-dichloro-o-anisic acid) was found to bethe auxin of choice for the clear distinction of the variousdevelopmental phases of soybean somatic embryos. Differencesin their protein patterns were determined using polyacrylamidegel electrophoresis. This analysis revealed distinguishabledifferences in protein profiles amongst the various developmentalstages, especially in heart stage embryos. Histological studieson somatic embryos revealed specific tissue types which closelyresemble those reported for zygotic embryos. Further evidenceis provided that there is a close similarity in tissue differentiation,between somatic and zygotic embryogenesis although there aresome unique features in the development of somatic embryos. Glycine max, callus cultures, developmental stage, liquid cultures, neomorphs, plant regeneration, stage specific proteins, histology     

Somatic Embryogenesis in Leguminous Plants

Abstract: This review examines recent advances in the induction and development of somatic embryos in leguminous plants. Emphasis has been given to identify the current trends and successful strategies for the establishment of somatic embryogenic systems, particularly in the economically important species. It appears that, in legumes, somatic embryogenesis can be realized relatively easily especially in young meristematic tissues such as immature embryos and developing leaves. In the majority of the species examined, chlorophenoxyacetic acids remained the most active inductive compounds; however, the new generation growth regulators such as thidiazuron are emerging as successful alternatives for high-frequency direct regeneration of somatic embryos, even from well differentiated explant tissues. Low-frequency embryo production, poor germination and conversion of somatic embryos into plantlets and somaclonal variation are the major impediments limiting the utility of somatic embryogenesis for biotechnological applications in legumes. These limitations, however, may be considerably reduced in the near future, as more newly developed growth regulators with specific morphogenic targets become available for experimentation. From the published data, it is apparent that more effort should be given to develop repetitive embryogenic systems with high frequency of germination and regeneration, since such systems will find immediate application in mass propagation and other crop improvement programmes. As our understanding of various morphogenic processes, including growth and differentiation of zygotic embryos, is fast expanding, it is conceivable that development of highly efficient somatic embryogenic systems with practical application can be anticipated, at least for the important leguminous crops, in the foreseeable future.     

体细胞胚胎发生相关类受体蛋白激酶基因(SERK)的研究进展

植物体内存在一个编码富亮氨酸重复受体蛋白激酶、与体细胞胚胎发生相关的类受体蛋白激酶基因(SERK)大家族,其在旱期胚胎、小孢子、成熟胚珠和维管组织中表达.文章从SERK的结构、编码的蛋白、基因表达、功能以及信号转导介绍了SERK的研究进展.     

Efficient Somatic Embryogenesis in Alstroemeria

In Alstroemeria high frequencies of compact embryogenic callus (CEC) induction (40%) and friable embryogenic callus (FEC) induction (15%) were obtained from nodes with axil tissue cultured first on a Murashige and Skoog (MS) medium supplemented with 10 μM thidiazuron and 0.5 μM indole-3-butyric acid and after that on a Schenk and Hildebrandt (SH) medium supplemented with 9.1 μM 2,4-dichlorophenoxy acetic acid and 2.2 μM benzylaminopurine (BA). Both types of callus were maintained on modified MS medium supplemented with 20.8 μM picloram. CEC and FEC formed somatic embryos and subsequently plants when transferred to MS medium supplemented with 2.2 μM BA. Plants were produced after 12 weeks (CEC) or after 16 weeks (FEC) of culture. Regenerated plants were established in the greenhouse and flowered normally.     

落叶松体细胞的胚胎发生

简要回顾了重要用材树种落叶松体细胞胚胎发生的研究历史,并对落叶松体细胞胚胎发生的基本步骤、影响体细胞胚胎发生的因素及其主要应用,进行了综述,同时就落叶松体胚发生的研究趋势作了展望.     

Ultrastructural Changes in Cotyledons of Pineapple Guava (Myrtaceae) During Somatic Embryogenesis

Ultrastructural studies (SEM and TEM) were performed on cotyledonsof pineapple guava ( Feijoa sellowiana Berg, Myrtaceae) inducedto form embryos on medium containing 1.0 mg l^-1(4.5µM2,4-D) and 0.3M sucrose. At the time of culture, the cells werefilled with protein and lipid bodies. Microbodies and poorlydifferentiated organelles could also be seen. In contrast togerminating cotyledons, where lipid and protein reserves werequickly metabolized, cells of the embryogenically induced cotyledonsshowed evidence of reserve consumption only after 5 d of culture.Subepidermal cells of the upper cotyledonary surface underwentseveral divisions giving rise to a meristematic layer of severalcells thickness from which somatic embryos developed. Embryoscould also be formed directly by successive divisions of epidermalcells. Cells involved in somatic embryo formation containeda large nucleus with a conspicuous nucleolus and dense cytoplasmwhere numerous ribosomes, mitochondria, plastids with starchand short profiles of rough endoplasmic reticulum were present.Plasmodesmata were present both in cell walls of the meristematiccells and in few celled embryos whereas in degenerating embryosor in more advanced stages of somatic embryo development noplasmodesmata could be found. Although oil bodies were not observedin the meristematic cells they were identified in very youngembryos, being the first reserve compounds to appear. Cellsnot involved in somatic embryo differentiation were characterizedby the presence of several microbodies containing a crystalloidinclusion and elongated mitochondria. Feijoa sellowiana ; pineapple guava; somatic embryogenesis; ultrastructural studies     

Direct Somatic Embryogenesis, Plant Regeneration and Evaluation of Plants Obtained from Mesophyll Protoplasts of Brassica juncea)

Isolated mesophyll protoplasts of Brassica Juncea directly developedinto somatic embryos on medium supplemented with an auxin anda cytokinin. The somatic embryos germinated into plantlets whenmedium was supplemented with GA₂, and ABA. The plantlets weretransferred to the field and the second generation (P₂) wasevaluated for various agronomic characters. Some of the P₂ linesshowed variation in height and time required for flowering.Only two out of 53 lines were comparable to the control in grainyield Brassica Juncea, Indian mustard, direct embryogenesis, protoclonal variation, yield     

松柏类植物体细胞胚胎发生的研究进展

松柏类植物的体细胞胚胎发生既是繁育的一种手段,又是研究胚胎发育过程中结构、生理和分子事件的一种重要的模式系统。整个体细胞胚胎发生过程主要包括3个步骤：胚性组织的诱导和增殖、体细胞胚的成熟以及体细胞胚的萌发和转换。过去为了提高胚胎发育过程所做的努力主要都集中在胚的成熟阶段,这是因为一直认为能否成功再生的关键在于胚发育成熟阶段的处理。然而,在过去几年里,结合生理生化以及分子生物学的研究发现,胚胎发生的早期阶段对于完成整个发育过程也是至关重要的,早期阶段培养条件的优化可以显著提高培养过程中体细胞胚的数量和质量。此外,萌发过程培养条件的调节对于提高成熟体细胞胚的萌发率和转换率也很重要。因此,这些新的研究成果对于改善松柏类植物体细胞胚胎发生中的胚的诱导率和转换率低的现象具有重要的意义。     

High Frequency Somatic Embryogenesis in Cotton

A highly reproducible system for efficient somatic embryogenesis was developed to regenerate plantlets from cotton (Gossypium hirsutum L.) cultivars (Nazilli M-503 and Nazilli 143). Shoot apices, hypocotyls and nodes of 10-d-old seedlings were used as explants. High frequency (100 %) embryogenic calli was initiated from all tested explants on Murashige and Skoog (1962) (MS) media supplemented with 1 g dm^–3 polyvinylpyrrolidone (PVP), 1 mg dm^–3 6-benzylaminopurine (BAP), 0.5 mg dm^–3 kinetin for Nazilli M-503 and 1 g dm^–3 PVP, 2 mg dm^–3 BAP, 0.5 mg dm^–3 kinetin for Nazilli-143. Globular stage somatic embryos were produced 4 months after transfer to hormone-free MS medium supplemented with 1 g dm^–3 PVP. Subsequent subculture of globular embryos every 3 weeks on hormone-free MS medium led to the development of torpedo and cotyledonary stage embryos with the frequency of 75 and 83.2 % from hypocotyl explants of Nazilli M-503 and Nazilli-143, respectively. Afterwards, mature somatic embryos were isolated and cultured on hormone-free MS medium for germination and development into plantlets. The highest germination frequency (42.9 %) for Nazilli M-503 somatic embryos were obtained on hormone-free MS medium after 5 months with hypocotyl explants, whereas germination frequencies of Nazilli-143 embryos from hypocotyl, node and apex explants varied between 22 – 30 %.     

棉花体细胞胚胎发生的研究进展

经过30多年的发展, 已经在多个不同的棉花品种中获得了体细胞胚, 并再生成苗。但由于体细胞胚胎发生往往受多种因素影响, 如何从愈伤组织高效率地转化为胚性愈伤组织依然是限制棉花组织培养与遗传转化的关键问题之一。本文概述了棉花体细胞胚胎发生的研究进展, 分别从棉花体细胞胚胎发生的起源、影响棉花体细胞胚胎发生的内外因素以及寻找棉花体细胞胚胎发生特异表达基因等几方面进行综述, 并对研究中存在的问题进行了讨论。     

植物体细胞胚发生的分子基础

植物通过体细胞胚胎发生途径形成再生植株已是及其普遍的现象,这一发育途径为研究植物细胞的分化、发育、全能性表达和作物品种改良、突变体筛选等提供了良好的实验体系,在理论上和应用中都具重大意义.体细胞分化为胚性细胞是受细胞内外多种因子所调控[1, 2],其中最重要的是受特定基因的调控,在胚性细胞的分化过程中伴随着特定的遗传信息表达,其分化过程的实质是基因按顺序表达调控,是相应基因产物作为胚性细胞形成的分子基础.本文结合我们的工作来探讨体细胞胚发生分子基础研究现状.     

松柏类植物体细胞胚胎发生的研究进展

松柏类植物的体细胞胚胎发生既是繁育的一种手段,又是研究胚胎发育过程中结构、生理和分子事件的一种重要的模式系统.整个体细胞胚胎发生过程主要包括3个步骤:胚性组织的诱导和增殖、体细胞胚的成熟以及体细胞胚的萌发和转换.过去为了提高胚胎发育过程所做的努力主要都集中在胚的成熟阶段,这是因为一直认为能否成功再生的关键在于胚发育成熟阶段的处理.然而,在过去几年里,结合生理生化以及分子生物学的研究发现,胚胎发生的早期阶段对于完成整个发育过程也是至关重要的,早期阶段培养条件的优化可以显著提高培养过程中体细胞胚的数量和质量.此外,萌发过程培养条件的调节对于提高成熟体细胞胚的萌发率和转换率也很重要.因此,这些新的研究成果对于改善松柏类植物体细胞胚胎发生中的胚的诱导率和转换率低的现象具有重要的意义.     

结球甘蓝游离小孢子胚胎发生

以结球甘蓝品种“强夏”为材料进行游离小孢子培养,对与胚胎发生关系密切的因子进行探讨。研究结果表明,在盛花前期取材最适宜;单核晚期至双核期的小孢子才能发育成胚状体;含17%蔗糖的培养液在培养初期有利于小孢子存活;培养3d后胚胎诱导则以14％蔗糖浓度为最好;高浓度（17％）蔗糖培养3d后添加低浓度（11％）蔗糖培养液能大大提高胚胎发生能力,比一直在14％蔗糖培养液培养的提高282．4％,比更新培养液培养的提高126．1％。     

Somatic Embryogenesis in Cultured Carrot Cells

Somatic embryogenesis in cultured plant cells is an ideal system for investigating the whole process of differentiation and development from single cells to whole plants, and especially the molecular mechanism of expression of totipotency. This review reports recent progress the studies on somatic embryogenesis.     

植物体细胞胚发生的分子基础①

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ABA促进针叶树体细胞胚胎分化

文章介绍ABA促进针叶树体细胞胚胎分化调控机制和应用的研究进展