An Ultrastructural Study of The Embryo/Endosperm Interface in the Developing Seeds of Solanum nigrum L. Zygote to Mid Torpedo Stage

The early developmental sequences in the formation of the Zoneof Separation and Secretion in a hexaploid species of Solanumnigrum L. are described. Ultrastructural changes which occurredduring the development of the embryo/endosperm interface couldbe related to the different stages in the embryo's development.The first step was the completion of the cell wall around thechalazal end of the zygote; a thin wall was formed along theendosperm cell(s) abutting the zygote. From the mature zygotestage to the quadrant stage, minute plasmalemma invaginationsoccurred along the endosperm wall facing the zygote. These invaginationsenlarged, and from the mid-globular stage onwards became filledwith a fine fibrillar material; this material accumulated betweenthe endosperm cell wall and the plasmalemma before being releasedinto the developing periembryonic and intercellular spaces tobecome the extracellular matrix. Cell wall development in theendosperm cells abutting the embryo followed an unusual path.During the quadrant stage, whilst the outer embryo wall increasedin thickness due to vesicle fusion, the endosperm cell wallfacing the embryo showed a loosening of the wall fibrils aswell as partial separation of these same endosperm cells fromeach other. From the early-globular stage, the endosperm cellwalls opposite the embryo became electron-translucent, disappearinginto the extracellular matrix. Enzymic secretions by the embryomay account for the alteration in the abutting endosperm cellwalls. Enzymic activity may also explain the development ofa homogenous electron-opaque layer over the outer embryo wallas well as the differences in the width of the fibrillar layerwhich accumulated around the cotyledons as the embryo grew throughthe Zone of Separation and Secretion. The potential roles ofthe extracellular matrix are briefly discussed. Solanum nigrum L.; embryo/endosperm interface; Zone of Separation and Secretion; embryo development; cellular endosperm     

An Ultrastructural Study on the Development of Egg- apparatus in Rice Embryo Sac

The development of the egg-apparatus (consisted of an egg cell and two synergids) of rice ( Oryza sativa L. ) was studied at the uhrastructural level. The walls of the egg cell and synergids, immediately after their formation, possessed numerous plasmodesmata. Plasmodesmata were also present on walls between the egg cell and synergids. During the enlargement phase of the egg cell and synergids, the walls at the tip region began to loosen and vesiculate. By the time the embryo sac became mature, the part of the wall of the egg cell and synergids, facing the chalaza, disappeared. Consequently, the tip regions of the egg cell and synergids were only protected by a plasma membrane. When the embryo sac reached full maturity, the upper and middle region of the wall of the synergids broke up into pieces. At that time one synergid began to degenerate. Plasmodesmata persisted at the hook region of the wall of both the egg cell and synergids. Most plastids in the egg cell contained starch grains that persisted throughout the period of the embryo sac development. Starch grains in the plastids of the synergids appeared only before the time when the two polar-nuclei moved into the region above the egg-apparatus. They then disappeared and did not appear again until the embryo sac had reached full maturity. The size and location of the vacuoles in the egg cell were different from those in the synergids. The time of formation was also different. Vacuoles in the egg cell formed late in comparison with the synergids. Vacuoles in the chalazal region of the egg cell (especially at the early stage of the embryo sac development) were much larger than those in the micropylar region. Vacuoles in the synergids tended to concentrate mainly in the chalazal region. There was a peak period of lipid formation in the two synergids. The peak appeared when the embryo sac neared maturity. At the early stage of development, the nuclei of the synergids were elliptical in shape and were situated at the central region near the micropyle. The shape of the nuclei at the late stage of development became less regular and tended to move more towards the micropylar region. Changes in the uhrastructure of the egg cell and synergids of rice appeared to be closely related to the metabolic processes controlling the embryo sac formation and development.     

少花龙葵种子萌发特性及其果汁对小白菜种子萌发的影响

对少花龙葵的成熟果实采用3种采种方式,于室内测定水分、温度、光照条件对不同采种方式所得种子的发芽影响,并就少花龙葵的果汁对小白菜种子萌发的影响进行分析.结果表明:(1)少花龙葵种子于25℃恒温下浸种8 h后吸水达到饱和,其适宜发芽温度为20℃～25℃,萌发受黑暗抑制;(2)3种采种方式中以捣烂果实后种子不从果实取出并不清洗而直接晾干的采留种方式最佳;(3)少花龙葵果汁原液和其5～10倍稀释液抑制广东小白菜种子发芽,20～50倍稀释液则促进其萌发,表明少花龙葵果汁具有化感效应.     

Ultrastructure of the Developing and Fertilized Embryo Sac of Amaranthus hypochondriacus L.

Amaranthus hypochondriacus embryo sac development was investigatedbefore and after fertilization. During the early stages of development,the young embryo sac displays three antipodal cells at the chalazalpole that degenerate very early in the maturation process, beforethe synergids and egg cell are completely differentiated. Themature embryo sac is composed only of the female germ unit.The synergid cells organize a filiform apparatus accompaniedby the presence of mitochondria and dictyosomes with numerousvesicles. The involvement of the synergids in transport andsecretory functions related to pollen tube attraction and guidance,are discussed. The egg cell is located at the micropylar polenear the synergids and displays exposed plasma membranes atthe chalazal pole. The fertilized egg cell does not exhibitmarked changes after fertilization except for the closure ofthe cell wall. The central cell is the largest cell of thisvery long embryo sac. The fused nucleus is close to the eggapparatus before fertilization and displays a remarkable chalazalmigration after gamete delivery. The ultrastructure of the centralcell cytoplasm and the numerous wall ingrowths around this cellsuggest an important role in nutrient transportation. Aftergamete delivery, the embryo sac displays electron dense bodiesthat aggregate within the intercellular space between the synergids,egg cell and central cell. These bodies, that appear in theembryo sac of several plants, are probably involved in gametedelivery for double fertilization. The possibility of biparentalinheritance of mitochondria in this plant is also discussed.Copyright 1999 Annals of Botany Company Amaranthus hypochondriacus, grain amaranth, embryo sac, fertilization.     

Endosperm Development in Solanum nigrum L. Formation of the Zone of Separation and Secretion

Endosperm development in Solanum nigrum was ab initio cellular.During early seed development, a Zone of Separation and Secretion(ZSS) differentiated within the endosperm. There were threephases in the formation of the ZSS. Phase I—stainabilityof the cell walls and middle lamella increased followed by numeroussmall plasmalemma invaginations (blebs) which became filledwith a fibrillar material. Phase II—the plasmalemma withdrewfrom the cell wall as a fibrillar lipo-carbohydrate matrix accumulatedoutside the plasmalemma. The middle lamella was gradually removedfrom between the cells forming the central axis of the cone.Phase III—the lipo-carbohydrate matrix continued to accumulateoutside the plasmalemma and also within the developing intercellularspaces. Some axial cells were completely separated from theremaining ZSS cells and became embedded in the matrix. The formationof the ZSS did not entail the destruction of the endosperm cellsand cell divisions were frequent. The ZSS was initially cone-shaped,capping the globular embryo. As the embryo sac enlarged, theZSS continued to differentiate. This resulted in a narrow curvedcorridor through the peripheral region of the endosperm whichterminated above the vascular trace. The embryo grew throughthe centre of the ZSS and pushed aside the separated axial cells.The ZSS facilitated the growth of the embryo through the restof the endosperm.Copyright 1993, 1999 Academic Press Lipo-carbohydrate matrix, extracellular matrix, endosperm development, Solanum nigrum, Zone of Separation and Secretion     

龙葵的营养成分及其开发利用

本文介绍了中国龙葵的资源概况及开发前景.它具有分布广、蕴藏量大、抗逆性强、易栽培、营养丰富等特点.龙葵有很高的营养价值和药用价值,它含有人体所需的多种营养元素:17种氨基酸、维生素、糖分和蛋白质等.龙葵除有抑菌作用外,对癌细胞有一定的抑制作用,有望成为抗癌新药.幼苗可食用,浆果是制作果酒和饮料的好原料.开发龙葵资源前景广阔.     

Changes in Properties of Malate Dehydrogenase Isolated from Solanum nigrum L. Seeds Imbibed at High Temperatures

Exposure of Solanum nigrum L. seeds for 48 h to high temperature(50°C) during imbibition, lowered considerably the activityof malate dehydrogenase in the mitochondria and in the cytosol.The affinity of both isozymes for their substrates and co-enzymeswas strongly depressed by this treatment. Optimal pH and optimaltemperature for maximal specific activity were also changed.Enzyme from treated seeds, although much less active, was moreheat tolerant. Separation on a DEAE cellulose column showedtwo distinct peaks of activity for cytosolic malate dehydrogenasefrom both treated and control seeds. Gel filtration througha G-75 Sephadex column showed only one peak of activity in bothcases. Gel electrophoresis of s-MDH from control seeds showedtwo bands of enzyme activity for each of the peaks eluting fromthe DEAE column. Only one activity band could be detected forenzyme from heat treated seeds and this band corresponded toone of the activity bands found in the control. From analysisof the data it appears that while part of the enzyme was denatured,due to exposure of the seeds to 50°C, a conformational changein the other part of the enzyme might have occurred which resultedin a change of enzyme properties and activity. However, on thebasis of the reported results an induction of synthesis of anew ‘heat tolerant’ enzyme, due to the treatment,cannot be ruled out. Key words: Solanum nigrum L., malate dehydrogenase, heat treatment, seeds     

龙葵规范化种植及资源的开发利用

阐述了龙葵规范化种植的关键性技术,并从营养价值和药用价值两方面说明了对其开发利用的情况,为规范龙葵的生产技术和资源的开发利用提供参考。     

Fine Structure of Nucellar Cells During Development of the Embryo Sac in Oenothera biennis L.

Developing nucellar cells in Oenothera biennis L. present distinctpatterns of differentiation at the chalaza and around the embryosac. The cytoplasm of nucellar cells surrounding the tetradof megaspores displays cytolysomes, lipid bodies and membranesof smooth ER enveloping different cytoplasmic components. Concomitantto the differentiation of the embryo sac the nucellar cellsconstituting these ‘parietal layers’ undergo cytoplasmicdegeneration with shrinkage and flattening. In addition to theregular nucellar cells the chalaza at this stage presents threeother types: One with pycnotic nuclei, paramural bodies andcytoplasm filled with polymorphic vacuoles containing membranes,granular or flocculent material and multivesicular bodies. Asecond cell type shows swollen perinuclear cisternae aroundtheir pycnotic nuclei and large cytoplasmic vacuoles accumulatingtannins. The third type of cells is characterized by large numbersof starch grains and advanced disorganization of cytoplasmicorganelles; these cells probably become reservoirs after death. Oenothera biennis L., evening primrose, embryo sac, nucellus, cytolysomes, ultrastructure     

微波辅助提取龙葵中总生物碱的研究

本文对龙葵中总生物碱(Tocal steroidal alkaloids,)的微波辅助提取(Microwave-assisted extraction,MAE)工艺、作用机理及对成分的结构影响进行了系统的研究。以酸性染料比色法为分析手段,设计正交试验得到了最佳提取工艺：以95％乙醇为溶剂,料液比1：20,在585w下提取8min;用扫描电镜(SEM)对样品处理前后形貌进行了观察,揭示了微波作用机理与细胞结构变化有关。同时薄层色谱(TLC)、反相高效液相色谱(RP-HPLC)定性分析显示,微波对有效成分的结构没有造成影响。     

Ovule and Embryo Sac Development in Malus pumila L. cv. Cox's Orange Pippin, from Dormancy to Blossom

Ovule and embryo sac development in the flowers of Cox's OrangePippin apple (Malus pumila L.) were studied from dormancy topetal fall using both scanning electron and light microscopy.The relative timing was established between these developmentsand the external development of the flower bud and flower. Malus pumila L. cv. Cox's Orange Pippin, apple, Cox, SEM, ovule development, anatomy, histology     

龙葵腺毛发育的细胞学研究

利用光学显微镜、扫描电镜和透射电镜技术,观察了龙葵“四叶一心”期时叶片及茎表皮的腺毛的种类、分布,探究了不同类型腺毛的起源、生长、成熟、分泌、衰老等发育过程的细胞学特征;通过组织化学染色和荧光显微技术,观察了龙葵腺毛成分、分布,为龙葵的进一步开发利用提供参考。结果表明：（1）龙葵腺毛分为单细胞头腺毛和多细胞头腺毛两类,前者主要分布于茎表面和叶上下表皮,后者主要分布于茎表面的单细胞头腺毛之间、叶脉及叶边缘;（2）龙葵腺毛发育起始于表皮细胞突起,单细胞头腺毛行顶端生长,具1-4个柄细胞,四种类型;多细胞头腺毛可再分为一层、两层与三层多细胞头腺毛,另具三种特殊类型;（3）龙葵成熟腺毛具分泌能力,通过皮下空间的物质积累导致腺毛头细胞表面形成突起、包块、破口,最终释放分泌物;而头细胞与柄细胞随即皱缩、衰老。（4）超微结构显示,腺毛头细胞中内质网与高尔基体极为丰富,合成代谢及分泌活动活跃,产生大量包裹嗜锇物质的囊泡,囊泡与细胞壁融合,进而将嗜锇物质转移至细胞壁并积累,随后储存在角质层下的皮下空间直至分泌释放;（5）组织化学染色结果表明,腺毛含有萜类、生物碱、脂类、蛋白质、酚类和多糖。头细胞中主要含有萜类、生物碱、脂类、蛋白质、酚类和中性多糖;柄细胞中主要含有萜类、生物碱、脂类。     

Cytology of a pentaploid hybrid and genome analysis in Solanum nigrum L.

Cytology of a pentaploid hybrid (2n=60) produced by crossing an autotetraploid (2n=48) of a diploid race of Solanum nigrum L. as seed parent with the naturally occurring hexaploid S. nigrum (2n=72) was studied which showed approximately 24_II+12_I. Chromosome pairing in the gametic complement of the hexaploid was deduced to be 12_II+12_I and on this basis it is concluded that the natural hexaploid is an autoallohexaploid, which has three sets (genomes) of 12 chromosomes each, two of which are to a large extent homologous to each other. Theoretically the genomic formula can be tentatively written as AAAABB. Since the natural hexaploid does not show any quadrivalents between the four homologous A genomes, chromosome pairing appears to be restricted to bivalent formation by a special genetic mechanism. The probability that S. nigrum could be an autohexaploid, parallelling Pheleum pratense, has been discussed.     

Protective effects of proline against cadmium toxicity in micropropagated hyperaccumulator, Solanum nigrum L.

Solanum nigrum is a newly discovered Cd-hyperaccumulator. In the present study, the protective effects of proline against cadmium toxicity of callus and regenerated shoots of S. nigrum are investigated based on a high frequency in vitro shoot regeneration system. Proline pretreatment reduces the reactive oxygen species levels and protects the plasma membrane integrity of callus under cadmium stress, and therefore improves the cadmium tolerance in S. nigrum. Inductively coupled plasma mass spectroscopy analysis shows that exogenous proline increases the cadmium accumulation in callus and regenerated shoots of S. nigrum. Further analysis indicates that the improvement of cadmium tolerance caused by proline pretreatment is correlated with an increase of superoxide dismutase and catalase activity and intracellular total glutathione content. The interaction between proline and enzymic or non-enzymic antioxidants is discussed.     

A two-year field study of phytoremediation using Solanum nigrum L. in China

A two-year in-situ phytoremediation trial was launched in Shenyang Zhangshi (Sewage) Irrigation Area (SZIA). The phytoremediation efficiency of Solanum nigrum L. was determined, by both monitoring the change of soil Cadmium level in the upper 20 cm of soil, and calculating the plant uptake of soil Cd. After two years experimental, by monitoring the soil Cd concentrations, The Cd concentrations decreased on average from 2.75 mg kg^?1to 2.45 mg kg^?1 in the first year and from 2.33 mg kg^?1 to 1.53 mg kg^?1 in the second year, amounting to a decrease by a factor of 10.6% in the first year and 12% in the second year. After two years phytoremediation by S. nigrum, Cd concentrations of the seven experimental plots with S. nigrum growth decreased from 2.75 mg kg^?1 to 1.53 mg kg^?1, a decrease by a factor of 24.9%. And the soil Cd concentration decreased only 2.1% and 1.7% in the bared experimental plot. And the calculating of Cd uptake by S. nigrum shown that, the plants uptake 4.46% and 5.18% of the total soil Cd in 2008 and 2009, while the soil Cd concentrations decreased by a factor of 10.6% in 2008 and 12.1% in 2009.     

Studies of Ultrastructure and ATPase Localization of Mature Embryo Sac in Vicia faba L.

Studies of ultrastructure and ATPase localization of the mature embryo sac in Vicia faba L. show that the egg cell has no cell wall at thechalazal end, it has a chalazally located nucleus and a large micropylar vacuole. There are many nuclear pores in the nuclear membrane. The cytoplasm is restricted around the nucleus. Dictyosome and mitochondria are few. There are some starch grains and lipid grains in the egg cytoplasm. There are no obvious differences between two synergids. No cell wall is seen at the chalazal end either, but there are some vesicles which project to vacuole of the central cell and fuse with its vacuolar membrane. Plasmodesmata connections occur within the synergid wall where it is adjacent to the central cell. The synergid has a micropylarly located nucleus and a chalazal vacuole, the nucleus is irregularly shaped. The synergid cytoplasm is rich in organelles. The filiform aparatus is of relatively heterogeneous structure. The central cell is occupied by a large vacuole and its cytoplasm is confined to a thin layer along the empryo sac wall, but is rich in various organelles, starch grains and lipid bodies. Nucleolar vacuoles are often present two polar nuclei. The nuclear membranes of two polar nuclei have partly fused. ATPase reactive product was located obviously at the endoplasmic reticulum in cytoplasm of the egg cell and central cell. The embryo sac wall consists of different density of osmiophilic layer. There are some wall ingrowths in chalazal region of the embryo sac. The long-shaped and cuneate cells of chalazal region are peculiar. Special tracks of ATPase reactive products are visible at their intercellular space which may be related to transportation of nutrients.     

A Physiological Study of Embryo Development in Heracleum sphondylium L.: I. The Effect of Temperature on Embryo Development

Growth of embryos within the seed of Heracleum sphondylium proceedsmore rapidly at low temperature than at room temperature. At2° growth is exponential and in 9 weeks the size is increased4 times and the dry weight 25 times. At 15° there is a progressivefalling off in the rate of growth, and growth ceases when bothsize and dry weight have been only doubled.     

The Nucellus, Embryo Sac, Endosperm, and Embryo of Aesculus and their Interdependence during Growth

Immature fruits of Aesculus yield powerful stimuli to growthand cell division. Therefore, the developing fruit of Aesculuswoerlitzensis Koehne has been investigated from pollinationto maturity. The fluid, or liquid endosperm, which containsthe growth-promoting substances is produced in a large vesiclewhich forms at the chalazal tip of the embryo sac. As the vesiclegrows, it encroaches upon the nucellus and, when the embryodevelops, one of its cotyledons penetrates into the vesicleof the embryo sac where it grows and absorbs the contents. Theembryo, which has only a vestigial suspensor, reaches the vesicleby growing along the neck of the long curved embryo sac. Thecotyledon which first penetrates the vesicle grows into a massivestructure; the other remains small. The tip of the cotyledonseems to function as an absorbing surface, for the endospermwith which it comes into contact disorganizes. Fertilizationand the presence of a viable embryo at the micropylar end ofthe embryo sac therefore sets in train a number of other events.These are the extensive development of the nucellus at the chalazalend of the embryo sac, the swelling of the vesicle and the formationof a free nuclear and some cellular endosperm, and the disorganizationof the nucellus as it is encroached upon by the vesiculate embryosac. Attention is directed to the organization of the nucellusin the vicinity of the embryo sac. Files or richly protoplasmicnucellar cells(hypostase) which converge upon the chalazal tipof the embryo sac suggest a principal route by which the vesiclemay be nourished. Special attention is drawn to the very differentsizes of cells, their nuclei and nucleoli, in the differentparts of the nucellus. The growth and development of the embryohas also been traced from the zygote to the mature seed. Thenutritive role of the veaiculate embryo sac, and the supplyof growthstimulating substances, through the function of a cotyledonas an absorbing organ, are now seen as important features ofthe development of the Aesulus embryo in the ovule. Many outstandingproblems still remain. The sequential events that follow fertilizationin the different interdependent regions (nucellus, embryo sac,cotyledon, &c.) are here described, but not casually explained.