韭菜胚囊发育与胚胎发生

韭菜胚囊发育为葱型,胚胎发生属柳叶菜型。成熟胚囊中,三个反足细胞形态上常类似卵器,其中二个呈助细胞状,一个呈卵细胞状。卵状反足细胞可分裂成多细胞原胚,但随着胚乳的发育而退化。在未受精胚囊中,卵细胞和卵状反足细胞均可分裂,它们的发生过程与合子胚相似,但因无胚乳哺育,均不能继续发育。论证了反足细胞胚的性质,初步探讨了胚乳与反足细胞无配子生殖的关系。     

韭菜幼小子房培养时胚囊的发育和一些异常现象

对韭菜开花前1天左右的子房进行培养可获得大量的单倍体植株。观察表明单倍体植株起源于未受精的卵细胞和反足细胞。为了探索培养不同发育时期的子房对单倍体原胚发生频率的影响,我们又对大孢子母细胞时期的幼     

韭菜未传粉子房培养中单倍体的胚胎发生和植株再生

在自然生长条件下,韭菜反足细胞可与合子同时分裂形成多细胞原胚,但很快退化,种子成熟时仅含有合子胚。在未传粉子房培养条件下,反足细胞和卵细胞可经相似的早期胚胎发生过程再生单倍体植株。高频率的胚胎发生为韭菜单倍体育种提供了一条新途径。文中讨论了反足细胞无配子生殖的有关问题。     

Pseudogamous embryogenesis and the degree of parthenogenesis inAllium tuberosum

Summary Early stages of egg embryony and antipodal embryony in ovules from both pollinated and unpollinated flowers ofAllium tuberosum, a diplosporous apomict, were observed. Whether flowers were pollinated or not, autonomous egg and antipodal embryonies occurred at nearly equal frequencies and progressed almost synchronously for several days. An electrophoretic analysis of endosperm esterase demonstrated the fertilization of polar nuclei. It was thus confirmed thatA. tuberosum is a pseudogamous apomict. The degree of parthenogenesis, calculated as the percentage of ovules in which egg cells showed autonomous embryonic development, ranged between 62% and 94% among six cultivars and was nearly equal to the degree of diplospory previously reported. The present results show that most unreduced egg cells and egg-like antipodal cells ofA. tuberosum have the ability to start embryogenesis independently of pollination.     

植物微核技术在监测水质污染中的应用

应用韭菜微核技术,检测哈尔滨市量具刃具厂含铬废水的遗传毒性,试验表明：含铬废水可诱导韭菜和蚕豆根尖细胞产生微核,进行回归分析,其蚕豆对Ｃｒ＾＋６诱变剂回归分析为ｙ＝２４．９４＋１２７．７７ｘ（ｒ＝０．９９６,Ｐ〈０．０１）,韭菜对Ｃｒ＾＋６诱变剂回归广泛为：ｙ＝２１．７４＋１００．２３ｘ（ｒ＝０．９００,Ｐ〈０．０１）,ｒ＝１１．１７＋３．３８ｘ（ｒ＝０．７８１,Ｐ〈０．０５）,韭菜根尖微核技术具     

水稻胚囊超微结构的研究

水稻(Oryza sativa L.)胚囊成熟时,卵细胞的合点端无细胞壁,核居细胞中部,细胞器集中在核周围,液泡分散于细胞周边区域。助细胞珠孔端有丝状器,合点端无壁,核位于细胞中部贴壁处,细胞器主要分布在珠孔端,液泡主要分布在合点端。开花前不久,一个助细胞退化。中央细胞为大液泡所占,两个极核靠近卵器而部分融合,细胞器集中在极核周围和靠近卵器处,与珠心相接的胚囊壁上有发达的内突。反足细胞多个形成群体,其增殖主要依靠无丝分裂与壁的自由生长,反足细胞含丰富活跃的细胞器,与珠心相接的壁上有发达的内突。开花后6小时双受精已完成,合子和两个助细胞合点端均形成完整壁。合子中开始形成多聚核糖体、液泡减小。退化助细胞含花粉管释放的物质,其合点端迴抱合子。极核已分裂成数个胚乳游离核,中央细胞中细胞器呈活化状态。反足细胞仍在继续增殖。讨论了卵细胞的极性、助细胞的退化、卵器与中央细胞间界壁的变化、反足细胞的分裂特点等问题。     

Ultrastructures of the Egg Apparatus and the Central Cell of Calystegia hederacea (Convolvulaceae) Before and After Fertilizati on

Ultrastructures of the mature embryo sac of Calystegia hederacea Wall. and its changes after fertilization are described. The positional organization of the egg cell, the two synergids and the central cell, as well as their interrelationships were studied. Some regions of the cell boundaries between the egg cell and the central cell, as well as between the egg cell and the synergids were devoid of typical cell wall before fertilization, displayed a feature quite similar to the characteristic absence of the cell wall in the fertilization target zone occurred in most angiosperms. Besides the genera ultrastructural characteristics of the egg apparatus and the central cell, there were several unusual aspects in C. hederacea, such as the egg nucleus located above the large vacuole near the chalazal end of the cell, many polyribosomes in the cytoplasm of the egg cell and wall ingrowths on both sides of the hooks of the central cell. All these unusual characteristics seemed to be closely associated with the short duration of the fertilization and the absence of antipodal cells in the mature embryo sac. It is concluded that the female germ unit of C. hecleracea is considered to be a topographical and physiological unit to realize their functions for successful double fertilization.     

An electron microscope study on in vitro parthenogenesis in sunflower

Summary Electron microscope studies have been conducted on the parthenogenesis induced by in vitro culture of unfertilized ovules of sunflower (Helianthus annuus). In comparison with the state of the egg prior to inoculation, some eggs 5 days after culture show striking ultrastructural changes, which include, among others, nuclear migration, an increase in the number and activity of the organelles, a loss of polarity and wall formation at the chalazal end of the cell. Most of these changes are similar to those that occur normally in the zygote, indicating that parthenogenic development has been triggered in these eggs. Such eggs have been termed activated and are presumed to be capable of undergoing parthenogenesis. The parthenogenic proembryos which result share some features in common with zygotic proembryos. In addition, some parthenogenic proembryos exhibit unique properties not found in zygotic proembryos. These include embryos that consist of two parts differing markedly in density, an inversion of polarity, the frequent occurrence of autophagic vacuoles, the thickening of cell walls, a centripetal growth mode of wall formation, the appearance of an incomplete cell wall, free nuclear division, amitosis and degeneration. We believe that these ultrastructural peculiarities are the effects of in vitro culture.     

甜菜无融合生殖单体附加系M14 成熟胚囊的超微结构特征

以甜菜无融合生殖单体附加系M14(Beta vulgaris, 2n=18+1)为实验材料, 利用电子显微镜技术对成熟胚囊及其超微结构进行研究。结果表明: M14成熟胚囊包括1个卵细胞、2个退化的助细胞、1个具有次生核的中央细胞和3-6个反足细胞。其卵细胞具有3种不同的形态: (1)极性正常的卵细胞, 细胞核位于合点端, 细胞质含有大量核糖体、线粒体、内质网等细胞器; (2)细胞核位于细胞中央; (3)细胞核位于珠孔端, 且后2种形态细胞器的种类与数量少。大多数胚囊中的2个助细胞在开花前已退化。中央细胞的次生核位于反足细胞附近; 未经受精自发分裂前的卵细胞与中央细胞的细胞核大、核仁明显, 细胞器的种类与数量多, 呈现旺盛代谢活动特征, 成为二倍体孢子无融合生殖过程中, 卵细胞与次生核自发分裂的细胞学标志。     

甜菜无融合生殖单体附加系M14成熟胚囊的超微结构特征

以甜菜无融合生殖单体附加系M14（Betavulgaris,2n=18＋1）为实验材料,利用电子显微镜技术对成熟胚囊及其超微结构进行研究。结果表明：M14成熟胚囊包括1个卵细胞、2个退化的助细胞、1个具有次生核的中央细胞和3-6个反足细胞。其卵细胞具有3种不同的形态：（1）极性正常的卵细胞,细胞核位于合点端,细胞质含有大量核糖体、线粒体、内质网等细胞器;（2）细胞核位于细胞中央;（3）细胞核位于珠孔端,且后2种形态细胞器的种类与数量少。大多数胚囊中的2个助细胞在开花前已退化。中央细胞的次生核位于反足细胞附近;未经受精自发分裂前的卵细胞与中央细胞的细胞核大、核仁明显,细胞器的种类与数量多,呈现旺盛代谢活动特征,成为二倍体孢子无融合生殖过程中,卵细胞与次生核自发分裂的细胞学标志。     

Changes of Plastids Mitochondria and Their DNA in the Egg Cell Before and After Fertilization in Pharbitis

The ultrastructure and cytoplasmic DNA in the egg cell and zygote of Pharbitis purpurea, (L.) Voyght and P. limbata Lindl. which were studied with electron microscopy and DNA epifiuorescence microscopy. The egg cell before fertilization was highly vacuolated with only a few cytoplasmic plastids and mitochondria. Plastids were spherical and/or rod- shaped containing 1 ～ 2 large starch grains. Most of the mitochondria were cup and/or circular. The cytoplasm in the zygote was much more abundant than that in the egg cell. The number of plastids and their electronic density were greatly increased, in most of which containing osmiophilic bodies. The mitochondria were rich and spherical-shaped in the zygote. Two types of cytoplasmic DNA nucleoids were detected in the egg cell, the more abundant one being big and circle-shaped and the other dot-shaped. Only dot-shaped nucleoids were present in the zygote. The content of nucleoids in the zygote was much less than that in the egg cell. Authors propose that some cytoplasmic DNA may degenerate after fertilization. The ultrastructural characteristics of the egg cell and the reduction of cytoplasmic DNA in the zygote may related to the mechanisms of plastid unipaternal inheritance in Pharbitis.     

莴苣卵细胞、合子与原胚细胞中钙的分布

用焦锑酸盐沉淀法对莴苣开花前后的卵细胞、合子与原胚细胞中的钙颗粒分布变化进行了观察。结果表明,开花前三天,刚形成的卵细胞内钙颗粒很少,开花前二天的卵细胞内钙颗粒开始增多,开花前一天的卵细胞形成了大液泡,建立了极性,细胞内的钙颗粒又减少。开花后、受精前的卵细胞的钙颗粒主要聚集在细胞核中。受精后合子中的钙颗粒又明显增多,在核质中分布一些较大的钙颗粒,在珠孔端大液泡中聚集了较多的絮状钙。二胞原胚中的钙颗粒又开始减少,多胞原胚细胞中的钙进一步减少,但原胚表面分布一层丰富的钙颗粒。探讨了钙在卵细胞分化成熟、受精以及原胚发育初期中的作用。     

向日葵胚囊的超微结构和雌性生殖单位问题

本文对向日葵胚囊中卵细胞、助细胞与中央细胞开花前和传粉后的超微结构变化进行了研究。着重报道了不同发育时期这三种细胞之间特定区域的界壁的消长动态。在此基础上结合现有文献资料探讨了由三者共同组成“雌性生殖单位”以适应受精作用的问题。     

Differences in the initiation of the zygotic and parthenogenetic pathway in the Salmon lines of wheat: ultrastructural studies

 The ultrastructure of the egg apparatus of the sexual (aestivum)-Salmon line (aS) and the isogenic but alloplasmic (kotschyi)-Salmon line (kS) of the Salmon system of wheat was studied by transmission electron microscopy 3 days before and during anthesis. Additionally, the zygotic stage of aS, 17 h after pollination, was included. Metabolic activity of egg cells from the sexual line aS was low 3 days before anthesis and increased dramatically after pollination and fertilization. This timing of increased activity was evident because of changes occurring in the egg cell nucleus and nucleolus, polysomes, endoplasmic reticulum and Golgi apparatus, and the completion of the cell wall around the zygote. In contrast to the sexual line, the egg cell of the parthenogenetic line showed high activity 3 days before anthesis. The metabolic and ultrastructural characters observed in the nucleus and cytoplasm of the kS line 3 days before and during anthesis corresponded with those of the isogenic sexual line aS during anthesis and 17 h after pollination, respectively. High metabolic activity observed in the persistent synergid of kS may be connected with the occurrence of additional embryos in seeds (twins) of this line. Received: 25 November 1997 / Revision accepted: 16 April 1998     

Fertilization and Histochemical Investigation on Pulsatilla chinensis (Bung) Regel

Fertilization and variation of protein and starch grains in Pulsatilla chinensis (Bung) Regel have been studied at light microscopic level with histochemical test. Based upon the observations, the main conclusions are summarized as follows: The mature pollen grains are two-celled in which the generative cell shows the stronger protein staining than the vegetative cell. And vegetative cells are full of starch garins. When the pollen tube enters into the embryo sac, one synergid is destroyed, or in a few cases synergids are intact. Occasionally two synergids are disorganized as pollen tube penetrates. However, most of the remaining syuergids break down during fertilization, only in a few cases it remains till early stage of embryo development. The contents discharged by the pollen tube consist of two sperms, which stain intensely blue with protein dyes, a great amount of protein and starch grains. Mature female gametophyte (embryo sac) consists of an egg apparatus, central cell, which has a huge secondary nucleus, and antipodal apparatus which retain in course of fertilization. A few of embryo sac contain two sets of egg apparatus, a central cell with two huge secondary nuclei and two sets of antipodal apparatus. In some nucleoli of the central cell the comb-like structure pattern may be detected clearly. There are 1–2 small nucleoli in some egg cells and central cells. All the cells in embryo sac show protein positive reaction. According to the different shades of the color in cells, its may be arranged in the following order: antipodal cells, synergids, central cell and egg cell. Only a few small starch grains are present near nuclei of central cell and egg cell before fertilization, but no starch grains remain in most of the central cell, the synergids and antipodal cells. The fertilization is of the premitotic type. The fusion of the sexual nuclei progresses in the following order: 1, sperms approach and lie on the egg nucleus and secondary nucleus; 2, sperm chromatin sinks themselves into female nucleus, and male nucleolus emerges with the sperm chromosome; and 3, male nucleoli fuse with the nucleoli of egg nucleus and central cell nucleus, and finally forming the zygote and the primary endosperm cells respectively. Nevertheless, as it is well known, the fertilization completes in central cell obviously earlier than that in egg cell. Though it has been explained in cereals and cotton, in Pulsatilla chinensis the main reason is that nucleolar fusion of the male and female nucleoli in egg nucleus is slower than that in secondary nucleus. And the dormancy of the primary endosperm nucleus is shorter than that of the zygote. In the process of fertilization, histochemical changes are considerably obvious in the following three parts: 1, from the begining of fusion of male and female nuclei to form zygote and primary endosperm cell, Protein staining around female nucleus appears to increase gradually; 2, no starch grains are detected in embryo sac. Though only starch grains are carried in by pollen tube, they are completely exhausted during this period; and 3, near completion of fertilization starch grains appear again in zygote, however, not yet in primary endosperm nucleus till its dividing for the first time. The present study reveals that antipodal cells and synergids seem to play a significant role in nutrition of the embryo sac during the fertilization.     

The Ultrastructural Study on the Early Embryonic Development of Radish

The ultrastructure of the mature embryo sac, the early stages of the embryo and endosperm development of common radish, Raphanur sativus was examined. The embryo sac consists of 7 cells with antipodal ceils disappeared when it matures. The egg cell is highly polarized. The wall surrounded the chalazal end of the egg cell is incomplete, showing a discontinuous structure of an electron dense material deposited intermittently in the space between the two plasma membranes of the egg cell and central cell. The synergid has filiform apparatus, rich in organelles and well developed ER. The two polar nuclei of the central cell are located near the egg apparatus because of the big vacuole, and the finger-like protrutions from the cell wall, as that in synergid, are found. The first division of the zygote occurs 4–5 days after pollination and the development of the embryo follows the Onagrad type, and the structure of the embryo cell is quite simple for containing small quantity of ER, plastids and other organelles. The primary endosperm nucleus deviates 2 days earlier than zygote. The endosperm is of nuclear-endosperm containing chloroplasts, well developed ER, and plentiful of mitochondria and golgi bodies and the nodule-like aggregation in both. the chalazal and micropylar ends of the embryo sac during the early development appeared, and cell wall starting at the micropylar end by freely-growing forms about 16 days after pollination.     

Cytological Studies of the Double Fertilization in Rice

Detailed studies on the process of double fertilization in rice were conducted in the present work. The results are summarized as follows: 1. In the embryosac 30 minutes after anthesis, the pollen tube has already reached the micropyle in every specimen. In some cases, it has even entered further into the embryosac and discharged its contents, including the two male gametes. 2. 1½ hours after anthesis, the male gamete enters into the egg cell. As soon as it comes in contact with the egg nucleus, it increases in size. 2 hours after anthesis, the male nucleus is found inside the female one. A male nucleolus is now clearly discernible. 3. The male nucleolus is gradually growing until it reaches the size of the female one, and then the fusion of the two takes place. The fusion is generally completed and the zygote is formed 7 hours after anthesis. 4. The first mitotic division of the zygote occurs 9 hours after anthesis. 5. The fusion of the male gamete and the polar nucleus proceeds in a similar way as that of the male and female gametes, but it takes a much shorter time usually being completed within 3 hours after anthesis. 6. The male gamete enters into one of the polar nuclei and reveals its nucleolus which increases rapidly in size and then unites with that of the polar nucleus. As soon as the union is completed, the nuclear membrane between the closely contacted parts of the two polar nuclei disappears and the primary endosperm nucleus is formed. 7. The first mitotic division of the primary endosperm nucleus begins right after its formation. 8. With the fusion of the male and female gametes and the development of the zygote, the mitochondria in the cytoplasm surrounding the nucleus increase in size and number. However, in the central cytoplasm about the polar nuclei they show no notice- able change during the fertilization process. 9. Based on the facts that in the embryosac a secondary pollen tube is often seen in every stage of the fertilization process and that additional nucleoli are also observed sometimes in the egg nucleus, the authors believe that polyspermy most probably exists in rice plants, and that this may be one of the causes of polyploid plants often found in rice field as reported by several authors.     

栽培甜菜卵细胞、合子及二细胞原胚的超微结构

为丰富被子植物生殖生物学资料, 并为甜菜相关研究提供参考, 应用透射电镜技术研究栽培甜菜（Beta vulgaris）卵细胞、合子和二细胞原胚的超微结构特征。结果如下：在成熟卵细胞中多聚核糖体数量不多, 且细胞代谢活性较弱; 初期合子内, 核仁大量合成核糖体前体物质, 胞质中多聚核糖体数目众多, 细胞代谢活性较强; 休眠期合子的核仁变小, 胞质中核糖体数量急剧减少, 仅有少量多聚核糖体, 细胞代谢活性较弱; 合子分裂前期和二细胞原胚期, 核仁显著, 胞质中核糖体的密度增加, 出现大量多聚核糖体, 细胞代谢活性较强。根据上述结果可以得出, 栽培甜菜从卵细胞成熟→合子初期→合子休眠期→合子分裂前期→二细胞原胚的超微结构变化中多聚核糖体的变化最为显著, 表现为“少→多→少→多”的数量变化过程, 反映出细胞代谢状态也经历了“弱→强→弱→强”的变化过程, 这种变化趋势与配子体世代向孢子体世代转变有关。     

Ovule,Female and Male Gametophyte and Fertilization of Kingdonia uniflora Balfour F. et W. W. Smith

The structure of ovule, female and male gametophyte, double fertilization and the distrubution of starch grains during the fertilization have been studied. The main results are as follows: ( 1 ) Ovule The ovule is anatropous, unitegmic and tenuinucellate. The nucetlus appears cylindric, since megaspores and embryo sac development, its internal cells of nucellus become disorganized, so that only a single layer of epidermal cells remains toward the side of the micropyle, On the other hand, the integument is not as long as nucellus, as a result micropyle is not formed. And no vascular bundle is found in the integument. (2) Female gametophyte The mature embryo sac is slender and is composed of an egg cell, two synergids, a central cell and three antipodal cells. The egg cell is situated slightly away from the tip of embryo sac. Some of them contain starch grains. Synergids occupy the tip of embryo sac. Its wall at micropylar region appears irregular in thickenes and irregular in ingrowths to form the filiform apparatus. The centrateell is very large, and strongly vacuolated Two polar nuclei come to contact closely with each other, but not fuse, or to fuse into a large secondary nucleus before fertilization. The polar nuclei or the secondary nucleus are usually situated at the middle-lower position of the central cell or nearer to the chalazal end above the antipodal cell. It is different from egg cell, no starch grains are found here. In most embryo sacs three antipodal cells are found. They are not as large as those in other plants of Ranunculaceae. But six antipodal cells or the antipodal cell with two nuclei may rarely be found. Like synergid, the wall of them appears not only irregularly thickened, but clearly with irregular ingrowths. In a few antipodal cells the starch garins are usually found near the nucleus. By the end of fertilization, antipodal cells become disintegrated. (3) Male gametophyte Most pollen grains are two-celled when shedding, and rich in starch grains. A few of them contain single nucleus or three-celled. (4) The double fertilization The fertilization of Kingdonia unifiora Balfour f. et W, W. Smith is wholly similar to some plants of Ranunculaceae studied. First, the pollen tube penetrates a degenerating synergid. And the pollen tube discharges its contents with two sperm nuclei into the degenerating synergid cell. One of the two sperms fuses with the nucleus of the egg, and the other fuses with two polar nuclei or the secondary nucleus of the central cell. If one sperm nucleus at first fuses with one of the polar nuclei, and then the fertilized polar nuclei again fuses with other polar nucleus. Secondly, the fertilization of the polar nuclei or the secondary nuclei completes earlier than that of the egg. The primary endosperm nucleus begins to divide earlier than the zygote. It seems that one of the sperm nuclei come to contact with egg nucleus, the other has already fused with polar nuclei or the secondary nucleus. The zygote with a single nucleolus appears until the endosperm with 16–20 cell. Thirdly, before and after fertilization there are one to some small nucleoli in egg nucleus and polar nuclei or secondary nucleus. However they increase in quantity from the beginning of the fusion of male nucleis. These nucleoli quite differ from male nucleoli by their small size, and most of them disappear at the end of fertilization. It may be concluded that the small nucleoli increase in quantity is related to the fusion of male and female nuclei. In the duration of fertilization, in ovule starch distribution is in the basal region of integument. But in embryo sac, onlysome egg cells, or zygotes contain starch grains, a part of which was brought in by pollen tube. Sometimes the starch grains are found in some synergids and antipodal cells. No starch grains are found in the central cell.     

Transmission of male cytoplasm during fertilization in Nicotiana tabacum

Serially sectioned embryo sacs of Nicotiana tabacum were examined during fertilization events using transmission electron microscopy. After pollen tube discharge, the outer membrane of the sperm pair is removed, the two sperm cells are deposited in the degenerate synergid and the sperm cells migrate to the chalazal edge of the synergid where gametic fusion occurs. During fertilization, the male cytoplasm, including heritable organelles, is transmitted into the female reproductive cells as shown by: (1) the cytoplasmic confluence of one sperm and the central cell during cellular fusion, (2) the occurrence of sperm mitochondria (distinguished by ultrastructural differences) in the zygote cytoplasm and adjacent to the sperm nucleus, (3) the presence of darkly stained aggregates which are found exclusively in mature sperm cells within the cytoplasm of both female cells soon after cell fusion, and (4) the absence of any large enucleated cytoplasmic bodies containing recognizable organelles outside the zygote or endosperm cells. The infrequent occurrence of plastids in the sperm and the transmission of sperm cytoplasm into the egg during double fertilization provide the cytological basis for occasional biparental plastid inheritance as reported previously in tobacco. Although sperm mitochondria are transmitted into the egg/zygote, their inheritance has not been detected genetically. In one abnormal embryo sac, a pair of sperm cells was released into the cytoplasm of the presumptive zygote. Although pollen tube discharge usually removes the inner pollen-tube plasma membrane containing the two sperm cells, this did not occur in this case. When sperm cells are deposited in a degenerating synergid or outside of a cell, this outer membrane is removed, as it apparently is for fertilization.