Dynamics of storage reserve deposition during Brassica rapa L. pollen and seed development in microgravity

Pollen and seeds share a developmental sequence characterized by intense metabolic activity during reserve deposition before drying to a cryptobiotic form. Neither pollen nor seed development has been well studied in the absence of gravity, despite the importance of these structures in supporting future long-duration manned habitation away from Earth. Using immature seeds (3-15 d postpollination) of Brassica rapa L. cv. Astroplants produced on the STS-87 flight of the space shuttle Columbia, we compared the progress of storage reserve deposition in cotyledon cells during early stages of seed development. Brassica pollen development was studied in flowers produced on plants grown entirely in microgravity on the Mir space station and fixed while on orbit. Cytochemical localization of storage reserves showed differences in starch accumulation between spaceflight and ground control plants in interior layers of the developing seed coat as early as 9 d after pollination. At this age, the embryo is in the cotyledon elongation stage, and there are numerous starch grains in the cotyledon cells in both flight and ground control seeds. In the spaceflight seeds, starch was retained after this stage, while starch grains decreased in size in the ground control seeds. Large and well-developed protein bodies were observed in cotyledon cells of ground control seeds at 15 d postpollination, but their development was delayed in the seeds produced during spaceflight. Like the developing cotyledonary tissues, cells of the anther wall and filaments from the spaceflight plants contained numerous large starch grains, while these were rarely seen in the ground controls. The tapetum remained swollen and persisted to a later developmental stage in the spaceflight plants than in the ground controls, even though most pollen grains appeared normal. These developmental markers indicate that Brassica seeds and pollen produced in microgravity were physiologically younger than those produced in 1 g. We hypothesize that microgravity limits mixing of the gaseous microenvironments inside the closed tissues and that the resulting gas composition surrounding the seeds and pollen retards their development.     

Gravity independence of seed-to-seed cycling in Brassica rapa

 Growth of higher plants in the microgravity environment of orbital platforms has been problematic. Plants typically developed more slowly in space and often failed at the reproductive phase. Short-duration experiments on the Space Shuttle showed that early stages in the reproductive process could occur normally in microgravity, so we sought a long-duration opportunity to test gravity's role throughout the complete life cycle. During a 122-d opportunity on the Mir space station, full life cycles were completed in microgravity with Brassica rapa L. in a series of three experiments in the Svet greenhouse. Plant material was preserved in space by chemical fixation, freezing, and drying, and then compared to material preserved in the same way during a high-fidelity ground control. At sampling times 13 d after planting, plants on Mir were the same size and had the same number of flower buds as ground control plants. Following hand-pollination of the flowers by the astronaut, siliques formed. In microgravity, siliques ripened basipetally and contained smaller seeds with less than 20% of the cotyledon cells found in the seeds harvested from the ground control. Cytochemical localization of storage reserves in the mature embryos showed that starch was retained in the spaceflight material, whereas protein and lipid were the primary storage reserves in the ground control seeds. While these successful seed-to-seed cycles show that gravity is not absolutely required for any step in the plant life cycle, seed quality in Brassica is compromised by development in microgravity. Received: 3 August 1999 / Accepted: 27 August 1999     

Pollination and embryo development in Brassica rapa L. in microgravity

Plant reproduction under spaceflight conditions has been problematic in the past. In order to determine what aspect of reproductive development is affected by microgravity, we studied pollination and embryo development in Brassica rapa L. during 16 d in microgravity on the space shuttle (STS-87). Brassica is self-incompatible and requires mechanical transfer of pollen. Short-duration access to microgravity during parabolic flights on the KC-135A aircraft was used initially to confirm that equal numbers of pollen grains could be collected and transferred in the absence of gravity. Brassica was grown in the Plant Growth Facility flight hardware as follows. Three chambers each contained six plants that were 13 d old at launch. As these plants flowered, thin colored tape was used to indicate the date of hand pollination, resulting in silique populations aged 8-15 d postpollination at the end of the 16-d mission. The remaining three chambers contained dry seeds that germinated on orbit to produce 14-d-old plants just beginning to flower at the time of landing. Pollen produced by these plants had comparable viability (93%) with that produced in the 2-d-delayed ground control. Matched-age siliques yielded embryos of equivalent developmental stage in the spaceflight and ground control treatments. Carbohydrate and protein storage reserves in the embryos, assessed by cytochemical localization, were also comparable. In the spaceflight material, growth and development by embryos rescued from siliques 15 d after pollination lagged behind the ground controls by 12 d; however, in the subsequent generation, no differences between the two treatments were found. The results demonstrate that while no stage of reproductive development in Brassica is absolutely dependent upon gravity, lower embryo quality may result following development in microgravity.     

Cytochemical Localization of Reserves during Seed Development in Arabidopsis thaliana under Spaceflight Conditions

Successful development of seeds under spaceflight conditionshas been an elusive goal of numerous long-duration experimentswith plants on orbital spacecraft. Because carbohydrate metabolismundergoes changes when plants are grown in microgravity, developingseed storage reserves might be detrimentally affected duringspaceflight. Seed development in Arabidopsis thaliana plantsthat flowered during 11 d in space on shuttle mission STS-68has been investigated in this study. Plants were grown to therosette stage (13 d) on a nutrient agar medium on the groundand loaded into the Plant Growth Unit flight hardware 18 h priorto lift-off. Plants were retrieved 3 h after landing and siliqueswere immediately removed from plants. Young seeds were fixedand processed for microscopic observation. Seeds in both theground control and flight plants are similar in their morphologyand size. The oldest seeds from these plants contain completelydeveloped embryos and seed coats. These embryos developed radicle,hypocotyl, meristematic apical tissue, and differentiated cotyledons.Protoderm, procambium, and primary ground tissue had differentiated.Reserves such as starch and protein were deposited in the embryosduring tissue differentiation. The aleurone layer contains alarge quantity of storage protein and starch grains. A seedcoat developed from integuments of the ovule with gradual changein cell composition and cell material deposition. Carbohydrateswere deposited in outer integument cells especially in the outsidecell walls. Starch grains decreased in number per cell in theintegument during seed coat development. All these characteristicsduring seed development represent normal features in the groundcontrol plants and show that the spaceflight environment doesnot prevent normal development of seeds in Arabidopsis. Arabidopsis ; spaceflight; embryo; endosperm; seed coat; storage reserves     

Reproduction during spaceflight by plants in the family Brassicaceae

Researchers report on studies of reproduction in Arabidopsis thaliana in space during during the Chromex-03 on STS-54, Chromex-04 on STS-51, and Chromex-05 on STS-68 missions. The obstacles to seed formation were related to carbon dioxide levels. Other experiments examined in flight pollination and seed production in Brassica rapa during parabolic flight, a 4-1/2 month stay on Mir, and on STS-87. During the Mir experiment, Brassica seeds were harvested from seeds sown in flight. The second generation seeds grew to produce new seeds that contained more starch and less protein and lipid when compared to ground control seeds.     

Distribution and changes of reserve materials in cotyledon cells of Panax ginseng related to direct somatic embryogenesis and germination

Cotyledon explants from zygotic embryos of Panax ginseng produced somatic embryos on Murashige and Skoog basal medium without growth regulators. Somatic embryos developed directly from epidermal cells at the cotyledon base. Somatic embryos were always formed from the side of the cotyledon opposite to the one attached to the medium surface regardless of cotyledon orientation. The frequency of somatic embryo formation from the abaxial epidermis (66%) was much higher than that from the adaxial epidermis (12%). Differences in embryogenic response were likely related to cell structure. Abaxial epidermal cells were filled with reserve materials (lipid bodies), while adaxial epidermal cells were devoid of any prominent reserves. During germination, the reserve materials in the cells of the cotyledons disappeared rapidly. At the same time, the competency of somatic embryo formation from cotyledon explants declined rapidly to zero. Upon culture of the cotyledon explants (for somatic embryo induction), lipid bodies slowly disappeared, but starch grains accumulated prominently. Reserve materials disappeared after commencement of embryogenic cell division. During germination, lipid bodies rapidly disappeared, and chloroplasts developed instead of starch grains. Received: 29 January 1997 / Revised version received: 16 April 1997 / Accepted: 9 May 1997     

Reserve nutrient substance accumulation in Brassica rapa L. seeds in microgravity conditions (STS-87)

The results of study of Brassica embryo differentiation and reserve nutrient substance accumulation in the seeds were represented. Near resemblance of the spaceflight and around control embryo development was revealed. Different character of the reserve substance accumulation was noted, despite of the morphologic similarity in seeds produced in spaceflight and on the ground. It allows to consider spaceflight embryos morphologically more younger compared to the ground control.     

Embryology in Norway spruce (Picea abies). An analysis of the composition of seed storage proteins and deposition of storage reserves during seed development and somatic embryogenesis

Seed cones were collected from open-pollinated trees of Norway spruce ( Picea abies ) in a seed orchard from pollination until maturation of the seeds. Immature embryos were isolated for embryogenic tissue cultures that were maintained either on solidified medium or as liquid cultures. By transferring young somatic embryos to medium containing 90 m M sucrose and 7. 6 μ M ABA growth continued to mature embryos that accumulated storage reserves in both the hypocotyl-shoot axis and the cotyledons. Both zygotic and somatic embryos at different developmental stages were processed for microscopy as were the megagametophytes. Total protein was extracted from the seed material at intervals during development and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These analyses revealed that storage protein started to accumulate in the megagametophytes at the time when embryos were growing into the gametophytic tissue, while it occurred a few weeks later in the embryos at rapid embryo growth and organ differentiation. Lipid bodies also became abundant in the mature plant material. Although plastids with prominent starch grains were very frequent in both megagametophytes and embryos during development they were not observed in the desiccated tissues. Zygotic and somatic embryos displayed a similar developmental pattern.
By sequential salt-extraction and dilution two fractions highly enriched in storage protein were obtained. One fraction (G-1), requiring higher salt concentration for protein solubilization, was dominated by a protein migrating to around M, 55000–60000 when separated under non-reduced condition. After exposure to reducing agent this protein was replaced by two new ones with M, 33000 and 22000 giving evidence of disulfide bonded polypeptides. The other fraction (G-2), was dominated by polypeptides around M, 42000 and low molecular mass polypeptides (<14000).     

Different functions of vicilin and legumin are reflected in the histopattern of globulin mobilization during germination of vetch (Vicia sativa L.)

The temporal and spatial patterns of storage-globulin mobilization were immunohistochemically pursued in the embryonic axis and cotyledons of vetch seed (Vicia sativa L.) during germination and early seedling growth. Embryonic axes as well as cotyledons of mature seeds contain protein bodies with stored globulins. Prevascular strands of axes and cotyledons, the radicle and epidermal layers of axis organs were nearly exclusively stained by vicilin antibodies whereas the cotyledonous storage mesophyll gave similar staining for vicilin and legumin. Globulin breakdown started locally where growth and differentiation commenced in the axis. There, vicilin mobilization preceded legumin mobilization. Thus vicilin represents the initial source of amino acids for early growth and differentiation processes in vetch. Legumin presumably only serves as a bulk amino acid source for subsequent seedling growth during postgerminative globulin degradation. During the first 2–3 d after the start of imbibition the axis was depleted of globulins whereas no decrease in immunostainability was detected in the cotyledons except in their vascular strands where immunostainability was almost completely lost at this time. Continuous vascular strands were established at the third day when globulin breakdown was finished in the axis but had just started in the cotyledon mesophyll. Protein mobilization proceeded in a small zone from the epidermis towards the vascular strands in the center of the cotyledons. In this zone the storage cells, which initially appeared densely packed with starch grains and protein bodies, concomitantly transformed into cells with a large central vacuole and only a thin cytoplasmic layer attached to the cell wall. These results agree well with the hypothesis that during the first 2 d after imbibition the axis is autonomous in amino acid provision. After the endogenous reserves of the axis are depleted and the conductive tissue has differentiated, globulins are mobilized in the cotyledons, suggesting that then the amino acid supply is taken over by the cotyledons. For comparison with other degradation patterns we used garden bean (Phaseolus vulgaris L) and rape (Brassica napus L.) as reference plants. Received: 3 August 1999 / Accepted: 11 December 1999     

Morphogenetic status of somatic embryos of <Emphasis Type="Italic">Citrus sinensis</Emphasis> from mature polyembryonic seeds and those produced in vitro

In tissue culture of sweet orange (Citrus sinensis (L.) Osbeck, cv. Tarocco), we obtained mass regeneration of somatic embryos with two morphologically distinct cotyledons about 3 mm in length, their numbers amounting to 110–150 embryos per petri dish and 60 to 80% of the population. The morphogenetic state of somatic embryos was compared using the embryos with the cotyledons of different size (from 3 to 10 mm) from mature polyembryonic seeds as a test system and the cell number, size, and ultrastructural organization, and the number of protein bodies in the cotyledon cells as morphological and biochemical criteria. Cell number in the cotyledons of different size was related to the content of protein bodies therein. Typical protein bodies where 33 kD polypeptide of storage proteins was identified were detected only in the cotyledons, which size was identical to that of embryonic cotyledons from monoembryonic seeds of citrus plants. In the cells of smaller cotyledons, we detected protein-accumulating vacuoles with electron-dense inclusions that irrespective of their size, shape and structure accumulated the gold label. The number of the cells with protein depositions in vacuoles decreased when the cotyledons became smaller. Irrespective of the origin of embryos (in vivo or in vitro), lipids were the major storage metabolites in the cells of 3-mm cotyledons. As the cotyledon-forming cells became smaller and less numerous, their metabolic activity tended to decrease in line with the fragmentation of endoplasmic reticulum, the absence of polysomic complexes, and indistinct inner organization of mitochondria and plastids. It was concluded that somatic embryos developing in vivo and in vitro were physiological dwarfs, that is, the structures with diminutive storage organ with characteristically incomplete cell differentiation. Apparently such forms emerged due to the suppression of cotyledon growth at the initial stages of their organogenesis; as a result, the cell population could not properly realize both organo- and histogenesis.     

莲种子萌发和幼苗生长时期营养物质的代谢变化

莲子叶细胞中储存了丰富的营养物质, 主要为蛋白质、淀粉和淀粉质体DNA。这些贮藏物质为种子萌发和幼苗的生长提供必需的能量和养料。通过组织化学和显微镜观察, 研究莲从种子萌发到植株生长至具有4个节时, 子叶中贮藏物质消耗的全过程。在此过程中, 子叶中的贮藏物质不断降解,营养物质发生转运。蛋白体首先发生降解, 其大量降解主要发生在幼苗三叶期。淀粉质体降解时会聚 集成团, 之后体积逐渐减小, 最后完全降解。种子萌发后65天是子叶贮藏物质消耗末期, 淀粉质体DNA的含量比萌发后20天的三叶期明显减少。细胞壁的形态结构发生多种形式的变化, 细胞壁发生的这些变化与子叶细胞间物质的运输有关。含多糖的球形颗粒通过维管束在子叶中运输。     

莲种子萌发和幼苗生长时期营养物质的代谢变化

莲子叶细胞中储存了丰富的营养物质,主要为蛋白质、淀粉和淀粉质体DNA.这些贮藏物质为种子萌发和幼苗的生长提供必需的能量和养料.通过组织化学和显微镜观察,研究莲从种子萌发到植株生长至具有4个节时,子叶中贮藏物质消耗的全过程.在此过程中,子叶中的贮藏物质不断降解,营养物质发生转运.蛋白体首先发生降解,其大量降解主要发生在幼苗三叶期.淀粉质体降解时会聚集成团,之后体积逐渐减小,最后完全降解.种子萌发后65天是子叶贮藏物质消耗末期,淀粉质体DNA的含量比萌发后20天的三叶期明显减少.细胞壁的形态结构发生多种形式的变化,细胞壁发生的这些变化与子叶细胞间物质的运输有关.含多糖的球形颗粒通过维管束在子叶中运输.     

Cell structure and mobilization of lipids and proteins from cotyledon under microgravity influence

The structural-functional organization of cotyledon parenchyma cells of 6-day soybean (Glycine max L.) seedlings that were grown on board the space Shuttle Columbia (STS-87) have been studied. The purafil (KMnO4) was used in the experiment for the removing of some part of ethylene that secretes out from seedlings. There were four variants of the experiment: ground control (+purafil), ground control (-purafil), microgravity (+purafil) and microgravity (-purafil). The electron microscopy, srereological, and pyroantimonate cytochemical methods have been used. It is established the some indices of changes of storage substances in cotyledon parenchyma cells under influence of microgravity. It is displayed in the change of cell ultrastructure, the decrease of relative volume of storage cytoplasmic lipid bodies, a disappearance of storage protein body into vacuole and the redistribution of ionized calcium in cell. It was supposed that microgravity is influenced on the acceleration of storage substances catabolism.     

甘蓝型油菜油体数量及面积之和与含油量的相关性

利用荧光染料尼罗红染色和激光扫描共聚焦显微观察技术,建立了油菜油体观察或生物体内中性脂类物质定性鉴定的研究体系。对高油品种宁油14号、宁油18号、ZH-088和低油品种ZL-366、NjY008、Westar共6个甘蓝型油菜品种子叶贮藏细胞内的油体进行了观察。研究发现：油菜种子成熟过程中,油体从着色不明显的小颗粒,逐渐发育形成着色清晰的球状大油体。种子成熟干燥后,油体间很少发生聚合。在成熟干燥的种子中,油体集中分布于子叶贮藏细胞中央,呈椭圆形或不规则形状,较少为圆形。通过研究种子内油体与含油量的关系,发现高油品种组与低油品种组之间在单个子叶贮藏细胞内油体数量和截面积之和存在明显差异,而在高油品种组内或低油品种组内的差异不明显。结果显示,油菜种子细胞中油体的数量和总面积与含油量之间存在正相关,可作为高油分材料的选择依据。     

甘蓝型油菜油体数量及面积之和与含油量的相关性

利用荧光染料尼罗红染色和激光扫描共聚焦显微观察技术, 建立了油菜油体观察或生物体内中性脂类物质定性鉴定的研究体系。对高油品种宁油14号、宁油18号、ZH-088和低油品种ZL-366、NjY008、Westar共6个甘蓝型油菜品种子叶 贮藏细胞内的油体进行了观察。研究发现: 油菜种子成熟过程中, 油体从着色不明显的小颗粒, 逐渐发育形成着色清晰的球状大油体。种子成熟干燥后, 油体间很少发生聚合。在成熟干燥的种子中, 油体集中分布于子叶贮藏细胞中央, 呈椭圆形或不规则形状, 较少为圆形。通过研究种子内油体与含油量的关系, 发现高油品种组与低油品种组之间在单个子叶贮藏细胞内油体数量和截面积之和存在明显差异, 而在高油品种组内或低油品种组内的差异不明显。结果显示, 油菜种子细胞中油体的数量和总面积与含油量之间存在正相关, 可作为高油分材料的选择依据。     

Ultrastructural and biochemical investigations of protein mobilization of Mucuna pruriens (L.) DC. cotyledons and embryo axis

The mobilization of storage reserves, with particular emphasis on storage proteins of Mucuna pruriens (L.) DC., cotyledons, and embryo was investigated from the ultrastructural and biochemical points of view. Proteins and starch were the two main storage substances in cotyledons, and proteins and lipids were the main ones in the embryo. Embryo protein bodies were smaller and fewer in number than those of cotyledons. Structural and ultrastructural data determined between 24 and 48 h after imbibition and between 48 and 72 h after imbibition, the end of significant embryo and cotyledon protein mobilization, respectively, indicating more precocious storage protein mobilization in the axis than cotyledons. Moreover, storage protein mobilization in embryo and cotyledons occurred before the end of germination. Water soluble proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis, producing 29 bands with molecular weights from 14 to 90 KDa. Embryo extract contained more proteins than cotyledon extract, contained seven characteristic bands, and showed a higher variability of the optical density trend than cotyledon.     

Histocytological changes and reserve accumulation during somatic embryogenesis in Eucalyptus globulus

We recently described a protocol for Eucalyptus globulus somatic embryogenesis (SE). For its immediate use at industrial levels, some stages of the process require better control. In particular, SE germination rates are variable, decreasing SE efficacy. As reserves may play a central role in embryogenic processes, we followed histocytological changes and reserve fluctuations, during SE. For SE induction, explants of mature zygotic embryos were grown on Murashige and Skoog (MS) medium with 3 mg l⁻¹ α-naphthalene acetic acid and later transferred to MS without growth regulators (MS_WH). Samples of zygotic embryo cotyledons (explants), of globular and dicotyledonar somatic embryos, and of embling leaves were analysed for reserve accumulation and histocytological profiles. Cotyledon cells of zygotic embryos were rich in lipid and protein bodies, having almost no starch. After 3 weeks of induction, starch grain density increased in differentiated mesophyll regions, while in meristematic regions their occurrence was diffuse. In globular somatic embryos, starch accumulation increased with time (in amyloplasts), but protein bodies were absent. Cotyledonary somatic embryos had lower density of starch grains and absence of lipid and protein bodies. Embling leaves showed typical histological organisation. This is the first comprehensive study on histological and cytological changes during Eucalyptus SE with emphasis in reserve accumulation. With this work we demonstrate that the presently available SE protocol for E. globulus leads to reserve fluctuations during the process. Moreover, the reserves of somatic embryo cotyledons differ from those of their zygotic embryo counterparts, which reinforce the importance of reserves in the embryogenic process and suggests that manipulating external conditions, SE may be optimised giving suitable emblings production for industrial purposes.     

Precociously germinating rapeseed embryos retain characteristics of embryogeny

We compared the germination of Brassica napus L. embryos at three stages of development-mid-cotyledon, maturation and mature dry-to determine at which stage they acquired the capacity for normal germination and seedling development. Embryos were removed from the seed and cultured on hormone-free medium, allowing them to germinate. The transition from embryogeny to germination was monitored both morphologically and biochemically, using synthesis of 12 S storage protein as a marker of embryogeny. The mature embryos (dry seeds) set the standard for normal seedling development: radicle emergence, hypocotyl extension and cotyledon expansion occurred within 2 d and true leaves were formed within a week of germination. Rocket immunoelectrophoresis indicated that the storage proteins in seedlings from mature dry embryos were completely degraded within a week. In contrast, the midcotyledon-stage embryos appeared to germinate abnormally, retaining many embryonic characteristics. Although the roots emerged, the hypocotyls did not elongate and secondary cotyledons instead of leaves were formed at the shoot apex. Also, the seedlings continued to synthesize and accumulate storage proteins. The maturation-stage embryos did develop into normal-looking seedlings, but complete degradation of storage proteins required several weeks, presumably reflecting continued synthesis and turnover. We conclude that embryogenic and germination-specific processes can occur concurrently and that the capacity to develop as normal seedlings is acquired gradually during the maturation process.Abbreviations dpa days post anthesis - EDTA ethylenedi-aminetetraacetic acid - FW fresh weight     

Histodifferentiation of somatic embryos in cotyledons of pineapple guava (Feijoa sellowiana Berg)

Summary Somatic embryos of pineapple guava (Feijoa sellowiana Berg, Myrtaceae) were induced particularly well from the adaxial face of the cotyledons of zygotic embryos cultured on MS medium containing 1.0 mg/l 2,4-D and 0.3 M sucrose. Somatic embryos were never obtained from globular and heart-shaped zygotic embryos and embryos at the torpedo stage produced somatic embryos at lower frequencies than mature zygotic embryos. At the time of explantation, cotyledonary cells were rich in storage proteins and lipids but no starch was found. After the first 5 days of culture most of the reserves had been mobilized in cotyledons of germinating embryos, but were still present in large amounts in cotyledons undergoing embryogenie induction. In contrast to cotyledons following the normal pattern of development, cells of embryogenically-induced cotyledons accumulated starch, especially those cells not involved in the embryogenie process. Two patterns of somatic embryo differentiation were observed: (1) from single epidermal cells or (2) from groups of meristematic cells near the adaxial surface. Comparative observations on cotyledons from germinating embryos and those undergoing embryogenesis suggest that the meristematic layer arises as the result of successive divisions of cells that, under normal conditions, would form the palisade parenchyma. These were the only mesophyll cells that showed mitotic divisions during the normal development.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - FAA formalin/acetic acid/ethyl alcohol - PAS periodic acid-Schiff     

Fertilization and Embryo Development of Populus lasiocarpa Oliv

The double fertilization and embryo development of P. lasiocarpa were studied using cytochemical method for DNA, RNA, polysaccharides and proteins. Stigmas were covered by secretion stained positively with PAS and mercuric bromphenol blue at receptive stage. The pollen grains germinated on the stigma in large quantities 6 hours after pollination. Fertilization started at the 6th days after pollination. The sperm nucleus fused with the secondary nucleus faster than the sperm nucleus with the egg nucleus. The syngamy belonged to peremitotic type. A great deal of starch grains in the embryo sac disappeared during fertilization. The endosperm was nuclear type and becomed a cel 31 days after pollination. The endosperm was characterized by a dense cytoplasm rich in protein. No discrete starch grains were observed in endosperm. Afterwards, the endosperm was consumed by the developing embryo, thus the mature seeds were non-endospermous. The zygote was dormant for 6–8 days. During the dormency, many striking changes took place, and then, the zygotes showed more pronounced polarity. These changes included the shinkage of the large vacuole, the reduced size, the reappearance of large vacuole, the enlarging of the size. The embryogenesis conformed to the Solanad type. The ovules matured into seeds successively 44 days after pollination. The mature embryo was straight. Two cotyledons folded each other.