党参的体细胞胚发生及不同发育阶段几种同工酶的分析

以党参为材料,在附加0.1 mg·L-1 2,4-D、0.3 mg·L-1 6-BA和3%蔗糖的MS培养基上获得大量发育良好的体细胞胚. 附加6-BA可以使胚性愈伤组织进行芽的分化,而添加0.1%活性炭后仅有根的分化.利用梯度凝胶电泳进行同工酶的研究表明在胚性愈伤组织和体细胞胚之间,酶谱差异比较大;而在不同发育时期的体细胞胚之间,差异较小.并讨论了同工酶酶谱和酶活性变化与体细胞胚发生、发育的关系.     

Pigmented Soybean (Glycine max) Seed Coats Accumulate Proanthocyanidins during Development

The dominant I gene inhibits accumulation of anthocyanin pigments in the epidermal layer of soybean (Glycine max) seed coats. Seed-coat color is also influenced by the R locus and by the pubescence color alleles (T, tawny; t, gray). Protein and RNA from cultivars with black (i,R,T) and brown (i,r,T) seed coats are difficult to extract. To determine the nature of the interfering plant products, we examined seed-coat extracts from Clark isogenic lines for flavonoids, anthocyanins, and possible proanthocyanidins by thin-layer chromatography. We show that yellow seed-coat varieties (I) do not accumulate anthocyanins (anthocyanidin glycosides) or proanthocyanidins (polymeric anthocyanidins). Mature, black (i,R,T) and imperfect-black (i,R,t) seed coats contained anthocyanins, whereas mature, brown (i,r,T) and buff (i,r,t) seed coats did not contain anthocyanins. In contrast, all colored (i) genotypes tested positive for the presence of proanthocyanidins by butanol/ HCl and 0.5% vanillin assays. Immature, black (i,R,T) and brown (i,r,T) seed coats contained significant amounts of procyanidin, a 3[prime],4[prime]-hydroxylated proanthocyanidin. Immature, black (i,R,T) or brown (i,r,T) seed-coat extracts also tested positive for the ability to precipitate proteins in a radial diffusion assay and to bind RNA in vitro. Imperfect-black (i,R,t) or buff (i,r,t) seed coats contained lesser amounts of propelargonidin, a 4[prime]-hydroxylated proanthocyanidin. Seed-coat extracts from these genotypes did not have the ability to precipitate protein or bind to RNA. In summary, the dominant I gene controls inhibition of not only anthocyanins but also proanthocyanidins in soybean seed coats. In homozygous recessive i genotypes, the T-t gene pair determines the types of proanthocyanidins present, which is consistent with the hypothesis that the T locus encodes a microsomal 3[prime]-flavonoid hydroxylase.     

Seed and Embryo Germination in Syringa vulgaris and S. reflexa as Affected by Temperature during Seed Development

A nitrogen source was needed for the flowering of Lemna gibba L., a long-day plant, and L. perpusilla Torr., a shortday plant. The level of endogenous amino acids analyzed by an Amino Acid Analyzer, rose during the first few inductive cycles, but was reduced during later stages of the flowering process. Serine and threonine levels increased during the light period and decreased during the dark period in L. perpusilla. Exogenous serine and threonine added to the culture medium at 10^?6M increased the rate of flowering by more than 35% over the controls. Cysteine inhibited flowering, while other amino acids had little or no promotive effect on flowering. Serine and threonine increased flowering rate in L. perpusilla only when added during a dark period of the inductive cycle. The addition of amino acids during a light period not followed by a dark period had no effect on flowering.     

P Nutrition during Seed Development : Leaf Senescence, Pod Retention, and Seed Weight of Soybean

Soybean (Glycine max [L.] Merrill) leaf senescence, which may partially result from mineral redistribution, appears to limit grain yield. Two experiments were designed to test the effects of supplemental inorganic phosphate (Pi), K, malate, and methionine (Met) infusions on senescence and yield. A novel stem infusion technique using pediatric intravenous kits was developed to supply these nutrients throughout seed growth. An average of 48.4 milliliters per plant was successfully infused into lower stem internodes during a 4 to 6 week period. Senescence was unaffected by K or malate infusions, but was delayed by Pi infusions (up to 8 days) and by increased nutrient solution Pi levels (up to 21 days) in separate experiments. Treatments which delayed senescence also improved yield as much as 3-fold, due primarily to increased pod retention and secondarily to increased seed size. Met infusions further increased pod retention at the lower, infused nodes, and thus increased total plant yield also. The influence of higher Pi levels during reproductive growth on soybean pod retention and yield may have been the result of sustained sucrose export due to altered C partitioning in leaves. The role of Met in improving yield was not clear. However, these results clearly demonstrate the importance of adequate Pi for delaying senescence and improving pod retention and yield.     

Preferential Loss of an Abundant Storage Protein from Soybean Pods during Seed Development

A temporary vegetative storage protein, composed of similar 25 kilodalton and 27 kilodalton subunits, was found to be abundant in soybean (Glycine max (L.) Herr. var Hobbit) leaves, stems, pods, flower petals, germinated cotyledons, and less abundant in roots, nodules and seeds. Total pod protein was highest at 3 weeks after flowering and declined by 37% within 3 weeks during seed development. During this time the vegetative storage protein declined from 18% to 1.5% of the total pod protein and accounted for 45% of the protein lost from pods. This indicates that the vegetative storage protein makes a significant contribution to the pool of nutrients mobilized from pods for transport to developing seeds.     

濒危植物百山祖冷杉种子发育特征及其胚培养

百山祖冷杉(Abies beshanzuensis)种子萌发率低,发育特性尚不明确,极大地限制了种群在原生境的自然更新。该研究以百山祖冷杉不同发育时期的雌球果为材料,通过研究球果中种子的胚与胚乳数量、重量和显微结构特性,及测定种子发育关键时期胚乳的初生代谢物,探究种子发育特征及影响种子发育的主要因素。结果表明,7月是百...     

Newly Synthesized mRNA Is Translated during the Initial Imbibition Phase of Germinating Maize Embryo

RNA synthesis is activated in the cells of the plant embryo very soon after the start of seed imbibition. We previously reported that mainly heterogeneous nuclear RNA is synthesized in the radicle of Zea mays embryo during the first hours of germination. The present study was undertaken in order to detect the time of appearance of the newly synthesized messenger RNA in the polysomes of germinating maize axes.

Free polysomes were prepared from embryonic axes rehydrated for 2 hours in the presence of radioactively labeled uridine. These polysomes were shown to be labeled and to contain labeled particles sedimenting, after dissociation with EDTA, in the 10S to 40S region of a sucrose gradient. The labeled polysomal RNA migrates heterogeneously in a gel with a mean size corresponding to about 16S, and 60% of these molecules are polyadenylated.

The data indicate that the newly synthesized RNA associated with the polysomes after 2 h of germination consists of messenger RNA molecules. Analysis of the polysomes prepared 0.5 and 1 h after the start of imbibition suggests that translation of the newly synthesized messenger RNA probably occurs within the 1st hour of imbibition of the isolated axis, thus well before the completion of the initial water uptake.

     

Soybean Seed Protein Genes Are Regulated Spatially during Embryogenesis

We used in situ hybridization to investigate Kunitz trypsin inhibitor gene expression programs at the cell level in soybean embryos and in transformed tobacco seeds. The major Kunitz trypsin inhibitor mRNA, designated as KTi3, is first detectable in a specific globular stage embryo region, and then becomes localized within the axis of heart, cotyledon, and maturation stage embryos. By contrast, a related Kunitz trypsin inhibitor mRNA class, designated as KTi1/2, is not detectable during early embryogenesis. Nor is the KTi1/2 mRNA detectable in the axis at later developmental stages. Outer perimeter cells of each cotyledon accumulate both KTi1/2 and KTi3 mRNAs early in maturation. These mRNAs accumulate progressively from the outside to inside of each cotyledon in a "wave-like" pattern as embryogenesis proceeds. A similar KTi3 mRNA localization pattern is observed in soybean somatic embryos and in transformed tobacco seeds. An unrelated mRNA, encoding [beta]-conglycinin storage protein, also accumulates in a wave-like pattern during soybean embryogenesis. Our results indicate that cell-specific differences in seed protein gene expression programs are established early in development, and that seed protein mRNAs accumulate in a precise cellular pattern during seed maturation. We also show that seed protein gene expression patterns are conserved at the cell level in embryos of distantly related plants, and that these patterns are established in the absence of non-embryonic tissues.     

Biochemical Studies during the Development of the Chick Embryo

The presence and the change of deoxyribosidic compounds in the acid extract of the embryo with the incubation were examined with an aid of the organism, L. leichmannii. The main deoxyribosidic compounds in the extract prepared from the 18 th day embryo were identified as uracil, cytosine and thymine deoxyribosides and deoxyribotides of cytosine and thymine from the behaviour on paper chromatographic and paper electrophoretic separation. A small amount of purine deoxyribosyl compound which was assumed as hypoxanthine deoxyriboside was detected, and the content of which per 1 g of fresh embryo changed with the lapse of the incubated day; especially, the content was minimum at the period from the 10 th to 15 th day incubation. At this period, the total growth promoting compounds contained 50% of deoxyribotide though deoxyribosides was lower than that of the other days. This period is the most significant stage of the embryo growth and the most active time of synthesis of DNA through the embryo growth.     

Biochemical Studies during the Development of the Chick Embryo

The devised method consists of the enzymatic hydrolysis, separation of deoxyribosides in the hydrolysate by paper chromatography and paper electrophoresis, and the estimation of the separated fractions with L. leichmannii. This method permits the determination of deoxyriboside composition of the smaller amounts of DNA or the related compounds with relatively higher accuracy even under the presence of some other compounds when nucleic acids and acid insoluble fractions of the chick embryo were analyzed.

The change of each deoxyriboside composition in acid insoluble fraction prepared from the 3 to 19 day old embryos investigated by the method. Among the major four deoxyribosides, the contents of deoxyguanosine and of deoxycytidine was nearly constant during the development of the embryo, whereas that of thymidine and of deoxyadenosine appeared to undergo the change slightly at the periods from 10 to 15 days incubation. It seems that this periods is also the most active time of the synthesis of DNA and of the changes of deoxyribosyl compounds in acid soluble fraction through the embryo growth.     

Proteins of Soybean Seeds: II. Accumulation of the Major Protein Components during Seed Development and Maturation

Fresh weight and dry weight as well as quantitative and qualitative protein changes in the developing soybean (Glycine max) seed were described from 12 days after flowering until maturity. The seed proteins were separated on sucrose density gradients into three major fractions, having average sedimentation coefficients of 2.2S, 7.5S, and 11.8S. The 2.2S sedimenting proteins predominated at very early stages of development (12 days after flowering) and decreased proportionately throughout maturation. The 7.5S and 11.8S components appeared to be synthesized later in maturity and in larger amounts than the 2.2S proteins. Electrophoretic studies on extracts from whole seeds and on isolated protein fractions confirmed the early abundance of proteins in the 2.2S fraction and revealed temporal differences in the accumulation of three components of the 7.5S fraction. The 11.8S sedimenting fraction appeared throughout seed development as a homogeneous protein which accumulated in the seed with a time course similar to that of the total 7.5S protein fraction.     

Early Development of the Seed Coat of Soybean (Glycine max)

Although the development of the soybean ovule has been fairlywell studied, knowledge of the sequence of events in the seedcoat during the first 3 weeks after flowering is incomplete.The goal of the present study was to document, using light microscopy,the early development of the soybean seed coat with respectto changes in structure and histochemistry. At anthesis, theseed coat consists of an outer layer of cuboidal epidermal cellssurrounding several layers of undifferentiated parenchyma (whichtogether constitute the outer integument), and an inner layerof cuboidal endothelial cells (the inner integument). At 3 dpost anthesis (dpa), the inner integument has expanded to includethree to five layers of relatively large cells with thick, heavily-stainingcell walls immediately adjacent to the endothelium. By 18 dpa,the outer integument has developed into a complex of tissuescomprised of an inner layer of thick-walled parenchyma, an outerlayer of thin-walled parenchyma containing vascular tissue whichhas grown down from the lateral vascular bundles in the hilumregion, a hypodermis of hourglass cells, and palisade layer(epidermis). The thick-walled parenchyma of the inner integumenthas become completely stretched and compressed, leaving a single,deeply staining wall layer directly above the endothelium. At21 dpa, the outermost cells of the endosperm have begun to compressthe endothelium. At 45 dpa (physiological maturity) the seedcoat retains only the palisade layer, hourglass cells, and afew layers of thin-walled parenchyma. The innermost layer ofthe endosperm, the aleurone layer, adheres to the inside ofthe seed coat. This knowledge will be invaluable in future studiesof manipulation of gene expression in the seed coat to modifyseed or seed coat characteristics. Copyright 1999 Annals ofBotany Company Soybean, Glycine max, seed coat, development, aleurone.     

Control of Lipid Synthesis during Soybean Seed Development: Enzymic and Immunochemical Assay of Acyl Carrier Protein

During soybean seed (Glycine max, var Am Soy 71) development, the rate of lipid biosynthesis per seed increases greatly. As the seed reaches maturity, lipid synthesis declines. To study the controls over the oil synthesis and storage process, we have chosen acyl carrier protein (ACP) as a representative marker for the fatty acid synthetase pathway. We have quantitated soybean ACP levels by both enzymic and immunochemical methods. Escherichia coli acyl-ACP synthetase was used as an assay for enzymically active ACP. Total ACP protein was determined by immunoassay using antibodies prepared in rabbits against spinach ACP. These antibody preparations also bind ACP isolated from soybeans, allowing development of a radioimmunoassay based on competition with [³H]palmitoyl-ACP. The enzymic and immunochemical measurement of ACP at various stages of seed development have indicated that ACP activity and ACP antigen increase markedly in correlation with the in vivo increase in lipid synthesis. These results indicate that a major control over the increase in lipid synthesis arises through regulation of the levels of the fatty acid biosynthetic proteins. However, as the seed reaches maturity and lipid biosynthesis declines, ACP per seed remains relatively high. In the mature seed, we found that more than 95% of the ACP is localized in the cotyledons, less than 5% is in the axis, and less than 1% is in the seed coat.     

Role of Phytohormones in Soybean (Glycine max) Seed Development

Russian Journal of Plant Physiology - Phytohormones play a key important role in the sink development of the seed. Endogenous content of IAA, PAA, GA, ABA, and kinetin were estimated in two...     

Raman Spectroscopic Imaging of the Whole Ciona intestinalis Embryo during Development

Intracellular composition and the distribution of bio-molecules play central roles in the specification of cell fates and morphogenesis during embryogenesis. Consequently, investigation of changes in the expression and distribution of bio-molecules, especially mRNAs and proteins, is an important challenge in developmental biology. Raman spectroscopic imaging, a non-invasive and label-free technique, allows simultaneous imaging of the intracellular composition and distribution of multiple bio-molecules. In this study, we explored the application of Raman spectroscopic imaging in the whole Ciona intestinalis embryo during development. Analysis of Raman spectra scattered from C. intestinalis embryos revealed a number of localized patterns of high Raman intensity within the embryo. Based on the observed distribution of bio-molecules, we succeeded in identifying the location and structure of differentiated muscle and endoderm within the whole embryo, up to the tailbud stage, in a label-free manner. Furthermore, during cell differentiation, we detected significant differences in cell state between muscle/endoderm daughter cells and daughter cells with other fates that had divided from the same mother cells; this was achieved by focusing on the Raman intensity of single Raman bands at 1002 or 1526 cm⁻¹, respectively. This study reports the first application of Raman spectroscopic imaging to the study of identifying and characterizing differentiating tissues in a whole chordate embryo. Our results suggest that Raman spectroscopic imaging is a feasible label-free technique for investigating the developmental process of the whole embryo of C. intestinalis.