The characteristics of light in floral induction in vitro of Cichorium intybus. The possible role of phytochrome

The action of light in the initiation of floral buds in vitro has been studied using monochromatic light qualities on root explants of a long day plant, Cichorium intybus L. cv. Witloof. Red light (660 nm, 0.30 W m^-2) promotes flowering, while far-red (730 nm, 0.31 W m^-2) and irradiation with combined red + far-red (0.20 + 0.41 W m^-2) have no effect. In short day conditions floral response can be obtained in two ways: 1) by interrupting the dark period with 5 brief irradiations of red light (0.45 W m^-2, 12 min) at regular intervals, although these are counteracted by far-red irradiations of equal intensity and duration; 2) by interrupting the long night with 5 h red light applied during the second third of the night, while at the beginning or at the end it is ineffective. Red light efficiency appears to depend on the photosynthetic activity of the tissues, so that flowering increases with increasing intensity of white light and is suppressed if no white light is supplied. The reproductive development is determined by the coordination of proper irradiation conditions with sufficient sensitivity of the perceiving meristematic cells. The period of highest sensitivity to environmental light conditions in the life cycle of a Cichorium root explant occurs between the 8th and the 16th day after the start of the culture. The data strongly suggest that phytochrome is involved in flower induction of Cichorium in vitro.     

Immunochemical detection with rabbit polyclonal and mouse monoclonal antibodies of different pools of phytochrome from etiolated and green Avena shoots

While two monoclonal antibodies directed to phytochrome from etiolated oat (Avena sativa L.) shoots can precipitate up to about 30% of the photoreversible phytochrome isolated from green oat shoots, most precipitate little or none at all. These results are consistent with a report by J.G. Tokuhisa and P.H. Quail (1983, Plant Physiol. 72, Suppl., 85), according to which polyclonal rabbit antibodies directed to phytochrome from etiolated oat shoots bind only a small fraction of the phytochrome obtained from green oat shoots. The immunoprecipitation data reported here indicate that essentially all phytochrome isolated from green oat shoots is distinct from that obtained from etiolated oat shoots. The data indicate further that phytochrome from green oat shoots might itself be composed of two or more immunochemically distinct populations, each of which is distinct from phytochrome from etiolated shoots. Phytochrome isolated from light-grown, but norflurazon-bleached oat shoots is like that isolated from green oat shoots. When light-grown, green oat seedlings are kept in darkness for 48 h, however, much, if not all, of the phytochrome that reaccumulates is like that from etiolated oat shoots. Neither modification during purification from green oat shoots of phytochrome like that from etiolated oat shoots, nor non-specific interference by substances in extracts of green oat shoots, can explain the inability of antibodies to recognize phytochrome isolated from green oat shoots. Immunopurified polyclonal rabbit antibodies to phytochrome from etiolated pea (Pisum sativum L.). shoots precipitate more than 95% of the photoreversible phytochrome obtained from etiolated pea shoots, while no more than 75% of the pigment is precipitated when phytochrome is isolated from green pea shoots. These data indicate in preliminary fashion that an immunochemically unique pool of phytochrome might also be present in extracts of green pea shoots.Abbreviation ELISA enzyme-linked immunosorbent assay - mU milliunit - Pfr far-red-absorbing form of phytochrome - Pr red-absorbing form of phytochrome     

Glutamate synthase in greening callus of Bouvardia ternifolia Schlecht

The distribution of the two glutamate-synthase (GOGAT) activities known to exist in higher plants (NADH dependent, EC 2.6.1.53; and ferredoxin dependent, EC 1.4.7.1) was studied in non-chlorophyllous and chlorophyllous cultured tissue as well as in young leaves of Bouvardia ternifolia. The NADH-GOGAT was present in all three tissues. Using a sucrose gradient we found it in both the soluble and the plastid fraction of non-chlorophyllous and chlorophyllous tissue, but exclusively in the chloroplast fraction of the leaves. Ferredoxin-GOGAT was found only in green tissues and was confined to the chloroplasts. Ferredoxin-GOGAT activity increased in parallel with the chlorophyll content of the callus during the greening process in Murashige-Skoog medium (nitrate and ammonium as the nitrogen sources), while NADH-GOGAT was not affected by the greening process in this medium. Furthermore, both activities were differentially affected by either nitrate or ammonium as the sole nitrogen source in the medium during this process. It is suggested that each GOGAT activity is a different entity or is differently regulated.Abbreviations GOGAT glutamate synthase - MS Murashige-Skoog (1962) medium - PMSF phenylmethylsulfonyl fluoride     

Lipoxygenase Metabolism of Arachidonic Acid in Brain

When blood-free mouse brain slices were incubated with exogenous radiolabeled arachidonic acid, gas chromatography/mass spectrometry confirmed that the major radioactive lipoxygenase enzyme product of arachidonic acid was 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), with lesser amounts of 5-hydroxy-5,6,8,11,14-eicosatetraenoic acid and 15-hydroxy-5,8,11,13-eicosatetraenoic acid. When 12-[2H]HETE was used to measure endogenous 12-HETE in brain tissue frozen with liquid nitrogen, the level of 12-HETE was 41 +/- 6 ng/g of wet weight tissue. This frozen tissue level was not due to the presence of blood. When brain slices were incubated in vitro for 20 min, the 12-HETE level increased to 964 +/- 35 ng/g of wet weight tissue. Elimination of residual intravascular blood before tissue incubation reduced the brain slice 12-HETE concentration by one-half.     

UV-microscopic studies on the vacuolar changes caused by the flavone “aglycone” isovitexin inSilene pratensis plants

Summary UV-microscopic and chromatographic studies have been performed on the variation in contents and configuration of the flavones present in epidermal cells of the petals, stem leaves, rosette leaves and cotyledons ofSilene pratensis plants. Most of the flavone contents is located in the vacuole of the upper epidermis cells, the concentration depending on the light intensity at which the plants were grown. In plants able to glycosylate isovitexin in the petals (genotypegG/. gl/gl fg/fg, accumulating isovitexin 7-O-glucoside) the vacuole is completely filled with the UV absorbing flavone. In plants which are unable to glycosylate isovitexin in their petals (genotypeg/g gl/gl fg/fg, accumulating only isovitexin) the upper epidermal cells of stem leaves and petals contain droplet like structures in their vacuoles. At high light intensities these structures increase in mass and become detectable in the visible light. These denser structures often condense to structures with radiating threads.As compared with the accumulation of isovitexin in upper epidermal cells of stem leaves and petals in genotypeg/g gl/gl fg/fg, the cotyledons and the rosette leaves contain two isovitexin glycosides. In the latter organs the upper epidermal cells are very similar to the upper epidermal cells fromgG/. gl/gl fg/fg plants, having a vacuole filled with UV absorbing material. It appears therefore that isovitexin itself causes the formation of the structurés in the cells. It was shown by varying the light intensity that a relative high concentration of isovitexin is necessary for the droplet like structures to appear. Still higher concentrations are needed for the formation of the structures with radiating threads. It is hypothesized that isovitexin interferes with the energy supply of the cells, which therefore are not able to maintain their turgor.     

Callus initiation and plant regeneration in ragi (Eleusine coracana Gaertn.)

Callus was successfully initiated on root, mesocotyl and leaf base segments of 3- to 4-day-old seedlings of ragi (Eleusine coracana Gaertn.). 2,4-D along with casein hydrolysate for Murashige and Skoog's basal medium was found to be most effective for callus initiation and maintenance. Mesocotyl and leaf base tissue derived calli gave shoot buds in medium in which the 2,4-D concentration was lowered.     

花椰菜(Brassica oleracea var botrytis)下胚轴培养过程中过氧化物酶活性及同工酶谱的变化

花椰菜下胚轴外植体在MS+6BA 5 ppm的培养基上能分化出芽,在MS+2,4-D2ppm的培养基上能脱分化而形成愈伤组织。用3种不同的酚类物质(咖啡酸、阿魏酸、愈创木酚及联苯胺)作氢供体发现分化过程中的过氧化物酶活性高于脱分化过程,其中以咖啡酸作氢供体显示的活性最高,阿魏酸及愈创木酚次之,而联苯胺最小。用聚丙烯酰胺凝胶电泳分离阴极向及阳极向过氧化物酶同工酶,在分化及脱分化培养过程中均不断出现新的酶带,前者有13条,后者为11条,两者的差别主要在阴极向酶带,在分化过程中多了两条酶带(C_1和C_3),同时C_2带活性也比脱分化的高。阳极向酶带也有差别,A_2和A_2两条酶带在分化过程中逐渐加强,但是在脱分化过程中却逐渐消失。反映了两个过程生理上的差别。     

甜茶组织培养研究

甜茶的茎段和实生苗培养在MS基本培养基中,研究植物激素对器官形成的影响,试验结果表明BA0.5-2.0毫克/升明显促进芽的形成和增殖;而对照(基本培养基)无形成芽。细胞分裂素对芽的起动是必需的。BA0.5-2.0毫克/升和GA_s1.0毫克/升配合使用,对茎段形成芽和增殖反而减少,但形成的苗较高和幼叶生长良好。通过继代培养,可繁殖大量小苗,它揭示出同一块外植体生长出许多小植株的可能,将无根苗转入含有IBA0.25-0.50毫克/升的1/2MS培养基中,能诱导生根,发展完整植株。试管苗移植土壤中,获得成功,幼苗生长良好。     

冷冻液温和季节对鼠尾过冷点的影响

为研究动物对寒冷的适应性,将鼠尾置于冷液浸冻,发现在一定条件下鼠尾组织可发生过冷现象。实验表明,鼠尾组织的过冷点和冷冻液温有关,同一季节冷冻液温越低过冷点越高;而不同季节相同冷冻条件下,冬季鼠尾组织的过冷点明显低于春季。 动物肢体组织的过冷特性是动物的抗寒冷特性,它和组织自身的物理化学性质有关。理沦证明,过冷度(△T)和表面张力(O)、摩尔质量(M),冰点(Ti)、密度(p)、摩尔凝固热(△H)及冰胚临界半径(rk)有关,其关系式为△T=26MTi/p△Hrk.     

Phénolamides et induction florale de Cichorium intybus dans différentes conditions de culture en serre ou in vitro

Phenolamides and floral induction of Cichorium intybus in different conditions of culture in glass-room or in vitro. Three complexes between phenols and amines (phenolamides) have been found in Cichorium intybus L., a plant with an absolute requirement of vernalisation followed by long days for flowering. Upon hydrolysis, these complexes (A, B and C) liberate aromatic amines whose exact identification is in progress, but which are closely related to dopamine, tyramine and serotonin, respectively. In a first series of experiments, phenolamides were studied in the buds of plants grown in the greenhouse under varying conditions. Only buds from plants which flower in long days contained large amounts of these compounds. Much smaller amounts were found in buds at the end of vernalisation (at 2–4°C) before long-day treatment as well as in buds kept in the vegetative state after vernalisation by being grown in short days (8 h light) or in total darkness. In a second series of experiments, phenolamides were studied in bud-forming calli induced in vitro on explants of tuberised root. After sixteen days of culture in continuous light, large quantities of phenolamide were found in the buds and calli of the upper part of the explant, while the lower part which never produces buds contained much less. Buds formed under continuous light produce inflorescences in approximately one month. Various other culture conditions make it possible to maintain the explants in the vegetative state. This can be obtained by short-day conditions, or otherwise under continuous illumination by decreasing the sugar or increasing the NAA levels in the medium. After 13 days of culture, the phenolamide levels were much lower under all of these conditions, than under conditions favourable to floral induction. Compound C is absent or present in trace amounts in vegetative buds. The significance of the differences observed between floral and vegetative buds is supported by the sensitivity of the analytical techniques used. The accumulation of phenolamides in tissues of Cichorium intybus appears to be closely linked to floral induction. Under continuous light it begins very early in young buds and even in the calli that bear these buds.