Metabolism of kinetin by soybean callus

Soybean callus metabolised applied 6-furfurylamino (8^-14C) purine very rapidly to polar compounds, some of which were retained on a Dowex 50 cation exchange resin, and were unaffected by alkaline phosphatase; while others were apparently phosphorylated and were detected in the aqueous fraction. Adenine was detected as an intermediate and it can be concluded that it was formed as a result of the rapid and efficient removal of the furfuryl side chain. The formed adenine was rapidly incorporated into the polar metabolites. Exactly how the presence of this cytokinin stimulates cell division is not apparent from the results.The financial support of the C.S.I.R., Pretoria, and The Natal University Development Fund is gratefully acknowledged.     

利用多组学手段解析番茄育种过程中代谢物变化的机制

番茄(Solanum lycopersicum)在育种过程中经历了驯化、改良、分化和渐渗等不同阶段, 在这一选择过程中番茄的果重和风味等均发生了显著改变, 但是目前对于番茄育种过程中代谢物的变化及其遗传基础却不是十分清楚。近期, 中国农业科学院深圳农业基因组研究所黄三文研究组与华中农业大学罗杰研究组利用多组学(变异组、转录组及代谢组)手段系统解析了番茄育种过程中代谢物的变化。结果表明, 在番茄驯化过程中有46个甾醇糖基生物碱类物质(SGAs)含量逐渐降低, 并获得了7个与其中44个物质显著相关的遗传位点。因此, 在番茄育种过程中通过优异等位位点的组合可以显著降低SGAs的含量; 同时发现在番茄以果重为目标的选择过程中, 控制果重基因周围其它基因的“搭车效应”是引起许多代谢物变化的重要遗传因素, 及在育种过程中对某一性状的选择会对其它性状产生重要影响。该研究首次利用多组学手段系统解析了选择对作物代谢物的影响, 为番茄品质改良奠定了良好的理论基础。     

Biological activity of 6-(2,3,4-trihydroxy-3-methylbutylamino)purine, an oxidation product of zeatin

6-(2,3,4-Trihydroxy-3-methylbutylamino)purine was identified as an oxidation product of cis -zeatin and is biologically as active as the parent compound. A comparison of trans -zeatin, cis -zeatin and (±)-dihydrozeatin indicated that trans -zeatin and (±)-dihydrozeatin were more active in the soybean callus bioassay than cis -zeatin. Both the trans - and cis -isomers of zeatin did, however, give an optimum response at 10^-5 M. Dihydrozeatin was more active at concentrations of 10^-6 and 10^-5 M than trans -zeatin. The significance of the formation of 6-(2,3,4-trihydroxy-3-methylbutylamino)purine with respect to stereochemistry and the oxidation of cytokinins with an unsaturated isopentenyl side chain is discussed.     

Plant regeneration from cotyledonary tissue of Glycine canescens,a perennial wild relative of soybean

Cotyledonary tissue from immature embryos of Glycine canescens was induced to callus and then form embryo-like structures. These structures could be cultured into whole plants and grown in soil.     

Metabolism of [14C]trans-zeatin and [14C]benzyladenine by letached yellow, green and variegated leaves of Schefflera

[8-¹⁴C]Benzyladenine (BA) and [8-¹⁴C] trans-zeatin (tZ) were fed through the petiole to mature, detached green, yellow and variegated leaves of Schefflera arboricola. Recovery of radioactivity from the plant material ranged between 4.2 and 22.1%. More radioactivity was recovered when tZ was applied compared to BA. Green leaves or the green parts of variegated leaves yielded more radioactivity than the yellow leaf material. BA was metabolized much faster than the endogenous cytokinin tZ. It would appear that while lower amounts of radioactivity were present in yellow leaves, as well as in yellow parts of variegated leaves, the rate of cytokinin metabolism was nevertheless faster. Metabolites that were formed to a greater extent in these yellow parts were the nucleotides of both cytokinins. Currently it is not known whether or not cytokinins influence chlorophyll and other pigment development in chimeric variegated leaves.     

抗生素对大豆愈伤组织的诱导和生长的影响

用红霉素、头孢唑唑钠、头孢拉定、头孢霉素（国产和进口）等5种抗生素对农杆菌LBA4404进行抑菌试验,以头孢霉素的抑菌效果最好。头孢霉素作为抑菌剂用大于豆遗传转化试验时,在下胚轴浓度以300mg/L,在子叶节以500mg/L。大豆品种对卡那霉素的反应在出愈率上表现相似,在褐化率上表现有些不同。大豆不同外植体对卡那霉素的反应存在较大差异,以真叶反应最敏感,下胚轴反应最迟钝。在以卡那霉素作为抗性选择标记时,选择压力真叶和子叶节以50－100mg/L为好,下胚轴以100－200mg/L为宜。     

Metabolism of cholesterol by callus culture of Holarrhena antidysenterica

A chemically defined medium was established for the growth of tissue cultures of Holarrhena antidysenterica. Administration of cholesterol-[4-¹⁴C] to 10-day-old callus yielded radioactive 24-methylenecholesterol, 28-isofucosterol, sitosterol, stigmasterol, and conessine, thereby indicating that the conversion of cholesterol into sitosterol is mediated through 24-methylenecholesterol and 28-isofucosterol in this system.     

Comparison of photomixotrophic and heterotrophic callus and suspension cultures of Pinus elliottii. 1. Photosynthetic properties and ultrastructural evidence for coexistence of starch granules and secondary metabolites

Photomixotrophic callus and suspension cultures of salsh pine (Pinus elliottii var. elliottii Engelm.) have been established. Callus tissues contained up to 2.76 g chlorophyll mg^-1 dry wt and suspensions 2.98 g chlorophyll mg^-1 dry wt. Maximum photosynthetic oxygen evolution was 25–32 mol O₂ h^-1 mg^-1 chlorophyll for callus and 35–39 mol O₂h^-1 mg^-1 chlorophyll for suspension, respectively. Photomixotrophic callus was friable with a high moisture content during early and exponential growth, but evolved into a compact and dense tissue during the latter stage of growth. Compact photomixotrophic callus accumulated and deposited secondary metabolites in the central vacuole and developed large starch granules in the chloroplasts. Secondary metabolites were not observed in photomixotrophic suspensions or in heterotrophic calli and suspensions. Photomixotrophic callus contained numerous mitochondria closely associated with well-developed chloroplasts containing 2–6 thylakoids per granum. Heterotrophic callus was characterized by a poorly developed cytoplasm and cup-shaped mitochondria.     

The biological activity of cytokinin derivatives in the soybean callus bioassay

The effect of 28 natural and synthetic cytokinins, including cytokinin nucleotides, the growth of soybean cotyledonary callus was investigated. Generally the nucleosides and nucleotides gave a slightly better response than their respective free bases. The differences in response were, however, not significant and there is a distinct possibility that rapid interconversions between these three types of cytokinin occur within the tissue. The O-glucosides of Z and ZR were the most active. Glucosylation in the 3, 7 and 9 positions reduced activity. In the case of BA-derivatives the order of activity of the N-glucosides was 3G > 9G > 7G. Since iso-pentenyl derivatives had little activity they may be very difficult to detect using the soybean callus bioassay.Abbreviations Z zeatin - DHZ dihydrozeatin - IP iso-pentenyladenine - BA benzyladenine - K Kinetin - R riboside - MP monophosphate - OG 0-glucoside - 3G 3-glucoside - 7G 7-glucoside - 9G 9-glucoside - GC-MS gas chromatography—mass spectrometry     

番茄子叶愈伤组织直接分化成花及果实

番茄（品种‘小番茄’）的子叶经一定条件诱导产生愈伤组织,随后在愈伤组织上直接产生花蕾,并可以开花结果。结果显示离体培养中的IBA在其成花诱导中起关键作用。IBA可能是番茄成花基因的启动信号。     

NADP-linked malic enzyme and malate metabolism in ageing tomato fruit

Malate dehydrogenase (oxaloacetate-decarboxylating) (NADP⁺) EC 1.1.1.40, malic enzyme, has been purified 40-fold to a homogeneous state using affinity chromatography and gel permeation chromatography. The M_r is 260–265 K with four subunits each of 64–65 K. The enzyme has some competitive or non-competitive inhibitors, particularly some of the Krebs cycle acids and exhibits a rapid rise in activity at the same time as activity of the enzymes of the Krebs cycle are decreasing in the tomato mitochrondrion. The malic enzyme is restricted to the cytosol. The relevance of this information to malate metabolism in plants is discussed.     

Infection of tomato roots using callii of broomrape

Parasitic weeds like members of the genera Orobanche and Striga cause heavy damage to grain, vegetables and other field crops. The germinating seedlings of the parasites attack the roots of their hosts, following a series of recognition events that control germination, seedling growth and attachment to the host root. An in vitro system has been developed that allows the production of partially differentiated callii of Orobanche aegyptiaca Pers. Protrusions of subcultures of these callii behaved like radicles of germinating seeds. Using this system normal infection of tomato roots was obtained in vitro. The infection process included haustorium formation and the development of young Orobanche plants under aseptic conditions. The system developed should now permit a study of biochemical events during infection of the host by Orobanche .     

Cytopathology of soybean tissue culture cells infected with southern bean mosaic virus

Summary Virus distribution patterns and ultrastructural changes in soybean callus cells after infection with the type, or bean strain, of southern bean mosaic virus (SBMV) were observed. Calli grown in liquid Linsmaier and Skoog (LS) medium were inoculated with SBMV and incubated in fresh LS medium. Calli were sampled at 5, 10, 15, and 20 d after inoculation and examined by transmission electron microscopy. Five days after inoculation, viruslike particles (VLP) measuring 22 to 27 nm in d were observed in the cytoplasm. The particles formed loose aggregates with some tendency to associate in regular patterns. By the 10th d after infection, particles were observed in the vacuoles in similar loose arrangements. Viruslike particles were readily identified in vacuoles because of the absence of ribosomes. Crystalline aggregations of VLP were found from Day 10 to Day 20 in the cytoplasm only. Five days after inoculation particles similar to the VLP observed in the cytoplasm also were present in nuclei. Other cytopathic effects were noted, particularly several types of inclusion bodies. These observations differ considerably from reports of the type strain in intact bean plant tissues in the frequent occurrence of VLP in vacuoles and virus crystals in cytoplasm of soybean callus infected with the same strain of virus. Michigan Agricultural Experiment Station Journal Article Number 10020. We thank Dr. Karen Baker for useful suggestions.     

Glucose metabolism and hexosamine pathway regulate oncogene-induced senescence

Oncogenic stress-induced senescence (OIS) prevents the ability of oncogenic signals to induce tumorigenesis. It is now largely admitted that the mitogenic effect of oncogenes requires metabolic adaptations to respond to new energetic and bio constituent needs. Yet, whether glucose metabolism affects OIS response is largely unknown. This is largely because of the fact that most of the OIS cellular models are cultivated in glucose excess. In this study, we used human epithelial cells, cultivated without glucose excess, to study alteration and functional role of glucose metabolism during OIS. We report a slowdown of glucose uptake and metabolism during OIS. Increasing glucose metabolism by expressing hexokinase2 (HK2), which converts glucose to glucose-6-phosphate (G6P), favors escape from OIS. Inversely, expressing a G6P, pharmacological inhibition of HK2, or adding nonmetabolizable glucose induced a premature senescence. Manipulations of various metabolites covering G6P downstream pathways (hexosamine, glycolysis, and pentose phosphate pathways) suggest an unexpected role of the hexosamine pathway in controlling OIS. Altogether, our results show that decreased glucose metabolism occurs during and participates to OIS.     

Quinones as plant growth regulators

The effects of benzoquinone, naphthaquinone and anthraquinone on the growth of tomato callus, whole plants of tomato and on rooting of mungbean cuttings were studied. Naphthaquinone effects on some oxidases and on the isozyme patterns of peroxidases in all the three systems were also observed. Quinones increased callus growth, the number of roots initiated in mungbean cuttings and the growth of tomato plants, significant increases being obtained with 10^–5M naphthaquinone. Naththaquinone also decreased the activities of IAA oxidase, ascorbic acid oxidase and polyphenol oxidase, and led to the disappearance of one of the isozyme of peroxidase in all systems.     

烟草愈伤组织生长和衰老期间呼吸代谢的改变

前人(Ross和Thorpe 1973,Thorpe和Laishley 1973,Brown和Thorpe 1982)曾报道了烟草愈伤组织芽形成期间呼吸速率、线粒体活性、底物代谢途径和有关呼吸酶活性的变化。我们对烟草愈伤组织呼吸代谢的研究证明:组织分化和芽原基的形成与HMP途径运行升高相联系(毕玉蓉和梁厚果1987);愈伤组织的呼吸链存