Leucine Aminopeptidase Activity in Tall and Dwarf Cultivars of Rice at Successive Stages of Development

Studies to determine the variations in leucine aminopeptidase(LAP) activity in tall and dwarf cultivars of rice were conductedby horizontal starch gel electrophoresis. The samples were takenat weekly intervals starting with soaked seeds (12 h) untilthe post-panicle stage. There is a distinct pattern of LAP isoenzymesin tall and dwarf cultivars studied. Some isoenzymes appearat a particular developmental stage and others disappear whilesome remain fairly constant once they are formed. A tall cultivar(Hansraj) shows greater fluctuations during the course of developmentthan the dwarf cultivars. These studies throw light on the transitorynature of these enzymes and show apparently differential geneaction.     

Isoenzymes of Japanese-radish Peroxidase

Japanese-radish root contained eighteen isoenzymes of peroxidase distinguishable on polyacrylamide gel electropherograms. The isoenzymes were found to be quite similar to those of horseradish peroxidase, although their quantities were different between two plants. The acidic components were the major isoenzyme in Japanese-radish peroxidase, while the neutral ones were the major one in horseradish. The chromatographic purification of the isoenzymes was performed on CM- and DEAE-Sephadex columns to characterize the components. The components in the preparations purified by the previously reported procedures of Morita et al. were also identified.     

Differential Carbon Monoxide Sensitivity of Cytochrome-Oxidase in the Leaves of Tall and Dwarf Wheat Cultivars

Differential response in the leaves of tall and dwarf wheat to CO, an inhibitor of cytochrome oxidase and to SHAM, an inhibitor of alternative oxidase appears to be correlated with presence of Rht dwarfing genes. This was detected by in vivo nitrate reductase assay after CO treatment and direct O₂ uptake in presence of SHAM. Pretreatment of the leaves with Triton X-100 at a concentration which specifically inhibits the accessibility of exogenous NAD(P)H to alternative oxidase, Significantly enhanced the CO response as assessed by in vivo NR assay. This supports the hypothesis that the competition for NADH between NR and mitochondrial respiration is regulated by NADH-dehydrogenase located on the outer surface of inner mitochondrial membrane.     

Quantitative Analysis of Endogenous Gibberellins in Normal and Dwarf Cultivars of Rice

Endogenous levels of gibberellins in shoots and ears of twodwarf rice (Oryza sativa L.) cultivars, Tan-ginbozu (dx mutant)and Waito-C (dy mutant), were analyzed and compared with thoseof normal rice cultivar, Nihonbare. The endogenous levels of13-hydroxylated gibberellins in Tan-ginbozu were much lowerthan those in Nihonbare. In Waito-C, the levels of GA₁₉ andGA₂₀ in the shoots were higher but that of GA₁ was lower thanthe levels of these gibberellins in Nihonbare. These resultssupport the hypothesis that the dy gene controls the 3ß-hydroxylationof GA₂₀ to GA₁ while the dx gene controls a much earlier stepin the gibberellin biosynthesis. Our results indicate that GA₁is the active gibberellin that regulates the vegetative growthof rice. The endogenous levels of GA₄ in the ears of the twodwarf cultivars of rice were higher than the level of GA₄ inthe ears of the normal cultivar, Nihonbare suggesting that thebiosynthesis of gibberellin is not blocked in the anthers ofthe dwarf rice. (Received April 27, 1989; Accepted July 12, 1989)     

Endogenous Gibberellins in the Vegetative Shoots of Tall and Dwarf Cultivars of Phaseolus vulgaris L.

A series of 13-hydroxygibberellins, gibberellin A₁ (GA₁), GA₁₉,GA₂₀, GA₄₄ and GA₅₃, were identified by GC/MS (full scan) fromvegetative shoots of tall (cv. Kentucky Wonder) and dwarf (cv.Masterpiece) Phaseolus vulgaris L. It is suggested that GA₁is active per se in the control of shoot elongation of P. vulgarisL., and that dwarfism in Masterpiece is not due to shortageof the active GA, but to its low ability to respond to the bioactiveGA. (Received August 29, 1988; Accepted November 21, 1988)     

太子参过氧化物酶同工酶分析

采用聚丙烯酰胺凝胶垂直电泳,分析了6个品种太子参的过氧化物酶同工酶,并运用相似关系R-链连接法进行了模糊聚类分析划分了类群,探讨类群之间的亲缘关系,从酶学水平的表型证实了宣参老品种是原生种,其它类群有一定程度分化,但都与宣参老品种有着密切的亲缘关系。     

On Extraction and Quantitation of Plant Peroxidase Isoenzymes

Peroxidase in tobacco callus tissue differed in extract-ability depending on the subcellular distribution of the enzyme. Based on extractability it consisted of four fractions: freely soluble and less freely soluble in phosphate buffer, KCl-soluble, and insoluble. The latter two fractions were un-extractable by a phosphate buffer alone. The different fractions contained varied proportions of peroxidase isoenzymes. The extractability of indoleacetic acid oxidase was similar. A medium of high ionic strength is essential for quantitative extraction of peroxidase and indoleacetic acid oxidase isoenzymes. For quantitation of isoperoxidase activity on polyacryl-amide gel following electrophoretic separation, benzidine and o-dianisidine were better hydrogen donors than guaiacol and pyrogallol. The optimum pH was 4.5, but a citrate buffer was inhibitory. The optimum conditions included an acetate buffer at pH 4.5, a substrate concentration of 0.03 %, benzidine as the hydrogen donor, and a 3-minute treatment with 7 % acetic acid after staining. The color intensity of the bands remained unchanged for at least three days. With appropriate sample size and reaction time there was a linear relationship between enzyme concentration and activity.     

The Peroxidase Isoenzymes of Cupressus Linn.

By means of disc polyacrylamide gel electrophoresis, peroxidase isoenzymes of 9 species of Cupressus Linn, were analysed. The interspecific zymogramatic differences are obvious. Each species possesses its specific zymogram, distinguishable form the others. According to the zymogramatic similarity among these species calculated with the method of polar ordination, they may be grouped into 5 groups, which may be grouped in turn into two categories. C. gigantea Cheng et L. K. Fu, C. torulosa D. Don, C. duclouxiana Hichel, C. chengiana S. Y. Hu, and C. jiangeensis N. Chao. fall into one category. The second category contains C. sempervirens, C. arizonica Greene, C. lusitanica and C. funebris Endl. The experimental result about peroxidase comfirms the interspecific relationships of Cupressus suggested by the previous works. A positive relation is found between the peroxidases isoenzyme zymogramatic similar degree and the geographical vicarism of the related species, which has been used for analysing the regularity of phytogeographical vicarism. The mean zymogram distance of Cupressus Linn. among species is 0.75, from which it is inferred that the divergency took place the Jurassic. The advantage of polar ordination method in the study of iso-enzyme zymogram is discussed.     

Role of Assimilates and Phosphates in the Control of Internode Elongation in Tall and Dwarf Indica Rice Varieties

Six indica rice varieties belonging to three duration groups,each group containing one tall and one dwarf variety, were grownunder irrigated field conditions during the wet season of 1986.At the time of culm elongation, the distal 5–6 internodesof a variety elongated. The pattern of extension was hierarchical,each successive internode dominating the one immediately belowit and hence the final internode lengths increased in acropetalfashion from the bottom to the top. Between the tall and dwarfvarieties, the lengths of the individual intemodes did not differmuch in the apical and basal positions, but significant differenceswere found between the lengths of the middle internodes. Withincrease in length, the internodes became visibly thinner anddry matter content per unit length decreased. Analyses of solublecarbohydrates, amino acids, and phosphate contents of the internodesindicated that the concentration of the metabolites increasedin acropetal succession from the base to the apex. In general,the dwarf varieties contained at least the same, if not a higherconcentration of the metabolites as the tall varieties. Thepossible role of the metabolites in internode extension is discussed. Key words: Rice, internode extension, assimilates, phosphates, sink     

Differential Uptake of Horseradish Peroxidase Isoenzymes by Cultured Neuroblastoma Cells

The endocytotic uptake and intracellular decay of horseradish peroxidase isoenzymes C and A by cultured mouse neuroblastoma cells were analyzed quantitatively by a direct spectrophotometric assay. At concentrations below 1 mg/ml, the rate of uptake of the isoenzyme C was more than three times as much as the isoenzyme A. This differential uptake suggests that previous claims of horseradish peroxidase being endocytosed only in the nonselective fluid phase are oversimplified. The implication of this selectivity in the biological significance of retrograde axonal transport of proteins by neuronal systems is discussed.     

Differential Expression of Peroxidase Isoenzymes in Soybean Roots Treated with the Benzothiadiazole

The protection compound benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) was applied to soybean roots or leaves in a dose of 20 cm³ of a solution containing 25 μg g⁻¹ of the active ingredient. Electrophoretic profiles of chitinase and superoxide dismutase were not altered by the product. Increased activity of two root anionic peroxidases and three differential isoforms of these enzymes were observed in plants with roots treated by BTH, which can be used as biochemical markers of the BTH effect. This revised version was published online in July 2006 with corrections to the Cover Date.     

Translocation of Photosynthates in Tall and Dwarf Varieties of Pea, Pisum sativum

Quantitative studies of the translocation of radiocarbon from a young expanded leaf of two tall varieties (Improved Pilot and Thomas Laxton) and two dwarf varieties (Little Marvel and Meteor) of Pisum sativum showed that 40 to 45 per cent of the radiocarbon was exported from the ¹⁴CO₂ treated leaf after 24 hours in all four varieties. Although substantial export to the upper shoot always occurred it was more marked in the two tall varieties. Pre-treatment with GA did not affect total fixation but increased total export from the ¹⁴CO₂ treated leaf in cv. Meteor and decreased it in cv. Improved Pilot. GA had no effect on the translocation pattern in the tall plants but modified that of the dwarf plants to correspond to that found in the tall varieties.     

Localization and General Properties of Developing Peach Seed Coat and Endosperm Peroxidase Isoenzymes

Changes of soluble and ionically bound peroxidase and indoleacetic acid (IAA) oxidase activities were followed during peach seed development. Soluble peroxidase activity was located mainly in the embryo plus endosperm tissue, whereas wall ionically bound activities were found predominantly in the integument tissue. The different peroxidase isoenzymes present in the extracts were characterized by polyacrylamide gel electrophoresis and isoelectric focusing; the main soluble isoenzyme of embryo plus endosperm tissue was an anionic isoperoxidase of R _F 0.07. Basic ionically bound isoenzymes were located only in the integument tissue, but two soluble anionic isoenzymes of R _F 0.23 and 0.51 were also present in this tissue. In parallel, peroxidase protein content was estimated specifically using polyclonal antibodies. The kinetic data and the changes of seed IAA oxidase activity during fruit development suggested that basic peroxidase isoenzymes from ionically bound extracts of integument might be involved in IAA degradation. Received September 11, 1997; accepted October 21, 1997     

Structure of Double-Shelled Rice Dwarf Virus

Rice dwarf virus (RDV), a member of the Reoviridae family, is a double-stranded RNA virus. Infection of rice plants with RDV reduces crop production significantly and can pose a major economic threat to Southeast Asia. A 25-Å three-dimensional structure of the 700-Å-diameter RDV capsid has been determined by 400-kV electron cryomicroscopy and computer reconstruction. The structure revealed two distinctive icosahedral shells: a T=13l outer icosahedral shell composed of 260 trimeric clusters of P8 (46 kDa) and an inner T=1 icosahedral shell of 60 dimers of P3 (114 kDa). Sequence and structural comparisons were made between the RDV outer shell trimer and the two crystal conformations (REF and HEX) of the VP7 trimer of bluetongue virus, an animal analog of RDV. The low-resolution structural match of the RDV outer shell trimer to the HEX conformation of VP7 trimer has led to the proposal that P8 consists of an upper domain of β-sandwich motif and a lower domain of α helices. The less well fit REF conformation of VP7 to the RDV trimer may be due to the differences between VP7 and P8 in the sequence of the hinge region that connects the two domains. The additional mass density and the absence of a known signaling peptide on the surface of the RDV outer shell trimer may be responsible for the different interactions between plants and animal reoviruses.     

ent-Kaurene Biosynthesis in Cell-Free Extracts of Excised Parts of Tall and Dwarf Pea Seedlings

Investigations on the sites of ent-kaur-16-ene (ent-kaurene) biosynthesis were conducted with cell-free extracts from several excised parts of 10-, 13-, and 16-d-old tall and dwarf pea (Pisum sativum L.) seedlings. [¹⁴C]Mevalonic acid was incorporated into ent-kaurene in cell-free extracts from young developing leaves and elongating internodes of tall (`Alaska') and dwarf (`Progress No.9') pea seedlings at all three stages of development. ent-Kaurene biosynthesis also occurred readily in cell-free extracts from shoot tips, petioles, and stipules near the young elongating internodes. The ent-kaurene-synthesizing activity found in young developing tissues declined as tissues matured. Little or no activity was detectable in enzyme extracts from cotyledons and root tips at different stages. In light grown tall pea internodes ent-kaurene-synthesizing activity was low as they began to elongate, reached a maximum when the internodes reached about 2 cm in length and declined as they matured. Activity in extracts of dwarf shoot tips and internodes was generally lower than in equivalent tall plants, but the activity in dwarf leaves and stipules was somewhat higher than in tall plants. With the exception of root tips, there is a strong correlation between growth potential of a tissue and the rate of ent-kaurene biosynthesis in extracts from that tissue.     

LDS-聚丙烯酰胺凝胶电泳分析植物过氧化物酶同工酶

以高粱和甘蓝型油菜叶片为材料,用十二烷基磺酸锂不连续聚丙烯酰胺凝胶电泳（LDS-PAGE）检测过氧化物酶同工酶的结果表明,LDS-PAGE的酶带条数比非变性不连续聚丙烯酰胺凝胶电泳（native PAGE）明显增加,分辨率大大提高,上样量少,胶片易保存;比复性电泳（G-PAGE）的步骤简单,电泳后无需除去LDS即可直接按常规活性染色方法染色。     

Peroxidase Ontogeny in a Dwarf Pea Stem as Affected by Gibberellin and Decapitation

The ontogeny of peroxidase activity and isoenzyme pattern wasinvestigated in the stem of dwarf pea plants. Peroxidase activityper unit soluble protein was a given internode is highest inthe youngest growth stage, drops during elongation, remainsconstant upon cessation of growth, and increase at senescence.The lower the internode on the stem the higher is its peroxidaseactivity. These developmental differences are already apparentat the youngest growth stage of the internodes adn increaseduring elongation. Several anodic and five cathodic isoperoxidasesare apparent after starch gel electrophoresis. This patternis constant for all internodes at all growth stages, but therelative importance of particular isoenzymes changes with time. Gibberellic acid (GA₃) treatment causes greatly elongated internodes,decreased soluble protein, and inhibition of the rise in peroxidaseactivity within 4–8 h. Application of GA₃ to young internodesleads to a persistent depression in peroxidase activity, whiletreated older internodes suffer only a temporary depression.GA₃ causes no qualitative changes in the isoenzyme pattern butproduces some quantitative alterations in internodes in whichits influence on peroxidase activity is persistent. Decapitation of untreated and GA₃-treated dwarfs has littleinfluence on internode elongation, causes an increase in peroxidaseactivity, especially in the upper internodes, and alters therelative activity of particular isoenzymes. By contrast, decapitationinhibits elongation of young internodes in genetically tallpea plants.     

浙江和河北发生的一种水稻、小麦、玉米矮缩病是水稻黑条矮缩病毒引起的

以浙江省的水稻黑条矮缩病和河北省的玉米粗缩病的病毒分离物为材料,对我国南北方两种病毒分离物进行了比较研究.两种病毒分离物的粒子大小形态相似,且在血清学上密切相关;二者的介体、寄主相同,并引起相同的症状.提纯两种病毒分离物的基因组片段凝胶电泳显示它们相应的基因组片段之间大小极其相似.根据水稻黑条矮缩病毒(Rice black streaked dwarf