Root Contraction in Hyacinthus orientalis

Root contraction is effected in many species by redirected growthof parenchyma cells, supplemented in some cases by other processes.In Hyacinthus, root contraction is associated with the growthof inner cortical cells, which after becoming fully elongatedin the normal growth of the root, then expand radially and contractlongitudinally. The contraction is, however, a growth process,since it occurs in turgid tissue and is partly reversible byplasmolysis. Moreover, the radial walls of the cells concernedincrease in area and the cells increase in volume. The changes in cell shape associated with contraction involvechanges in cell-wall structure which, in so far as they aredetectable by polarization microscopy, are described and discussedin the light of current views on cell-wall growth.     

Further Observations on Root Contraction

Further observations, by light and electron microscopy, on theanatomy of root contraction in Hyacinthus orientalis cvs. arereported, together with some comparisons with Narcissus andGladiolus. It is maintained that root contraction in these andsome other species is essentially a growth process, as previousinvestigators have shown, and that an understanding of the re-directedgrowth of the cortical cells which brings it about may be basedon the specialized structural features of their cell walls,here described. Physical, anatomical and comparative reasonsare given for our belief that the alternative explanation ofthe contractile process in Gladiolus which relates it to cellcollapse resulting from transpirational ‘pull’ isuntenable. anatomy, contraction, Hyacinthus, Narcissus, Gladiolus, root     

Cytokinins in Gladiolus (Gladiolus grandiflorus) Corms

Ten cytokinin-like substances, termed X₁, X₂, X₃, X_4a, X_4b,X_5a, X_5b, X₆, X₇, and X₈, active in the soya bean hypocotyltest, were detected in gladiolus corms. The factors X_4a, X_5aand X₄ were tentatively identified as zeatin (Z), isopentenyladenosine (iPA) and isopentenyl adenine (iP), respectively,based on their behaviour in Sephadex LH-20 column chromatography,paper chromatography and high pressure liquid chromatography.Factor X₃, which behaved like zeatin riboside (ZR) in the abovesystems could be ZR and/or dihydrozeatin riboside (DHZR). Thebehaviour in Sephadex and ion-exchange column chromatographysuggested that X₁ and X₂ may be cytokinin glucosides and X₅a cytokinin nucleotide or a cytokinin conjugate similar to lupinicacid. The total cytokinin content and the concentration of Z,ZR/DHZR and iPA were higher in non-dormant than in dormant corms.The concentrations of X₁ and X₂ were higher in dormant corms. Gladiolus grandiflorus, gladiolus, dormancy, cytokinins, Sephadex column chromatography, high pressure liquid chromatography     

Evidence For Root Contraction In White Clover (Trifolium repens L.)

White clover (Trifolium repens L.) stolons become buried inthe field. It was observed that this also occurred in the greenhousewhere the accepted mechanisms of burial, treading by livestockand earthworm casting, did not occur. It was also observed thatthe crown of seedling T. repens plants become closely appressedto the soil. Experiments showed that, regardless of varietyof T. repens or depth of planting, all seedling hypocotyls firstlift the cotyledons clear of the soil, then ‘ contract’towards the soil until the cotyledons are in contact with orbelow the soil surface. Auxanometers were used to measure therate and extent of this contraction and were also attached tostolon nodes in experiments which showed that stolons move downwardsrelative to the soil surface and that the speed and extent ofthis duration varied with soil type. A further experiment showedthat only rooted nodes show this behaviour. The force exertedby the contraction of nodal roots was estimated experimentallyas 0.21 N g^-1fresh root. A mechanism for the root contraction,based on examination of root anatomy of seedling tap-roots andnodal roots, is suggested. These experiments provide evidencefor root contraction in T. repens which may lead to stolon burial.The importance of this to T. repens as a pasture species andas a means of further improving T. repens varieties is discussed.Copyright 1999 Annals of Botany Company White clover, Trifolium repens, L., stolon, seedling, burial, root, nodes, nodal, force, contractile, soil resistance, pasture, phloem, fibres.     

Somatic embryogenesis and plant regeneration of Gladiolus (Gladiolus hort.)

Summary Friable embryogenic callus and somatic embryos of 4 Gladiolus cultivars were obtained on Murashige and Skoog (MS) medium with various concentration of auxins from the following explants: corm slices, young leaf bases and whole, intact plantlets. Somatic embryos transferred on MS hormone-free medium regenerated into plantlets. All plantlets obtained through embryogenesis did not differ phenotypically from the parental clones. The embryogenic friable callus has been maintained for over 2 years in culture and has retained a very high regeneration capacity.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - KIN kinetin - NAA naphthaleneacetic acid - MS Murashige and Skoog Medium (1962) - E embryogenic callus - NE non-embryogenic callus     

Complete Amino Acid Sequence of Chitinase-a from Bulbs of Gladiolus (Gladiolus gandavensis)

The complete amino acid sequence of gladiolus bulb chitinase-a (GBC-a) was determined. First the tryptic peptides from GBC-a after it was reduced and S-carboxymethylated were sequenced and then the peptides were further studied by chemical cleavage of the enzyme. GBC-a consisted of 274 amino acid residues and had a molecular mass of 30,714 Da. Two consensus sequences essential for chitinase activity by plant class III chitinases were conserved in GBC-a, although its sequence similarity with plant class III chitinases was less than 20%. Sequence comparison of GBC-a with sequences of other proteins in a protein identification resource (PIR) showed that the GBC-a sequence was 33% similar to that of narbonin, a seed storage 2S globulin from narbon beans.     

OBLIQUELY STRIATED MUSCLE : III. Contraction Mechanism of Ascaris Body Muscle

Segments of the obliquely striated body muscle of Ascaris were fixed at minimum body length after treatment with acetylcholine and at maximum body length after treatment with piperazine citrate and then studied by light and electron microscopy. Evidence was found for two mechanisms of length change: sliding of thin filaments with respect to thick filaments such as occurs in cross-striated muscle, and shearing of thick filaments with respect to each other such that the degree of their stagger increases with extension and decreases with shortening. The shearing mechanism could account for great extensibility in this muscle and in nonstriated muscles in general and could underlie other manifestations of "plasticity" as well. In addition, it is suggested that the contractile apparatus is attached to the endomysium in such a way that the sarcomeres can act either in series, as in cross-striated muscle, or individually. Since the sarcomeres are virtually longitudinal in orientation and are almost coextensive with the muscle fiber, it would, therefore, be possible for a single sarcomere contracting independently to develop tension effectively between widely separated points on the fiber surface, thus permitting very efficient maintenance of isometric tension.     

Hormonal Regulation of Cormel Dormancy in Gladiolus grandiflorus

The germination of dormant gladiolus corrnels is promoted bycold storage and by treatment with 6-benzyladenine (BA). Itis inhibited by abscisic acid (ABA) and by gibberellin A₃. Ethrelpromotes the germination of dormant cormels but inhibits thegermination of non-dormant ones. ABA was identified by ORD,GLC, TLC, and wheat coleoptile bioassay as the major endogenousgrowth inhibitor controlling cormel germination. The ABA levelin dormant cormels (summer crop stored at 25 °C) is fiveto 10 times that in non-dormant ones (winter crop, or cold-storedsummer crop). The ABA content of the deeply dormant varietyTexas is higher than that of the less-dormant variety Friendship.     

Nd：YAG激光对提高根管治疗术效果的作用机理探讨

用波长1.06μm,输出功率20W的Nd:YAG激光照射根管壁后,常规根管糊剂＋牙胶尖侧压法充填,对照组,直接根管填。通过测量酚醛树脂在根管模截面中所占面积比值和染料渗入长度,发现实验组和对照组之间无明显差异（P＞0.05）。认为单纯激光照射对根尖封闭能力的影响并不明显。激光照射在根管治疗术中的作用可能是通过其它途径。     

The induction of contractile roots in Gladiolus grandiflorus

The number of contractile roots formed in gladioli was inversely related to the depth of the planted corm. Below a certain depth, no contractile roots were produced. Large corms did not produce contractile roots at any planting depth but produced two or more small corms. Depth perception is a function of two independent mechanisms, namely, temperature fluctuations in the root-initiation zone and the amount of light perceived mainly by the upper sheath leaf, the length of which varies with planting depth. Various growth substances applied to the leaves or corms did not induce contractile roots in dark-grown plants but roots were induced by indole-3-butyric acid in both small and large corms grown at constant temperatures and light. Abscisic acid retarded the formation of contractile roots under inductive conditions.Abbreviations CR contractile root(s) - IBA indole-3-butyric acid     

Signaling in Muscle Contraction

Signaling pathways regulate contraction of striated (skeletal and cardiac) and smooth muscle. Although these are similar, there are striking differences in the pathways that can be attributed to the distinct functional roles of the different muscle types. Muscles contract in response to depolarization, activation of G-protein-coupled receptors and other stimuli. The actomyosin fibers responsible for contraction require an increase in the cytosolic levels of calcium, which signaling pathways induce by promoting influx from extracellular sources or release from intracellular stores. Rises in cytosolic calcium stimulate numerous downstream calcium-dependent signaling pathways, which can also regulate contraction. Alterations to the signaling pathways that initiate and sustain contraction and relaxation occur as a consequence of exercise and pathophysiological conditions.     

The role of abscisic acid (ABA) in ethylene insensitive Gladiolus (Gladiolus grandiflora Hort.) flower senescence

Gladiolus flowers are ethylene insensitive and the signals that start catabolic changes during senescence of gladiolus flower are largely not known. Therefore, experiments were performed to understand the role of abscisic acid (ABA) in ethylene insensitive floral senescence in gladiolus (Gladiolus grandiflora Hort.). It was observed that ABA accumulation increased in attached petals of gladiolus flowers as they senesced. Exogenous application of ABA in vase solution accelerated senescence process in the flowers due to change in various senescence indicators such as enhanced membrane leakage, reduced water uptake, reduced fresh weight and ultimately vase life. Enhancement of in vivo ABA level in petals by creating osmotic stress also upregulates the same parameters of flower senescence as those occurring during natural senescence and also akin to exogenous application of ABA. Attempts to increase vase life of flowers by application of putative ABA biosynthesis inhibitor fluridone in vase solution to counteract ABA effect were unsuccessful. In contrast, ABA action was mitigated by application of GA₃ in holding solution along with ABA which is basically an antagonist of ABA action. The present study provides valuable insights into the role of ABA as a hormonal trigger in ethylene insensitive senescence process and therefore would be helpful for dissecting the complex mechanism underlying ABA-regulated senescence process in gladiolus.     

铵减弱拟南芥主根向地性及其相关作用途径

向地性是决定植物根系空间构型的主要因素之一,对植物锚定和水分养分吸收至关重要。除了重力,根系向地性还受土壤环境因子影响。本文采用琼脂培养方法,研究了铵对拟南芥主根向地性反应的影响及相关作用途径。结果表明：短期内,不同浓度（NH4）2SO4均显著抑制主根向地性弯曲,但随着时间的延长,根尖向地性角度逐渐变小。而等（NH4）2SO4浓度的NaCl对主根向地性抑制效应较小,不同浓度的甘露醇不阻碍主根向地性弯曲。纽织化学染色结果显示铵处理12h以内,Col-0根尖没有淀粉体的快速降解过程,并且铵对淀粉体缺失突变体pgm—1主根向地性的影响同Col-0相似。铵处理部分恢复生长素转运载体突变体auxl-22和eir1-1主根向地性缺失。这些结果表明,铵对拟南芥主根向地性的影响独立于根尖淀粉体参与的重力感应途径。     

Enhanced expression of serine proteases during floral senescence in Gladiolus

Programmed cell death during senescence in plants is associated with proteolysis that helps in remobilization of nitrogen to other growing tissues. In this paper, we provide one of the few reports for the expression of specific serine proteases during senescence associated proteolysis in Gladiolus grandiflorus flowers. Senescence in tepals, stamens and carpels results in an increase in total protease activity and a decrease in total protein content. Of the total protease activity, serine proteases account for about 67-70% while cysteine proteases account for only 23-25%. In-gel assays using gelatin as a substrate and specific protease inhibitors reveal the enhanced activity of two trypsin-type serine proteases of sizes 75 kDa and 125 kDa during the course of senescence. The activity of the 125 kDa protease increases not only during tepal senescence but also during stamen and carpel senescence indicating that it is responsive to general senescence signals.     

26个唐菖蒲品种RAPD分析

唐菖蒲是世界著名的切花之一,由于是纯粹的外来品种,目前国际上对其分类尚无统一的方法,主要是依据其生物习性等形态特征进行分类,受环境影响很大。同工酶是基因的产物,利用同工酶可以进行唐菖蒲品种鉴定和分类,但它在植物的不同器官组织发育的不同时期存在差异,而分子标记技术具有不受环境、器官、组织发育不同时期影响、遗传性稳定、分析简单等特点而被广泛应用在花卉品种分类上。利用RAPD技术对26个主要唐菖蒲切花品种进行分类和亲缘关系的研究,从520个随机引物中筛选出33个用于PCR反应,共在206个位点上扩增出条带,平均每个引物扩增位点6.24个,多态性位点185个,占总带数的89.8%,可以进行品种的鉴定。从分子水平揭示出唐菖蒲切花品种种质资源遗传基础狭窄,夏花大花型唐菖蒲品种间存在一定的亲缘关系。     

Expression of a polyubiquitin promoter isolated from Gladiolus

A polyubiquitin promoter (GUBQ1) including its 5′UTR and intron was isolated from the floral monocot Gladiolus because high levels of expression could not be obtained using publicly available promoters isolated from either cereals or dicots. Sequencing of the promoter revealed highly conserved 5′ and 3′ intron splicing sites for the 1.234 kb intron. The coding sequence of the first two ubiquitin genes showed the highest homology (87 and 86%, respectively) to the ubiquitin genes of Nicotiana tabacum and Oryza sativa RUBQ2. Transient expression following gene gun bombardment showed that relative levels of GUS activity with the GUBQ1 promoter were comparable to the CaMV 35S promoter in gladiolus, tobacco, rose, rice, and the floral monocot freesia. The highest levels of GUS expression with GUBQ1 were attained with Gladiolus. The full-length GUBQ1 promoter including 5′UTR and intron were necessary for maximum GUS expression in Gladiolus. The relative GUS activity for the promoter only was 9%, and the activity for the promoter with 5′UTR and 399 bp of the full-length 1.234 kb intron was 41%. Arabidopsis plants transformed with uidA under GUBQ1 showed moderate GUS expression throughout young leaves and in the vasculature of older leaves. The highest levels of transient GUS expression in Gladiolus have been achieved using the GUBQ1 promoter. This promoter should be useful for genetic engineering of disease resistance in Gladiolus, rose, and freesia, where high levels of gene expression are important.