The chemical synthesis of 1-O-(indol-3′-ylacetyl)-β-d-glucopyranose. The higher activity of the glucoside in comparison with exogenous indol-3-ylacetic acid in plant-section elongation tests

1. The synthesis of 1-O-(indol-3'-ylacetyl)-beta-d-glucopyranose via the fully benzylated 1-O-(indol-3'-ylacetyl)-d-glucopyranose is described. The configuration of the free ester glucoside was confirmed by complete hydrolysis with beta-glucosidase and by the n.m.r. spectrum of the tetra-acetyl derivative. 2. The growth-promoting effect of the glucoside in Avena coleoptile- and pea stem-section tests distinctly exceeds the responses stimulated by equimolar amounts of indol-3-ylacetic acid or equimolar mixtures of indol-3-ylacetic acid and glucose at all concentrations investigated. Time-sequence experiments revealed that the sections stimulated by the glucoside exhibit a markedly greater rate of elongation than those promoted by indol-3-ylacetic acid. 3. 1-O-(Indol-3'-ylacetyl)-beta-d-glucopyranose was isolated from intact Avena coleoptiles. 4. According to the results, the conjugation of indol-3-ylacetic acid with glucose could not be considered merely as a detoxication mechanism for indol-3-ylacetic acid in plant tissues.     

Comparative Studies on Differentiation of Regenerated Tissue in Broussonetia papyrifera

This paper describes the differentiation process of regenerated tissue after ordinary girdling or after removal of a section of xylem from the stem, and the disparity in differentiation of the regenerated tissues after being differently treateds in Broussonetia papyrifera. After ordinary girdling for 3–4 weeks, new bark regenerated in the xylem. During the process of rind' formation, many specks of meristematic tissue were formed in the callus, from which vascular tissue clusters were developed. In addition, the new periderm appeared almost at the same time as the new vascular cambium was seen. When a section of xylem was removed from the stem, numerous calli developed rapidly on the inner surface of the bark. Meanwhile, the vascular cambium appeared in the immature phloem. Soon after, discontinued meristematic tissue bands also occurred in the callus. These meristematic tissues then connected with each other to form a concave oblate cambial ring which developed xylem inward and phloem outward. About 2–3 weeks later, the concave oblate trunk grew lengthwisely connecting with the upper anct lower portions of the normal stem. By then, the tree continued to grow. The inner surface tissue of the bark, after the xylem was removed, differentiated about one week earlier than the tissue on the surface of the xylem after girdling.     

The role of plant hormones in higher plant cellular differentiation. II. Experiments with the vascular cambium, and sclereid and tracheid differentiation in the pine, Pinus contorta

In sterile-cultured explants of stems of the pine Pinus contorta Dougl., fusiform cambial cells differentiated entirely into axial parenchyma cells when exogenous indol-3yl-acetic acid (IAA) was omitted. The normal appearance of the cambial zone was maintained when IAA was included in the medium. The IAA-maintained stability of cambial structure suggests physiological rather than epigenetic control over vascular cambium structure. IAA was essential for the occurrence of callus growth in stem explants. Callus growth was similar in appearance and extent in winter- and summer-explanted material. Tracheids differentiated in explants only when actively differentiating tracheids were already present at the moment of explanting, suggesting the absence of factors necessary for tracheid differentiation in over-wintering tissues. Sclereid differentiation, which normally does not occur in phloem or xylem development in P. contorta, occurred in callus derived from active cambial explants. The sclereids were identical to sclereids which differentiated in pith of intact stems. The possibility that sclereid and tracheid differentiation may be fundamentally similar types of gene expression is discussed. Growth of P. contorta trees in continuous darkness resulted in extensive compression-wood tracheid differentiation in the upright main stem. Normal-wood tracheids differentiated in similar trees grown in light. More tracheids differentiated in light than in darkness. This apparently is the first report of induction of compression-wood tracheid differentiation in the absence of hormone treatment or tilting of trees. Different types and numbers of tracheids differentiated at different position in two-year-old disbudded defoliated stem cuttings of P. contorta in response to apically supplied IAA. No evidence for new tracheid differentiation was seen in control cuttings; however, the results suggest that neither cambial cell division nor tracheid differentiation were actually initiated by IAA. Directed transport of additional regulatory factors toward areas of high IAA concentration is formulated as a hypothesis to explain these observations. Gibberellic acid, (S)-abscisic acid and IAA inhibited tracheid differentiation when individually supplied to basal ends of P. contorta cuttings predisposed to differentiate new tracheids. Experiments with single intact needles on Pinus cembroides var. monophylla cuttings confirmed a previous interpretation that the mature pine needle, rather than the short-shoot apical meristem at its base, promotes tracheid differentiation in the stem.     

Histogenesis of Xylem of Eucommia ulmoides Cultured in Vitro

Following a complete ringing of the main stem of Eucommia ulmoides Oliv. regeneration of normal new bark has been observed as a subsequence of repeated partial differentiation of the immature xylem into cambium. The immature xylem, when cultured in vitro, showed production of callus tissue from the ray cells. After 15–30 days of continuous culture, meristematic tissue appeared as a discontinuous and more or less regularly arranged.zone was visible within the callus tissue. However, the meristematic cells, unlike the elongated fusif0rm initial cells, are isometric in shape. This meristem differentiated into tracheids centripetally. Nevertheless, no centrifugal differentiation into phloem was evidenced. The vascular tissues were ultimately degenerated after 6 months cultured in vitro.     

Cell differentiation,secondary cell-wall formation and transformation of callus tissue of<Emphasis Type="Italic"> Pinus radiata</Emphasis> D. Don

Tracheid and sclereid differentiation was induced in callus cultures of Pinus radiata D. Don by culturing on a basal medium containing activated charcoal but no phytohormones; sclereids differentiated in callus derived from xylem strips, but not in callus derived from hypocotyl segments. The tracheids differentiated in hypocotyl-derived callus had helical, scalariform, reticulated or pitted secondary cell-wall patterns, but those differentiated in xylem-derived callus had a reticulate or pitted pattern. The thickened tracheid and sclereid walls contained lignin as indicated by the red colour reaction given with phloroglucinol-HCl. The presence of lignin in the cell walls of differentiated callus was confirmed using pyrolysis gas chromatography-mass spectrometry by the detection of phenylpropanoid components derived from lignin. Lignin was also detected using solid-state (13)C cross-polarisation/magic-angle spinning nuclear magnetic resonance spectroscopy and quantified as thioglycolic acid lignin. Monosaccharide analyses of the cell walls isolated from differentiated and undifferentiated calli showed that the cell walls of the differentiated calli contained higher proportions of glucose and mannose, consistent with the presence of greater proportions of gluco- and/or galactogluco-mannans in the secondary cell walls of the differentiated cells. A protocol for the stable transformation of undifferentiated, xylem-derived cultures was successfully developed. Transgenic cell lines were established following Biolistic particle bombardment with a plasmid containing the coding region of the nptII gene and the coding region of the cad gene from P. radiata. Expression of the nptII gene in transgenic lines was confirmed by an NPTII-enzyme-linked immunosorbent assay. The overexpression of cad in the transgenic lines resulted in a down-regulation of cinnamyl alcohol dehydrogenase (EC 1.1.1.195) expression.     

Tissue Culture of Cassava on Chemically Defined Media

Defined media that promote the initiation and undifferentiated growth of callus derived from stem explants of four cultivars of cassava, Manihot esculenta Crantz, are described. Growth rates and yields of cassava callus after 4 weeks of culture are shown to be comparable to those of callus of Nicotiana tabacum L. cv. Wisconsin No. 38. Nitrogen sources of ammonium nitrate or of ammonium chloride plus succinate supported growth of all four cultivars. Sucrose was superior to glucose as a carbon source. The cassava cultivars differed in their response to increasing concentrations of sucrose between 0.5% (w/v) and 3%, two of them increasing in dry matter with increasing sucrose concentrations of up to 3%. When cultured in the light on defined media that contained higher ratios of cytokinin to auxin, callus of the latter two cultivars turned green. Roots but not shoots differentiated from the callus of all cultivars. The influence of hormone concentrations, sucrose level, and nitrogen source on greening and root formation is summarized.     

Tracheary Element Differentiation Induced in Isolated Cylinders of Lettuce Pith: a Bipolar Gradient Technique

To study the influence of morphogenetic gradients on vasculardifferentiation patterns, a new technique was developed whichallows different substances to be applied at opposite ends ofa tissue block. It yielded information on the mobility of particularmorphogens and on the dependence of callus formation and trachearyelement differentiation on their presence. Application of indol-3ylacetic acid (1AA) (10 mg l^–1), zeatin (0.1 mg l^–1)and sucrose (3 per cent, w/v) in various combinations to theends of cylindrical explants of lettuce pith (Lactuca sativaL.) showed that (a) callus formation was stimulated by IAA,whereas induction of tracheary elements required both IAA andzeatin; (b) callus was confined to a few millimetres at theends of the explants, and tracheary elements occurred mainlywithin the callus; (c) sucrose or its metabolic products diffusedthe 10 mm length of the explants, while IAA and zeatin wereeffective only close to the application site; and (d) some callusand tracheary elements formed when no sucrose was applied, butboth increased with sucrose application, though inhibition oftracheary elements formation occurred with high sucrose concentrations. differentiation, pith explant, tissue culture, xylogenesis, indol-3yl acetic acid, sucrose, zeatin, lettuce, Lactuca sativa     

EXPERIMENTAL INDUCTION OF VASCULAR TISSUES IN CALLUS OF ANGIOSPERMS

Wetmore , Ralph H. (Harvard U., Cambridge, Mass.), and John P. Rier . Experimental induction of vascular tissues in callus of angiosperms . Amer. Jour. Bot. 50(5): 418–430. Illus. 1963.—Callus tissues in established maintenance culture lack morphological and physiological organization. Such callus consists of homogeneous parenchyma. Movement of auxin and sugar, therefore, must be along diffusion gradients. The only vascular tissues occurring in callus are induced. Experimental induction of vascular tissues has been successful in callus of 3 sp. of the Oleaceae: a tree, Fraxinus americana, and 2 shrubs, Syringa vulgaris and Ligustrum vulgare; another tree, Salix purpurea, var. lambertiana; a vine, Parthenocissus tricuspidata; and an herb, Helianthus tuberosus. In each of these species, an auxin (IAA or NAA in these studies) and a sugar (sucrose or glucose in these studies) prove necessary for the induction and complete differentiation of xylem and phloem in callus tissues. Varying concentrations of sugar alter the proportions of xylem to phloem: low concentrations, 1.5%–2.5%, favor xylem formation; high, 3%–4%, favor phloem. Middle concentrations, 2.5%–3.5%, favor the presence of xylem and phloem, usually with a cambium between. The almost universal association of xylem and phloem may have its explanation in this middle concentration of sugar. Grafting of apices into callus or direct application of appropriate concentrations of an auxin and a sugar in agar to the surface of callus causes nodules of vascular tissue to be formed, mostly in a circular pattern when seen in section transverse to the axis of orientation of the callus in the medium. The diameter of this circle varies directly with the auxin concentration at the place of application, 0.05 mg/liter giving a narrow, and 1 mg/liter, a wide pith. In individual nodules, xylem is characteristically oriented towards the center of the callus and the phloem towards the outside. Variable cross-sectional views of nodule distribution in calli under different treatments suggest experimental approaches to understanding stelar patterns. The induction and differentiation in callus of xylem and phloem tissues has no relation to conduction. Any use of vascular tissues can occur only after their induction.     

Metabolic differences between gymnosperms and angiosperms in the formation of syringyl lignin

Sliced xylem tissue from shoots of both poplar and cherry reduces ferulic and sinapic acids to the corresponding aldehydes and alcohols, while tissue from gymnosperms such as Japanese red pine and ginkgo can reduce only ferulic acid. In young, less differentiated, xylem tissue and callus tissue of angiosperms the ability to reduce sinapic acid is markedly lower than that of the fully differentiated xylem.Both gymnosperm and angiosperm tissues reduced coniferyl and sinapyl aldehydes to the corresponding alcohols and, further, the peroxidases from both classes gave similar dehydrogenation polymers from a mixture of coniferyl and sinapyl alcohols. In agreement with these findings, sinapyl aldehyde and sinapyl alcohol, when fed to living plants and tissue cultures of gymnosperms, were shown to be readily converted to syringyl lignin which was not originally present.     

Hormonal control of cambial activity and vessel differentiation in Quercus robur

Cambial activity and vessel differentiation of the Quercus robur stem were investigated in relation to concentration of growth regulators and sucrose, seasonal changes in the sensitivity of cambial cells, and axial polarity of the stem. Basipetal efflux of natural auxin was measured in the oak stem cambial region. IAA, GA₃, kinetin and sucrose affected cambial activity and/or initiation of vessel differentiation differently, depending upon concentration. Depending upon the season, kinetin increased or reduced the stimulation of cambial activity caused by IAA and GA₃, but it did not affect the differentiation of vessels. Supply of sucrose in higher concentrations reduced the number of differentiated vessels but did not decrease the stimulation of cambial divisions.Unlike stimulation of cambial activity by GA₃, auxin stimulation of cambial divisions and differentiation of vessels were highly dependent upon stem polarity, 2,3,5-triiodobenzoic acid (TIBA) inhibited formation of vessels, but not cambial activity. The oscillations in basipetal efflux of natural auxin from the cambial stem region of successive 6 mm long sections substantiate the hypothesis that the histogenesis of xylem tissue in ring-porous species is under control of the vectoriat field that is associated with oscillatory phenomena in polar auxin transport.     

Storage Organ Development in Radish (Raphanus sativus L.). 2. Effects of Growth Promoters on Cambial Activity in Cultured Roots, Decapitated Seedlings and Intact Plants

The radish varieties Cherry Belle and Long White Icicle wereused to investigate the role of the shoot and the effects ofsynthetic growth promoters in controlling cambial activity inthe seedling axis. Development was compared in excised roots, roots with hypocotylsattached and intact seedlings cultured aseptically on a nutrientmedium. No cambial divisions were seen in isolated radicleswhich had been cultured for ten days following excision butretention of hypocotyl tissue or the entire shoot resulted incambial activity and the production of secondary vascular tissues.Enriching the culture medium by raising the sucrose conantrationto 8% and including 10^–5 M indol-3yl acetic acid (IAA)5 x 10^–6 M 6-benzylaminopurine (BA) and 5 x 10^–4Minositol enhanced root thickening, increasing stele and xylemdiameters in roots cultured both with and without attached shoottissues. The effects of shoot tissues and enrichment of themedium were additive. The effects of auxin, cytokinin and gibberellin (gibberellicacid, GA²) were also studied on daxpitated seedlings. BA wasmuch more effective in inducing cell divisions in the hypocotylthan either IAA or GA supplied separately but a mixture of IAA+GAalso produced clearly defined arcs of cambial tissue. Littlesecondary tissue had been produced after seven days' treatment,and stelar enlargement was due to the development of a cambialzone and cell expansion in the primary tissues. Only minor differencesin response were observed between the two varieties. No stimulation of storage organ development occurred when auxin,cytokinin or inositol was inwrporated into the inorganic culturesolution in which plants of Cherry Belle were grown. Rnphanus sarivus, radish, storage organ, cambial activity, growth promoters, indol-3-ylacetic acid, 6-benzylaminopurine, gibberellic acid     

Auxins and cytokinins exuded during formation of roots by detached primary leaves and stems of dwarf French bean (Phaseolus vulgaris L.)

Summary Hypocotyls of detached stems standing in culture solution produced adventitious roots sooner than did petioles of detached primary leaves. An auxin, probably indol-3-ylacetic acid, appeared in the solutions before the hypocotyls or petioles produced roots. After attaining a maximum, the amounts of auxin in the solutions decreased as fewer roots were formed. Two cytokinins were found in the culture solutions; one had a similar R_f to zeatin, the other ran more slowly on chromatograms. The amounts of cytokinin in the solutions were associated with root formation. Stems soon died unless their hypocotyls formed roots, but the primary leaves survived without roots forming provided a callus formed on the petiole. Hence adventitious roots, or callus tissues, may have produced cytokinins that replaced those produced by the original roots, found in sap exuded from the stem stumps, and were essential for survival of the stems and leaves.     

The production of auxin by autolysing tissues

Summary Autolysing plant tissues are known to produce auxin when extracted with ether. It has been shown that autolysing plant, yeast and rat liver tissues produce auxin in vitro; this suggests that relatively unspecific mechanisms are involved. Furthermore, sterile plant and animal tissues which have been killed by freezing and thawing induce nodules of differentiated cells in a previously undifferentiated callus of Phaseolus vulgaris. The callus tissue is known to differentiate in response to applied gradients of auxin. Plant and animal tissues killed by boiling were considerably less effective in inducing differentiation in the tissue. The evidence indicates that auxin is a normal product of autolysing cells. It is suggested that dying cells are an important source of auxin in the plant.     

Studies on some factors affecting solasodine contents in tissue cultures of Solanum nigrum

Tissue cultures of Solanum nigrum L. were initiated from leaf explants on a solid medium containing inorganic salts [Murashige and Skoog (1962), Physiol. Plant. 15: 473–497], vitamins [Gamborg et al. (1968) Exp. Cell Res. 50:151–158], 3% sucrose and combinations of indoleacetic acid and benzyladenine. Solasodine content was determined in differentiated and undifferentiated (callus) tissues by a colorimetric technique and thin layer chromatography. Indoleacetic acid and sucrose in the medium markedly stimulated the production of solasodine in the tissue cultures. In the cultures grown in darkness the differentiated tissues produced significantly more (anywhere from 1.5 to 10 times) solasodine than the callus in several media. When sucrose concentration was increased to 4, 6 and 10% level in the medium which contained 10 μ M benzyladenine as the sole growth regulator, a significant increase of solasodine production in cultures was found.     

荞麦愈伤组织分化与过氧化物酶活性及其同工酶关系的研究

在附加不同外源激素的培养基中,龙山荞的子叶愈伤组织表现出不同的分化状态:(1)不分化;(2)分化根;(3)分化芽;(4)分化全苗。四种愈伤组织的过氧化物酶活性的相对比值为1:1.47:5.95:7.78,并且过氧化物酶同工酶谱也存在明显差异。酶带4'为分化愈伤组织所特有;酶带2'为未分化和分化愈伤组织所共有;在分化根和未分化愈伤组织中缺少酶带1';未分化愈伤组织比分化愈伤组织多出酶带3'。     

Protein Synthesis as a Requirement for Wound Xylem Differentiation

An increasing rate of protein synthesis was observed during the first 2 days after the isolation of 2 mm thick internodal stem slices of Coleus on a sucrose-agar medium. This rise in the rate of protein synthesis preceeded the first visible signs of wound-vessel member differentiation in the cultured stem slices. Irradiation of tissue slices with 4000 R of x-rays at isolation reduced the numbers of wound-vessel members differentiated after 7 days in culture by 51 per cent, and this level of x-irradiation was observed to inhibit protein synthesis by the cultured stem slices. Treatment of the tissue slices with exogenous auxin (0.05 mg/1) after irradiation did not alter the degree of inhibition of xylem differentiation. Actinomycin D inhibited wound-vessel member differentiation, but it had no effect on the endogenous growth of the cultured stem slices. Similarly, auxin at 0.05 mg/1 was without effect on the endogenous growth rate of the stem slices. Actinomycin D treatment was highly effective in inhibiting xylem differentiation if it was supplied to the tissues within the first 48 hours after isolation; actinomycin D treatment had no significant effect on xylem differentiation when it was given after the first 2 days of culture. Chloramphenicol (10^?3M) inhibited both xylem differentiation and the endogenous growth of the cultured stem slices.     

Enzymic synthesis of 1-O-indol-3-ylacetyl-beta-D-glucose and indol-3-ylacetyl-myo-inositol.

An enzyme fraction from extracts of immature kernels of Zea mays catalyses the formation of 1-O-indol-3-ylacetyl-beta-D-glucose from indol-3-ylacetic acid and UDP-glucose. A second enzyme fraction catalyses the formation of indol-3-ylacetyl-myo-inositol from 1-O-indol-3-ylacetyl-beta-D-glucose and myo-inositol. To our knowledge, this is the first example of hydroxy-group acylation by a 1-O-acyl sugar. The following reaction sequence is proposed: Indol-3-ylacetic acid + UDP-glucose leads to indol-3-ylacetylglucose + UDP (1) Indol-3-ylacetylglucose + myo-inositol leads to indol-3-ylacetyl-myo-inositol + glucose (2) The enzyme catalysing reaction (1) is called UDP-glucose:indol-3-ylacetate glucosyl-transferase (indol-3-ylacetylglucose synthase), and that catalysing reaction (2) is indol-3-ylacetylglucose:myo-inositol indol-3-ylacetyltransferase (indol-3-ylacetyl-myo-inositol synthase). We further show that indol-3-ylacetylglucose synthase is specific for UDP-glucose and, at the stage of purity tested, the enzyme will use either indol-3-ylacetic acid or naphthalene-1-acetic acid, but not 2.4-dichlorophenoxyacetic acid, as glucose acceptor. The indol-3-ylacetyl-myo-inositol synthase is specific for indol-3-ylacetyl-glucose and will not use naphthalene-1-acetylglucose as substrate, and it is specific for myo-inositol among the alcohol acceptors tested. Thus, of the auxins tested, only indol-3-ylacetic acid forms the myo-inositol ester.     

Histochemical Study of Xylem Cells in In Vitro Culture of Iris sibirica L.

In this study, lignin content data are presented for annual regenerant Iris sibirica plants, comparable to those in six-year-old intact plants. The structure of the shoots of Iris sibirica grown on artificial nutrient media was studied by the histochemical method. Features of the formation of the xylem in Iris sibirica on artificial nutrient media were revealed. Regenerants very quickly developed a complex system consisting of vascular bundles containing sieve tubes, vessels and tracheids, and hydrocyte systems. Hydrocytes of Iris sibirica were tracheids with lignified thickening, but, in contrast to tracheids and vessels of xylem (they are formed based on procambium or cambium—special lateral primary or secondary meristem), hydrocytes differentiated from the cells of permanent tissues (like phellogen), which probably possessed meristematic activity at the time of differentiation. In Iris sibirica hydrocytes covered the vascular bundle by the thick layer and strung along it up to a certain height. High lignin content in young regenerant Iris sibirica plants was due to the formation of the dense tissue from lignified tracheal elements. The study of the differentiation of xylem elements under controlled conditions can serve as a model for our understanding of wood formation processes.

     

组蛋白乙酰化对成体干细胞生物学性状的影响

成体干细胞（adult stem cells,ASCs）是指存在于一种已经分化组织中的未分化细胞,它们可以再生修复损伤的组织和器官,是组织工程和细胞治疗的理想细胞。但是ASCs在体外扩增过程中容易发生自主分化和衰老,影响其在临床的广泛应用。组蛋白乙酰化作为表观遗传调节的重要机制,参与细胞分化、衰老及凋亡等众多细胞活动的调控。该文就组蛋白乙酰化对成体干细胞生物学性状的影响进行综述。     

Role of an acid phosphatase isoenzyme in callus tissue during cytodifferentiation

Summary Both histological and isoenzyme patterns of acid phosphatase were observed in callus tissue of Vigna unquiculate (L.) Walp. up to the tenth passage from its initiation. It was observed that when un-differentiated cells begin to transform into a differentiated condition in the form of tracheids, and xylem vessels, a new acid phosphatase band appears at the anionic end of the polyacrylamide gel. The transformation of living cells into a dead, empty tracheid during cellular differentiation and the biosynthesis of the acid phosphatase enzyme are functionally related to the autolysis of the cell contents and lignin synthesis.