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At least 127 records · Page 7Linked to original sources
PubMed2005

Polyamines promote root elongation and growth by increasing root cell division in regenerated Virginia pine (Pinus virginiana Mill.) plantlets.

Polyamines have been demonstrated to play an important role in adventitious root formation and development in plants. Here, we present a detailed analysis of influence of exogenously added polyamines on adventitious root development and its relationship to cold tolerance in Virginia pine (Pinus virginia Mill.). Our results demonstrated that polyamines putrescine (Put), spermidine (Spd), and spermine (Spm) at 0.001 mM improve rooting frequency and promote root elongation. Put, Spd, and Spm at 0.01-1 mM decrease rooting frequency and reduce root elongation root elongation. Measurements of diamine oxidase (DAO, EC 1.4.3.6) and polyamine oxidase (PAO, EC 1.4.3.4) activities showed that higher DAO and PAO enzyme activities were obtained when high concentrations of polyamines were applied and when plantlets were treated for 5-7 week at 4 degrees C and 16 degrees C. Survival rate of plantlets increased with the treatment of polyamines at low temperature. Polyamines increased mitotic index of cells in root tips of regenerated plantlet cultured on medium containing 0.001 microM Put, Spd, or Spm, but did not increase mitotic index in tissues of needle tips of the same plantlets. These results demonstrated that polyamines promote root elongation and growth by increasing root cell division in regenerated Virginia pine plantlets.

Amine Oxidase (Copper-Containing)↗
PubMed2006

A novel plant-specific family gene, ROOT PRIMORDIUM DEFECTIVE 1, is required for the maintenance of active cell proliferation.

Hypocotyl segments of Arabidopsis (Arabidopsis thaliana) produce adventitious roots in response to exogenously supplied auxin. root primordium defective 1 (rpd1) is a temperature-sensitive mutant isolated on the basis of impairment in this phenomenon. This study describes further phenotypic analysis of the rpd1 mutant and isolation of the RPD1 gene. When adventitious root formation was induced from the rpd1 explants at the restrictive temperature, cell proliferation leading to root promordia formation was initiated at the same time as in wild-type explants. However, development of the root primordia was arrested thereafter in the mutant. Temperature-shift experiments indicated that RPD1 exerts its function before any visible sign of root primordium formation. The expression patterns of the auxin-responsive gene DR5:beta-glucuronidase and the cytodifferentiation marker gene SCARECROW suggest that the rpd1 mutation interferes with neither axis formation nor cellular patterning at the initial stage of root primordium development. Taken together with the effect of the rpd1 mutation on callus cell proliferation, these data imply a role for RPD1 in prearranging the maintenance of the active cell proliferation during root primordium development. Positional cloning of the RPD1 gene revealed that it encodes a member of a novel protein family specific to the plant kingdom. Disruption of the RPD1 gene by a T-DNA insertion caused embryogenesis arrest at the globular to transition stages. This phenotype is consistent with the hypothesized function of RPD1 in the maintenance of active cell proliferation.

Amino Acid Sequence↗
PubMedDate not supplied

Vegetative propagation of Cecropia obtusifolia (Cecropiaceae).

Cecropia is a relatively well-known and well-studied genus in the Neotropics. Methods for the successful propagation of C. obtusifolia Bertoloni, 1840 from cuttings and air layering are described, and the results of an experiment to test the effect of two auxins, naphthalene acetic acid (NAA) and indole butyric acid (IBA), on adventitious root production in cuttings are presented. In general, C. obtusifolia cuttings respond well to adventitious root production (58.3% of cuttings survived to root), but air layering was the better method (93% of cuttings survived to root). The concentration of auxins used resulted in an overall significantly lower quality of roots produced compared with cuttings without auxin treatment. Future experiments using Cecropia could benefit from the use of isogenic plants produced by vegetative propagation.

Butyrates↗
PubMed2006

Leaf senescence is delayed in tobacco plants expressing the maize knotted1 gene under the control of a wound-inducible promoter.

To extend the shelf life of freshly harvested vegetables and cut flowers, a maize homeobox gene Knotted1 (kn1) was placed under the control of a wound-inducible promoter win3.12 from hybrid poplar (Populus trichocarpa x P. deltoides) and introduced into tobacco plants (Nicotiana tabacum cv. Xanthi). Transgenic win3.12::kn1 plants were morphologically normal. A leaf-detachment assay demonstrated that senescence in win3.12::kn1 leaves could be delayed by at least 2 weeks compared with wild type leaves. Furthermore, all leaves of win3.12::kn1 shoots remained green and healthy 3 weeks after excision and incubation in water, while older leaves of control shoots senesced under the same conditions. Additionally, a number of adventitious roots produced at the cut ends of wild type shoots after a 3-week incubation, but much a less number of adventitious roots appeared in win3.12::kn1 shoots. The delay in senescence was also confirmed by a higher total chlorophyll (a + b) content in win3.12::kn1 leaves relative to that of the control plants. RT-PCR analysis showed that the kn1 transcript was detected in win3.12::kn1 leaves with wounding treatment, but otherwise was not observed in leaves of wild type and unwounded transgenic plants. The results presented here indicate that expression of kn1 gene driven by the wound-inducible promoter win3.12 is potentially useful to delay senescence of vegetable crops and commercial horticulture after harvest.

Homeodomain Proteins↗
PubMed2004

Influence of nutrient application rate on growth and rooting potential of the West African hardwood Triplochiton scleroxylon.

Effects of stock plant nutrition on growth and subsequent rooting of leafy stem cuttings of the commercially important west African tree Triplochiton scleroxylon K. Schum. were investigated to identify the primary morphological variables influencing adventitious root formation. Potted plants were watered as required with one of four balanced nutrient solutions (0, 15, 63 or 125 mg N l(-1)). Increasing the nutrient supply to stock plants increased growth rate and rate of adventitious root production of subsequently harvested cuttings, but an optimum nutrient regime was not identified. Rooting percentage increased from 27% in cuttings harvested from stock plants receiving a low nutrient supply to 64% for cuttings harvested from stock plants receiving eight times the amount of nutrients extractable from plants under typical field conditions in West Africa. The ability of a cutting to retain its leaf during propagation and the length of the cutting were the primary measured characteristics associated with rooting and accounted for 43% of the variance fitted in the model. The length of the new shoot, total leaf area and within-shoot position (node position) were also significantly associated with rooting. After these characteristics were fitted to the model, the genetic origin (clone) was not statistically significant. We conclude that genetic variation in rooting potential is mediated through variations in morphological and physiological traits, rather than through genetic variation in cell differentiation or related aspects of root initiation.

Malvaceae↗
PubMed1988

Adaptations to intermittent drying in germinating Eucalyptus sieberi L. Johnson seeds and young seedlings.

Before Eucalyptus sieberi L. Johnson seeds germinate, the protein reserves in a small group of cells in the collet are mobilized and the cells swell sufficiently to break the seed coat allowing further water uptake. If the seedling is desiccated at this stage, the embryo remains viable and when the seed is rewetted reserves are mobilized in the cells immediately behind those which expanded initially. Mobilization of reserves and subsequent cell elongation occur sequentially along the hypocotyl after successive dry periods until the reserves are exhausted. Early in the sequence, the distal end of the hypocotyl extends and is positively geotropic, whereas at the end of the sequence the proximal end of the hypocotyl extends and is negatively geotropic, raising the cotyledons rapidly. If the radicle is destroyed or unable to elongate, it is replaced by two adventitious roots, one below the petiole of each cotyledon. Indole acetic acid and sucrose can substitute for the cotyledons in the production of adventitious roots.

Journal Article↗
PubMed2002

[Comparison of morphology, physiology and mineral element contents among genotypes of sesame with different tolerance to waterlogging under anaerobic condition].

The morphological and physiological indexes and the mineral element contents in different organs of 4 genotypes of sesame were examined under controlled oxygen supply. The number of adventitious roots of flooding tolerant varieties, Wild No. 7 and Yuzhi No. 1, increased 4-5 fold, the activity of ADH enhanced about twice, but the net photosynthetic rate (Pn) decreased slightly. There were significant increase in Ca and P and little decrease in K in roots, and decrease in other elements in roots and 8 elements in stems and leaves. As for less flooding-tolerant genotypes, Danbackaggce and Suiping Xiaozhihuang, however, the number of adventitious roots increased little, the activity of ADH enhanced 5-9 folds, and Pn decreased by 50-60%. An increase in Ca and P, and a significant reduction in K was found in roots. It was concluded that the waterlogging tolerance of sesame depended firstly on the structural adaptation, then on the anoxia metabolism, and that Ca and P may play an important role in the metabolic adaptation to the anaerobic environment for plant survival.

Adaptation, Biological↗
PubMed1969

Presence and possible mode of action of a proteinaceous gonadotropin-like growth regulating factor in plant systems.

Antiserum to human chorionic gonadotropin (HCG) caused marked inhibition of adventitious rooting of Begonia semperflorens and Chrysanthemum morifolium stem cuttings. Immuno-absorption of crude protein extract from chrysanthemum foliage through a column of polymerized and unsolubilized HCG antibodies resulted in a significant reduction in adventitious root promoting activity of the extract. These results are discussed in the light of a hypothesis that an endogenous protein growth regulating substance which immunologically resembles HCG exists in plant systems. Further experimentation with HCG suggests that its mode of action is possibly via the regulation of peroxidase enzymatic control of auxin levels.

Animals↗
PubMed2005

FPF1 transgene leads to altered flowering time and root development in rice.

AtFPF1 (FLOWERING PROMOTING FACTOR 1) is a gene that promotes flowering in Arabidopsis. An expression vector containing AtFPF1 driven by a Ubi-1 promoter was constructed. The gene was introduced into rice callus by Agrobacterium-mediated transformation and fertile plants were obtained. The presence of AtFPF1 in rice plants was confirmed by PCR, Southern and Northern blot analyses, as well as by beta-glucuronidase assay. The results showed that, as in Arabidopsis, AtFPF1 reduced flowering time in rice. Furthermore, introduction of AtFPF1 enhanced adventitious root formation but inhibited root growth in rice during the seedling stage. The results suggest that AtFPF1 promotes flowering time in both dicots and monocots, and plays a role in the initiation of adventitious roots in rice.

Arabidopsis Proteins↗
PubMed1982

Immunocytochemical localization of wheat germ agglutinin in wheat.

Immunocytological techniques were developed to localize the plant lectin, wheat germ agglutinin (WGA), in the tissues and cells of wheat plants. In a previous study we demonstrated with a radioimmunoassay that the lectin is present in wheat embryos and adult plants both in the roots and at the base of the stem. We have now found, using rhodamine, peroxidase, and ferritin-labeled secondary antibodies, that WGA is located in cells and tissues that establish direct contact with the soil during germination and growth of the plant In the embryo, WGA is found in the surface layer of the radicle, the first adventitious roots, the coleoptile, and the scutellum. Although found throughout the coleorhiza and epiblast, it is at its highest levels within the cells at the surface of these organs. In adult plants, WGA is located only in the caps and tips of adventitious roots. Reaction product for WGA was not visualized in embryonic or adult leaves or in other tissues of adult plants. At the subcellular level, WGA is located at the periphery of protein bodies, within electron-translucent regions of the cytoplasm, and at the cell wall-protoplast interface. Since WGA is found at potential infection sites and is known to have fungicidal properties, it may function in the defense against fungal pathogens.

Cell Wall↗
PubMed2000

The roles of Rirol and Ngrol genes in hairy root induction in Nicotiana debneyi.

The function of Rirol genes in TL-DNA of the Ri plasmid of Agrobacterium rhizogenes has been previously studied in Nicotiana tabacum and Daucus carota, but it was reported that these plants have a TL-DNA-similar sequence in their genome. We investigated the function of Rirol genes in N. debneyi by infection with A. tumefaciens harboring these genes, because the genome of N. debneyi does not contain a TL-DNA-similar sequence. The single gene RirolB induced adventitious roots in N. debneyi. Introduction of a DNA fragment that contained RirolB, RirolC, RiORF13 and RiORF14 resulted in more intense and earlier root formation than that of RirolB. Ngrol genes (NgrolB, NgrolC, NgORF13, and NgORF14) in the genome of Nicotiana glauca that are similar in sequence to Rirol genes were also examined. In contrast with Rirol genes, Ngrol genes did not induce adventitious roots on leaf segments of N. debneyi. Further infection analysis revealed that one of the reasons for this diversity of their functions might be the difference in the rolB region between the sequence of bacteria and plants. The difference in function between the genes of plants and bacteria is analyzed and the molecular evolution of Ngrol genes is discussed.

Journal Article↗
PubMed2000

The development of Archaeopteris: new evolutionary characters from the structural analysis of an Early Famennian trunk from southeast Morocco.

A 5 m long trunk of a young Archaeopteris/Callixylon erianum tree from the Late Devonian of Morocco shows new branching patterns for early lignophytes. This progymnosperm tree produces a helical pattern of traces that we infer belonged to reduced, short-lived, primary (apical) branches (type A) as well as two types of adventitious traces (types B and H). We infer that type-B traces supplied branches that initiate close to the site of attachment on the trunk of some, but not all type-A branches in an irregular but nonrandom pattern. Unlike ephemeral type-A branches, those of type B persist and become long-lived, potentially permanent units of the architecture of Archaeopteris trees. Type-H adventitious traces are also short-lived and occur singly or in serial groups, but differ from traces of either type A or B branches by lacking differentiation into a readily identifiable organ category. We interpret type-H traces as supplying latent primordia that could develop into either adventitious roots or shoots depending on extrinsic factors. Our new data suggest that Archaeopteris had a wide range of branch primordium amplitude. Type-B branches compare with axillary lateral branch buds of some Early Carboniferous spermatophytes (Calamopitys) and are a major developmental departure from the strictly apical, pseudomonopodial shoot branching of older aneurophyte progymnosperms. Type-H traces suggest that Archaeopteris trees had some potential for formation of adventitious roots or shoots in response to environmental factors, such as partial burial by overbank sedimentation. Collectively, these novel methods of tree branching may partly explain the extraordinary success and worldwide dominance of Archaeopteris forests on fluvially dominated, Late Devonian floodplains.

Journal Article↗
PubMed1998

Patterns of ENOD40 gene expression in stem-borne nodules of Sesbania rostrata.

At the base of adventitious root primordia, located on the stem of the tropical legume Sesbania rostrata, nitrogen-fixing nodules are formed upon inoculation with the microsymbiont Azorhizobium caulinodans. This pattern of nodule development presents features of indeterminate and determinate nodules in early and later stages, respectively. A S. rostrata cDNA clone homologous to early nodulin ENOD40 genes was isolated from a cDNA library of developing stem nodules. SrENOD40-1 contained the conserved regions I and II of other ENOD40 genes. By reverse transcriptase PCR, enhanced SrENOD40-1 expression was observed in the adventitious root primordia between 4 and 8 h after inoculation with A. caulinodans. In situ hybridization showed that SrENOD40-1 transcripts, present around the central vascular bundle of the uninfected root primordia, were strongly enhanced upon induction of nodule development. De novo SrENOD40-1 expression was observed in the initiating and growing nodule primordia and around vascular bundles. When cell type specification sets in, the expression became pronounced in cells derived from the meristematic regions. In other parts of the plant, weak SrENOD40-1 expression was associated with vascular bundles and was observed in leaf and stipule primordia.

Amino Acid Sequence↗
PubMed2002

Effect of clinorotation on in vitro cultured explants of Mentha piperita L.

An in vitro culture system was used to study the influence of gravity on axillary shoot formation and adventitious root regeneration in Mentha piperita L. The direction of the gravity vector was altered by displacing stem node explants in different orientations. Also, microgravity conditions were simulated by rotating the explants on a horizontal clinostat so that the main axis of nodes was either parallel (Cpa) or perpendicular to the clinostat axis (Ccp and Ccf, centripetally and centrifugally oriented, respectively). Mint nodes were cultured on solidified Linsmaier and Skoog's medium [Physiol. Plant. 18 (1965) 100] adding a filter-sterilized aqueous solution of 2 mg/l benzyladenine (BA) in half of the cultures. The proliferation of axillary shoots as well as adventitious root formation were not affected by altering upright explant orientation. On the contrary clinorotation was able to modify plantlet development. In absence of BA, leaf width was hindered by Cpa treatment and penultimate internode length was enhanced by Ccp. Furthermore, a negative effect of Cpa treatment was observed in root length parameter, while Ccp increased the root number both in absence and in presence of BA. An effect strictly connected to clinorotation in presence of BA was the occurrence of hyperhydricity. Moreover, explants under clinorotation treatments switched their gravitropic response modifying shoot curvature.

Adenine↗
PubMed2005

Epidermal cell death in rice is regulated by ethylene, gibberellin, and abscisic acid.

Programmed cell death (PCD) of epidermal cells that cover adventitious root primordia in deepwater rice (Oryza sativa) is induced by submergence. Early suicide of epidermal cells may prevent injury to the growing root that emerges under flooding conditions. Induction of PCD is dependent on ethylene signaling and is further promoted by gibberellin (GA). Ethylene and GA act in a synergistic manner, indicating converging signaling pathways. Treatment of plants with GA alone did not promote PCD. Treatment with the GA biosynthesis inhibitor paclobutrazol resulted in increased PCD in response to ethylene and GA presumably due to an increased sensitivity of epidermal cells to GA. Abscisic acid (ABA) was shown to efficiently delay ethylene-induced as well as GA-promoted cell death. The results point to ethylene signaling as a target of ABA inhibition of PCD. Accumulation of ethylene and GA and a decreased ABA level in the rice internode thus favor induction of epidermal cell death and ensure that PCD is initiated as an early response that precedes adventitious root growth.

Abscisic Acid↗
PubMed2006

Isolation and characterization of a bluegill-degrading microorganism, and analysis of the root hair-promoting effect of the degraded products.

Bluegill-degrading bacteria were isolated from various environmental sources. Brevibacillus sp. BGM1 degraded bluegill efficiently at 50 degrees C, and its culture supernatant showed the highest peptide and amino acid concentrations as trichloroacetic acid (TCA) soluble fraction (ASF) (10.7 mg/ml) of all supernatants obtained with bluegill as a substrate. Strain BGM1 secreted a protease(s) into the medium, and the concentration of peptides and amino acids gradually increased. The fertile effect of the degraded bluegill products (DGP) on Brassica rapa was also investigated. The root hair density of B. rapa grown with DGP at a concentration of 30 mug peptides and amino acids/ml was about 1.7 times higher than when grown with the same concentration of undegraded bluegill. DGP was shown to increase root hair numbers and adventitious root formation. The results of this study suggest that a specific peptide(s) for promotion of root hair is produced from the order Perciformes with a protease(s) from BGM1.

Animals↗
PubMed2004

Agrobacterium rhizogenes-mediated transformation of Taraxacum platycarpum and changes of morphological characters.

Transformed hairy roots were efficiently induced from seedlings of Taraxacum platycarpum by infection with Agrobacterium rhizogenes 15834. Root explants produced transformed roots at a higher frequency (76.5+/-3.5%) as compared to stem (32.7+/-4.8%) or cotyledon (16.2+/-5.7%). Hairy roots exhibited active elongation with high branching of roots on growth regulator-free medium. The competence of plant regeneration from non-transformed adventitious roots and transformed hairy roots was compared. The frequency of adventitious shoot formation from transformed roots was much higher (88.5+/-9.8%) than that of non-transformed roots (31.7 +/-9.5%) on hormone-free medium. Rooting of hairy root-derived adventitious shoots occurred easily on growth regulator-free medium but no rooting was observed on non-transformed shoots. The stable introduction of rol genes into Taraxacum plants was confirmed by PCR and Southern hybridization. Transgenic plantlets showed considerable differences in their morphology when compared to the corresponding wild-type (non-transgenic) plants. Plantlets formed from transformed roots had numerous fibrous roots with abundant lateral branches instead of the thickened taproots in non-transformed plants. The differences observed may reflect the modification of morphological root characters by introduction of rol genes.

Culture Media↗
PubMed2001

Expression pattern of transcripts encoding water channel-like proteins in Norway spruce (Picea abies).

With the aim of identifying cells and tissues with high expression of aquaporins (water channels) or homologous genes in Norway spruce (Picea abies), we report the expression patterns of such transcripts in seedlings, in roots of various ages, and in needles. In situ hybridization experiments with a conserved area of a tonoplast intrinsic protein (TIP) gene from P. abies gave high expression signals in differentiating vascular tissues and in the columella cells of the seedling root cap. High-staining signals were also seen in guard cells and in the bundle sheath cells of needles. Moreover, a slightly increased staining signal was seen in cells forming lateral roots as well as in adventitious roots formed from hypocotyl cuttings. By using PCR-based procedures we also identified a full-length aquaporin-like cDNA (mipr) from roots of two-week old seedlings. Sequence homology analysis of the gene suggests that it belongs to the TIP subgroup within the large MIP (major intrinsic protein) family. A phylogenetic analysis of the plant MIP family, including both plasmamembrane (PIP) and tonoplast intrinsic protein (TIP) from Picea, suggests that MIP subgroups evolved already 330 million years ago, as this is the dating of conifer and angiosperm divergence.

Amino Acid Sequence↗