TY - JOUR. T1 - Cryptochrome photoreceptors cry1 and cry2 antagonistically regulate primary root elongation in Arabidopsis thaliana. AU - Canamero, Roberto C.. AU - Bakrim, Nadia. AU - Bouly, Jean Pierre. AU - Garay, Alvaro. AU - Dudkin, Elizabeth Anne. AU - Habricot, Yvette. AU - Ahmad, Margaret. PY - 2006/10/1. Y1 - 2006/10/1. N2 - Cryptochromes are blue-light receptors controlling multiple aspects of plant growth and development. They are flavoproteins with significant homology to photolyases, but instead of repairing DNA they function by transducing blue light energy into a signal that can be recognized by the cellular signaling machinery. Here we report the effect of cry1 and cry2 blue light receptors on primary root growth in Arabidopsis thaliana seedlings, through analysis of both cryptochrome-mutant and cryptochrome-overexpressing lines. Cry1 mutant seedlings show reduced root elongation in blue light while overexpressing seedlings show significantly increased elongation as compared to ...

Lateral roots are initiated postembryonically in response to environmental cues, enabling plants to explore efficiently their underground environment. However, the mechanisms by which the environment determines the position of lateral root formation are unknown. In this study, we demonstrate that in Arabidopsis thaliana lateral root initiation can be induced mechanically by either gravitropic curvature or by the transient bending of a root by hand. The plant hormone auxin accumulates at the site of lateral root induction before a primordium starts to form. Here we describe a subcellular relocalization of PIN1, an auxin transport protein, in a single protoxylem cell in response to gravitropic curvature. This relocalization precedes auxin-dependent gene transcription at the site of a new primordium. Auxin-dependent nuclear signaling is necessary for lateral root formation; arf7/19 double knock-out mutants normally form no lateral roots but do so upon bending when the root tip is removed. Signaling ...

TY - JOUR. T1 - Root growth, secondary root formation and root gravitropism in carotenoid-deficient seedlings of Zea mays L.. AU - Ng, Yuk Kiu. AU - Moore, Randy. N1 - Funding Information: This research represents a portion of a thesis submitted in partial fulfillment of the requirements for a Master of Science degree in Biology at Baylor University. We thank Prof. J. D. Smith for providing us with the vp-9 mutants and Dr Jim Barrentine for providing us with Fluridone. This research was supported by funds provided by the University Research Committee and the Department of Biology of Baylor University.. PY - 1985/3. Y1 - 1985/3. N2 - The effect of ABA on root growth, secondary-root formation and root gravitropism in seedlings of Zea mays was investigated by using Fluridone-treated seedlings and a viviparous mutant, both of which lack carotenoids and ABA. Primary roots of seedlings grown in the presence of Fluridone grew significantly slower than those of control (i.e. untreated) roots. Elongation ...

Lateral roots originate deep within the parental root from a small number of founder cells at the periphery of vascular tissues and must emerge through intervening layers of tissues. We describe how the hormone auxin, which originates from the developing lateral root, acts as a local inductive signal which re-programmes adjacent cells. Auxin induces the expression of a previously uncharacterized auxin influx carrier LAX3 in cortical and epidermal cells directly overlaying new primordia. Increased LAX3 activity reinforces the auxin-dependent induction of a selection of cell-wall-remodelling enzymes, which are likely to promote cell separation in advance of developing lateral root primordia.. Nature Cell Biology 10 (8), 946-954 ...

Phosphate (Pi), an essential macronutrient for growth and development of plant, is often limiting in soils. Plants have evolved an array of adaptive strategies including modulation of root system architecture (RSA) for optimal acquisition of Pi. In rice, a major staple food, RSA is complex and comprises embryonically developed primary and seminal roots and post-embryonically developed adventitious and lateral roots. Earlier studies have used variant hydroponic systems for documenting the effects of Pi deficiency largely on primary root growth. Here, we report the temporal effects of Pi deficiency in rice genotype MI48 on 15 ontogenetically distinct root traits by using easy-to-assemble and economically viable modified hydroponic system. Effects of Pi deprivation became evident after 4 d- and 7 d-treatments on 2 and 8 different root traits, respectively. The effects of Pi deprivation for 7 d were also evident on 14 different root traits of rice genotype Nagina 22 (N22). There were genotypic differences

Root system architecture is important for water acquisition and nutrient acquisition for all crops. In soybean breeding programs, wild soybean alleles have been used successfully to enhance yield and seed composition traits, but have never been investigated to improve root system architecture. Therefore, in this study, high-density single-feature polymorphic markers and simple sequence repeats were used to map quantitative trait loci (QTLs) governing root system architecture in an inter-specific soybean mapping population developed from a cross between Glycine max and Glycine soja. Wild and cultivated soybean both contributed alleles towards significant additive large effect QTLs on chromosome 6 and 7 for a longer total root length and root distribution, respectively. Epistatic effect QTLs were also identified for taproot length, average diameter, and root distribution. These root traits will influence the water and nutrient uptake in soybean. Two cell division-related genes (D type

Certain crosses of common bean (Phaseolus vulgaris) result in temperature-dependent hybrid weakness associated with a severe root phenotype. This is controlled by the interaction of the root- and shoot-expressed semidominant alleles dosage-dependent lethal 1 (DL1) and DL2, which communicate via long-distance signaling. Previously, apparent reciprocal effects on root growth and the restoration of normal root growth by exogenous sucrose led to the hypothesis that the dosage-dependent lethal (DL) system may control root-shoot carbon partitioning. Here, recombinant inbred lines were used to map the DL loci and physiological and biochemical analysis, including metabolite profiling, was used to gain new insights into the signaling interaction and the root phenotype. It is shown that the DL system does not control root-shoot carbon partitioning and that roots are unlikely to die from carbon starvation. Instead, root death likely occurs by defense-related programmed cell death, as indicated by salicylic ...

Roots show positive hydrotropism in response to moisture gradients, which is believed to contribute to plant water acquisition. This article reviews the recent advances of the physiological and molecular genetic studies on hydrotropism in seedling roots of Arabidopsis thaliana. We identified MIZU-KUSSEI1 (MIZ1) and MIZ2, essential genes for hydrotropism in roots; the former encodes a protein of unknown function, and the latter encodes an ARF-GEF (GNOM) protein involved in vesicle trafficking. Because both mutants are defective in hydrotropism but not in gravitropism, these mutations might affect a molecular mechanism unique to hydrotropism. MIZ1 is expressed in the lateral root cap and cortex of the root proper. It is localized as a soluble protein in the cytoplasm and in association with the cytoplasmic face of endoplasmic reticulum (ER) membranes in root cells. Light and ABA independently regulate MIZ1 expression, which influences the ultimate hydrotropic response. In addition, MIZ1 ...

The action of auxin in triggering the inhibition by low P of the elongation of the PR (point 1 of the model) is suggested first by the observation that exogenous auxin supply amplified this effect (Fig. 6) and, second, by the fact that the axr4 mutant with reduced sensitivity to auxin had similar PR elongation rate at both levels of P supply (Figs. 6 and 8A). Our interpretation is that P starvation stimulates auxin accumulation in the PR apex, which resulted in a reduced elongation rate of the root. This is in agreement with the well-known negative action of auxin on PR elongation (Evans et al., 1994; Hobbie and Estelle, 1995; Timpte et al., 1995), and is further supported by our data showing that low P indeed resulted in a higher auxin concentration and an increased activity of the auxin-inducible DR5 promoter in the PR apex (Figs. 9 and 10).. The postulated decrease by P starvation of the auxin concentration in the LR initiation zone of the PR (point 2 of the model) could not be confirmed by ...

Root release of phytosiderophores (PSs) is an important step in iron (Fe) acquisition of grasses, and this adaptive reaction of plants is affected by various plant and environmental factors. The objectives of this study were to study the effects of varied nitrogen (N) supply on (1) root and leaf concentrations of methionine, a precursor in the PS biosynthesis, (2) PS release from roots, (3) mobilization and uptake of Fe from (59) Fe-labeled Fe(III)-hydroxide [(59) Fe(OH)(3) ] and (4) root uptake of (59) Fe-labeled Fe(III)-deoxymugineic acid (DMA) by durum wheat (Triticum durum, cv. Balcali2000) plants grown in a nutrient solution. Enhanced N supply from 0.5 to 6 mM in a nutrient solution significantly increased the root release of PS under Fe deficiency. High N supply was also highly effective in increasing mobilization and root uptake of Fe from (59) Fe-hydroxide under low Fe supply. With adequate Fe, N nutrition did not affect mobilization and uptake of Fe from (59) Fe(OH)(3) . Root uptake and shoot

Auxin is involved in many aspects of root development and physiology, including the formation of lateral roots. Improving our understanding of how the auxin response is mediated at the protein level over time can aid in developing a more complete molecular framework of the process. This study evaluates the effects of exogenous auxin treatment on the Arabidopsis root proteome after exposure of young seedlings to auxin for 8, 12, and 24 h, a timeframe permitting the initiation and full maturation of individual lateral roots. Root protein extracts were processed to peptides, fractionated using off-line strong-cation exchange, and analyzed using ultra-performance liquid chromatography and data independent acquisition-based mass spectrometry. Protein abundances were then tabulated using label-free techniques and evaluated for significant changes. Approximately 2000 proteins were identified during the time course experiment, with the number of differences between the treated and control roots increasing over

BackgroundPlant adaptation to limited phosphate availability comprises a wide range of responses to conserve and remobilize internal phosphate sources and to enhance phosphate acquisition. Vigorous restructuring of root system architecture provides a developmental strategy for topsoil exploration and phosphate scavenging. Changes in external phosphate availability are locally sensed at root tips and adjust root growth by modulating cell expansion and cell division. The functionally interacting Arabidopsis genes, LOW PHOSPHATE RESPONSE 1 and 2 (LPR1/LPR2) and PHOSPHATE DEFICIENCY RESPONSE 2 (PDR2), are key components of root phosphate sensing. We recently demonstrated that the LOW PHOSPHATE RESPONSE 1 - PHOSPHATE DEFICIENCY RESPONSE 2 (LPR1-PDR2) module mediates apoplastic deposition of ferric iron (Fe3+) in the growing root tip during phosphate limitation. Iron deposition coincides with sites of reactive oxygen species generation and triggers cell wall thickening and callose accumulation, which ...

BackgroundPlant adaptation to limited phosphate availability comprises a wide range of responses to conserve and remobilize internal phosphate sources and to enhance phosphate acquisition. Vigorous restructuring of root system architecture provides a developmental strategy for topsoil exploration and phosphate scavenging. Changes in external phosphate availability are locally sensed at root tips and adjust root growth by modulating cell expansion and cell division. The functionally interacting Arabidopsis genes, LOW PHOSPHATE RESPONSE 1 and 2 (LPR1/LPR2) and PHOSPHATE DEFICIENCY RESPONSE 2 (PDR2), are key components of root phosphate sensing. We recently demonstrated that the LOW PHOSPHATE RESPONSE 1 - PHOSPHATE DEFICIENCY RESPONSE 2 (LPR1-PDR2) module mediates apoplastic deposition of ferric iron (Fe3+) in the growing root tip during phosphate limitation. Iron deposition coincides with sites of reactive oxygen species generation and triggers cell wall thickening and callose accumulation, which ...

Specific root respiration rates typically increase with increasing tissue N concentration. As a result, it is often assumed that external factors inducing greater root N concentration, such as chronic N deposition, will lead to increased respiration rates. However, enhanced N availability also alters root biomass, making the ecosystem‐level consequences on whole‐root‐system respiration uncertain. The objective of this study was to determine the effects of chronic experimental N deposition on root N concentrations, specific respiration rates, and biomass for four northern hardwood forests in Michigan. Three of the six measurement plots at each location have received experimental N deposition (3 g ‐N m−2 yr−1) since 1994. We measured specific root respiration rates and N concentrations of roots from four size classes (|0.5, 0.5-1, 1-2, and 2-10 mm) at three soil depths (0-10, 10-30, and 30-50 cm). Root biomass data for the same size classes and soil depths was used in combination with specific

Experiments were conducted to compare differences in P uptake characteristics between two winter wheat cultivars Stephens and Yamhill (Triticum aestivum L) as related to root morphologies. Root length, root surface area and mean root radius were compared. Plant roots and shoots were separately analyzed for P content. The cultivars were grown in a growth chamber with a 16 hour light period at 22° C and an 8 hour darkness at 16° C for approximately three weeks. A growth medium deficient only in P and with a pH high enough (6.4 to 6.6) to prevent Al toxicity was prepared by mixing a silt loam and a sand. Soil P variables were established by adding phosphoric acid (H₃PO₄) to the soil at rates of 0, 25 and 100 ug P g⁻¹ soil. The root growth rates of the cultivars were exponential with time. Stephens had more rapid root growth rate, greater root length and root surface area than Yamhill. There were no significant cultivar differences in root radius. Stephens had higher root to shoot ratio ...

In order to test the hypothesis that multiple integrated root phenotypes would co-optimize drought tolerance, we phenotyped the root anatomy and architecture of 400 mature maize genotypes under well-watered and water-stressed conditions in the field. We found substantial variation in all 23 root phenes measured. A phenotypic bulked segregant analysis revealed that bulks representing the best and worst performers in the field displayed distinct root phenotypes. In contrast to the worst bulk, the root phenotype of the best bulk under drought consisted of greater cortical aerenchyma formation, more numerous and narrower metaxylem vessels, and thicker nodal roots. Partition against medians (PAM) clustering revealed several clusters of unique root phenotypes related to plant performance under water stress. Clusters associated with improved drought tolerance consisted of phene states that likely enable greater soil exploration by reallocating internal resources to greater root construction (increased ...

PINOID, a serine threonine protein kinase in Arabidopsis, controls auxin distribution through a positive control of subcellular localization of PIN auxin efflux carriers. Compared with the rapid progress in understanding mechanisms of auxin action in dicot species, little is known about auxin action in monocot species. Here, we describe the identification and characterization of OsPID, the PINOID ortholog of rice. Phylogenetic analysis showed that the rice genome contains a single PID ortholog, OsPID. Constitutive overexpression of OsPID caused a variety of abnormalities, such as delay of adventitious root development, curled growth of shoots and agravitropism. Abnormalities observed in the plants that overexpress OsPID could be phenocopied by treatment with an inhibitor of active polar transport of auxin, indicating that OsPID could be involved in the control of polar auxin transport in rice. Analysis of OsPID mRNA distribution showed a complex pattern in shoot meristems, indicating that it ...

Regulation of gene expression is crucial for organism growth, and it is one of the challenges in systems biology to reconstruct the underlying regulatory biological networks from transcriptomic data. The formation of lateral roots in Arabidopsis thaliana is stimulated by a cascade of regulators of which only the interactions of its initial elements have been identified. Using simulated gene expression data with known network topology, we compare the performance of inference algorithms, based on different approaches, for which ready-to-use software is available. We show that their performance improves with the network size and the inclusion of mutants. We then analyze two sets of genes, whose activity is likely to be relevant to lateral root initiation in Arabidopsis, and assess causality of their regulatory interactions by integrating sequence analysis with the intersection of the results of the best performing methods on time series and mutants. The methods applied capture known interactions ...

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Using PI as an apoplastic tracer, we evaluated the presence of an apoplastic barrier in the myb36 mutants. To quantify this barrier function, we counted the number of endodermal cells from the onset of elongation to the point where PI fluorescence was no longer observed in the stele-facing cell wall of the endodermis. We found that blockage of PI penetration into the stele in the myb36 mutants was delayed compared with wild-type and was similar to the delay observed in esb1-1 (Fig. 2D). This result indicates that the loss of the centrally located Casparian strip in myb36 eliminates the apoplastic barrier in that region of the root. Furthermore, the ectopic lignin-like material deposited in the corners of myb36 endodermal cells is not able to form an effective barrier to apoplastic transport. However, the diffusional barrier in myb36 is recovered in the more mature region of the root, where suberin is normally deposited in wild-type (1).. Similar to esb1-1 and casp1;casp3 (4), the myb36 mutants ...

Both trichomes and root hairs, the rhizoids of many vascular plants, are lateral outgrowths of a single cell of the epidermal layer. Root hairs form from trichoblasts, the hair-forming cells on the epidermis of a plant root. Root hairs vary between 5 and 17 micrometres in diameter, and 80 to 1,500 micrometres in length (Dittmar, cited in Esau, 1965). Root hairs can survive for two to three weeks and then die off. At the same time new root hairs are continually being formed at the top of the root. This way, the root hair coverage stays the same. It is therefore understandable that repotting must be done with care, because the root hairs are being pulled off for the most part. This is why planting out may cause plants to wilt. The genetic control of patterning of trichomes and roots hairs shares similar control mechanisms. Both processes involve a core of related transcription factors that control the initiation and development of the epidermal outgrowth. Activation of genes that encode specific ...

Both trichomes and root hairs, the rhizoids of many vascular plants, are lateral outgrowths of a single cell of the epidermal layer. Root hairs form from trichoblasts, the hair-forming cells on the epidermis of a plant root. Root hairs vary between 5 and 17 micrometres in diameter, and 80 to 1,500 micrometres in length (Dittmar, cited in Esau, 1965). Root hairs can survive for two to three weeks and then die off. At the same time new root hairs are continually being formed at the top of the root. This way, the root hair coverage stays the same. It is therefore understandable that repotting must be done with care, because the root hairs are being pulled off for the most part. This is why planting out may cause plants to wilt. The genetic control of patterning of trichomes and roots hairs shares similar control mechanisms. Both processes involve a core of related transcription factors that control the initiation and development of the epidermal outgrowth. Activation of genes that encode specific ...

Nitrogen (N), the primary limiting factor for plant growth and yield in agriculture, has a patchy distribution in soils due to fertilizer application or decomposing organic matter. Studies in solution culture over-simplify the complex soil environment where microbial competition and spatial and temporal heterogeneity challenge roots ability to acquire adequate amounts of nutrients required for plant growth. In this study, various ammonium treatments (as 15N) were applied to a discrete volume of soil containing tomato (Solanum lycopersicum) roots to simulate encounters with a localized enriched patch of soil. Transcriptome analysis was used to identify genes differentially expressed in roots 53 hrs after treatment. The ammonium treatments resulted in significantly higher concentrations of both ammonium and nitrate in the patch soil. The plant roots and shoots exhibited increased levels of 15N over time, indicating a sustained response to the enriched environment. Root transcriptome analysis identified

Formulated with nine wild-crafted traditional botanicals, New Roots Essence promotes the elimination of accumulated toxins through the kidneys, skin, and mucous membranes. Nutrient-rich burdock root serves as the botanical backbone of New Roots Essence with its potent ant... Where can I buy New Roots Essence

Flooding reduces supply of oxygen to the roots affecting plant water uptake. Some flooding-tolerant tree species including tamarack (Larix laricina (Du Roi) K. Koch) produce adventitious roots in response to flooding. These roots were reported to have higher hydraulic conductivity under flooding conditions compared with non-adventitious roots. In the present study, we examined structural and functional modifications in adventitious roots of tamarack seedlings to explain their flooding tolerance. Seedlings were subjected to the flooding treatment for six months, which resulted in an almost complete disintegration of the existing root system and its replacement with adventitious roots. We compared gas exchange parameters and water relations of flooded plants with the plants growing in well-drained soil and examined the root structures and root water transport properties. Although flooded seedlings had lower needle chlorophyll concentrations, their stomatal conductance, net photosynthesis rates and shoot

Further evidence for a role of EIR1 in auxin transport comes from Luschnig et al.s experiments with the altered lateral root1 (alf1) mutant, in which elevated endogenous auxin levels lead to decreased root elongation and increased lateral root formation (Celenza et al., 1995). The double mutant eir1 alf1 does not display the root-elongation defect, suggesting that eir1 acts to suppress the effects of high endogenous auxin levels conferred by alf1. Importantly, the eir1 mutation does not confer resistance to auxin that is simply added to the medium, a characteristic that experiments with the aux1 mutant suggest is more likely to be associated with defects in an auxin influx carrier.. Perhaps the most compelling evidence offered by Luschnig et al. (1998) that the eir1 mutation causes defects in an auxin efflux carrier comes from their experiments with EIR1-expressing yeast cells, which are resistant to toxic fluoroindoles. Although other explanations are possible, resistance to these compounds is ...

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With climate change and an ever-increasing human population threatening food security, developing a better understanding of the genetic basis of crop performance under stressful conditions has become increasingly important. Here, we used genome-wide association studies to genetically dissect variation in seedling growth traits in cultivated sunflower (Helianthus annuus L.) under well-watered and water-limited (i.e., osmotic stress) conditions, with a particular focus on root morphology. Water limitation reduced seedling size and produced a shift toward deeper rooting. These effects varied across genotypes, and we identified 13 genomic regions that were associated with traits of interest across the two environments. These regions varied in size from a single marker to 186.2 Mbp and harbored numerous genes, some of which are known to be involved in the plant growth/development as well as the response to osmotic stress. In many cases, these associations corresponded to growth traits where the common allele

When primary Arabidopsis roots grow down a tilted agar plate, they do not elongate following the gravitational vector along a straight line, but instead they slant noticeably to the right-hand. This process is seen mostly in the ecotypes Wassilewskji

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Adventitious root (AR) formation in the stem base of cuttings is the basis for propagation of many plant species and petunia is used as model to study this developmental process. Following AR formation from 2 to 192 hours after excision (hpe) of cuttings, transcriptome analysis by microarray revealed a change of the character of the rooting zone from stem base to root identity. The greatest shift in the number of differentially expressed genes was observed between 24 and 72 hpe, when the categories storage, mineral nutrient acquisition, anti-oxidative and secondary metabolism, and biotic stimuli showed a notable high number of induced genes. Analyses of phytohormone-related genes disclosed multifaceted changes of the auxin transport system, auxin conjugation and the auxin signal perception machinery indicating a reduction in auxin sensitivity and phase-specific responses of particular auxin-regulated genes. Genes involved in ethylene biosynthesis and action showed a more uniform pattern as a high number

The results presented in this work are significant for both fundamental and applied plant biology. They strongly argue that both NO and cGMP are downstream messengers in the IAA-signaling pathway that promotes adventitious root development. NO treatments were able to induce adventitious rooting in cucumber explants to the same extent as the plant hormone IAA. Because the specific NO-scavenger cPTIO causes a significant reduction of adventitious root number in IAA-treated explants, endogenous NO appears to play a key role in the auxin-mediated adventitious rooting process (Fig. 1). The endogenous IAA is synthesized in the apical bud, above cotyledons, and is basipetally transported down the plant stem via the polar transport system (Ford et al., 2001). The involvement of polar auxin transport in supplying the auxin for rooting was clearly established in carnation (Dianthus caryophyllus) cuttings (Guerrero et al., 1999). To clarify the nature of the IAA-NO communication, a pretreatment leading to ...

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Potassium ion and Na+ influx and efflux rates into and from excised barley roots are compared with the maximum capacity of accumulation. Potassium ion and Na+ influx and efflux involve a cation exchange that is independent of simultaneous exchange of the accompanying anion. These exchange fluxes depend on the concentration and cation composition of the solutions from which they originate. Selective differences between K+ and Na+ fluxes are sufficient to account for a cationic distribution within the roots that differs markedly from that of the external solution and that persists for extended time periods. The accumulation maximum is a cation exchange equilibrium with the cation influx and efflux rates approaching equality. The equilibrium level is independent of the individual cation fluxes and the external solution concentration. It is a finite quantity which appears to be determined by the internal anion concentration including accumulated as well as endogenous anions.. ...

After wounding, nitric oxide promotes, in AR development in response to nitric oxide has been also observed in, ss [95]. controlling the localization and transcription of, 78]. Phytohormones, together with many other internal and external stimuli, coordinate and guide every step of AR formation from the first event of cell reprogramming until emergence and outgrowth. ; Benson, F.C. fic Ethylene-Insensitive Mutants in Arabidopsis. ; Black, C.R. The WUSCHEL-related homeobox gene WOX11 is, Zhao, Y.; Cheng, S.; Song, Y.; Huang, Y.; Zhou, S.; Liu, X.; Zhou, D.-X. Provide Support 3. Adventitious roots form from stem tissues, generally as a result of damage or removal of the primary root system. In addition, gene products related to gibberellin (GA) biosynthesis and signaling, auxin homeostasis, and xylem differentiation were confirmed to participate in adventitious root formation. From Wikipedia, the free encyclopedia. All rights reserved. ; Kumari, S.; Cho, M.; Lee, S.H. which encodes an AP2/ERF ...

The word mycorrhizae comes from the Greek words for fungus and root, and refers to the symbiotic relationship that exists between plant roots and certain fungi. In natural settings, these mycorrhizal fungi are present in the soil in association with plant roots. The fungi colonize by attaching to the surface of the root (ectomycorrhizal) or to the inside of the root cells (endomycorrhizal). Then they send their filaments (called mycelium) into the surrounding soil, effectively extending the plants roots and root absorbing capacity ten to 1000 times-far beyond what the plant can do alone.3 Several miles of these ultra-fine filaments can be present in less than a thimbleful of soil. Mycorrhizae supply the water and nutrients needed by the plant for establishment and survival, and, in return, receive from the plant roots sugars and other compounds needed by the fungus. Mycorrhizae are much smaller than roots, so they can easily penetrate into smaller spaces between soil particles, where they ...

The patterned assignment of different cell fates, shortly termed patterning, lies at the basis of growth, development and reproduction of multicellular organisms. The single-layered epidermal tissue of Arabidopsis thaliana is characterized by hair-like cellular protuberances, the root hairs and the leaf trichomes, respectively, emerging from a subset of cells. Specification of hair and non-hair cell fate occurs in a tightly controlled fashion by gene regulatory networks of overlapping components that, however, often have opposite functions in root and shoot. Moreover, the root epidermis displays organization in hair- and non-hair cell files while leaf trichomes are distributed in a regular spacing pattern over the leaf. In contrast to the shoot, assignment of a cell files fate in the root epidermis depends on the cells position with respect to the underlying root cortical cell layer, which defines cells atop the border of two cortical cells as hair- and cells atop a single cortical cell as ...

In this study effects of strong, complex, rhythmic accent classical music with sekunda and kvarta intervals and frequently reprized and opus with rhythmic dynamically changing lyrics which contain more extensive kvinta septa oktava intervals on mitotic index and root growth were investigated in onion (Allium cepa) root tip cells during germination. For this aim, music samples from Wagner, Mozart, Musorgsky, (Boris Godunov) Chopin, Tchaikovski, Schubert were chosen. We found correlation between root elongation and Mitotic Index (MI). Both kinds of music have positive effects on root growth and mitotic divisions in onion root tip cells but rhythmic dynamically changing lyrics affected much better. In this study light microscopy techniques were used but ultrastructure of root tip cells will be studied with electron microscope in the following study. © 2007 Asian Network for Scientific Information ...

Mycorrhizal fungi influence plant nutrition and therefore likely modify competition between plants. By affecting mycorrhiza formation and nutrient availability of plants, Collembola may influence competitive interactions of plant roots. We investigated the effect of Collembola (Protaphorura fimata Gisin), a mycorrhizal fungus (Glomus intraradices Schenck and Smith), and their interaction on plant growth and root structure of two plant species, Lolium perenne L. (perennial ryegrass) and Trifolium repens L. (white clover). In a laboratory experiment, two individuals of each plant species were grown either in monoculture or in competition to the respective other plant species. Overall, L. perenne built up more biomass than T. repens. The clover competed poorly with grass, whereas the L. perenne grew less in presence of conspecifics. In particular, presence of conspecifics in the grass and presence of grass in clover reduced shoot and root biomass, root length, number of root tips, and root volume. ...

In this work, we have shown that a unique homolog of an Arabidopsis cytokinin receptor, Mt CRE1, is required for the regulation of several aspects of root architecture in the model legume species M. truncatula. This gene controls secondary root organogenesis, with a positive effect on symbiotic nodule development and a negative impact on lateral root formation. Crosstalk between the cytokinin and Nod factor signaling pathways involving Mt RR1, Mt RR4, and Mt NIN could be identified.. In Arabidopsis, several HKs display distinct specificities regarding their involvement in root development. The closest homolog of Mt CRE1, AHK4/CRE1/WOL, was initially associated with root development, as the wol allele only showed a root phenotype (Scheres et al., 1995; Mahonen et al., 2000). By contrast, mutations in the other AHKs, ahk2 and ahk3, showed no root phenotype, whereas an ahk2 ahk3 double mutant was semidwarfed and its roots, despite a normal response to cytokinins, showed increased branching ...

Piriformospora indica is known as a fungus that can easily colonize a wide range of plants and enhance hosts growth and tolerance to abiotic stresses, including salinity. The mechanistic basis behind this phenomenon remains poorly understood. This work was aimed to fill in this gap and reveal mechanisms enhancing salinity tolerance in maize roots colonised by P. indica. A range of agronomic and physiological characteristics were compared between inoculated and non-inoculated maize plants under 0/100/200 mM NaCl conditions. The impact of P. indica inoculation or roots cytosolic K+ retention ability were also assessed using micro-electrode ion flux estimation technique. The results showed that inoculated plants had higher biomass, higher stomatal conductance, lower K+ efflux from roots and higher potassium content in shoots than non-inoculated plants under salt stress. Collectively, the results indicated that the beneficial effects of inoculation on plant performance under saline conditions were ...

article{445484, abstract = {The rate, polarity, and symmetry of the flow of the plant hormone auxin are determined by the polar cellular localization of PIN-FORMED (PIN) auxin efflux carriers. Flavonoids, a class of secondary plant metabolites, have been suspected to modulate auxin transport and tropic responses. Nevertheless, the identity of specific flavonoid compounds involved and their molecular function and targets in vivo are essentially unknown. Here we show that the root elongation zone of agravitropic pin2/eir1/wav6/agr1 has an altered pattern and amount of flavonol glycosides. Application of nanomolar concentrations of flavonols to pin2 roots is sufficient to partially restore root gravitropism. By employing a quantitative cell biological approach, we demonstrate that flavonoids partially restore the formation of lateral auxin gradients in the absence of PIN2. Chemical complementation by flavonoids correlates with an asymmetric distribution of the PIN1 protein. pin2 complementation ...

ethylene; Ein2; germination; RbohD; submergence; hypoxia; post-submergence recovery; legumes; plant water relations; shoot to root ratio; Lotus japonicus; leaf greenness; leaf desiccation; stomatal conductance; aerenchyma; auxin; rice (Oryza sativa); root; waterlogging; leaf gas exchange; waterlogging tolerance; organic compound; plant growth; Physalis peruviana L.; anaerobiosis; anoxia; Arabidopsis; flooding; rice; development; apoplastic barrier; barrier to radial oxygen loss (ROL); lignin; Oryza glumaepatula; O. rufipogon; rice (O. sativa); suberin; wild rice; acetolactate synthase; ethanol fermentation; imidazolinones; mode of action; aerobic fermentation; Oryza sativa; Submergence; Activity of antioxidant enzymes; Chlorophyll content; phytoglobin; VII Ethylene Response Factor; PRT6 N-degron pathway of proteolysis; Solanum tuberosum; Solanum lycopersicum; Solanum dulcamara; coleoptile; root hypoxia; oxygen sensing; jasmonate; root meristem; abiotic stress; RNA-seq; transcription factor; ...

Infestation pattern of P. indica in barley roots. (a) By 8 dai, hyphae excessively occupy rhizodermal and cortical cells of the differentiation zone. The elongation zone is less colonized, with occasional intercellular subepidermal hyphal structures. The root cap is heavily infested with hyphae. (b-e) After penetration (arrows) fungal hyphae colonize the subepidermal layer. (b) To better visualize the position of hyphae in the z axis, a confocal laser scanning image consisting of 30 frames of adjacent focal planes (z axis) was displayed as a maximum projection with the fluorescent signal of the wheat germ agglutinin-stained fungal hyphae displayed in red for the upper (abaxial) 15 frames and in green for the lower (adaxial, subepidermal) 15 frames. (c and d) For visualization of plant cell walls, two close-up bright-field images of two different focal planes are superimposed with the respective frames of the fluorescence images. Intercellular hyphae start branching and proliferate within the ...

TY - JOUR. T1 - O2 dynamics in the rhizosphere of young rice plants (Oryza sativa L.) as studied by planar optodes. AU - Larsen, Morten. AU - Santner, Jakob. AU - Oburger, Eva. AU - Wenzel, Walter W.. AU - Glud, Ronnie N.. PY - 2015/5/1. Y1 - 2015/5/1. KW - planar optode, rice (Oryza sativa L), radial oxygen loss, rhizosphere, plaques imaging, oxygen, iron plaque-formation, marine sediments, zostera marina, submerged rice, aerenchyma formation, stagnant solution, solution culture, root aeration, ph. U2 - 10.1007/s11104-015-2382-z. DO - 10.1007/s11104-015-2382-z. M3 - Article. VL - 390. SP - 279. EP - 292. JO - Plant and Soil. JF - Plant and Soil. SN - 0032-079X. IS - 1. ER - ...

Root gravitropism may be an important element of plant response to phosphorus availability because it determines root foraging in fertile topsoil horizons, and thereby phosphorus acquisition. In this study we seek to test this hypothesis in both two-dimensional paper growth pouch and three-dimensional solid media of sand and soil cultures. Five common bean ( Phaseolus vulgaris ) genotypes with contrasting adaptation to low phosphorus availability were evaluated in growth pouches over 6 days of growth, and in sand culture and soil culture over 4 weeks of growth. In all three media, phosphorus availability regulated the gravitropic response of basal roots in a genotype-dependent manner. In pouches, sand, and soil, the phosphorus-inefficient genotype DOR 364 had deeper roots with phosphorus stress, whereas the phosphorus-efficient genotype G19833 responded to phosphorus stress by producing shallower roots. Genotypes were most responsive to phosphorus stress in sand culture, where relativeroot ...

Appearance: Root-knot nematodes are about one-tenth the size of a pinhead and are typically embedded inside roots. They are impossible to see with the naked eye. Juvenile root-knot nematodes (both males and females), as well as adult males, are vermiform (i.e., worm-shaped) and live in the soil. Adult females are spherical in shape and live inside roots. Both males and females possess a thin, tube-like structure called a stylet that they use for penetrating root tissue.. Symptoms and Effects: When root-knot nematodes enter roots, they release chemicals that cause nearby root cells to enlarge. This leads to the formation of swollen, distorted areas in roots known as galls or knots. The number and size of galls varies depending on plant species and cultivar, and the number of root-knot nematodes in the soil. On some hosts (e.g., grasses) root swelling can be very difficult to detect. Nematode feeding interferes with proper root function (e.g., water and nutrient movement). Thus infected plants may ...

Looking for cichorium intybus? Find out information about cichorium intybus. chicory chicory Leaves look like dandelion leaves, but the rest of the plant is quite different. Chicory has tall, almost empty stick-like stalks with light... Explanation of cichorium intybus

In plants, undifferentiated meristem tissue provides stem cells to produce roots and shoots. The root meristem contains a few of these stem cells in a region called the quiescent center. Ortega-Martínez et al. studied Arabidopsis plants with a defect in a gene that controls ethylene biosynthesis and found that it produced more of the gaseous hormone ethylene. The quiescent center cells in these mutants went through more cell divisions than normal, resulting in extra stem cells in the root meristem. Adding exogenous ethylene also increased quiescent cell division, and blocking its synthesis in the mutants prevented extra divisions.. O. Ortega-Martínez, M. Pernas, R. J. Carol, L. Dolan, Ethylene modulates stem cell division in the Arabidopsis thaliana root. Science 317, 507-510 (2007). [Abstract] [Full Text] ...

MBI-3X is a new nematicide formulated from fermented and killed microbial broth. The broth contains large amounts of dead cells and an array of secondary metabolites in the fermentation supernatant with a corresponding array of potential effects on plants and agricultural pests. Some of these metabolites have been observed to have phytotoxic or herbicidal effects on plant tissue when applied at high rates. However, preliminary observations also suggest there may be positive plant health effects in certain species, particularly root crops. If MBI-3X is confirmed to promote plant health, this could be the result of fertilization by the nutrient broth, hormesis, or some unpredicted factor. Experiments were conducted to confirm the existence of plant health effects on selected commercially important underground plant structures such as radish (Raphanus sativus), sugar beet (Beta vulgaris), onion (Allium cepa), and other root crops. The nature of plant health effects was represented by collecting ...

TY - JOUR. T1 - The role of the plasma membrane H+-ATPase in plant responses to aluminum toxicity. AU - Zhang, Jiarong. AU - Wei, Jian. AU - Li, Dongxu. AU - Kong, Xiangying. AU - Rengel, Zed. AU - Chen, Limei. AU - Yang, Ye. AU - Cui, Xiuming. AU - Chen, Qi. PY - 2017/10/17. Y1 - 2017/10/17. N2 - Aluminum (Al) toxicity is a key factor limiting plant growth and crop production on acid soils. Increasing the plant Al-detoxification capacity and/or breeding Al-resistant cultivars are a cost-effective strategy to support crop growth on acidic soils. The plasma membrane H+-ATPase plays a central role in all plant physiological processes. Changes in the activity of the plasma membrane H+-ATPase through regulating the expression and phosphorylation of this enzyme are also involved in many plant responses to Al toxicity. The plasma membrane H+-ATPase mediated HC influx may be associated with the maintenance of cytosolic pH and the plasma membrane gradients as well as Al-induced citrate efflux mediated ...

High/ Low Phosphate diet I. A five-day low phosphate diet / A five-day low phosphate diet with the addition of a phosphate binder / A five-day high phosphate diet.. II. A five-day low phosphate diet / A five-day high phosphate diet / A five-day low phosphate diet with the addition of a phosphate binder III. A five-day high phosphate diet / A five-day low phosphate diet with the addition of a phosphate binder / A five-day low phosphate diet.. IV. A five-day high phosphate diet / A five-day low phosphate diet / A five-day low phosphate diet with the addition of a phosphate binder.. V. A five-day low phosphate diet with the addition of a phosphate binder / A five-day low phosphate diet / A five-day high phosphate diet.. VI. A five-day low phosphate diet with the addition of a phosphate binder / A five-day high phosphate diet / A five-day low phosphate diet. ...

Dietary sources of phosphorus include milk products, egg yolk, legumes, nuts, and whole grains. 1. Diseases such as Crohns disease and celiac disease impair the bodys ability to absorb nutrients such as phosphorus. Phosphorus is a mineral that is vitally important to the normal metabolism of numerous compounds and (in solution) an acid that, with sulfur, must be neutralized by the base-forming ions of sodium, potassium, calcium, and magnesium. [PHOSPHORUS DEFICIENCY IN HUMANS?]. Its deficiency though is uncommon as … Severe phosphorus deficiency can manifest as widespread organ dysfunction. However a deficiency of phosphorus is rare as it is present in most foods. Phosphorus deficiency may cause bone diseases such as rickets in children and osteomalacia in adults. Phosphorus deficiency (hypophosphatemia) is rare in the United States and is almost never the result of low dietary intakes [ 1 ]. Phosphate is what you get when you combine the mineral phosphorus with oxygen. [Article in Swedish] ...

Aluminum (Al) toxicity is one of the main factors limiting crop productivity in strongly acidic soils. Plant tolerance to Al toxicity has been widely studied even if the mechanisms involved in the plant response are yet not fully elucidated. White lupin is well known to release organic acids and flavonoids under nutrient deficiency, while less is known about its response to elevated Al concentrations. The aim of this work was therefore to shed light to the adaptive response of white lupin to Al toxicity, analysing the root exudate pattern. A pH buffer (MES) or inhibitor compounds were used in order to further investigate the mechanisms adopted by white lupin to release root exudates as response to Al toxicity. The results showed that not only organic acids but also phenolic compounds are involved in the response to elevated concentrations of Al together with the alkalinisation of the growth medium ...

TY - JOUR. T1 - Seasonal water uptake and movement in root systems of Australian phraeatophytic plants of dimorphic root morphology: a stable isotope investigation. AU - Dawson, T.E.. AU - Pate, John. PY - 1996. Y1 - 1996. N2 - A natural abundance hydrogen stable isotope technique was used to study seasonal changes in source water utilization and water movement in the xylem of dimorphic root systems and stem bases of several woody shrubs or trees in mediterranean-type ecosystems of south Western Australia. Samples collected from the native tree Banksia prionotes over 18 months indicated that shallow lateral roots and deeply penetrating tap (sinker) roots obtained water of different origins over the course of a winter-wet/summer-dry annual cycle. During the wet season lateral roots acquired water mostly by uptake of recent precipitation (rain water) contained within the upper soil layers, and tap roots derived water from the underlying water table. The shoot obtained a mixture of these two water ...

Rice (Oryza sativa) is a staple food that feeds more than half the world population. As rice is highly sensitive to soil salinity, current trends in soil salinization threaten global food security. To better understand the mechanistic basis of salinity tolerance in rice, three contrasting rice cultivars - Reiziq (tolerant), Doongara (moderately tolerant), and Koshihikari (sensitive) - were examined and the differences in operation of key ion transporters mediating ionic homeostasis in these genotypes were evaluated. Tolerant varieties had reduced Na+ translocation from roots to shoots. Electrophysiological and quantitative reverse transcription PCR experiments showed that tolerant genotypes possessed 2-fold higher net Na+ efflux capacity in the root elongation zone. Interestingly, this efflux was only partially mediated by the plasma membrane Na+/H+ antiporter (OsSOS1), suggesting involvement of some other exclusion mechanisms. No significant difference in Na+ exclusion from the mature root ...

Since sugarcane is a ratoon crop, genome evaluation of plant growth-promoting bacteria that exist in its soil rhizosphere, can present alternative to better perceive their traits and use of such bacteria in flip, might particularly enhance perennial crop productiveness. In the current examine, genome of two bacterial strains, one every of B. megaterium (BM89) and B. subtilis (BS87), isolated and reported earlier (Chandra et al., 2018), had been sequenced and characterized. Though each strains have demonstrated plant development selling properties and enhanced in-vitro plant development responses, purposeful annotation and evaluation of genes indicated superiority of BS87 because it possessed extra plant development promotion attributable genes over BM89.. Apart from some frequent genes, trehalose metabolism, glycine betaine manufacturing, peroxidases, tremendous oxide dismutase, chilly shock proteins and phenazine manufacturing related genes had been selectively recognized in BS87 genome ...

Induction and emergence of hairy roots. A. rhizogenes strain K599 could induce hairy root formation in 47% excised leaf explants. The time period required for hairy root induction and frequency of transformation varied with respect to the age of explants. Leaf explants obtained from 3 and 4 weeks old in vitro cultures were only the responsive explants (Figure 1) and exhibited 46.6 and 35.0% TF after 25 and 28 days of bacterial infection respectively. Young leaf explants showed higher TF (47%) which decreased with an increase in explants age. A number of previous studies showed that type and age of explant have a great influence on hairy root induction since age of explant is a major factor that alters the physiological properties of the cell (Dupre et al. 2000). A strong correlation between TF and the age of wheat donor plants was observed when two different varieties of wheat were used for transformation with Agrobacterium. The mean TF increased from 0.7% to 5% using immature embryo from old ...

Main conclusion: Aluminum toxicity and sulfate deprivation both regulate microRNA395 expression, repressing its low-affinity sulfate transporter (SULTR2;1) target. Sulfate deprivation also induces the high-affinity sulfate transporter gene (SULTR12), allowing enhanced sulfate uptake. Few studies about the relationships between sulfate, a plant nutrient, and aluminum, a toxic ion, are available; hence, the molecular and physiological processes underpinning this interaction are poorly understood. The Al-sulfate interaction occurs in acidic soils, whereby relatively high concentrations of trivalent toxic aluminum (Al3+) may hamper root growth, limiting uptake of nutrients, including sulfur (S). On the other side, Al3+ may be detoxified by complexation with sulfate in the acid soil solution as well as in the root-cell vacuoles. In this review, we focus on recent insights into the mechanisms governing plant responses to Al toxicity and its relationship with sulfur nutrition, emphasizing the role of ...

The epidermis of roots is composed of hair and non-hair cells. Patterning of this epidermis results from spatially regulated differentiation of these cell types. Root epidermal development in vascular plants may be divided into three broad groups based on the mode of hair development; Type 1: any cell in the epidermis can form a tool hair; Type 2: the smaller product of an asymmetric cell division forms a root hair; Type 3: the epidermis is organized into discrete files of hair and non- hair cells. The Arabidopsis root epidermis is composed of discrete files of hair and non-hair cells (Type 3). Genetic trod physiological evidence indicates that ethylene is a positive regulator of hair cell development Genes with opposite roles in the development of hair cells in the shoot (trichomes) and hair cells in the root have been identified. Plants with presumptive loss of function alleles in the TRANSPARENT TESTA GLABRA (TTG) or GLABRA2 (GL2) genes are devoid of trichomes indicating that these genes are positive

Strigolactones, first discovered as germination stimulants for parasitic weeds [1], are carotenoid-derived phytohormones that play major roles in inhibiting lateral bud outgrowth and promoting plant-mycorrhizal symbiosis [2-4]. Furthermore, strigolactones are involved in the regulation of lateral and adventitious root development, root cell division [5, 6], secondary growth [7], and leaf senescence [8]. Recently, we discovered the strigolactone transporter Petunia axillaris PLEIOTROPIC DRUG RESISTANCE 1 (PaPDR1), which is required for efficient mycorrhizal colonization and inhibition of lateral bud outgrowth [9]. However, how strigolactones are transported through the plant remained unknown. Here we show that PaPDR1 exhibits a cell-type-specific asymmetric localization in different root tissues. In root tips, PaPDR1 is co-expressed with the strigolactone biosynthetic gene DAD1 (CCD8), and it is localized at the apical membrane of root hypodermal cells, presumably mediating the shootward ...

The growth of plant organs is influenced by a stream of the phytohormone auxin that flows from the shoot apex to the tip of the root. However, until now it has not been known how auxin regulates the cell proliferation and enlargement that characterizes organ growth. Here we show that auxin controls …

Hydrotropism is a genuine response of roots to a moisture gradient to avoid drought. An experimental system for the induction of hydrotropic root response in petri dishes was designed by pioneering groups in the field. This system uses split agar plates containing an osmolyte only in a region of the plate in order to generate a water potential gradient. Arabidopsis seedlings are placed on the MS agar plate so that their root tips are near the junction between plain MS medium and the region supplemented with the osmolyte. This elicits a hydrotropic response in Arabidopsis roots that can be measured as the root curvature angle.. ...

This study aimed to evaluate the impact of genetically modified (GM) wheat with introduced pm3b mildew resistance transgene, on two types of root-colonizing microorganisms, namely pseudomonads and arbuscular mycorrhizal fungi (AMF). Our investigations were carried out in field trials over three field seasons and at two locations. Serial dilution in selective Kings B medium and microscopy were used to assess the abundance of cultivable pseudomonads and AMF, respectively. We developed a denaturing gradient gel electrophoresis (DGGE) method to characterize the diversity of the pqqC gene, which is involved in Pseudomonas phosphate solubilization. A major result was that in the first field season Pseudomonas abundances and diversity on roots of GM pm3b lines, but also on non-GM sister lines were different from those of the parental lines and conventional wheat cultivars. This indicates a strong effect of the procedures by which these plants were created, as GM and sister lines were generated via tissue

Seedlings of the annual grass Vulpia ciliata ssp. ambigua were grown in sterilized sand with a dark septate root fungus, Phialophora graminicola, which had been isolated from a natural population of the grass. Tiller number and shoot, root and total biomass of seedlings grown with P. graminicola were enhanced relative to uninoculated control plants in a growth room and a glasshouse experiment. Root length of seedlings grown with P. graminicola was significantly increased, but no effects of the fungus on root diameter, number of root hairs or specific root length were recorded. Root nitrogen content and shoot, root and total phosphorus contents of seedlings grown with the fungus were enhanced, but shoot nitrogen concentration of these plants was reduced. Shoot biomass and specific root length of inoculated plants were positively associated with the number of P. graminicola colonies re-isolated from roots. These data indicate that P. graminicola acts as a beneficial associate of V. ciliata ssp. ...

The objectives of this study were to detect coarse tree root and to estimate root biomass in the field by using an advanced 3D Ground Penetrating Radar (3D GPR) system. This study obtained full-resolution 3D imaging results of tree root system using 500 MHz and 800 MHz bow-tie antennas, respectively. The measurement site included two larch trees, and one of them was excavated after GPR measurements. In this paper, a searching algorithm, based on the continuity of pixel intensity along the root in 3D space, is proposed, and two coarse roots whose diameters are more than 5 cm were detected and delineated correctly. Based on the detection results and the measured root biomass, a linear regression model is proposed to estimate the total root biomass in different depth ranges, and the total error was less than 10%. Additionally, based on the detected root samples, a new index named

Plant performance is, at least partly, linked to the location of roots with respect to soil structure features and the micro-environment surrounding roots. Measurements of root distributions from intact samples, using optical microscopy and field tracings have been partially successful but are imprecise and labour-intensive. Theoretically, X-ray computed micro-tomography represents an ideal solution for non-invasive imaging of plant roots and soil structure. However, before it becomes fast enough and affordable or easily accessible, there is still a need for a diagnostic tool to investigate root/soil interplay. Here, a method for detection of undisturbed plant roots and their immediate physical environment is presented. X-ray absorption and phase contrast imaging are combined to produce projection images of soil sections from which root distributions and soil structure can be analyzed. The clarity of roots on the X-ray film is sufficient to allow manual tracing on an acetate sheet fixed over the ...

Rice is a well-established salt-sensitive cereal crop and is the second most widely grown and consumed food crop worldwide. It is also a semi-aquatic cereal crop. The rice plant has many adaptations for surviving the aquatic environment, which include the development of specialised roots called adventitious roots, increase in aerenchymal area, increase in the number of roots, reduction of laterals, stunted growth, thickening of the apoplastic barrier in the roots and induction of the radial oxygen loss (ROL) barrier. How these adaptations respond to salinity is a question that has been least explored, and is addressed in this book. A number of interesting findings on the response of the plant to salinity under stagnant deoxygenated conditions (waterlogged conditions for performing laboratory level studies were established using hydroponics) were compared to the normal way of growing rice plants using hydroponics (fully aerated solutions). The purpose of this study is to give a precise representation

UV-B irradiation of barley (Hordeum vulgare L.) roots (1 W/m2, 15 min) or leaves (3 W/m2, 3.3 h) and also one-day-long root incubation in the Knop solution supplemented with 1-4 μM ABA, 1 mM salicylic acid, 16 μM ionomycin, or 0.1 mM colchicine induced growth retardation and subapical root swelling. All factors, except for colchicine, initiated growth of root hairs on the surface of swellings and suppressed their initiation and growth in more basal root region. During the first hour after unilateral root UV-B irradiation, their growth sharply retarded and hydraulic conductivity of membranes in the rhizodermis of growth zone rose 1.5-fold. In 2.5 h, root tips bent toward the source of irradiation. In 4.5 h, the ratio of longitudinal to transverse root extensibility in the root growth zone reduced twofold. In 8 h, root diameter in the subapical zone increased and root hairs appeared in this zone and attained 300 μm in length. In a day after irradiation, on unirradiated root side, meristematic cells

Understanding the molecular mechanisms that convey salt tolerance in plants is a crucial issue for increasing crop yield. The ice plant (Mesembryanthemum crystallinum) is a halophyte that is capable of growing under high salt conditions. For example, the roots of ice plant seedlings continue to grow in 140 mM NaCl, a salt concentration that completely inhibits Arabidopsis thaliana root growth. Identifying the molecular mechanisms responsible for this high level of salt tolerance in a halophyte has the potential of revealing tolerance mechanisms that have been evolutionarily successful. In the present study, deep sequencing (RNAseq) was used to examine gene expression in ice plant roots treated with various concentrations of NaCl. Sequencing resulted in the identification of 53,516 contigs, 10,818 of which were orthologs of Arabidopsis genes. In addition to the expression analysis, a web-based ice plant database was constructed that allows broad public access to the data. The results obtained ...

TY - JOUR. T1 - Lettuce, a shallow-rooted crop, and Lactuca serriola, its wild progenitor, differ at QTL determining root architecture and deep soil water exploitation. AU - Johnson, W. C.. AU - Jackson, L. E.. AU - Ochoa, O.. AU - Van Wijk, R.. AU - Peleman, J.. AU - St. Clair, D. A.. AU - Michelmore, Richard W. PY - 2000. Y1 - 2000. N2 - Wild plant species are often adapted to more stressful environments than their cultivated relatives. Roots are critical in exploiting soil resources that enable plants to withstand environmental stresses, but they are difficult to study. Cultivated lettuce (Lactuca sativa L.) and wild L. serriola L. differ greatly in both shoot and root characteristics. Approximately 100 F(2:3) families derived from an interspecific cross were evaluated in greenhouse and field experiments. In the greenhouse, root traits (taproot length, number of laterals emerging from the taproot, and biomass) and shoot biomass were measured 4 weeks after planting. In the field, plants were ...

Fig. (6) Staining of invertase activity on the parts of the transverse sections of a maize root tip from the region of the beginning of the elongation zone (A, B) and from the basal part of the meristem (C). The parts of the sections contain rhizodermis (rh), cortex (cor), endodermis (en), pericycle (pc) and stele (A, B) and a region of vascular cylinder (C). The reaction with (A, C) or without (В) sucrose in the incubation medium. Bar - 100 µm (A, B), 25 µm (C). ph - phloem, mx - metaxylem vessel, px - protoxylem vessel. ...

Ionic aluminum (mainly Al3+) is rhizotoxic and can be present in acid soils at concentrations high enough to inhibit root growth. Many forest tree species grow naturally in acid soils and often tolerate high concentrations of Al. Previously, we have shown that aspen (Populus tremula) releases citrate and oxalate from roots in response to Al exposure. To obtain further insights into the root responses of aspen to Al, we investigated root gene expression at Al conditions that inhibit root growth. Treatment of the aspen roots with 500 μM Al induced a strong inhibition of root growth within 6 h of exposure time. The root growth subsequently recovered, reaching growth rates comparable to that of control plants. Changes in gene expression were determined after 6 h, 2 d, and 10 d of Al exposure. Replicated transcriptome analyses using the Affymetrix poplar genome array revealed a total of 175 significantly up-regulated and 69 down-regulated genes, of which 70% could be annotated based on Arabidopsis genome

The other IBA-response mutants utilize stored fatty acids during germination normally (Figure 3, Table 2). Because these mutants are generally as resistant to IBA as the putative peroxisomal mutants (Figure 2), we do not believe that they are simply extremely leaky peroxisomal mutants. These nonperoxisomal mutants can be further subdivided into three classes. The class 2 mutants (ibr1-1, ibr1-2, ibr2, and ibr3) are resistant to the auxin effects of IBA on both root elongation and lateral root proliferation, but have wild-type responses to other auxins (IAA and 2,4-D) and auxin transport inhibitors (NPA, TIBA, and HFCA). The class 2 mutants could be defective in enzymes that convert IBA to IAA but are not necessary for the β-oxidation of seed storage lipids. Alternatively, these mutants may be defective in an IBA receptor, signaling pathway, or response factor. If these mutants have normal IBA to IAA conversion, it will suggest that IBA plays at least two roles in the promotion of lateral roots, ...

Nodules are a growth on the roots of leguminous plants where the bacteria reside. The plant roots secrete amino acids and sugars into the rhizosphere. The rhizobia move toward the roots and attach to the root hairs. The plant then releases flavanoids, which induce the expression of nod genes within the bacteria. The expression of these genes results in the production of enzymes called Nod factors that initiate root hair curling. During this process, the rhizobia are curled up with the root hair. The rhizobia penetrate the root hair cells with an infection thread that grows through the root hair into the main root. This causes the infected cells to divide and form a nodule. The rhizobia can now begin nitrogen fixation.. ...