Calcium-accumulating cells in the meristematic region of grapevine root apices

2003 ◽  
Vol 30 (6) ◽  
pp. 719 ◽  
Author(s):  
Richard Storey ◽  
R. Gareth Wyn Jones ◽  
Daniel P. Schachtman ◽  
Michael T. Treeby
Keyword(s):  
Primary Root ◽  
Outer Region ◽  
Root Apex ◽  
Root Tip ◽  
Cortical Cells ◽  
Major Cations ◽  
High Calcium ◽  
High Concentrations ◽  
Root Apices ◽  
Crystal Idioblast

Apical roots of grapevines were examined by cryo-SEM (scanning electron microscopy) and the intracellular distribution of Ca was demonstrated by X-ray microanalysis in different regions of the primary root. We show that large amounts of Ca are accumulated as raphide crystals in the vacuoles of specialised cortical cells (idioblast cells) of the root apex. These crystal idioblast cells appeared to form a discontinuous cone of cells in the outer region of the root meristem. The raphide crystals within these cells were less apparent in older regions of the root, 10–12 mm basipetal to the root tip. We suggest that the raphide crystals could initially act as another Ca sink involved in the regulation of Ca levels in root apices. In older regions of the root these cells are spaced at intervals around the periphery of the cortex and the subsequent disappearance of the raphides may be indicative of remobilisation, perhaps in the zone of elongation where cell wall synthesis occurs and Ca demand is high. Calcium-accumulating cells were also observed in the older regions of the root, forming endodermal protrusions extending into the cortex. These cells may play a part in regulating Ca delivery to the xylem stream by sequestration of Ca from the radial flow of water at the endodermis. The observed distribution of Ca in root apices was different from the other major cations (e.g. K) and anions (e.g. Cl) because high concentrations were localised to specific cells. We interpret the results in the context of a model of the dynamics of grapevine root growth and cell differentiation, and the temporal balance of solute supply from the protophloem and the external medium.

Observations on bud formation and proliferations on cytokinin-treated root segments of Ophioglossum petiolatum

1969 ◽  
Vol 47 (10) ◽  
pp. 1579-1583 ◽  
Author(s):  
R. L. Peterson
Keyword(s):  
Apical Cell ◽  
Root Apex ◽  
Leaf Primordia ◽  
Distilled Water ◽  
Water Control ◽  
Cortical Cells ◽  
Root Segments ◽  
Low Concentrations ◽  
High Concentrations ◽  
Intact Root

Root segments of the fern Ophioglossum petiolatum with either an intact root apex or with the apex removed were treated with distilled water (control) or a range of concentrations of kinetin or benzyladenine in aqueous solution. Buds initiated on segments treated with distilled water or low concentrations of cytokinins had an apical meristem consisting of an apical cell with derivatives and a few leaf primordia located immediately beneath an air cavity formed by the lysis of cortical cells of the parent root. There was little cortical proliferation associated with the initiation of these buds. However, application of cytokinins at relatively high concentrations induced considerable proliferation of root tissue and a concomitant organization of numerous apical meristems in this tissue. Each induced meristem was structurally similar to those initiated on control root segments or those treated with low concentrations of cytokinins with the exception that leaf primordia were not as readily visible. Groups of tracheid-like cells were present in the callus-like outgrowths and, in root segments treated with 10.0 mg/l kinetin, large starch-filled parenchyma cells were evident at the periphery of the proliferations.

scholarly journals The Arabidopsis Root Tip (Phospho)Proteomes at Growth-Promoting versus Growth-Repressing Conditions Reveal Novel Root Growth Regulators

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1665
Author(s):  
Natalia Nikonorova ◽  
Evan Murphy ◽  
Cassio Flavio Fonseca de Lima ◽  
Shanshuo Zhu ◽  
Brigitte van de Cotte ◽  
...  
Keyword(s):  
Cell Wall ◽  
Root Growth ◽  
Growth Regulators ◽  
Growth Regulation ◽  
Phosphorylation Site ◽  
Primary Root ◽  
Root Tip ◽  
Arabidopsis Root ◽  
Growth Promoting ◽  
The Impact

Auxin plays a dual role in growth regulation and, depending on the tissue and concentration of the hormone, it can either promote or inhibit division and expansion processes in plants. Recent studies have revealed that, beyond transcriptional reprogramming, alternative auxin-controlled mechanisms regulate root growth. Here, we explored the impact of different concentrations of the synthetic auxin NAA that establish growth-promoting and -repressing conditions on the root tip proteome and phosphoproteome, generating a unique resource. From the phosphoproteome data, we pinpointed (novel) growth regulators, such as the RALF34-THE1 module. Our results, together with previously published studies, suggest that auxin, H+-ATPases, cell wall modifications and cell wall sensing receptor-like kinases are tightly embedded in a pathway regulating cell elongation. Furthermore, our study assigned a novel role to MKK2 as a regulator of primary root growth and a (potential) regulator of auxin biosynthesis and signalling, and suggests the importance of the MKK2 Thr31 phosphorylation site for growth regulation in the Arabidopsis root tip.

scholarly journals The Arabidopsis TETRATRICOPEPTIDE THIOREDOXIN-LIKE 1 Gene Is Involved in Anisotropic Root Growth during Osmotic Stress Adaptation

Genes ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 236
Author(s):  
María Belén Cuadrado-Pedetti ◽  
Inés Rauschert ◽  
María Martha Sainz ◽  
Vítor Amorim-Silva ◽  
Miguel Angel Botella ◽  
...  
Keyword(s):  
Osmotic Stress ◽  
Root Growth ◽  
Cell Walls ◽  
Primary Root ◽  
Stress Adaptation ◽  
Elongation Zone ◽  
Cortical Cells ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Mean

Mutations in the Arabidopsis TETRATRICOPEPTIDE THIOREDOXIN-LIKE 1 (TTL1) gene cause reduced tolerance to osmotic stress evidenced by an arrest in root growth and root swelling, which makes it an interesting model to explore how root growth is controlled under stress conditions. We found that osmotic stress reduced the growth rate of the primary root by inhibiting the cell elongation in the elongation zone followed by a reduction in the number of cortical cells in the proximal meristem. We then studied the stiffness of epidermal cell walls in the root elongation zone of ttl1 mutants under osmotic stress using atomic force microscopy. In plants grown in control conditions, the mean apparent elastic modulus was 448% higher for live Col-0 cell walls than for ttl1 (88.1 ± 2.8 vs. 16.08 ± 6.9 kPa). Seven days of osmotic stress caused an increase in the stiffness in the cell wall of the cells from the elongation zone of 87% and 84% for Col-0 and ttl1, respectively. These findings suggest that TTL1 may play a role controlling cell expansion orientation during root growth, necessary for osmotic stress adaptation.

Identification and characterization of novel QTL conferring internal detoxification of aluminum in soybean

2021 ◽  
Author(s):  
Yang Li ◽  
Heng Ye ◽  
Li Song ◽  
Tri D Vuong ◽  
Qijian Song ◽  
...  
Keyword(s):  
Root Length ◽  
Root Elongation ◽  
Primary Root ◽  
Pedigree Analysis ◽  
Length Ratio ◽  
Root Tip ◽  
Root Initiation ◽  
Al Tolerance ◽  
Al Stress ◽  
Root Length Ratio

Abstract Aluminum (Al) toxicity inhibits soybean root growth, leading to insufficient water and nutrient uptake. In this research, two soybean lines (Magellan and PI 567731) were identified differing in Al tolerance as determined by primary root length ratio (PRL_Ratio), total root length ratio (TRL_Ratio), and root tip number ratio (RTN_Ratio) under Al stress compared to unstressed controlled conditions. Serious root necrosis was observed in PI 567731, but not in Magellan under Al stress. An F8 recombinant inbred line population derived from a cross between Magellan and PI 567731 was used to map the quantitative trait loci (QTL) for Al-tolerance. Three QTL on chromosomes 3, 13, and 20, with tolerant-alleles from Magellan, were identified. qAl_Gm13 and qAl_Gm20, explained large phenotypic variations (13-27%) and played roles in maintaining root elongation. qAl_Gm03 was involved in maintaining root initiation under Al stress. These results suggested the importance of using the parameters of root elongation and root initiation in Al tolerance studies. In addition, qAl_Gm13 and qAl_Gm20 were confirmed in near-isogenic backgrounds and were identified to epistatically regulate Al tolerance in internal detoxification instead of Al 3+ exclusion. The candidate genes for qAl_Gm13 and qAl_Gm20 were suggested by analyzing a previous RNA-seq study. Phylogenetic and pedigree analysis identified the tolerant alleles of both loci derived from the US ancestor line, A.K.[FC30761], originally from China. Our results provide novel genetic resources for breeding Al-tolerant soybeans and suggest that the internal detoxification contributes to soybean tolerance to excessive soil Al.

scholarly journals Multiwalled carbon nanotubes in alfalfa and wheat: toxicology and uptake

2012 ◽  
Vol 9 (77) ◽  
pp. 3514-3527 ◽  
Author(s):  
Pola Miralles ◽  
Errin Johnson ◽  
Tamara L. Church ◽  
Andrew T. Harris
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Root Elongation ◽  
Wheat Root ◽  
Root Tip ◽  
Multiwalled Carbon ◽  
Wheat Seedlings ◽  
Industrial Grade ◽  
High Concentrations ◽  
Multiwalled Cnts

Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l −1 CNTs, and root elongation was enhanced in alfalfa and wheat seedlings exposed to CNTs. Remarkably, catalyst impurities also enhanced root elongation in alfalfa seedlings as well as wheat germination. Thus the impurities, not solely the CNTs, impacted the plants. CNT internalization by plants was investigated using electron microscopy and two-dimensional Raman mapping. The latter showed that CNTs were adsorbed onto the root surfaces of alfalfa and wheat without significant uptake or translocation. Electron microscopy investigations of internalization were inconclusive owing to poor contrast, so Fe 3 O 4 -functionalized CNTs were prepared and studied using energy-filter mapping of Fe 3 O 4 . CNTs bearing Fe 3 O 4 nanoparticles were detected in the epidermis of one wheat root tip only, suggesting that internalization was possible but unusual. Thus, alfalfa and wheat tolerated high concentrations of industrial-grade multiwalled CNTs, which adsorbed onto their roots but were rarely taken up.

scholarly journals Comparative Proteomics of Root Apex and Root Elongation Zones Provides Insights into Molecular Mechanisms for Drought Stress and Recovery Adjustment in Switchgrass

Proteomes ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 3 ◽  
Author(s):  
Zhujia Ye ◽  
Sasikiran Reddy Sangireddy ◽  
Chih-Li Yu ◽  
Dafeng Hui ◽  
Kevin Howe ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Drought Stress ◽  
Molecular Mechanisms ◽  
Root Zone ◽  
Root Apex ◽  
Root Tip ◽  
Leaf Water Content ◽  
Severe Drought ◽  
Proteomics Data ◽  
Drought Treatment

Switchgrass plants were grown in a Sandwich tube system to induce gradual drought stress by withholding watering. After 29 days, the leaf photosynthetic rate decreased significantly, compared to the control plants which were watered regularly. The drought-treated plants recovered to the same leaf water content after three days of re-watering. The root tip (1cm basal fragment, designated as RT1 hereafter) and the elongation/maturation zone (the next upper 1 cm tissue, designated as RT2 hereafter) tissues were collected at the 29th day of drought stress treatment, (named SDT for severe drought treated), after one (D1W) and three days (D3W) of re-watering. The tandem mass tags mass spectrometry-based quantitative proteomics analysis was performed to identify the proteomes, and drought-induced differentially accumulated proteins (DAPs). From RT1 tissues, 6156, 7687, and 7699 proteins were quantified, and 296, 535, and 384 DAPs were identified in the SDT, D1W, and D3W samples, respectively. From RT2 tissues, 7382, 7255, and 6883 proteins were quantified, and 393, 587, and 321 proteins DAPs were identified in the SDT, D1W, and D3W samples. Between RT1 and RT2 tissues, very few DAPs overlapped at SDT, but the number of such proteins increased during the recovery phase. A large number of hydrophilic proteins and stress-responsive proteins were induced during SDT and remained at a higher level during the recovery stages. A large number of DAPs in RT1 tissues maintained the same expression pattern throughout drought treatment and the recovery phases. The DAPs in RT1 tissues were classified in cell proliferation, mitotic cell division, and chromatin modification, and those in RT2 were placed in cell wall remodeling and cell expansion processes. This study provided information pertaining to root zone-specific proteome changes during drought and recover phases, which will allow us to select proteins (genes) as better defined targets for developing drought tolerant plants. The mass spectrometry proteomics data are available via ProteomeXchange with identifier PXD017441.

Primary vascular patterns in root meristems of Pontederia cordata and their relevance to studies of root development

1980 ◽  
Vol 58 (12) ◽  
pp. 1351-1369 ◽  
Author(s):  
W. A. Charlton
Keyword(s):  
Apical Meristem ◽  
Vascular System ◽  
Root Apex ◽  
Root Apical Meristem ◽  
Vascular Pattern ◽  
Quiescent Centre ◽  
Vascular Differentiation ◽  
Pontederia Cordata ◽  
Distribution Of Components ◽  
Root Apices

There are several files of metaxylem cells in root apices of Pontederia cordata L., each considered to consist of a series of prospective vessels with their ends in contact. Two longitudinally adjacent vessels may be in the same file of cells produced by the root apex or in adjacent files. As the root grows, successive prospective vessels are added to the apical ends of most of the files but not all files are continued. Addition of prospective vessels appears to take place within the "quiescent centre" of the root apical meristem. Where files are not continued there is no immediate readjustment of remaining files. The longitudinal and transverse distribution of components of the vascular system (including protophloem and protoxylem) is discussed in relation to the means by which the pattern of development may be controlled. Rates of production of vessels and the final lengths of the vessels are estimated. The observations and deductions are discussed in relation to other studies of root growth, vascular differentiation, and vascular pattern formation and maintenance.

scholarly journals Malate-dependent Fe accumulation is a critical checkpoint in the root developmental response to low phosphate

2017 ◽  
Vol 114 (17) ◽  
pp. E3563-E3572 ◽  
Author(s):  
Javier Mora-Macías ◽  
Jonathan Odilón Ojeda-Rivera ◽  
Dolores Gutiérrez-Alanís ◽  
Lenin Yong-Villalobos ◽  
Araceli Oropeza-Aburto ◽  
...  
Keyword(s):  
Primary Root ◽  
Root System Architecture ◽  
Root Apical Meristem ◽  
Root Tip ◽  
Al Tolerance ◽  
Short Root ◽  
Meristematic Cells ◽  
Isolation And Characterization ◽  
Root Response ◽  
Primary Root Growth

Low phosphate (Pi) availability constrains plant development and seed production in both natural and agricultural ecosystems. When Pi is scarce, modifications of root system architecture (RSA) enhance the soil exploration ability of the plant and lead to an increase in Pi uptake. In Arabidopsis, an iron-dependent mechanism reprograms primary root growth in response to low Pi availability. This program is activated upon contact of the root tip with low-Pi media and induces premature cell differentiation and the arrest of mitotic activity in the root apical meristem, resulting in a short-root phenotype. However, the mechanisms that regulate the primary root response to Pi-limiting conditions remain largely unknown. Here we report on the isolation and characterization of two low-Pi insensitive mutants (lpi5 and lpi6), which have a long-root phenotype when grown in low-Pi media. Cellular, genomic, and transcriptomic analysis of low-Pi insensitive mutants revealed that the genes previously shown to underlie Arabidopsis Al tolerance via root malate exudation, known as SENSITIVE TO PROTON RHIZOTOXICITY (STOP1) and ALUMINUM ACTIVATED MALATE TRANSPORTER 1 (ALMT1), represent a critical checkpoint in the root developmental response to Pi starvation in Arabidopsis thaliana. Our results also show that exogenous malate can rescue the long-root phenotype of lpi5 and lpi6. Malate exudation is required for the accumulation of Fe in the apoplast of meristematic cells, triggering the differentiation of meristematic cells in response to Pi deprivation.

scholarly journals Strigolactones Control Root System Architecture and Tip Anatomy in Solanum lycopersicum L. Plants under P Starvation

Plants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 612 ◽  
Author(s):  
Veronica Santoro ◽  
Michela Schiavon ◽  
Francesco Gresta ◽  
Andrea Ertani ◽  
Francesca Cardinale ◽  
...  
Keyword(s):  
Solanum Lycopersicum ◽  
Lateral Root ◽  
Primary Root ◽  
Root Traits ◽  
Root System Architecture ◽  
Root Tip ◽  
Root Number ◽  
Wild Type ◽  
Solanum Lycopersicum L ◽  
P Supply

The hormones strigolactones accumulate in plant roots under phosphorus (P) shortage, inducing variations in plant phenotype. In this study, we aimed at understanding whether strigolactones control morphological and anatomical changes in tomato (Solanum lycopersicum L.) roots under varying P supply. Root traits were evaluated in wild-type seedlings grown in high vs. low P, with or without exogenous strigolactones, and in wild-type and strigolactone-depleted plants grown first under high vs. no P, and then under high vs. no P after acclimation on low P. Exogenous strigolactones stimulated primary root and lateral root number under low P. Root growth was reduced in strigolactone-depleted plants maintained under continuous P deprivation. Total root and root hair length, lateral root number and root tip anatomy were impaired by low strigolactone biosynthesis in plants grown under low P or transferred from low to no P. Under adequate P conditions, root traits of strigolactone-depleted and wild-type plants were similar. Concluding, our results indicate that strigolactones (i) control macro- and microscopic changes of root in tomato depending on P supply; and (ii) do not affect root traits significantly when plants are supplemented with adequate P, but are needed for acclimation to no P and typical responses to low P.

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