Croissance, activité peroxydasique et modifications ultrastructurales induites par le cadmium dans la racine de tomate

2002 ◽  
Vol 80 (9) ◽  
pp. 942-953 ◽  
Author(s):  
Wahbi Djebali ◽  
Wided Chaïbi ◽  
Mohamed Habib Ghorbel
Keyword(s):  
Metal Accumulation ◽  
Root Apex ◽  
Membrane System ◽  
Editorial Staff ◽  
Tomato Plants ◽  
Electron Dense Material ◽  
Meristematic Cells ◽  
Vesicular Membrane ◽  
Root Tissues ◽  
Oxidative State

Accumulation of Cd in the organs of young tomato plants (Lycopersicon esculentum var. Ibiza F1), as well as its effects on growth, peroxidasic activity, and root ultrastructure were evaluated. Plants previously cultivated in a basic nutrient solution and then treated for 10 days with different concentrations of CdCl2 (0, 5, 10, 20, 50, 100 μM) accumulated high quantities of cadmium in their root tissues and showed reduced growth. Increased peroxidasic activity observed at this level reflects a state of oxidative stress induced by cadmium. An ultrastructural study of the root apex showed a strong vacuolization in the meristematic cells as well as deposition of electron-dense material in vacuoles and plastids. On either side of the cell wall, a medullated-like and (or) vesicular membrane system developed over a significant periplasmic space. Results suggest an endocellular metal accumulation leading to a disorganization of membrane systems, probably related to the onset of an oxidative state of stress.Key words: cadmium, tomato, peroxidases, ultrastructure, root.[Translated by editorial staff]

scholarly journals Treatment with the Mycoparasite Pythium oligandrum Triggers Induction of Defense-Related Reactions in Tomato Roots When Challenged with Fusarium oxysporum f. sp. radicis-lycopersici

1997 ◽  
Vol 87 (1) ◽  
pp. 108-122 ◽  
Author(s):  
Nicole Benhamou ◽  
Patrice Rey ◽  
Mohamed Chérif ◽  
John Hockenhull ◽  
Yves Tirilly
Keyword(s):  
Plant Defense ◽  
Fusarium Oxysporum ◽  
Host Cell ◽  
Cell Walls ◽  
Pythium Oligandrum ◽  
Tomato Plants ◽  
Host Cytoplasm ◽  
Defense Reactions ◽  
Tomato Roots ◽  
Root Tissues

The influence exerted by the mycoparasite Pythium oligandrum in triggering plant defense reactions was investigated using an experimental system in which tomato plants were infected with the crown and root rot pathogen Fusarium oxysporum f. sp. radicis-lycopersici. To assess the antagonistic potential of P. oligandrum against F. oxysporum f. sp. radicis-lycopersici, the interaction between the two fungi was studied by scanning and transmission electron microscopy (SEM and TEM, respectively). SEM investigations of the interaction region between the fungi demonstrated that collapse and loss of turgor of F. oxysporum f. sp. radicis-lycopersici hyphae began soon after close contact was established with P. oligandrum. Ultrastructural observations confirmed that intimate contact between hyphae of P. oligandrum and cells of the pathogen resulted in a series of disturbances, including generalized disorganization of the host cytoplasm, retraction of the plasmalemma, and, finally, complete loss of the protoplasm. Cytochemical labeling of chitin with wheat germ agglutinin (WGA)/ovomucoid-gold complex showed that, except in the area of hyphal penetration, the chitin component of the host cell walls was structurally preserved at a time when the host cytoplasm had undergone complete disorganization. Interestingly, the same antagonistic process was observed in planta. The specific labeling patterns obtained with the exoglucanase-gold and WGA-ovomucoid-gold complexes confirmed that P. oligandrum successfully penetrated invading cells of the pathogen without causing substantial cell wall alterations, shown by the intense labeling of chitin. Cytological investigations of samples from P. oligandrum-inoculated tomato roots revealed that the fungus was able to colonize root tissues without inducing extensive cell damage. However, there was a novel finding concerning the structural alteration of the invading hyphae, evidenced by the frequent occurrence of empty fungal shells in root tissues. Pythium ingress in root tissues was associated with host metabolic changes, culminating in the elaboration of structural barriers at sites of potential fungal penetration. Striking differences in the extent of F. oxysporum f. sp. radicis-lycopersici colonization were observed between P. oligandrum-inoculated and control tomato plants. In control roots, the pathogen multiplied abundantly through much of the tissues, whereas in P. oligandrum-colonized roots pathogen growth was restricted to the outermost root tissues. This restricted pattern of pathogen colonization was accompanied by deposition of newly formed barriers beyond the infection sites. These host reactions appeared to be amplified compared to those seen in nonchallenged P. oligandrum-infected plants. Most hyphae of the pathogen that penetrated the epidermis exhibited considerable changes. Wall appositions contained large amounts of callose, in addition to be infiltrated with phenolic compounds. The labeling pattern obtained with gold-complexed laccase showed that phenolics were widely distributed in Fusarium-challenged P. oligandrum-inoculated tomato roots. Such compounds accumulated in the host cell walls and intercellular spaces. The wall-bound chitin component in Fusarium hyphae colonizing P. oligandrum-inoculated roots was preserved at a time when hyphae had undergone substantial degradation. These observations provide the first convincing evidence that P. oligandrum has the potential to induce plant defense reactions in addition to acting as a mycoparasite.

scholarly journals Effects of water soluble oncostatic fraction from Rheum officinale Baill. rhizomes on Allium cepa root meristem. III. Morphological changes in cytoplasm

2015 ◽  
Vol 45 (4) ◽  
pp. 453-458
Author(s):  
A. Dawidowicz-Grzegorzewska
Keyword(s):  
Allium Cepa ◽  
Metabolic Activity ◽  
Light Microscope ◽  
Root Meristem ◽  
Morphological Changes ◽  
Root Apex ◽  
Water Soluble ◽  
Prolonged Treatment ◽  
Defence Reaction ◽  
Meristematic Cells

Spiral concentric and linear configurations of membraneous structures were observed in the cytoplasm of fixed meristematic cells from the root apex of <i>Allium cepa</i> under the light microscope. They appeared after incubation in sublethal and lethal conditions in <i>Rheum ofiicinale</i> rhizome extracts. During postincubation these structures disappeared. They were interpreted as ER membranes. On the basis of literature data the physiological significance of these structures is discussed. It would seem that they are an indication of enhanced metabolic activity evoked either exogenously by various injuries as a form of defence reaction of the protoplast or endogenously during cytodifferentiation. Prolonged treatment in ,noxious conditions causes the ER membranes to transform into inactive myelin structures

Localisation of aluminium in root apex cells of two Australian perennial grasses by X-ray microanalysis

1998 ◽  
Vol 25 (4) ◽  
pp. 427 ◽  
Author(s):  
Simon A. Crawford ◽  
Alan T. Marshall ◽  
Sabine Wilkens
Keyword(s):  
Significant Positive Correlation ◽  
Root Apex ◽  
Root Cap ◽  
Perennial Grasses ◽  
Elemental Distribution ◽  
X Ray ◽  
Positive Correlation ◽  
Distribution Maps ◽  
Meristematic Cells ◽  
Root Apices

To determine if an increased aluminium (Al) sensitivity is the result of greater accumulation of Al in root apices, the quantity and distribution of Al in root apex cells of Danthonia linkii Kunth and Microlaena stipoides (Labill.) R.Br. was investigated by X-ray microanalysis. Seedlings were grown in nutrient solution with 0, 185 and 370 µM total Al for 24 h after which the terminal 5 mm of the roots were excised, rapidly frozen and embedded using freeze-substitution. Elemental distribution maps of root apices showed that Al had accumulated in the nuclei of root cap and meristematic cells in Al-stressed roots of D. linkii but not in M. stipoides. Al appeared to be co-localised with phosphorous (P) in the nuclei of these cells. Quantitation of Al revealed that Al-stressed root apex cells of D. linkiiaccumulated significantly more Al than M. stipoides. Exposure of D. linkii roots to Al resulted in substantial increases in the P content of root apex cells, and a significant positive correlation was found between Al and P in both root cap and meristematic cells. Analysis of intracellular structures showed that the majority of Al had accumulated in the nuclei of cells. A significant positive correlation was found between Al and P in the nuclei, but not in the cytoplasm or cell walls. No positive correlation was found between Al and P in root apex cells of M. stipoides.

scholarly journals Membrane distribution in dividing endosperm cells of Haemanthus.

1982 ◽  
Vol 94 (3) ◽  
pp. 637-643 ◽  
Author(s):  
W T Jackson ◽  
B G Doyle
Keyword(s):  
Mitotic Spindle ◽  
Osmium Tetroxide ◽  
Membrane System ◽  
Potassium Ferrocyanide ◽  
Polar Regions ◽  
Chromosome Movement ◽  
Prominent Feature ◽  
Cell Organelles ◽  
Electron Dense Material

Membranes in cell-wall-free dividing endosperm cells of Haemanthus were examined after postfixation with osmium tetroxide-potassium ferrocyanide. We found that preservation and staining of membranes in metaphase cells was highly variable. Even adjacent cells often showed different degrees of preservation of membrane. However, this method does reveal a much more extensive membrane system in the mitotic spindle of Haemanthus than has been revealed previously using glutaraldehyde-osmium fixation. At prometaphase a system of membranes becomes associated with the kinetochore bundles. By metaphase, membranes constitute a prominent feature of kinetochore bundles, terminating near the kinetichores. Minipoles, identified by converging microtubules and associated membranes, are distributed in a zone extending laterally across the polar regions of the cell. The microtubules appear to terminate at the minipoles, whereas the membrane system becomes oriented generally perpendicular to the spindle axis and interfaces distally with a region of amorphous electron-dense material, helical polyribosomes, and cell organelles. The role of this extensive membrane system, if any, in chromosome movement is unknown. However, its distribution is coincident with the distribution of calcium-rich membranes and kinetochore fibers at metaphase in these cells (Wolniak, S. M., P. K. Hepler, and W. T. Jackson, 1981, Eur. J. Cell Biol., 25:171-174). Thus, these membranes may function in creating calcium domains that, in turn, may play a regulatory role in chromosome movement.

scholarly journals Meristematic Connectome: A Cellular Coordinator of Plant Responses to Environmental Signals?

Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2544
Author(s):  
Donato Chiatante ◽  
Antonio Montagnoli ◽  
Dalila Trupiano ◽  
Gabriella Sferra ◽  
John Bryant ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Root Apex ◽  
Plant Responses ◽  
Reaction Wood ◽  
Root Tips ◽  
Tree Roots ◽  
Long Distance ◽  
Meristematic Cells ◽  
Plant Body ◽  
Single Structure

Mechanical stress in tree roots induces the production of reaction wood (RW) and the formation of new branch roots, both functioning to avoid anchorage failure and limb damage. The vascular cambium (VC) is the factor responsible for the onset of these responses as shown by their occurrence when all primary tissues and the root tips are removed. The data presented confirm that the VC is able to evaluate both the direction and magnitude of the mechanical forces experienced before coordinating the most fitting responses along the root axis whenever and wherever these are necessary. The coordination of these responses requires intense crosstalk between meristematic cells of the VC which may be very distant from the place where the mechanical stress is first detected. Signaling could be facilitated through plasmodesmata between meristematic cells. The mechanism of RW production also seems to be well conserved in the stem and this fact suggests that the VC could behave as a single structure spread along the plant body axis as a means to control the relationship between the plant and its environment. The observation that there are numerous morphological and functional similarities between different meristems and that some important regulatory mechanisms of meristem activity, such as homeostasis, are common to several meristems, supports the hypothesis that not only the VC but all apical, primary and secondary meristems present in the plant body behave as a single interconnected structure. We propose to name this structure “meristematic connectome” given the possibility that the sequence of meristems from root apex to shoot apex could represent a pluricellular network that facilitates long-distance signaling in the plant body. The possibility that the “meristematic connectome” could act as a single structure active in adjusting the plant body to its surrounding environment throughout the life of a plant is now proposed.

scholarly journals INFLUENCE OF PESTICIDES ON NITROGEN CONTENT OF TOMATO PLANT S

HortScience ◽  
1993 ◽  
Vol 28 (4) ◽  
pp. 273D-273
Author(s):  
David N. Sasseville
Keyword(s):  
Nitrate Uptake ◽  
Calcium Nitrate ◽  
Dry Weight ◽  
Control Treatment ◽  
Nitrate Content ◽  
N Content ◽  
Total N ◽  
Tomato Plants ◽  
Growing Medium ◽  
Root Tissues

Tomato plants were grown in a greenhouse in a sand:soil mixture with six pesticide treatments applied weekly at 1 mg a.i./kg soil mixture as a soil drench. Plants were grown for six weeks with nitrogen applied weekly at 80 mg per plant as calcium nitrate. Glyphosate (Roundup) was toxic to plants with reduced dry weight of all tissues, but greater nitrate concentration in the leaf and root tissues. Captan produced the greatest dry weight, with mot tissues dry weights significantly greater than the control treatment. Captan resulted in significantly higher nitrate content in the tissues, but there was no difference between captan and the control on total N content. Both nitrapyrin (N-Serve) and sethoxydim (Poast) had significantly less growth and total N content than the control, as well as higher nitrate content in the growing medium. It appears that these two chemicals may inhibit nitrate uptake or cause other phytotoxic effects The other chemicals metalaxyl (Subdue) and etridiazole (Terrazole) had intermediate responses. While they both had reduced growth and total N content, these were not significantly different from the control treatment. Etridiazole had reduced nitrate content, but metalaxyl nitrate content was significantly greater than the control and comparable to captan, primarily because of high nitrate content in the leaves.

scholarly journals Chloroplast ultrastructure in leaves of Cucumis sativus chlorophyll mutant

2014 ◽  
Vol 52 (2) ◽  
pp. 131-137 ◽  
Author(s):  
Irena Palczewska ◽  
Barbara Gabara ◽  
Eugienia Mikulska ◽  
Bogusław Kubicki
Keyword(s):  
Cucumis Sativus ◽  
Control Plant ◽  
Chloroplast Ultrastructure ◽  
Normal Structure ◽  
Membrane System ◽  
Lamellar System ◽  
Electron Dense Material ◽  
Young Leaves ◽  
Chlorophyll Mutants ◽  
Irregular Arrangement

The developing and young leaves of <em>Cucumis sativus</em> chlorophyll mutants are yellow, when mature they become green and do not differ in their colour from those of control plants. The mesophyll of yellow leaves contains a diversiform plastid population with a varying degree of defectiveness, which is mainly manifested in the reduction or disorganization of the typical thylakoid system. DNA areas, ribosome-like particles and aggregates of electron-dense material are preserved in the stroma of mutated plastids. Starch grains are deficient. Apart from mutated plastids, chloroplasts with a normal structure, as in control plants, were also observed.The leaf greening process is accompanied by a reconstruction and rearrangement of the inner chloroplast lamellar system and an ability to accumulate starch. However, in the mutant chloroplasts as compared with control-plant ones, an irregular arrangement of grana and reduced number of inter-grana thylakoids can be seen. An osmiophilic substance stored in the stroma of mutated plastids and the vesicles formed from an internal plastid membrane take part in restoration of the membrane system.

scholarly journals Assessment of NaCl-Induced Stress in Tomato (Lycopersicon esculentum L.)

2021 ◽  
pp. 41-47
Author(s):  
Abhishek Kumar ◽  
Khushbu Jain ◽  
Mahesh Kumar ◽  
Md. Shamim ◽  
Jitesh Kumar ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Salt Stress ◽  
Root Growth ◽  
Root Length ◽  
Primary Root ◽  
H2o2 Production ◽  
Salt Treatment ◽  
Tomato Plants ◽  
Comparative Response ◽  
Root Tissues

Comparative study about the salt-induced oxidative stress and lipid peroxidation has been realised in primary root tissues for Tomato (Lycopersicon esculantum L.) in order to evaluate their responses to salt stress. Salinity impacts in terms of root growth, H2O2 generation, lipid peroxidation and membrane destabilisation were more pronounced in roots. Salt treatment in form of NaCl was given to the roots of the tomato plants in hydroponics culture. Root length was measured by centimetre scale, H2O2 and lipid peroxidation was confirmed by spectrophotometer. Absorbance for H2O2 estimation was recorded at 480 nm whereas for Lipid peroxidation was done at 600nm. When the tomato plants were treated with different concentrations of NaCl, it was observed that as the concentration of NaCl was increasing, there  was decreased root growth resulting in reduced root length and  proportionate increase in the amount of H2O2  production level with increase in the concentrations of NaCl treatment upto 300mM Concentration and  Significant increase in Lipid peroxidation was observed with the increase in NaCl concentrations upto 500mM Concentration. Comparative response may be helpful in developing a better understanding of tolerance mechanisms to salt stress in Tomato.

Anatomical differences of poplar (Populus × euramericana clone I-214) roots exposed to zinc excess

Biologia ◽  
2012 ◽  
Vol 67 (3) ◽  
Author(s):  
Miroslava Stoláriková ◽  
Marek Vaculík ◽  
Alexander Lux ◽  
Daniela Baccio ◽  
Antonio Minnocci ◽  
...  
Keyword(s):  
Essential Element ◽  
Root Apex ◽  
High Concentration ◽  
Populus Euramericana ◽  
Casparian Bands ◽  
Zinc Excess ◽  
Suberin Lamellae ◽  
Root Tissues ◽  
Poplar Root ◽  
Fast Growth Rate

AbstractPoplar is one of the suitable candidates for phytoremediation due to extensive root system, fast growth rate, easy propagation and high biomass production. Zinc (Zn) is an essential element, but at high concentration becomes toxic to plants, similarly like cadmium (Cd). In order to evaluate the effect of Zn on root tissue development we conducted experiments with poplar (Populus × euramericana clone I-214) grown in hydroponics. Plants were treated with low (control) and excess level of Zn (1 mM). Changes in the development of apoplasmic barriers — Casparian bands and suberin lamellae in endodermis, as well as lignification of xylem vessels have been investigated. We found that both apoplasmic barriers developed closer to the root apex in higher Zn-treated root when compared with control root. Similar changes were observed in lignification of xylem vessels. For localization of Zn within root tissues, cryo-SEM/EDXMA analyses were used. Most of Zn was localized in the cortical tissues and four-time less Zn was determined in the inner part of the root below the endodermis. This indicates that endodermis serves as efficient barrier of apoplasmic Zn transport across the poplar root.

scholarly journals ENHANCED RESISTANCE OF TOMATO PLANTS TO FUSARIUM OXYSPORUM F.SP. RADICIS-LYCOPERSICI UPON TREATMENT WITH CHITOSAN: CYTOCHEMICAL ASPECTS OF INDUCED RESISTANCE

HortScience ◽  
1994 ◽  
Vol 29 (4) ◽  
pp. 254d-254
Author(s):  
Nicole Benhamou
Keyword(s):  
Fusarium Oxysporum ◽  
Plant Protection ◽  
Host Cells ◽  
Root Pathogen ◽  
Tomato Plants ◽  
Enhanced Resistance ◽  
Infected Root ◽  
Physical Barriers ◽  
Wall Appositions ◽  
Root Tissues

Chitosan, a polymer of β-1,4-d-glucosamine derived from crabshell chitin, was applied to tomato plants before inoculation with the root pathogen Fusarium oxysporum f.sp. radicis-lycopersici. Whether chitosan was applied by leaf spraying, root coating, or seed coating, it reduced the number of root lesions caused by the fungus and increased the formation of physical barriers in infected root tissues. Formation of wall appositions such as papillae and occlusion of xylem vessels with coating substances were among the most typical features of host reactions. Another type of response was the accumulation of globular structures and electron-opaque masses in host cells neighboring colonized areas. Gold cytochemistry revealed that callose and lignin-like material were the main structural compounds induced in response to chitosan treatment and infection. Biochemical investigations showed that PR proteins as well as enzymes of the secondary metabolism were also significantly induced. The potential of chitosan as a biocontrol compound is discussed in relation to its ability to enhance plant protection against root pathogens.

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