scholarly journals Recent advances in aluminum toxicity and resistance in higher plants

2005 ◽  
Vol 17 (1) ◽  
pp. 129-143 ◽  
Author(s):  
Victor Alexandre Vitorello ◽  
Flávia Regina Capaldi ◽  
Vanderlei Antonio Stefanuto
Keyword(s):  
Cell Wall ◽  
Aluminum Toxicity ◽  
Higher Plants ◽  
Al Toxicity ◽  
Mechanisms Of Toxicity ◽  
Cellular Effects ◽  
Membrane Cytoskeleton ◽  
Specific Manner ◽  
Made In

Aluminum toxicity is a major soil constraint to food and biomass production throughout the world. Considerable advances in the understanding of the mechanism of resistance involving exudation of organic acids have been made in recent years. However, despite intense research efforts, there are many aspects of Al toxicity that remain unclear. This article reviews the features of the chemistry of Al relevant to its toxicity followed by an examination of the mechanisms of toxicity and resistance. Emphasis, however, is given to the mechanisms of Al toxicity, since resistance has been covered recently by several reviews. Some topics which are specifically discussed in this review are: a) The possible role of cellular effects of low pH in Al toxicity, which has been largely ignored and needs to be addressed; b) The relevance of non-genotypic (cell-to-cell) variations in sensitivity to Al; c) Evidence indicating that although Al may well exert its toxic effects in the cell wall, it is highly unlikely that Al does so in a non-specific manner by mere exchangeable binding; and d) The hypothesis that the primary target of Al toxicity resides in the cell wall-plasma membrane-cytoskeleton (CW-PM-CSK) continuum has the potential to integrate and conciliate much of the apparently conflicting results in this field.

scholarly journals Unearthing The Alleviatory Mechanisms of Hydrogen Sulfide in Aluminum Toxicity in Rice

2021 ◽  
Author(s):  
Chun Quan Zhu ◽  
Wen Jun Hu ◽  
QianQian Wei ◽  
Hui Zhang ◽  
Xiao Chuang Cao ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Cell Wall ◽  
Ascorbic Acid ◽  
Hydrogen Sulfide ◽  
Aluminum Toxicity ◽  
Al Toxicity ◽  
Negative Effects ◽  
Al Content ◽  
Rice Roots ◽  
Wall Components

Abstract Hydrogen sulfide (H2S) improves aluminum (Al) resistance in rice; however, the underlying molecular mechanism remains unclear. In the present study, treatment with 30-μM Al significantly inhibited rice root growth and increased the total Al content and apoplastic and cytoplasm Al concentration in the rice roots. However, pretreatment with NaHS (H2S donor) reversed these negative effects. Transcriptomics and physiological experiments confirmed that H2S increased the ATP, sucrose, glutathione, and ascorbic acid contents, which was accompanied by decreased O2·- and H2O2 contents, to alleviate Al toxicity. H2S significantly inhibited ethylene emissions in the rice and then inhibited pectin synthesis and increased the pectin methylation degree to reduce cell wall Al deposition. The phytohormones indole-3-acetic and brassinolide were also involved in the alleviation of Al toxicity by H2S. In addition, other pathways of material and energy metabolism, secondary metabolism, cell wall components, signal transduction, and transcriptional and translational pathways in the rice roots were also regulated by H2S under Al toxicity conditions. These findings improve our understanding of how H2S affects rice responses to Al toxicity, which will facilitate further studies on crop safety.

scholarly journals Aggregations of organelles in meiotic cells of higher plants

2014 ◽  
Vol 57 (4) ◽  
pp. 637-654 ◽  
Author(s):  
Bohdan Rodkiewicz ◽  
Ewa Duda
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Higher Plants ◽  
Early Prophase ◽  
Equatorial Plate ◽  
Prophase I

During early prophase I in microsporocytes and sporocytes of various plants all mitochondria and plastids aggregate in a group, where some plastids seem to undergo division. This group desintegrates by middle prophase I. Further aggregations of plastids and mitochondria occur in microsporogenesis and sporogenesis is of a simultaneous type. Organelles aggregate the second time at the end of prophase 1 and during or after telophase I they form a dense equatorial plate which lasts until telophase IL Since the phragmoplast is dismantled after telophase I and there is no cytokinesis, organelles aggregated in the plate apparently prevent merging of the nuclei and spindles of meiosis II, thus taking over a role of a phragmoplast and cell wall. In some plants after telophase II organelle aggregation changes shape and occupies the planes where cell walls will be built in simultaneous cytokinesis. Positioning of plastids and mitochondria along these planes may facilitate their equal apportionment among the postmeiotic cells.

Wall ecology: A frontier for urban biodiversity and ecological engineering

2010 ◽  
Vol 35 (1) ◽  
pp. 43-63 ◽  
Author(s):  
Robert A. Francis
Keyword(s):  
Urban Areas ◽  
Higher Plants ◽  
Ecological Engineering ◽  
Urban Ecosystems ◽  
Urban Biodiversity ◽  
Key Characteristics ◽  
Wall Materials ◽  
Physical Engineering ◽  
Made In

Walls are extensive, ubiquitous urban ecosystems that can act as habitat for a range of different species and support non-standard cosmopolitan assemblages. Most investigations into wall ecology have focused on botanical surveys rather than testing hypotheses, but it is apparent that walls can be surprisingly diverse. They also have the potential to be ecologically engineered to encourage a greater diversity and range of species. This review considers the development of wall ecology, highlighting the key characteristics of walls that have been found to influence their ability to support species, with a focus on higher plants. It then examines the kinds of plant assemblages that are found on walls and the broader role of walls within urban biodiversity, before discussing the potential for ecological engineering of walls. Some progress has recently been made in the latter area with the installation of living walls and the physical engineering of wall materials, but much more needs to be done to effectively increase their physical complexity and habitat quality. Walls therefore represent a substantial potential (as well as existing) habitat within urban areas.

scholarly journals Rhamnogalacturonan lyase: a pectin modification enzyme of higher plants

2018 ◽  
Author(s):  
Verónica-Alhelí Ochoa-Jiménez, Guillermo Berumen-Varela ◽  
Rigel Fernández-Valle Martín-Ernesto Tiznado-Hernández
Keyword(s):  
Cell Wall ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Plant Biology ◽  
Wall Structure ◽  
Rhamnogalacturonan I ◽  
Elimination Mechanism ◽  
Rhamnogalacturonan Lyase ◽  
And Function

Plant cell wall is constituted by three main polysaccharides: cellulose, hemicellulose and pectin. The principal pectin domains comprise homogalacturonan, rhamnogalacturonan I (RG-I) and ramnogalacturonan II. Rhamnogalacturonan lyase (RGL) enzyme is capable of catalyzing the degradation of the RG-I backbone by a b-elimination mechanism. RGL enzyme have been studied in fungi and bacteria species, however, little data is available related with its function in plant biology. This review tries to fill the gaps on the knowledge about RGL enzyme. Here, we discuss our recent published work regarding the role of RGL in plants. In addition, we highlight results from different sequence analysis, RGL activity and function associated with plant development and fruit ripening, as well as its role in cell wall structure. The knowledge of this enzyme is essential to comprehend and elucidate its role in plant and fruit physiology.

scholarly journals Phosphorus Reduces Aluminum Toxicity in Oil Tea Roots by Regulating the Cell Wall Components and Antioxidant Defense System

2021 ◽  
Vol 25 (03) ◽  
pp. 623-631
Author(s):  
Xinjing Qu
Keyword(s):  
Cell Wall ◽  
Oxidative Damage ◽  
Aluminum Toxicity ◽  
Antioxidant Defense System ◽  
Al Toxicity ◽  
Acidic Soils ◽  
Cell Wall Components ◽  
Al Stress ◽  
Scavenging Enzymes ◽  
Wall Components

Aluminum (Al) toxicity is one of the most important impeding factors for plant growth and productivity in acidic soils. Phosphorus (P) application may alleviate Al stress in many plants. In this study we investigated the effect of P on Al toxicity in cell wall components and oxidative stress and to explore the underlying mechanisms in oil tea (Camellia oleifera Abel.) roots. Results indicated that Al toxicity severely inhibited root elongation, changed cell wall components, and caused oxidative damage to the roots of oil tea. However, P supply reduced the adsorption of Al in the cell wall by decreasing the demethylesterfied pectin content and hemicellulose 1 content that decreased the Al binding sites. Moreover, the addition of Palleviated the inhibition of xyloglucan endotransglucosylase and endo-β-1,4-glucanases activities under Al stress, which enhanced the loosening of the cell wall. P addition reduced the activities of polyphenol oxidase and phenylalanine ammonia lyase and enhanced the activities of reactive oxygen species scavenging enzymes, which reduced the oxidative damage caused by Al toxicity. The results reveal important mechanisms of P-induced mitigation of Al stress in oil tea roots that might be useful in the cultivation of plants on acidic soils.© 2021 Friends Science Publishers

scholarly journals Nutritional and Structural Role of Silicon in Attenuating Aluminum Toxicity in Sugarcane Plants

2021 ◽  
Author(s):  
Gilmar da Silveira Sousa Junior ◽  
Alexander Calero Hurtado ◽  
Jonas Pereira de Souza Junior ◽  
Renato de Mello Prado ◽  
Durvalina Maria Mathias Dos Santos
Keyword(s):  
Adverse Effect ◽  
Growth Medium ◽  
Aluminum Sulfate ◽  
Aluminum Toxicity ◽  
Al Toxicity ◽  
Shoot Biomass ◽  
Use Efficiency ◽  
Hydroponic Conditions ◽  
Si Addition

Abstract Purpose: We investigated the interactive role of Si-mediated attenuation to aluminum (Al) toxicity in two sugarcane cultivars (‘CTC9002’ and ‘CTC9003’) grown in hydroponic conditions. Methods: Two pot experiments were distributed in randomized blocks in a factorial design (4 × 2) with four replications. The treatments consisted of 0, 10, 15, and 20 mg L−1 Al (as aluminum sulfate [Al2 (SO4)3·18H2O)], which were combined with the absence and presence of Si [(2.0 mmol L−1 as potassium silicate (K2SiO3)]. Results: Both sugarcane cultivars (‘CTC9002’ and ‘CTC9003’) were affected by Al toxicity (above 10 mg L−1), resulting in nutritional disorders and decreasing plant growth, which were drastically reversed by Si addition in the growth medium. Si supplementation decrease Al concentration and translocation to the shoots of both cultivars when Al and Si were simultaneously supplied in the growth medium. We demonstrated that in shoots of both sugarcane seedlings, Si concentration are positively related to the lignin concentrations (ranging from 12.0% to 41% in cv. ‘CTC9002’ and 12% to 47% in cv. ‘CTC9003’). In addition, Si fertilization enhanced mineral nutrition and use efficiency of macros- and micronutrients, irrespective of the cultivar. Therefore, the use of cultivar ‘CTC9003’ under Si fertilization is more recommended to cope with the adverse effect caused by Al stress. Conclusions: The findings of this study suggest that Si fertilization in sugarcane seedlings is an economic and viable strategy strongly recommended to cope with the adverse effect caused by Al toxicity at concentrations less than 20 mg L−1, which lead to increase the shoot biomass production.

Host–parasite relations in mycoparasite. I. Fine structure of host, parasite, and their interface

1971 ◽  
Vol 49 (9) ◽  
pp. 1677-1681 ◽  
Author(s):  
M. S. Manocha ◽  
K. Y. Lee
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Host Cell ◽  
Higher Plants ◽  
Host Cytoplasm ◽  
Host Cell Wall ◽  
Choanephora Cucurbitarum ◽  
A Cell ◽  
Host Parasite

A mycoparasite, Piptocephalis virginiana, shows resemblance to other fungal parasites of higher plants in the fine structure of hyphae and haustoria. The mode of penetration of the host cell, Choanephora cucurbitarum, probably involves mechanical forces. Although the presence of a cell wall degrading enzyme was not detected by conventional techniques, its role in penetration can not be ruled out. A collar around the haustorial neck is formed as an extension of the host cell wall. No papilla was detected although appressorium was seen during penetration. The young haustorium is enclosed in highly invaginating plasmalemma of the host cell and numerous cisternae of endoplasmic reticulum (ER). Appearance of an electron-dense sheath around the mature haustorium seems to coincide with the disappearance of cisternae of ER from the host cytoplasm in the vicinity of the haustorium. The role of host cytoplasm, particularly of ER, in the development of the sheath is discussed. Extensive accumulation of spherosome-like bodies, containing lipids, is found in haustorium, parasite, and host hypha.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

ASPECTS IN BUILDING A COMPANY WEB-SITE AND ITS ROLE FOR THE DEVELOPMENT OF BUSINESS

2018 ◽  
pp. 117-124
Author(s):  
Petar Halachev ◽  
Victoria Radeva ◽  
Albena Nikiforova ◽  
Miglena Veneva
Keyword(s):  
Life Cycle ◽  
Web Site ◽  
The Internet ◽  
A Company ◽  
The Web ◽  
Design Construction ◽  
Made In ◽  
Site Types

This report is dedicated to the role of the web site as an important tool for presenting business on the Internet. Classification of site types has been made in terms of their application in the business and the types of structures in their construction. The Models of the Life Cycle for designing business websites are analyzed and are outlined their strengths and weaknesses. The stages in the design, construction, commissioning, and maintenance of a business website are distinguished and the activities and requirements of each stage are specified.

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