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Plasmodesmata-Related Structural and Functional Proteins: The Long Sought-After Secrets of a Cytoplasmic Channel in Plant Cell Walls.
Han, X, Huang, LJ, Feng, D, Jiang, W, Miu, W, Li, N
International journal of molecular sciences. 2019;(12)
Abstract
Plant cells are separated by cellulose cell walls that impede direct cell-to-cell contact. In order to facilitate intercellular communication, plant cells develop unique cell-wall-spanning structures termed plasmodesmata (PD). PD are membranous channels that link the cytoplasm, plasma membranes, and endoplasmic reticulum of adjacent cells to provide cytoplasmic and membrane continuity for molecular trafficking. PD play important roles for the development and physiology of all plants. The structure and function of PD in the plant cell walls are highly dynamic and tightly regulated. Despite their importance, plasmodesmata are among the few plant cell organelles that remain poorly understood. The molecular properties of PD seem largely elusive or speculative. In this review, we firstly describe the general PD structure and its protein composition. We then discuss the recent progress in identification and characterization of PD-associated plant cell-wall proteins that regulate PD function, with particular emphasis on callose metabolizing and binding proteins, and protein kinases targeted to and around PD.
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Cell Wall Proteins Play Critical Roles in Plant Adaptation to Phosphorus Deficiency.
Wu, W, Zhu, S, Chen, Q, Lin, Y, Tian, J, Liang, C
International journal of molecular sciences. 2019;(21)
Abstract
Phosphorus is one of the mineral nutrient elements essential for plant growth and development. Low phosphate (Pi) availability in soils adversely affects crop production. To cope with low P stress, remodeling of root morphology and architecture is generally observed in plants, which must be accompanied by root cell wall modifications. It has been documented that cell wall proteins (CWPs) play critical roles in shaping cell walls, transmitting signals, and protecting cells against environmental stresses. However, understanding of the functions of CWPs involved in plant adaptation to P deficiency remains fragmentary. The aim of this review was to summarize advances in identification and functional characterization of CWPs in responses to P deficiency, and to highlight the critical roles of CWPs in mediating root growth, P reutilization, and mobilization in plants.
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3.
Fruit ripening: the role of hormones, cell wall modifications, and their relationship with pathogens.
Forlani, S, Masiero, S, Mizzotti, C
Journal of experimental botany. 2019;(11):2993-3006
Abstract
Fruits result from complex biological processes that begin soon after fertilization. Among these processes are cell division and expansion, accumulation of secondary metabolites, and an increase in carbohydrate biosynthesis. Later fruit ripening is accomplished by chlorophyll degradation and cell wall lysis. Fruit maturation is an essential step to optimize seed dispersal, and is controlled by a complex network of transcription factors and genetic regulators that are strongly influenced by phytohormones. Abscisic acid (ABA) and ethylene are the major regulators of ripening and senescence in both dry and fleshy fruits, as demonstrated by numerous ripening-defective mutants, effects of exogenous hormone application, and transcriptome analyses. While ethylene is the best characterized player in the final step of a fruit's life, ABA also has a key regulatory role, promoting ethylene production and acting as a stress-related hormone in response to drought and pathogen attack. In this review, we focus on the role of ABA and ethylene in relation to the interconnected biotic and abiotic phenomena that affect ripening and senescence. We integrate and discuss the most recent data available regarding these biological processes, which are crucial for post-harvest fruit conservation and for food safety.
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4.
A Report on Fungal (1→3)-α-d-glucans: Properties, Functions and Application.
Złotko, K, Wiater, A, Waśko, A, Pleszczyńska, M, Paduch, R, Jaroszuk-Ściseł, J, Bieganowski, A
Molecules (Basel, Switzerland). 2019;(21)
Abstract
The cell walls of fungi are composed of glycoproteins, chitin, and α- and β-glucans. Although there are many reports on β-glucans, α-glucan polysaccharides are not yet fully understood. This review characterizes the physicochemical properties and functions of (1→3)-α-d-glucans. Particular attention has been paid to practical application and the effect of glucans in various respects, taking into account unfavourable effects and potential use. The role of α-glucans in plant infection has been proven, and collected facts have confirmed the characteristics of Aspergillus fumigatus infection associated with the presence of glucan in fungal cell wall. Like β-glucans, there are now evidence that α-glucans can also stimulate the immune system. Moreover, α-d-glucans have the ability to induce mutanases and can thus decompose plaque.
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5.
Secondary cell wall biosynthesis.
Zhong, R, Cui, D, Ye, ZH
The New phytologist. 2019;(4):1703-1723
Abstract
Contents Summary 1703 I. Introduction 1703 II. Cellulose biosynthesis 1705 III. Xylan biosynthesis 1709 IV. Glucomannan biosynthesis 1713 V. Lignin biosynthesis 1714 VI. Concluding remarks 1717 Acknowledgements 1717 References 1717 SUMMARY Secondary walls are synthesized in specialized cells, such as tracheary elements and fibers, and their remarkable strength and rigidity provide strong mechanical support to the cells and the plant body. The main components of secondary walls are cellulose, xylan, glucomannan and lignin. Biochemical, molecular and genetic studies have led to the discovery of most of the genes involved in the biosynthesis of secondary wall components. Cellulose is synthesized by cellulose synthase complexes in the plasma membrane and the recent success of in vitro synthesis of cellulose microfibrils by a single recombinant cellulose synthase isoform reconstituted into proteoliposomes opens new doors to further investigate the structure and functions of cellulose synthase complexes. Most genes involved in the glycosyl backbone synthesis, glycosyl substitutions and acetylation of xylan and glucomannan have been genetically characterized and the biochemical properties of some of their encoded enzymes have been investigated. The genes and their encoded enzymes participating in monolignol biosynthesis and modification have been extensively studied both genetically and biochemically. A full understanding of how secondary wall components are synthesized will ultimately enable us to produce plants with custom-designed secondary wall composition tailored to diverse applications.
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6.
The cell biology of secondary cell wall biosynthesis.
Meents, MJ, Watanabe, Y, Samuels, AL
Annals of botany. 2018;(6):1107-1125
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Abstract
BACKGROUND Secondary cell walls (SCWs) form the architecture of terrestrial plant biomass. They reinforce tracheary elements and strengthen fibres to permit upright growth and the formation of forest canopies. The cells that synthesize a strong, thick SCW around their protoplast must undergo a dramatic commitment to cellulose, hemicellulose and lignin production. SCOPE This review puts SCW biosynthesis in a cellular context, with the aim of integrating molecular biology and biochemistry with plant cell biology. While SCWs are deposited in diverse tissue and cellular contexts including in sclerenchyma (fibres and sclereids), phloem (fibres) and xylem (tracheids, fibres and vessels), the focus of this review reflects the fact that protoxylem tracheary elements have proven to be the most amenable experimental system in which to study the cell biology of SCWs. CONCLUSIONS SCW biosynthesis requires the co-ordination of plasma membrane cellulose synthases, hemicellulose production in the Golgi and lignin polymer deposition in the apoplast. At the plasma membrane where the SCW is deposited under the guidance of cortical microtubules, there is a high density of SCW cellulose synthase complexes producing cellulose microfibrils consisting of 18-24 glucan chains. These microfibrils are extruded into a cell wall matrix rich in SCW-specific hemicelluloses, typically xylan and mannan. The biosynthesis of eudicot SCW glucuronoxylan is taken as an example to illustrate the emerging importance of protein-protein complexes in the Golgi. From the trans-Golgi, trafficking of vesicles carrying hemicelluloses, cellulose synthases and oxidative enzymes is crucial for exocytosis of SCW components at the microtubule-rich cell membrane domains, producing characteristic SCW patterns. The final step of SCW biosynthesis is lignification, with monolignols secreted by the lignifying cell and, in some cases, by neighbouring cells as well. Oxidative enzymes such as laccases and peroxidases, embedded in the polysaccharide cell wall matrix, determine where lignin is deposited.
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Vitamin C: A Natural Inhibitor of Cell Wall Functions and Stress Response in Mycobacteria.
Syal, K, Chatterji, D
Advances in experimental medicine and biology. 2018;:321-332
Abstract
Tuberculosis, caused by Mycobacterium tuberculosis, has re-emerged as a threat to human race. Conventional antibiotic treatments are failing due to different stress response strategies adopted by bacterial pathogens. Since time immemorial, Vitamin C is known to protect against pathogens by boosting immunity in humans. Recently, Vitamin C has been shown to directly kill M. tuberculosis including multiple drug-resistant strains by generation of oxidative radicals through Fenton's reaction. Concurrently, it inhibits (p)ppGpp-mediated stringent response thus effectively shutting down long-term survival and persistence in mycobacteria. Here, we have discussed historical perspective and recent evidences on Vitamin C-mediated inhibition of several key pathways of M. tuberculosis such as (p)ppGpp synthesis and mycobacterial cell wall function. Several cell wall components including mycolic acids are critical for mycobacterial virulence. We observed downregulation of various mycolic acids in M. smegmatis upon treatment with Vitamin C, and data have been presented here. Vitamin C has been shown to inhibit the biofilm growth as well as disrupt the formed biofilm in mycobacteria. Additionally, Vitamin C role in cell-mediated and humoral immunity has been elucidated. Vitamin C is toxic at high concentration; therefore we have proposed the idea of derivatizing Vitamin C in order to lower the minimal inhibition concentration (MIC) necessary to target M. tuberculosis.
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Cell Wall Biogenesis During Elongation and Division in the Plant Pathogen Agrobacterium tumefaciens.
Figueroa-Cuilan, WM, Brown, PJB
Current topics in microbiology and immunology. 2018;:87-110
Abstract
A great diversity of bacterial cell shapes can be found in nature, suggesting that cell wall biogenesis is regulated both spatially and temporally. Although Agrobacterium tumefaciens has a rod-shaped morphology, the mechanisms underlying cell growth are strikingly different than other well-studied rod-shaped bacteria including Escherichia coli. Technological advances, such as the ability to deplete essential genes and the development of fluorescent D-amino acids, have enabled recent advances in our understanding of cell wall biogenesis during cell elongation and division of A. tumefaciens. In this review, we address how the field has evolved over the years by providing a historical overview of cell elongation and division in rod-shaped bacteria. Next, we summarize the current understanding of cell growth and cell division processes in A. tumefaciens. Finally, we highlight the need for further research to answer key questions related to the regulation of cell wall biogenesis in A. tumefaciens.
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9.
Interplay between Ions, the Cytoskeleton, and Cell Wall Properties during Tip Growth.
Bascom, CS, Hepler, PK, Bezanilla, M
Plant physiology. 2018;(1):28-40
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Abstract
Tip growth is a focused and tightly regulated apical explosion that depends on the interconnected activities of ions, the cytoskeleton, and the cell wall.
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10.
Interactions between cell wall polysaccharides and polyphenols.
Zhu, F
Critical reviews in food science and nutrition. 2018;(11):1808-1831
Abstract
In plant-based food systems such as fruits, vegetables, and cereals, cell wall polysaccharides and polyphenols co-exist and commonly interact during processing and digestion. The noncovalent interactions between cell wall polysaccharides and polyphenols may greatly influence the physicochemical and nutritional properties of foods. The affinity of cell wall polysaccharides with polyphenols depends on both endogenous and exogenous factors. The endogenous factors include the structures, compositions, and concentrations of both polysaccharides and polyphenols, and the exogenous factors are the environmental conditions such as pH, temperature, ionic strength, and the presence of other components (e.g., protein). Diverse methods used to directly characterize the interactions include NMR spectroscopy, size-exclusion chromatography, confocal microscopy, isothermal titration calorimetry, molecular dynamics simulation, and so on. The un-bound polyphenols are quantified by liquid chromatography or spectrophotometry after dialysis or centrifugation. The adsorption of polyphenols by polysaccharides is mostly driven by hydrophobic interactions and hydrogen bonding, and can be described by various isothermal models such as Langmuir and Freundlich equations. Quality attributes of various food and beverage products (e.g., wine) can be significantly affected by polysaccharide-polyphenol interactions. Nutritionally, the interactions play an important role in the digestive tract of humans for the metabolism of both polyphenols and polysaccharides.