Cell Wall Pattern Research Articles

Occurrence of xylan and mannan polysaccharides and their spatial relationship with other cell wall components in differentiating compression wood tracheids of Cryptomeria japonica

Compression wood (CW) tracheids have different cell wall components than normal wood (NW) tracheids. However, temporal and spatial information on cell wall components in CW tracheids is poorly understood. We investigated the distribution of arabino-4-O-methylglucuronoxylans (AGXs) and O-acetyl-galactoglucomannans (GGMs) in differentiating CW tracheids. AGX labeling began to be detected in the corner of the S(1) layer at the early S(1) formation stage. Subsequently, the cell corner middle lamella (ccML) showed strong AGX labeling when intercellular spaces were not fully formed. AGX labeling was uniformly distributed in the S(1) layer, but showed uneven distribution in the S(2) layer. AGX labeling was mainly detected in the inner S(2) layer after the beginning of the helical cavity formation. The outer S(2) layer showed almost no labeling of low substituted AGXs. Only a very small amount of high substituted AGXs was distributed in the outer S(2) layer. These patterns of AGX labeling in the S(2) layer opposed the lignin and β-1-4-galactan distribution in CW tracheids. GGM labeling patterns were almost identical to AGX labeling in the early stages of CW tracheids, and GGM labeling was detected in the entire S(2) layer from the early S(2) formation stage of CW tracheids with some spatial differences in labeling density depending on developmental stage. Compared with NW tracheids, CW tracheids showed significantly different AGX distributions in the secondary cell wall but similar GGM labeling patterns. No significant differences were observed in labeling after delignification of CW tracheids.

Wood Cell-Wall Structure Requires Local 2D-Microtubule Disassembly by a Novel Plasma Membrane-Anchored Protein

Plant cells have evolved cortical microtubules, in a two-dimensional space beneath the plasma membrane, that regulate patterning of cellulose deposition. Although recent studies have revealed that several microtubule-associated proteins facilitate self-organization of transverse cortical microtubules, it is still unknown how diverse patterns of cortical microtubules are organized in different xylem cells, which are the major components of wood. Using our newly established in vitro xylem cell differentiation system, we found that a novel microtubule end-tracking protein, microtubule depletion domain 1 (MIDD1), was anchored to distinct plasma membrane domains and promoted local microtubule disassembly, resulting in pits on xylem cell walls. The introduction of RNA interference for MIDD1 resulted in the failure of local microtubule depletion and the formation of secondary walls without pits. Conversely, the overexpression of MIDD1 reduced microtubule density. MIDD1 has two coiled-coil domains for the binding to microtubules and for the anchorage to plasma membrane domains, respectively. Combination of the two coils caused end tracking of microtubules during shrinkage and suppressed their rescue events. Our results indicate that MIDD1 integrates spatial information in the plasma membrane with cortical microtubule dynamics for determining xylem cell wall pattern.

Tricarboxylic Acid Cycle Activity Regulates Tomato Root Growth via Effects on Secondary Cell Wall Production

Transgenic tomato (Solanum lycopersicum 'Moneymaker') plants independently expressing fragments of various genes encoding enzymes of the tricarboxylic acid cycle in antisense orientation have previously been characterized as exhibiting altered root growth. In this study, we evaluate the rates of respiration of roots from these lines in addition to determining their total dry weight accumulation. Given that these features were highly correlated, we decided to carry out an evaluation of the cell wall composition in the transformants that revealed a substantial reduction in cellulose. Since the bulk of cellulose is associated with the secondary cell walls in roots, we reasoned that the transformants most likely were deficient in secondary wall cellulose production. Consistent with these findings, cross-sections of the root collar (approximately 15 mm from the junction between root and stem) displayed reduced lignified secondary cell walls for the transformants. In contrast, cell and cell wall patterning displayed no differences in elongating cells close to the root tip. To further characterize the modified cell wall metabolism, we performed feeding experiments in which we incubated excised root tips in [U-(14)C]glucose in the presence or absence of phosphonate inhibitors of the reaction catalyzed by 2-oxoglutarate dehydrogenase. Taken together, the combined results suggest that restriction of root respiration leads to a deficit in secondary cell wall synthesis. These data are discussed in the context of current models of biomass partitioning and plant growth.

Role of polyamines in plant vascular development

Several pieces of evidence suggest a role for polyamines in the regulation of plant vascular development. For instance, polyamine oxidase gene expression has been shown to be associated with lignification, and downregulation of S-adenosylmethionine decarboxylase causes dwarfism and enlargement of the vasculature. Recent evidence from Arabidopsis thaliana also suggests that the active polyamine in the regulation of vascular development is the tetraamine thermospermine. Thermospermine biosynthesis is catalyzed by the aminopropyl transferase encoded by ACAULIS5, which is specifically expressed in xylem vessel elements. Both genetic and molecular evidence support a fundamental role for thermospermine in preventing premature maturation and death of the xylem vessel elements. This safeguard action of thermospermine has significant impact on xylem cell morphology, cell wall patterning and cell death as well as on plant growth in general. This manuscript reviews recent reports on polyamine function and places polyamines in the context of the known regulatory mechanisms that govern vascular development.

ArabidopsisCortical Microtubules Are Initiated along, as Well as Branching from, Existing Microtubules

The principles by which cortical microtubules self-organize into a global template hold important implications for cell wall patterning. Microtubules move along bundles of microtubules, and neighboring bundles tend to form mobile domains that flow in a common direction. The bundles themselves move slowly and for longer than the individual microtubules, with domains describing slow rotary patterns. Despite this tendency for colinearity, microtubules have been seen to branch off extant microtubules at approximately 45 degrees . To examine this paradoxical behavior, we investigated whether some microtubules may be born on and grow along extant microtubule(s). The plus-end markers Arabidopsis thaliana end binding protein 1a, AtEB1a-GFP, and Arabidopsis SPIRAL1, SPR1-GFP, allowed microtubules of known polarity to be distinguished from underlying microtubules. This showed that the majority of microtubules do branch but in a direction heavily biased toward the plus end of the mother microtubule: few grow backward, consistent with the common polarity of domains. However, we also found that a significant proportion of emergent comets do follow the axes of extant microtubules, both at sites of apparent microtubule nucleation and at cross-over points. These phenomena help explain the persistence of bundles and counterbalance the tendency to branch.

Analytical studies of silica biomineralization: towards an understanding of silica processing by diatoms

Diatoms have continued to attract research interest over a long time. One important reason for this research interest is the amazingly beautiful microstructured and nanostructured patterning of the silica-based diatom cell walls. These materials become increasingly important from the materials science point of view. However, many aspects of diatom cell wall formation and patterning are still not fully understood. The present minireview article summarizes our recent knowledge especially with respect to two major topics related to diatom cell wall formation and patterning: (1) uptake and metabolism of silicon by living diatom cells and (2) understanding of the genetic control of cell wall formation. Analytical techniques as well as recent results concerning these two topics are highlighted in this review.

Biological Templating: Bioinspired Design of SrAl2O4:Eu2+ Phosphor (Adv. Funct. Mater. 4/2009)

The morphology of native pine wood is replicated to generate a novel cellular phosphor material based on Eu-doped strontium aluminate. On page 599, the authors describe the infiltration and conversion of the original cell wall pattern using the biotemplating technique. The obtained materials show a strong green photoluminescence. Biological templates offer a novel approach for designing advanced micropatterned phosphor materials.

Characterization of Halanaerobaculum tunisiense gen. nov., sp. nov., a new halophilic fermentative, strictly anaerobic bacterium isolated from a hypersaline lake in Tunisia

A new halophilic anaerobe was isolated from the hypersaline surface sediments of El-Djerid Chott, Tunisia. The isolate, designated as strain 6SANG, grew at NaCl concentrations ranging from 14 to 30%, with an optimum at 20-22%. Strain 6SANG was a non-spore-forming, non-motile, rod-shaped bacterium, appearing singly, in pairs, or occasionally as long chains (0.7-1 x 4-13 microm) and showed a Gram-negative-like cell wall pattern. It grew optimally at pH values between 7.2 and 7.4, but had a very broad pH range for growth (5.9-8.4). Optimum temperature for growth was 42 degrees C (range 30-50 degrees C). Strain 6SANG required yeast extract for growth on sugars. Glucose, sucrose, galactose, mannose, maltose, cellobiose, pyruvate, and starch were fermented. The end products from glucose fermentation were acetate, butyrate, lactate, H(2), and CO(2). The G + C ratio of the DNA was 34.3 mol%. Strain 6SANG exhibited 16S rRNA gene sequence similarity values of 91-92% with members of the genus Halobacteroides, H. halobius being its closest phylogenetic relative. Based on phenotypic and phylogenetic characteristics, we propose that this bacterium be classified as a novel species of a novel genus, Halanaerobaculum tunisiense gen. nov., sp. nov. The type strain is 6SANG(T) (=DSM 19997(T)=JCM 15060(T)).

ACAULIS5 controlsArabidopsisxylem specification through the prevention of premature cell death

Cell size and secondary cell wall patterning are crucial for the proper functioning of xylem vessel elements in the vascular tissues of plants. Through detailed anatomical characterization of Arabidopsis thaliana hypocotyls, we observed that mutations in the putative spermine biosynthetic gene ACL5 severely affected xylem specification: the xylem vessel elements of the acl5 mutant were small and mainly of the spiral type, and the normally predominant pitted vessels as well as the xylem fibers were completely missing. The cell-specific expression of ACL5 in the early developing vessel elements, as detected by in situ hybridization and reporter gene analyses, suggested that the observed xylem vessel defects were caused directly by the acl5 mutation. Exogenous spermine prolonged xylem element differentiation and stimulated cell expansion and cell wall elaboration in xylogenic cell cultures of Zinnia elegans, suggesting that ACL5 prevents premature death of the developing vessel elements to allow complete expansion and secondary cell wall patterning. This was further supported by our observations that the vessel elements of acl5 seemed to initiate the cell death program too early and that the xylem defects associated with acl5 could be largely phenocopied by induction of premature, diphtheria toxin-mediated cell death in the ACL5-expressing vessel elements. We therefore provide, for the first time, mechanistic evidence for the function of ACL5 in xylem specification through its action on the duration of xylem element differentiation.

The tensor-based model for growth and cell divisions of the root apex. I. The significance of principal directions

Plant organs grow symplastically, i.e. in a continuous and coordinated way. Such growth is of a tensor nature, which is manifested in the property that at every point of the organ three mutually orthogonal principal growth directions (PDG) can be recognized. The PDGs are postulated to affect orientation of cell divisions. This paper shows for the first time the 2D simulation model for growth in which cells divide taking into account the PDGs. The model, conceptually based on the growth tensor (GT), is applied to the root apex of radish, having a quiescent centre (QC). It shows the simulation of how exemplary cell pattern of the real root apex develops in time. The results provide satisfactory description of the root growth. The computer-generated cell pattern is realistic and more or less steady indicating that PDGs are important for growth. Presumably cells detect PDGs and obey them in the course of cell divisions. Computer generated division walls, perpendicular to PDGs, form periclinal and anticlinal zigzags as regular as those observed in microscopic sections. Growth tensor defines a field of growth rates at the organ level. QC, fundamental in this field, determines the group of quiescent initial cells which is, in turn, surrounded by active functional initials, from which all tissues of the root apex originate. The present simulations have shown that stability of generated cell pattern depends on whether the group of the functional initials is permanent; if this is not the case, the cell wall pattern changes in accordance with PDGs.

Isolation and Identification of Streptomyces fradiae SU-1 from Thailand and Protoplast Transformation with the Chitinase B Gene from Nocardiopsis prasina OPC-131

Thirty-two strains of actinomycetes obtained from soil samples of Thailand were selected. Actinomycete strain SU-1 is the most effective in terms of antagonism of Fusarium moniliforme. It produces antifungal substances on agar medium against F. moniliforme. On the basis of microscopical observations of its morphology and biochemical tests as well as analysis of cell wall and fatty acid pattern, this strain was identified as Streptomyces fradiae. The chitinase gene B (chiB337) from Nocardiopsis prasina OPC-131 was inserted into an integrating plasmid pFIS318, an Escherichia coli-Streptomyces shuttle vector. The new plasmid pFIS319-1 carrying the chitinase gene was used to transform protoplasts of S. fradiae strain SU-1. The obtained recombinant strain SU-1 pFIS319-1 exhibited higher chitinase activity than the wild-type in chitinase induction medium. Chitinase activity after renaturing protein from SDS-PAGE was detected rapidly by using 4-methylumbelliferyl beta-D: -N,N''-diacetylchitobioside as the substrate. S. fradiae SU-1 secreted two chitinases with estimated molecular masses of 26 kDa and 43 kDa whereas the recombinant strain secreted three chitinases of about 26 kDa, 31.5 kDa (ChiB), and 43 kDa. The supernatant of the recombinant strain grown in chitinase induction medium inhibited the hyphal extension of F. moniliforme.

Comments on Recent Progress Toward Reconstructing the Diatom Phylogeny

Much attention is being directed toward understanding and co-opting the mechanisms by which diatoms control patterning of silica for nanotechnology applications. Given the enormous diversity of cell-wall patterns among diatom taxa, a complete understanding of these mechanisms will require comparative analysis of nanopatterning strategies from a diversity of diatom taxa. A well-supported phylogenetic tree provides the best basis for such comparisons because closely related taxa will have many similar attributes (morphological, physiological, ecological, etc.) simply because they share a recent common ancestor. Phylogenetic information is exploited in as diverse a set of fields as pharmacology, epidemiology, and geology. Nanotechnologists can use the phylogenetic tree of diatoms to help select exemplar taxa and to streamline the search for alternative nanopatterning strategies. We review the progress made thus far in reconstructing the phylogeny of diatoms. Most analyses have been based on small subunit ribosomal DNA sequences, and inferences have varied substantially depending on the number and diversity of taxa included in the analyses. We review several seminal studies on diatom phylogeny in light of theoretical and empirical investigations that have emphasized the critical importance of taxonomic sampling on phylogenetic inference. One consistent result is that centric diatoms grade into araphid pennates, and araphid pennates grade the raphe-bearing pennate diatoms, which are a natural group. Including more taxa and more characters (molecular and morphological) should yield a better supported hypothesis of diatom relationships.

Structural integration at the shoot apical meristem: models, measurements, and experiments

The shoot apical meristem (SAM) produces stem and initiates leaves. Its structure is maintained despite a continuous flow of cells basipetally from the distal portion of the meristem. The apoplasm and symplasm are the obvious means of cell integration, and their role in chemical cell-to-cell signaling is known. However, the cell wall apoplasm is most likely also involved in a mechanical integration mode, in which mechanical stress and strains (elastic and plastic strain, i.e., growth) are putative signaling factors. Shoot apex cells grow symplastically and their growth is in general anisotropic. Therefore tensor of growth rates that depends on the displacements caused by growth is the most suitable physical entity to describe growth. The tensor approach introduces the concept of principal directions of growth, i.e., the directions in which growth rates attain extremal values. Because of the symplastic mode of growth, the cell wall pattern within the shoot apical meristem informs us about the sequence and planes of cell divisions and about the deformation of existing walls. In consequence, within the meristem, periclines and anticlines can be recognized, both representing the principal directions of growth.

Secondary walls in hyaline cells of Sphagnum

The cytoskeleton and ultrastructural events associated with cell differentiation and secondary cell wall and pore formation in hyaline cells of Sphagnum are investigated. Microtubules reorient from random arrays in undifferentiated hyaline cells to transverse arrays in elongating cells. Once cells are fully elongated, broad bands of microtubules aggregate into a spiral that predicts the site of secondary cell wall deposition. The secondary wall has a similar fibrillar composition to the primary wall. After the secondary wall is deposited, the thin primary wall covering the pore breaks down, usually by cell-wall degradation at the centre of the pore and around its margin. Finally, the hyaline cell undergoes cytoplasmic degeneration. The orientation of microtubules associated with hyaline-cell formation and secondary cell wall patterning resembles ultrastructural development in tracheary elements of higher plants. The similarities in cytoskeletal arrays during cell differentiation and secondary-wall formation suggest a fundamental pathway of development shared by bryophytes and higher plants.

Degradation of pyrene and characterization ofSaccharothrix sp. PYX-6 from the oligotrophic Tianchi Lake in Xinjiang Uygur Autonomous Region, China

Bacterial strain PYX-6 that utilizes anthracene, phenanthrene, or pyrene for carbon and energy sources for growth was isolated from a non-polluted lake (Tianchi Lake) in Xinjiang Uygur Autonomons Region of China. Its morphology, physiological and biochemical properties, cell wall pattern and G+C mol% content of DNA molecules were characterized. The 16S rRNA gene of strain PYX-6 was sequenced and analyzed for similarities to related bacterial species. Results indicated that strain PYX-6 is a member of the GenusSaccharothrix, and the strain was namedSaccharothrix sp. PYX-6. When pyrene was the sole carbon source in cultural medium, the strain PYX-6 assimilated pyrene for growth and 0.005% of yeast extract stimulated pyrene degradation and assimilation. The optimal pH of cultural medium and the optimal shaking frequency during cultivation were 6–8 and 200 r/m, respectively. It was found that the disappearance of pyrene in medium occurred before significant growth of strain PYX-6 took place. Phthalic acid, benzylacetic acid, and benzylpropenoic acid were detected as catabolic intermediates during pyrene degradation with mass spectroscopy and this result indicated thatSaccharothrix sp. PYX-6 adopted a pathway that is different from the pathway of the previously reported pyrene-degradingMycobacterium sp. PYR-1.

Cell differentiation, secondary cell-wall formation and transformation of callus tissue of Pinus radiata D. Don.

Tracheid and sclereid differentiation was induced in callus cultures of Pinus radiata D. Don by culturing on a basal medium containing activated charcoal but no phytohormones; sclereids differentiated in callus derived from xylem strips, but not in callus derived from hypocotyl segments. The tracheids differentiated in hypocotyl-derived callus had helical, scalariform, reticulated or pitted secondary cell-wall patterns, but those differentiated in xylem-derived callus had a reticulate or pitted pattern. The thickened tracheid and sclereid walls contained lignin as indicated by the red colour reaction given with phloroglucinol-HCl. The presence of lignin in the cell walls of differentiated callus was confirmed using pyrolysis gas chromatography-mass spectrometry by the detection of phenylpropanoid components derived from lignin. Lignin was also detected using solid-state (13)C cross-polarisation/magic-angle spinning nuclear magnetic resonance spectroscopy and quantified as thioglycolic acid lignin. Monosaccharide analyses of the cell walls isolated from differentiated and undifferentiated calli showed that the cell walls of the differentiated calli contained higher proportions of glucose and mannose, consistent with the presence of greater proportions of gluco- and/or galactogluco-mannans in the secondary cell walls of the differentiated cells. A protocol for the stable transformation of undifferentiated, xylem-derived cultures was successfully developed. Transgenic cell lines were established following Biolistic particle bombardment with a plasmid containing the coding region of the nptII gene and the coding region of the cad gene from P. radiata. Expression of the nptII gene in transgenic lines was confirmed by an NPTII-enzyme-linked immunosorbent assay. The overexpression of cad in the transgenic lines resulted in a down-regulation of cinnamyl alcohol dehydrogenase (EC 1.1.1.195) expression.

Tracheoid Variation among Bignoniaceae Seed Wings, with Emphasis on Campsis radicans

Seed wings of 20 species of Bignoniaceae, representing five of the eight tribes, were cleared and stained in order to reveal cell wall patterns of the tracheoids. Tracheoids of some species lacked ornamented secondary walls; others had annular, helical, reticulate, or pitted walls. Some species had all one type of tracheoid wall pattern; others exhibited an array of wall patterns. Wall patterns were not correlated with seed or wing size, which was quite variable. Campsis radicans had an almost complete range of wall patterns; therefore, it was studied in detail using clearings, macerations, resin sections, and scanning electron microscopy. This is the first survey to sample most tribes of Bignoniaceae and to report tracheoid wall pattern variations that equal or surpass those of tracheary elements in xylem.

Micromorphology and Adaptation of leaf epidermal traits in Rhizophoraceae to Coastal Wetland Ecosystem

The leaf epidermal/cuticular micromorphological feature was studied in four genera vis-a-vis Rhizophora, Kandelia, Ceriops and Bruguiera of family Rhizophoraceae. While Rhizophora has the means to exude excess salt through their stomatal modification (cork-wart-like structure), Kandelia shows rupture in the epithelium perhaps for the same reason. No cork-wart-like structure was found in Kandelia, Ceriops and Bruguiera species. The epidermal cell size, stomatal length and breadth, stomatal index and differentiation in the costal and intercostal cell wall pattern are the identifiable traits in all the species studied. Rhizophora apiculata and Bruguiera caryophylloides shows increase/ decrease in the epidermal cell size and Stomatal indices with the varying coastal ecology. During salinity related stress the cork-wart-like structure in Rhizophora apiculata on the lower epidermis becomes rudimentary and non-functional while it is well developed and of larger size in normal ecological conditions. Bruguiera cylindrica differs with all the species in having undulate cell wall pattern in the coastal area studded with the stomata and shows closer affinity with B. gymnorrhiza (costal cells distinct but with sinuate anticlinal cell wall) and not with its Syn. B. caryophylloides in this respect. The stomatal index (SI) in Rhizophora apiculata shows similarity with that of Bruguiera parviflora and B. gymnorrhiza. However, R apiculata growing in stressed environment shows similar SI as in Bruguiera sexangula and other species of Rhizophora, Ceriops and Kandelia. It is understood that perhaps Rhizophora apiculata and C. decandra (Syn. C. roxburghiana) and B. cylindrica (Syn. B. caryophylloides) have SI as a non-consistent feature that tends to vary with the changing environment. Mangrove species showing similarity in the epidermal traits and their adaptive features may thrive together in a common coastal environment. Leaf epidermal traits of Rhizophoraceae would help in the identification of fossil cuticles at a specific level and their non-consistent features adapting to the changing coastal environment would provide potential proxy data for interpreting palaeoecology.

Halonatronum saccharophilum gen. nov. sp. nov--a new haloalkalophilic bacteria from the order Haloanaerobiales from Lake Magadi

A new alkaliphilic and moderately halophilic chemoorganotrophic anaerobic bacterium (strain Z-7986), which is spore-forming, rod-shaped, and has a gram-negative cell wall pattern, was isolated from the coastal lagoon mud of the highly mineralized Lake Magadi (Kenya). The organism is an obligatorily carbonate- and sodium chloride-dependent. It is a motile peritrichously flagellated rod that has developed within 3-17% NaCl concentration (with an optimum at 7-12% NaCl) and within a pH range of 7.7-10.3 (with an optimum at pH values of 8-8.5). It is a moderate thermophile with a broad temperature optimum from 36-55 degrees C and a growth maximum at 60 degrees C. The bacterium catabolizes glucose, fructose, sucrose, maltose, starch, glycogen, N-acetyl-D-glucosamine, and, to a slight degree, peptone and yeast extract. Its anabolism requires yeast extract or casamino acids. Glucose fermentation yields formate, acetate, ethanol, H2, and CO2. The bacterium is sulfidetolerant and capable of the nonspecific reduction of S0 to H2S. The G + C content of the DNA is 34.4 mol %. The analysis of the 16S rRNA sequence revealed that strain Z-7986 belongs to the order Haloanaerobiales and represents a new genus in the family Halobacteroidaceae. We suggest calling the organism Halonatronum saccharophilum gen. nov. sp. nov. The type strain of this species is Z-7986T (= DSM13868, = Uniqem 211).

Ultrastructure of stomatal development in Arabidopsis (Brassicaceae) leaves

Stomatal development was studied in wild-type Arabidopsis leaves using light and electron microscopy. Development involves three successive types of stomatal precursor cells: meristemoid mother cells, meristemoids, and guard mother cells (GMCs). The first two types divide asymmetrically, whereas GMCs divide symmetrically. Analysis of cell wall patterns indicates that meristemoids can divide asymmetrically a variable number of times. Before meristemoid division, the nucleus and a preprophase band of microtubules become located on one side of the cell, and the vacuole on the other. Meristemoids are often triangular in shape and have evenly thickened walls. GMCs can be detected by their roughly oval shape, increased starch accumulation, and wall thickenings on opposite ends of the cells. Because these features are also found in developing stomata, stomatal differentiation begins in GMCs. The wall thickenings mark the division site in the GMC since they overlie a preprophase band of microtubules and occur where the cell plate fuses with the parent cell wall. Stomatal differentiation in Arabidopsis resembles that of other genera with kidney-shaped guard cells. This identification of stages in stomatal development in wild-type Arabidopsis provides a foundation for the analysis of relevant genes and of mutants defective in stomatal patterning, cell specification, and differentiation.