Histochemical analysis of the root epidermal mucilage in maize and wheat

2004 ◽  
Vol 82 (10) ◽  
pp. 1419-1428
Author(s):  
Pedro HPA Schildknecht ◽  
Marília de M Castro ◽  
Benedicto C Vidal
Keyword(s):  
Cell Wall ◽  
Triticum Aestivum L ◽  
Root Surface ◽  
Histochemical Analysis ◽  
Lipophilic Compounds ◽  
Main Compound ◽  
Root Mucilage ◽  
Soil Interface ◽  
Crystalline Array ◽  
Important Structure

The root epidermal mucilage is an important structure at the root–soil interface, but its composition is not fully understood. In contrast to the root cap mucilage, the epidermal mucilage layer is firmly attached to the cell walls and cannot be collected easily in water. In this work, we examined histochemically the compounds present in the epidermal mucilage of Zea mays L. and Triticum aestivum L., as well as its anisotropic characteristics. Birefringence analysis showed a highly crystalline array of microfibrils arranged parallel to the root surface. Tests for lignin, lipophilic compounds, pectin, callose, and cellulose detected only the two latter compounds. Callose occurred sporadically as interrupted deposits in the epidermal mucilage and was detected in only a few plants. Cellulose was the main compound of this layer. We speculate that the epidermal mucilage is synthesized by the root epidermal cells and is firmly anchored to the wall at so many points as to give the appearance of being part of the cell wall. The cellulose present in the outer surface of the roots may act as a filtering mesh and a barrier to the external environment. The epidermal mucilage may also be involved in protection against physical, biological, and chemical agents.Key words: cell wall, root mucilage, cellulose, rhizosphere, maize.

Cytological and histochemical characteristics of the axenic root surface of Alnus glutinosa

1986 ◽  
Vol 64 (10) ◽  
pp. 2216-2226 ◽  
Author(s):  
Yves Prin ◽  
Mireille Rougier
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Root Hairs ◽  
Root Apex ◽  
Alnus Glutinosa ◽  
Root Surface ◽  
Infection Process ◽  
Root Cap ◽  
A Cell ◽  
Histochemical Tests

The aim of the present study was to investigate the Alnus root surface using seedlings grown axenically. This study has focused on root zones where infection by the symbiotic actinomycete Frankia takes place. The zones examined extend from the root cap to the emerging root hair zone. The root cap ensheaths the Alnus root apex and extends over the root surface as a layer of highly flattened cells closely appressed to the root epidermal cell wall. These cells contain phenolic compounds as demonstrated by various histochemical tests. They are externally bordered by a thin cell wall coated by a thin mucilage layer. The root cap is ruptured when underlying epidermal cells elongate, and cell remnants are still found in the emerging root hair zone. Young emerging root hairs are bordered externally by a cell wall covered by a thin mucilage layer which reacts positively to the tests used for the detection of polysaccharides, glycoproteins, and anionic sites. The characteristics of the Alnus root surface and the biological function of mucilage and phenols present at the root surface are discussed in relation to the infection process.

scholarly journals A Novel Class of Ectomycorrhiza-Regulated Cell Wall Polypeptides in Pisolithus tinctorius

1999 ◽  
Vol 12 (10) ◽  
pp. 862-871 ◽  
Author(s):  
Pascal Laurent ◽  
Catherine Voiblet ◽  
Denis Tagu ◽  
Dulcinéia de Carvalho ◽  
Uwe Nehls ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Adhesion ◽  
Polyacrylamide Gel Electrophoresis ◽  
State Level ◽  
Root Surface ◽  
Pisolithus Tinctorius ◽  
Surface Proteins ◽  
Ectomycorrhizal Symbiosis ◽  
Fungal Cell ◽  
Fungal Hyphae

Development of the ectomycorrhizal symbiosis leads to the aggregation of fungal hyphae to form the mantle. To identify cell surface proteins involved in this developmental step, changes in the biosynthesis of fungal cell wall proteins were examined in Eucalyptus globulus-Pisolithus tinctorius ectomycorrhizas by two-dimensional polyacrylamide gel electrophoresis. Enhanced synthesis of several immunologically related fungal 31- and 32-kDa polypeptides, so-called symbiosis-regulated acidic polypeptides (SRAPs), was observed. Peptide sequences of SRAP32d were obtained after trypsin digestion. These peptides were found in the predicted sequence of six closely related fungal cDNAs coding for ectomycorrhiza up-regulated transcripts. The PtSRAP32 cDNAs represented about 10% of the differentially expressed cDNAs in ectomycorrhiza and are predicted to encode alanine-rich proteins of 28.2 kDa. There are no sequence homologies between SRAPs and previously identified proteins, but they contain the Arg-Gly-Asp (RGD) motif found in cell-adhesion proteins. SRAPs were observed on the hyphal surface by immunoelectron microscopy. They were also found in the host cell wall when P. tinctorius attached to the root surface. RNA blot analysis showed that the steady-state level of PtSRAP32 transcripts exhibited a drastic up-regulation when fungal hyphae form the mantle. These results suggest that SRAPs may form part of a cell-cell adhesion system needed for aggregation of hyphae in ectomycorrhizas.

scholarly journals Characterizing the Role of TaWRKY13 in Salt Tolerance

2019 ◽  
Vol 20 (22) ◽  
pp. 5712 ◽  
Author(s):  
Shuo Zhou ◽  
Wei-Jun Zheng ◽  
Bao-Hua Liu ◽  
Jia-Cheng Zheng ◽  
Fu-Shuang Dong ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Oryza Sativa L ◽  
Triticum Aestivum L ◽  
Regulatory Elements ◽  
Root Surface ◽  
Root Surface Area ◽  
Functional Identification ◽  
Positive Role ◽  
Data Set

The WRKY transcription factor superfamily is known to participate in plant growth and stress response. However, the role of this family in wheat (Triticum aestivum L.) is largely unknown. Here, a salt-induced gene TaWRKY13 was identified in an RNA-Seq data set from salt-treated wheat. The results of RT-qPCR analysis showed that TaWRKY13 was significantly induced in NaCl-treated wheat and reached an expression level of about 22-fold of the untreated wheat. Then, a further functional identification was performed in both Arabidopsis thaliana and Oryza sativa L. Subcellular localization analysis indicated that TaWRKY13 is a nuclear-localized protein. Moreover, various stress-related regulatory elements were predicted in the promoter. Expression pattern analysis revealed that TaWRKY13 can also be induced by polyethylene glycol (PEG), exogenous abscisic acid (ABA), and cold stress. After NaCl treatment, overexpressed Arabidopsis lines of TaWRKY13 have a longer root and a larger root surface area than the control (Columbia-0). Furthermore, TaWRKY13 overexpression rice lines exhibited salt tolerance compared with the control, as evidenced by increased proline (Pro) and decreased malondialdehyde (MDA) contents under salt treatment. The roots of overexpression lines were also more developed. These results demonstrate that TaWRKY13 plays a positive role in salt stress.

Colonization and invasion of peanut (Arachis hypogaea L.) roots by gusA-marked Bradyrhizobium sp.

2001 ◽  
Vol 79 (6) ◽  
pp. 733-738 ◽  
Author(s):  
Eiji Uheda ◽  
Hiroyuki Daimon ◽  
Fumiki Yoshizako
Keyword(s):  
Cell Wall ◽  
Arachis Hypogaea ◽  
Hair Cells ◽  
Root Hair ◽  
Root Nodules ◽  
Lateral Roots ◽  
Middle Lamella ◽  
Root Surface ◽  
Arachis Hypogaea L ◽  
Root Hair Cells

Tufted rosettes of long root hairs occur in axils of young lateral roots of peanut (Arachis hypogaea L.). Analyses of serial sections of the axils of emerging lateral roots revealed multiple layers of root hair cells. The cells of the outer layer partially overlie the adjacent cells of the inner layer. When Bradyrhizobium cells with an integrated gusA gene were inoculated onto peanut roots and the roots subsequently stained with X-gluc, blue spots indicating the presence of colonies of Bradyrhizobium were observed in the axils of lateral roots. Blue spots were also observed in other areas on the root surface. Transmission electron microscopy revealed that the primary wall of the base of root hair cells has a loose construction. Upon inoculation of Bradyrhizobium, bacteria entered only between root hair cells through the middle lamella. In other areas of the root surface other than axils of lateral roots, the cells had modified walls similar to those at the base of root hair cells. However, invasion by Bradyrhizobium of the cell wall was not observed.Key words: Arachis hypogaea, gusA-marked Bradyrhizobium, cell wall, invasion, root hair cell, root nodules.

Biophysical interactions at the root–soil interface: a review

1998 ◽  
Vol 130 (1) ◽  
pp. 1-7 ◽  
Author(s):  
I. M. YOUNG
Keyword(s):  
Crop Yields ◽  
Farming Systems ◽  
Root Surface ◽  
Biological Properties ◽  
Water Dynamics ◽  
Limited Attention ◽  
Small Scale ◽  
Soil Matrix ◽  
Increased Risk ◽  
Soil Interface

Soil close to roots generally has chemical, physical and biological properties which are significantly different from those of soil located some distance away (Jenny & Grossenbacher 1963; Hawes & Pueppke 1986; Young 1995). The root–soil interface is defined as soil near to or adhered to the root surface to some small distance into the soil matrix. This distance may vary between <1 mm and c. 10 mm. Working definitions include rhizosphere, where ‘zones of influence’ are inferred, and rhizosheath, when soil adhered to the root is discussed. Most work carried out at the root–soil interface has concentrated on biological or chemical processes, due both to the fact that the relevant techniques required to examine these processes have been more advanced than the physical techniques, and also because the farmer is generally offered either biological or chemical solutions to his everyday problems, as these are readily accessible, easy to use and cheap. The main manipulation of soil physical conditions occurs during cultivations, and the addition or removal of water from the soil profile. Intensive cultivations are a regular occurrence in many farming systems, despite the potential drawbacks: damage of the soil structure, leading to reduced crop yields and an increased risk of erosion.The main aim of this review is not to cover all the complex issues related to the root–soil interface. Instead, it concentrates on the biophysical processes which, compared with conventional plant physiological and soil microbiological research, have attracted relatively limited attention (e.g. see Waisel et al. 1996). The review examines small-scale (μm-mm) interactions and, where possible, links their impact to the larger scale. Three interacting areas are investigated: the physical structure of the soil and root growth, water dynamics and microbial dynamics.

Tapetal development and abiotic stress: a centre of vulnerability

2012 ◽  
Vol 39 (7) ◽  
pp. 553 ◽  
Author(s):  
Roger W. Parish ◽  
Huy A. Phan ◽  
Sylvana Iacuone ◽  
Song F. Li
Keyword(s):  
Cell Wall ◽  
Abiotic Stress ◽  
Oryza Sativa L ◽  
Triticum Aestivum L ◽  
Pollen Abortion ◽  
Cell Wall Invertase ◽  
Developmental Program ◽  
Specific Effects ◽  
Hexose Sugars ◽  
Microspore Stage

Many self-fertilising crops are particularly sensitive to abiotic stress at the reproductive stage. In rice (Oryza sativa L.) and wheat (Triticum aestivum L.), for example, abiotic stress during meiosis and the young microspore stage indicates the tapetum is highly vulnerable and that the developmental program appears to be compromised. Tapetal hypertrophy can occur as a consequence of cold and drought stress, and programmed cell death (PCD) is delayed or inhibited. Since the correct timing of tapetal PCD is essential for pollen reproduction, substantial losses in grain yield occur. In wheat and rice, a decrease in tapetal cell wall invertase levels is correlated with pollen abortion and results in the amount of hexose sugars reaching the tapetum, and subsequently the developing microspores, being severely reduced (‘starvation hypothesis’). ABA and gibberellin levels may be modified by cold and drought, influencing levels of cell wall invertase(s) and the tapetal developmental program, respectively. Many genes regulating tapetal and microspore development have been identified in Arabidopsis thaliana (L.) Heynh. and rice and the specific effects of abiotic stresses on the program and pathways can now begin to be assessed.

Extractability and digestibility of plant cell wall polysaccharides during hydrothermal and enzymatic degradation of wheat straw (Triticum aestivum L.)

2014 ◽  
Vol 55 ◽  
pp. 63-69 ◽  
Author(s):  
Mads A.T. Hansen ◽  
Louise I. Ahl ◽  
Henriette L. Pedersen ◽  
Bjørge Westereng ◽  
William G.T. Willats ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
Cell Wall ◽  
Wheat Straw ◽  
Plant Cell ◽  
Enzymatic Degradation ◽  
Plant Cell Wall ◽  
Triticum Aestivum L ◽  
Cell Wall Polysaccharides
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