scholarly journals Transcriptional networks underpinning ploidy related increased leaf potassium in neo-tetraploids

2021 ◽  
Author(s):  
Sina Fischer ◽  
Paulina Flis ◽  
Fang-Jie Zhao ◽  
David E. Salt
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Ion Transport ◽  
Differentially Expressed Genes ◽  
Mutational Analysis ◽  
Root Hairs ◽  
Transcriptional Networks ◽  
Physiological Effects ◽  
K Uptake ◽  
Uptake Transporters

AbstractNeo-tetraploid Arabidopsis thaliana have elevated leaf potassium (K) driven by processes within the root. The root transcriptome of neo-tetraploids is distinct from diploids, with evidence of altered K homeostasis. Mutational analysis revealed that the canonical K-uptake transporters AKT1 and HAK5 are not required for this elevated leaf K in neo-tetraploids, while the endodermis, root hairs, and SOS signaling are. Contrasting the root transcriptomes of neo-tetraploids and diploids of mutants that block the neo-tetraploid K phenotype, allowed us to identify 91 differentially expressed genes associated with elevated leaf K in neo-tetraploids. This set of genes connects WGD to elevated leaf K, and is enriched in functions such as cell wall and Casparian strip development, and ion-transport, in the endodermis, root hairs, and procambium. This gene set provides tools to test the intriguing idea of recreating the physiological effects of WGD within a diploid genome.

SRPP, a cell-wall protein is involved in development and protection of seeds and root hairs in Arabidopsis thaliana

2017 ◽  
pp. pcx008 ◽  
Author(s):  
Natsuki Tanaka ◽  
Hiroshi Uno ◽  
Shohei Okuda ◽  
Shizuka Gunji ◽  
Ali Ferjani ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Root Hairs ◽  
Cell Wall Protein ◽  
A Cell

scholarly journals LRR-extensins of vegetative tissues are a functionally conserved family of RALF1 receptors interacting with the receptor kinase FERONIA

2019 ◽  
Author(s):  
Aline Herger ◽  
Shibu Gupta ◽  
Gabor Kadler ◽  
Christina Maria Franck ◽  
Aurélien Boisson-Dernier ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Cell Growth ◽  
Mechanical Stability ◽  
Root Hairs ◽  
Cell Wall Integrity ◽  
Receptor Kinase ◽  
Growth Processes ◽  
Evolutionary Diversification

AbstractPlant cell growth requires the coordinated expansion of the protoplast and the cell wall that confers mechanical stability to the cell. An elaborate system of cell wall integrity sensors monitors cell wall structures and conveys information on cell wall composition and growth factors to the cell. LRR-extensins (LRXs) are cell wall-attached extracellular regulators of cell wall formation and high-affinity binding sites for RALF (rapid alkalinization factor) peptide hormones that trigger diverse physiological processes related to cell growth. RALF peptides are also perceived by receptors at the plasma membrane and LRX4 of Arabidopsis thaliana has been shown to also interact with one of these receptors, FERONIA (FER). Here, we demonstrate that several LRXs, including the main LRX protein of root hairs, LRX1, interact with FER and RALF1 to coordinate growth processes. Membrane association of LRXs correlate with binding to FER, indicating that LRXs represent a physical link between intra- and extracellular compartments via interaction with membrane-localized proteins. Finally, despite evolutionary diversification of the LRR domains of various LRX proteins, many of them are functionally still overlapping, indicative of LRX proteins being central players in regulatory processes that are conserved in very different cell types.Author SummaryCell growth in plants requires the coordinated enlargement of the cell and the surrounding cell wall, which is ascertained by an elaborate system of cell wall integrity sensors, proteins involved in the exchange of information between the cell and the cell wall. In Arabidopsis thaliana, LRR-extensins (LRXs) are localized in the cell wall and are binding RALF peptides, hormones that regulate cell growth-related processes. LRX4 also binds the plasma membrane-localized receptor kinase FERONIA (FER), establishing a link between the cell and the cell wall. It is not clear, however, whether the different LRXs of Arabidopsis have similar functions and how they interact with their binding partners. Here, we demonstrate that interaction with FER and RALFs requires the LRR domain of LRXs and several but not all LRXs can bind these proteins. This explains the observation that mutations in several of the LRXs induce phenotypes comparable to a fer mutant, establishing that LRX-FER interaction is important for proper cell growth. Some LRXs, however, appear to influence cell growth processes in different ways, which remain to be identified.

Defective control of growth rate and cell diameter in tip-growing root hairs of the rhd4 mutant of Arabidopsis thaliana

1999 ◽  
Vol 77 (4) ◽  
pp. 494-507 ◽  
Author(s):  
M E Galway ◽  
D C Lane ◽  
J W Schiefelbein
Keyword(s):  
Growth Rate ◽  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Osmotic Stress ◽  
Tip Growth ◽  
Turgor Pressure ◽  
Root Hairs ◽  
Recessive Mutation ◽  
Cell Diameter ◽  
Hair Diameter

A recessive mutation in the RHD4 gene of Arabidopsis thaliana L. affects the control of tip growth in seedling root hairs. Fully grown rhd4 root hairs are half the length of wild-type (WT) hairs. The hairs are wider, and they vary in diameter during tip growth. Light microscopy and motion analysis revealed that rhd4 hairs grow more slowly and that hair growth rate varies more than in WT hairs. Hair diameter increases at the rhd4 hair tips when tip growth slows. Ultrastructural analysis revealed cell wall thickenings in some mutant hairs. WT hairs were grown in a hyperosmotic medium in an attempt to mimic the rhd4 hairs and investigate the control of root hair morphology. Osmotic stress increased WT hair diameter and induced hair bulging and also increased the diameters of rhd4 hairs. Osmotic stress could disrupt tip growth through reduced turgor pressure and (or) reduced concentrations of cytosolic calcium. Together these results indicate that RHD4 is required to maintain a uniform rate of tip growth in root hairs.Key words: Arabidopsis thaliana, cell wall, cryofixation, mutant, root hairs, tip growth.

scholarly journals Apoplastic class III peroxidases PRX62 and PRX69 regulate ROS-homeostasis and cell wall associated extensins linked to root hair growth at low-temperature in Arabidopsis thaliana

2021 ◽  
Author(s):  
Javier Martínez Pacheco ◽  
Philippe Ranocha ◽  
Luciana Kasulin ◽  
Corina M. Fusari ◽  
Lucas Servi ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Low Temperature ◽  
Root Hair ◽  
Developmental Process ◽  
Association Studies ◽  
Root Hairs ◽  
Genome Wide Association Studies ◽  
Class Iii ◽  
Ros Homeostasis

Root hairs (RH) growth is highly influenced by endogenous as well as by external environmental signals that coordinately regulate its final cell size. RHs actively expand the root surface responsible for nutrient uptake and water absorption. We have recently determined that RH growth was unexpectedly boosted when Arabidopsis thaliana seedlings are cultivated at low temperatures. It was proposed that RH growth plasticity in response to cold was linked to a reduced nutrient availability in the media. Here, we explored the molecular basis of this strong RH growth response by using the Genome Wide Association Studies (GWAS) approach on Arabidopsis thaliana natural accessions. We identified the poorly characterized PEROXIDASE 62 (PRX62) as a key protein triggering this conditional growth under a moderate low-temperature stress. In addition, we identified the related protein PRX69 as an important factor in this developmental process. The prx62 prx69 double mutant and the PRX62 and PRX69 over-expressing lines showed contrasting RH phenotypes, peroxidase activities and cyt/apoReactive Oxygen Species (ROS) levels. Strikingly, a cell wall protein extensin (EXT) reporter revealed the effect of peroxidase activity on the EXT cell wall association at 10C in the RH apical zone. EXT cell wall insolubilization was enhanced at 10C, which was completely abolished under the PRX inhibitor salicylhydroxamic acid (SHAM) treatment. Finally, we demonstrated that the Root Hair defective 6 like 4 (RSL4) transcription factor directly controls the expression of PRX69 under low-temperature. Collectively, our results indicate that both PRX62 and PRX69 are key apoplastic PRXs that modulate ROS-homeostasis and cell wall EXT-insolubilization linked to RH elongation at low-temperature.

SEM and fluorescence imaging of callose deposition in root hair tips and suspension cultures of Streptanthus tortuosus

1990 ◽  
Vol 48 (3) ◽  
pp. 698-699
Author(s):  
K.S. Walters ◽  
R.D. Sjolund ◽  
K.C. Moore
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Cultured Cells ◽  
Root Hairs ◽  
Callus Cultures ◽  
Callose Deposition ◽  
Culture Cells ◽  
Wall Structures ◽  
Ultraviolet Illumination ◽  
Callose Formation

Callose, B-1,3-glucan, a component of cell walls, is associated with phloem sieve plates, plasmodesmata, and other cell wall structures that are formed in response to wounding or infection. Callose reacts with aniline blue to form a fluorescent complex that can be recognized in the light microscope with ultraviolet illumination. We have identified callose in cell wall protuberances that are formed spontaneously in suspension-cultured cells of S. tortuosus and in the tips of root hairs formed in sterile callus cultures of S. tortuosus. Callose deposits in root hairs are restricted to root hair tips which appear to be damaged or deformed, while normal root hair tips lack callose deposits. The callose deposits found in suspension culture cells are restricted to regions where unusual outgrowths or protuberances are formed on the cell surfaces, specifically regions that are the sites of new cell wall formation.Callose formation has been shown to be regulated by intracellular calcium levels.

scholarly journals Inhibition of cell expansion enhances cortical microtubule stability in the root apex of Arabidopsis thaliana

2021 ◽  
Vol 28 (1) ◽  
Author(s):  
Veronica Giourieva ◽  
Emmanuel Panteris
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Expansion ◽  
Cortical Microtubule ◽  
Root Apex ◽  
Cellulose Synthase ◽  
Cellulose Biosynthesis ◽  
Cortical Microtubules ◽  
Wild Type ◽  
Microtubule Stability

Abstract Background Cortical microtubules regulate cell expansion by determining cellulose microfibril orientation in the root apex of Arabidopsis thaliana. While the regulation of cell wall properties by cortical microtubules is well studied, the data on the influence of cell wall to cortical microtubule organization and stability remain scarce. Studies on cellulose biosynthesis mutants revealed that cortical microtubules depend on Cellulose Synthase A (CESA) function and/or cell expansion. Furthermore, it has been reported that cortical microtubules in cellulose-deficient mutants are hypersensitive to oryzalin. In this work, the persistence of cortical microtubules against anti-microtubule treatment was thoroughly studied in the roots of several cesa mutants, namely thanatos, mre1, any1, prc1-1 and rsw1, and the Cellulose Synthase Interacting 1 protein (csi1) mutant pom2-4. In addition, various treatments with drugs affecting cell expansion were performed on wild-type roots. Whole mount tubulin immunolabeling was applied in the above roots and observations were performed by confocal microscopy. Results Cortical microtubules in all mutants showed statistically significant increased persistence against anti-microtubule drugs, compared to those of the wild-type. Furthermore, to examine if the enhanced stability of cortical microtubules was due to reduced cellulose biosynthesis or to suppression of cell expansion, treatments of wild-type roots with 2,6-dichlorobenzonitrile (DCB) and Congo red were performed. After these treatments, cortical microtubules appeared more resistant to oryzalin, than in the control. Conclusions According to these findings, it may be concluded that inhibition of cell expansion, irrespective of the cause, results in increased microtubule stability in A. thaliana root. In addition, cell expansion does not only rely on cortical microtubule orientation but also plays a regulatory role in microtubule dynamics, as well. Various hypotheses may explain the increased cortical microtubule stability under decreased cell expansion such as the role of cell wall sensors and the presence of less dynamic cortical microtubules.

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.

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