Root hairs enhance Arabidopsis seedling survival upon soil disruption.
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ABSTRACT:
SUBMITTER: Choi HS
PROVIDER: S-EPMC6671945 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Soil is essential for sustaining life on land. Plant roots play a crucial role in stabilising soil and minimising erosion, although these mechanisms are still not completely understood. Consequently, identifying and breeding for plant traits to enhance erosion resistance is challenging. Root hair mutants in Arabidopsis thaliana were studied using three different quantitative methods to isolate their effect on root-soil cohesion. We present compelling evidence that micro-scale interactions of root hairs with surrounding soil increase soil cohesion and reduce erosion. Arabidopsis seedlings with root hairs were more difficult to detach from soil, compost and sterile gel media than those with hairless roots, and it was 10-times harder to erode soil from roots with than without hairs. We also developed a model that can consistently predict the impact root hairs make to soil erosion resistance. Our study thus provides new insight into the mechanisms by which roots maintain soil stability.
| S-EPMC7125084 | biostudies-literature
Project description:BACKGROUND: Quantitative information on gene activity at single cell-type resolution is essential for the understanding of how cells work and interact. Root hairs, or trichoblasts, tubular-shaped outgrowths of specialized cells in the epidermis, represent an ideal model for cell fate acquisition and differentiation in plants. RESULTS: Here, we provide an atlas of gene and protein expression in Arabidopsis root hair cells, generated by paired-end RNA sequencing and LC/MS-MS analysis of protoplasts from plants containing a pEXP7-GFP reporter construct. In total, transcripts of 23,034 genes were detected in root hairs. High-resolution proteome analysis led to the reliable identification of 2,447 proteins, 129 of which were differentially expressed between root hairs and non-root hair tissue. Dissection of pre-mRNA splicing patterns showed that all types of alternative splicing were cell type-dependent, and less complex in EXP7-expressing cells when compared to non-root hair cells. Intron retention was repressed in several transcripts functionally related to root hair morphogenesis, indicative of a cell type-specific control of gene expression by alternative splicing of pre-mRNA. Concordance between mRNA and protein expression was generally high, but in many cases mRNA expression was not predictive for protein abundance. CONCLUSIONS: The integrated analysis shows that gene activity in root hairs is dictated by orchestrated, multilayered regulatory mechanisms that allow for a cell type-specific composition of functional components.
| S-EPMC3707065 | biostudies-literature
Project description:BackgroundMitochondria are dynamic organelles that move along actin filaments, and serve as calcium stores in plant cells. The positioning and dynamics of mitochondria depend on membrane-cytoskeleton interactions, but it is not clear whether microfilament cytoskeleton has a direct effect on mitochondrial function and Ca2+ storage. Therefore, we designed a series of experiments to clarify the effects of actin filaments on mitochondrial Ca2+ storage, cytoplasmic Ca2+ concentration ([Ca2+]c), and the interaction between mitochondrial Ca2+ and cytoplasmic Ca2+ in Arabidopsis root hairs.ResultsIn this study, we found that treatments with latrunculin B (Lat-B) and jasplakinolide (Jas), which depolymerize and polymerize actin filaments respectively, decreased membrane potential and Ca2+ stores in the mitochondria of Arabidopsis root hairs. Simultaneously, these treatments induced an instantaneous increase of cytoplasmic Ca2+, followed by a continuous decrease. All of these effects were inhibited by pretreatment with cyclosporin A (Cs A), a representative blocker of the mitochondrial permeability transition pore (mPTP). Moreover, we found there was a Ca2+ concentration gradient in mitochondria from the tip to the base of the root hair, and this gradient could be disrupted by actin-acting drugs.ConclusionsBased on these results, we concluded that the disruption of actin filaments caused by Lat-B or Jas promoted irreversible opening of the mPTP, resulting in mitochondrial Ca2+ release into the cytoplasm, and consequent changes in [Ca2+]c. We suggest that normal polymerization and depolymerization of actin filaments are essential for mitochondrial Ca2+ storage in root hairs.
| S-EPMC2923527 | biostudies-literature
Project description:The physical role of root hairs in anchoring the root tip during soil penetration was examined. Experiments using a hairless maize mutant (Zea mays: rth3-3) and its wild-type counterpart measured the anchorage force between the primary root of maize and the soil to determine whether root hairs enabled seedling roots in artificial biopores to penetrate sandy loam soil (dry bulk density 1.0-1.5g cm(-3)). Time-lapse imaging was used to analyse root and seedling displacements in soil adjacent to a transparent Perspex interface. Peak anchorage forces were up to five times greater (2.5N cf. 0.5N) for wild-type roots than for hairless mutants in 1.2g cm(-3) soil. Root hair anchorage enabled better soil penetration for 1.0 or 1.2g cm(-3) soil, but there was no significant advantage of root hairs in the densest soil (1.5g cm(-3)). The anchorage force was insufficient to allow root penetration of the denser soil, probably because of less root hair penetration into pore walls and, consequently, poorer adhesion between the root hairs and the pore walls. Hairless seedlings took 33h to anchor themselves compared with 16h for wild-type roots in 1.2g cm(-3) soil. Caryopses were often pushed several millimetres out of the soil before the roots became anchored and hairless roots often never became anchored securely.The physical role of root hairs in anchoring the root tip may be important in loose seed beds above more compact soil layers and may also assist root tips to emerge from biopores and penetrate the bulk soil.
| S-EPMC4753853 | biostudies-other
Project description:Roots hairs are cylindrical extensions of root epidermal cells that are important for acquisition of nutrients, microbe interactions, and plant anchorage. The molecular mechanisms involved in the specification, differentiation, and physiology of root hairs in Arabidopsis are reviewed here. Root hair specification in Arabidopsis is determined by position-dependent signaling and molecular feedback loops causing differential accumulation of a WD-bHLH-Myb transcriptional complex. The initiation of root hairs is dependent on the RHD6 bHLH gene family and auxin to define the site of outgrowth. Root hair elongation relies on polarized cell expansion at the growing tip, which involves multiple integrated processes including cell secretion, endomembrane trafficking, cytoskeletal organization, and cell wall modifications. The study of root hair biology in Arabidopsis has provided a model cell type for insights into many aspects of plant development and cell biology.
| S-EPMC4075452 | biostudies-other
Project description:Manganese (Mn) is the second most prevalent transition metal in the Earth's crust but its availability is often limited due to rapid oxidation and low mobility of the oxidized forms. Acclimation to low Mn availability was studied in Arabidopsis seedlings subjected to Mn deficiency. As reported here, Mn deficiency caused a thorough change in the arrangement and characteristics of the root epidermal cells. A proportion of the extra hairs formed upon Mn deficiency were located in atrichoblast positions, indicative of a post-embryonic reprogramming of the cell fate acquired during embryogenesis. When plants were grown under a light intensity of >50 micromol m(-2) s(-1) in the presence of manganese root hair elongation was substantially inhibited, whereas Mn-deficient seedlings displayed stimulated root hair development. GeneChip analysis revealed several candidate genes with potential roles in the reprogramming of rhizodermal cells. None of the genes that function in epidermal cell fate specification were affected by Mn deficiency, indicating that the patterning mechanism which controls the differentiation of rhizodermal cells during embryogenesis have been bypassed under Mn-deficient conditions. This assumption is supported by the partial rescue of the hairless cpc mutant by Mn deficiency. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis revealed that, besides the anticipated reduction in Mn concentration, Mn deficiency caused an increase in iron concentration. This increase was associated with a decreased transcript level of the iron transporter IRT1, indicative of a more efficient transport of iron in the absence of Mn.
| S-EPMC2529234 | biostudies-literature
Project description:In this paper, we provide direct evidence of the importance of root hairs on pore structure development at the root-soil interface during the early stage of crop establishment. This was achieved by use of high-resolution (c. 5 ?m) synchrotron radiation computed tomography (SRCT) to visualise both the structure of root hairs and the soil pore structure in plant-soil microcosms. Two contrasting genotypes of barley (Hordeum vulgare), with and without root hairs, were grown for 8 d in microcosms packed with sandy loam soil at 1.2 g cm-3 dry bulk density. Root hairs were visualised within air-filled pore spaces, but not in the fine-textured soil regions. We found that the genotype with root hairs significantly altered the porosity and connectivity of the detectable pore space (> 5 ?m) in the rhizosphere, as compared with the no-hair mutants. Both genotypes showed decreasing pore space between 0.8 and 0.1 mm from the root surface. Interestingly the root-hair-bearing genotype had a significantly greater soil pore volume-fraction at the root-soil interface. Effects of pore structure on diffusion and permeability were estimated to be functionally insignificant under saturated conditions when simulated using image-based modelling.
| S-EPMC5601222 | biostudies-literature
Project description:BackgroundPrevious studies have shown that plant mitochondrial movements are myosin-based along actin filaments, which undergo continuous turnover by the exchange of actin subunits from existing filaments. Although earlier studies revealed that actin filament dynamics are essential for many functions of the actin cytoskeleton, there are little data connecting actin dynamics and mitochondrial movements.Methodology/principal findingsWe addressed the role of actin filament dynamics in the control of mitochondrial movements by treating cells with various pharmaceuticals that affect actin filament assembly and disassembly. Confocal microscopy of Arabidopsis thaliana root hairs expressing GFP-FABD2 as an actin filament reporter showed that mitochondrial distribution was in agreement with the arrangement of actin filaments in root hairs at different developmental stages. Analyses of mitochondrial trajectories and instantaneous velocities immediately following pharmacological perturbation of the cytoskeleton using variable-angle evanescent wave microscopy and/or spinning disk confocal microscopy revealed that mitochondrial velocities were regulated by myosin activity and actin filament dynamics. Furthermore, simultaneous visualization of mitochondria and actin filaments suggested that mitochondrial positioning might involve depolymerization of actin filaments on the surface of mitochondria.Conclusions/significanceBase on these results we propose a mechanism for the regulation of mitochondrial speed of movements, positioning, and direction of movements that combines the coordinated activity of myosin and the rate of actin turnover, together with microtubule dynamics, which directs the positioning of actin polymerization events.
| S-EPMC2694364 | biostudies-literature
Project description:Calcium oscillations play a role in the regulation of the development of tip-growing plant cells. Using optical microscopy, calcium oscillations have been observed in a few systems (e.g. pollen tubes, fungal hyphae and algal rhizoids). High-resolution, non-phototoxic and rapid imaging methods are required to study the calcium oscillation in root hairs. We show that light sheet fluorescence microscopy is optimal to image growing root hairs of Arabidopsis thaliana and to follow their oscillatory tip-focused calcium gradient. We describe a protocol for performing live imaging of root hairs in seedlings expressing the cytosol-localized ratiometric calcium indicator Yellow Cameleon 3.6. Using this protocol, we measured the calcium gradient in a large number of root hairs. We characterized their calcium oscillations and correlated them with the rate of hair growth. The method was then used to screen the effect of auxin on the properties of the growing root hairs.
| S-EPMC6383626 | biostudies-literature
Project description:The synthesis and composition of cell walls is dynamically adapted in response to many developmental and environmental signals. In this respect, cell wall proteins involved in controlling cell elongation are critical for cell development. Transcriptome analysis identified a gene in Arabidopsis thaliana, which was named proline-rich protein-like, AtPRPL1, based on sequence similarities from a phylogenetic analysis. The most resemblance was found to AtPRP1 and AtPRP3 from Arabidopsis, which are known to be involved in root hair growth and development. In A. thaliana four proline-rich cell wall protein genes, playing a role in building up the cross-connections between cell wall components, can be distinguished. AtPRPL1 is a small gene that in promoter::GUS (β-glucuronidase) analysis has high expression in trichoblast cells and in the collet. Chemical or mutational interference with root hair formation inhibited this expression. Altered expression levels in knock-out or overexpression lines interfered with normal root hair growth and etiolated hypocotyl development, but Fourier transform-infrared (FT-IR) analysis did not identify consistent changes in cell wall composition of root hairs and hypocotyl. Co-localization analysis of the AtPRPL1-green fluorescent protein (GFP) fusion protein and different red fluorescent protein (RFP)-labelled markers confirmed the presence of AtPRPL1-GFP in small vesicles moving over the endoplasmic reticulum. Together, these data indicate that the AtPRPL1 protein is involved in the cell's elongation process. How exactly this is achieved remains unclear at present.
| S-EPMC4400542 | biostudies-literature