scholarly journals A Method Enabling Comprehensive Isolation of Arabidopsis Mutants Exhibiting Unusual Root Mechanical Behavior

2021 ◽  
Vol 12 ◽  
Author(s):  
Hiroshi Tojo ◽  
Aki Nakamura ◽  
Ali Ferjani ◽  
Yusuke Kazama ◽  
Tomoko Abe ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Mechanical Behavior ◽  
Molecular Mechanisms ◽  
Primary Root ◽  
Land Plants ◽  
Root Penetration ◽  
Wild Type ◽  
Arabidopsis Mutants ◽  
Primary Roots ◽  
Similar Phenotype

Root penetration into soils is fundamental for land plants to support their own aboveground parts and forage water and nutrients. To elucidate the molecular mechanisms underlying root mechanical penetration, mutants defective in this behavior need to be comprehensively isolated; however, established methods are currently scarce. We herein report a method to screen for these mutants ofArabidopsis thalianaand present their phenotypes. We isolated five mutants using this method, tentatively namedcreep1tocreep5, the primary roots of which crept over the surface of horizontal hard medium that hampered penetration by the primary root of the wild type, thereby forcing it to spring up on the surface and die. By examining root skewing, which is induced by a touch stimulation that is generated as the primary roots grow along a vertical impenetrable surface, the fivecreepmutants were subdivided into three groups, namely mutants with the primary root skewing leftward, those skewing rightward, and that growing dispersedly. While the majority of wild type primary roots skewed slightly leftward, nearly half of the primary roots ofcreep1andcreep5skewed rightward as viewed from above. The primary roots ofcreep4displayed scattered growth, while those ofcreep2andcreep3showed a similar phenotype to the wild type primary roots. These results demonstrate the potential of the method developed herein to isolate various mutants that will be useful for investigating root mechanical behavior regulation not only in Arabidopsis, but also in major crops with economical value.

scholarly journals Root cap size and shape influence responses to the physical strength of the growth medium in Arabidopsis thaliana primary roots

2019 ◽  
Author(s):  
J Roué ◽  
H Chauvet ◽  
N Brunel-Michac ◽  
F Bizet ◽  
B Moulia ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Growth Medium ◽  
Root Cap ◽  
Arabidopsis Mutants ◽  
Physical Strength ◽  
Size And Shape ◽  
Primary Roots ◽  
Root Responses ◽  
Shape Influence

Analysis of the growth and orientation of roots of Arabidopsis mutants with differing root cap sizes and shapes indicates that the form of the cap affects root responses to variations in the strength of the growth medium.

scholarly journals Nitrate Induction of Primary Root Growth Requires Cytokinin Signaling in Arabidopsis thaliana

2019 ◽  
Vol 61 (2) ◽  
pp. 342-352 ◽  
Author(s):  
Pamela A Naulin ◽  
Grace I Armijo ◽  
Andrea S Vega ◽  
Karem P Tamayo ◽  
Diana E Gras ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Division ◽  
Root Growth ◽  
Primary Root ◽  
Growth Arrest ◽  
Root Tip ◽  
Wild Type ◽  
Cytokinin Signaling ◽  
Control Growth ◽  
Primary Root Growth

Abstract Nitrate can act as a potent signal to control growth and development in plants. In this study, we show that nitrate is able to stimulate primary root growth via increased meristem activity and cytokinin signaling. Cytokinin perception and biosynthesis mutants displayed shorter roots as compared with wild-type plants when grown with nitrate as the only nitrogen source. Histological analysis of the root tip revealed decreased cell division and elongation in the cytokinin receptor double mutant ahk2/ahk4 as compared with wild-type plants under a sufficient nitrate regime. Interestingly, a nitrate-dependent root growth arrest was observed between days 5 and 6 after sowing. Wild-type plants were able to recover from this growth arrest, while cytokinin signaling or biosynthesis mutants were not. Transcriptome analysis revealed significant changes in gene expression after, but not before, this transition in contrasting genotypes and nitrate regimes. We identified genes involved in both cell division and elongation as potentially important for primary root growth in response to nitrate. Our results provide evidence linking nitrate and cytokinin signaling for the control of primary root growth in Arabidopsis thaliana.

Ultrastructural Studies of Root Swelling in Mutants of Arabidopsis Thaliana

2001 ◽  
Vol 7 (S2) ◽  
pp. 64-65
Author(s):  
Y. Naidoo ◽  
T.I. Baskin ◽  
G. Naidoo
Keyword(s):  
Arabidopsis Thaliana ◽  
Primary Root ◽  
Root Apex ◽  
Cellulose Microfibrils ◽  
Cellulose Synthesis ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Root Tips ◽  
Ultrastructural Studies ◽  
Essentially Normal

Growth is “anisotropic” when growth rates in different directions are not equal. Anisotropic elongation is controlled by cortical microtubules and cellulose microfibrils of the cell wall. Distorted anisotropic growth results when there are aberrations in either the cellulose network or microtubule cytoskeleton. in this ultrastructural study, the roots of wild type (control) and mutants of Arabidopsis thaliana (L.) Heynh, ecotype Columbia, were compared to determine the role of microtubule organisation, cellulose synthesis and cytokinesis on root expansion.Three mutations, obtained by treating seeds of A. thaliana with ethane-methylsulfonate and backcrossing once to wild type after four selfed generations, were isolated and designated as rsw (radially swollen). These phenotypes are all temperature sensitive, growing and appearing as wild type at 19°C but expressing the mutant phenotype at or above 30°C. Segments of intact root tips from the three mutants and wild type were prepared and examined for TEM with a Jeol 1200EX. The overall appearance of rsw seedlings at 19°C is the same as wild type. At 30°C these phenotypes lead to extensive swelling of the root apex. Despite considerable alteration in the morphology of the root apex, the appearance of the root cap and root hairs seems essentially normal. When mutant roots expressing these phenotypes at 30°C are returned to 19°C, a wild type appearance of the root apex and elongation gradually returns.The primary root of the wild type has a remarkably uniform cellular organisation with regularly arranged dense cytoplasmic cells (Fig. 1). At 19°C, rsw4, rsw6 and rsw7 were indistinguishable from wild type; however, at 30°C, the well-defined anatomy was distorted in all tissues by additional cell walls in unusual positions (Fig. 2).

scholarly journals The cap size and shape of Arabidopsis thaliana primary roots impact the root responses to an increase in medium strength

2018 ◽  
Author(s):  
J. Roué ◽  
H. Chauvet ◽  
N. Brunel-Michac ◽  
F. Bizet ◽  
B. Moulia ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Primary Root ◽  
Root Cap ◽  
Size And Shape ◽  
Primary Roots ◽  
Medium Strength ◽  
Cell Layers ◽  
Root Responses ◽  
Mutant Lines

AbstractDuring root progression in soil, root cap cells are the first to encounter obstacles. The root cap is known to sense environmental cues, making it a relevant candidate for a mechanosensing site. An original two-layer medium was developed in order to study root responses to growth medium strength and the importance of the root cap in the establishment of these responses. Root growth and trajectory of primary roots of Arabidopsis thaliana seedlings were investigated using in vivo image analysis. After contact with the harder layer, the root either penetrated it or underwent rapid curvature, enabling reorientation of the root primary growth. The role of the root cap in tip reorientation was investigated by analyzing the responses of Arabidopsis mutant roots with altered caps. The primary root of fez-2 mutant lines, which has fewer root cap cell layers than wild-type roots, showed impaired penetration ability. Conversely, smb-3 roots of mutant lines, which display a higher number of root cap cells, showed enhanced penetration abilities. This work highlights that alterations in root cap shape and size affect the root responses to medium strength.HighlightThe analysis of the growth and orientation of Arabidopsis thaliana mutant roots affected in root cap size and shape showed that properly formed root cap is required to trigger the root responses to medium strength.AbbreviationsCOLcolumella;LRCLateral Root Cap;SISharpness Index;SMBSOMBRERO.

scholarly journals Integrative Roles of Phytohormones on Cell Proliferation, Elongation and Differentiation in the Arabidopsis thaliana Primary Root

2021 ◽  
Vol 12 ◽  
Author(s):  
Estephania Zluhan-Martínez ◽  
Brenda Anabel López-Ruíz ◽  
Mónica L. García-Gómez ◽  
Berenice García-Ponce ◽  
María de la Paz Sánchez ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Arabidopsis Thaliana ◽  
Molecular Mechanisms ◽  
Primary Root ◽  
Longitudinal Axis ◽  
Growth Responses ◽  
Root Cells ◽  
Multicellular Organisms ◽  
External Stimuli

The growth of multicellular organisms relies on cell proliferation, elongation and differentiation that are tightly regulated throughout development by internal and external stimuli. The plasticity of a growth response largely depends on the capacity of the organism to adjust the ratio between cell proliferation and cell differentiation. The primary root of Arabidopsis thaliana offers many advantages toward understanding growth homeostasis as root cells are continuously produced and move from cell proliferation to elongation and differentiation that are processes spatially separated and could be studied along the longitudinal axis. Hormones fine tune plant growth responses and a huge amount of information has been recently generated on the role of these compounds in Arabidopsis primary root development. In this review, we summarized the participation of nine hormones in the regulation of the different zones and domains of the Arabidopsis primary root. In some cases, we found synergism between hormones that function either positively or negatively in proliferation, elongation or differentiation. Intriguingly, there are other cases where the interaction between hormones exhibits unexpected results. Future analysis on the molecular mechanisms underlying crosstalk hormone action in specific zones and domains will unravel their coordination over PR development.

scholarly journals The Plastid-Localized AtFtsHi3 Pseudo-Protease of Arabidopsis thaliana Has an Impact on Plant Growth and Drought Tolerance

2021 ◽  
Vol 12 ◽  
Author(s):  
Laxmi S. Mishra ◽  
Sanatkumar Mishra ◽  
Daniel F. Caddell ◽  
Devin Coleman-Derr ◽  
Christiane Funk
Keyword(s):  
Arabidopsis Thaliana ◽  
Drought Tolerance ◽  
Plant Growth ◽  
Crop Production ◽  
Molecular Mechanisms ◽  
Wild Type ◽  
Drought Tolerant ◽  
Darwinian Fitness ◽  
Intrinsic Water Use Efficiency ◽  
Stomata Size

While drought severely affects plant growth and crop production, the molecular mechanisms of the drought response of plants remain unclear. In this study, we demonstrated for the first time the effect of the pseudo-protease AtFtsHi3 of Arabidopsis thaliana on overall plant growth and in drought tolerance. An AtFTSHi3 knock-down mutant [ftshi3-1(kd)] displayed a pale-green phenotype with lower photosynthetic efficiency and Darwinian fitness compared to wild type (Wt). An observed delay in seed germination of ftshi3-1(kd) was attributed to overaccumulation of abscisic acid (ABA); ftshi3-1(kd) seedlings showed partial sensitivity to exogenous ABA. Being exposed to similar severity of soil drying, ftshi3-1(kd) was drought-tolerant up to 20 days after the last irrigation, while wild type plants wilted after 12 days. Leaves of ftshi3-1(kd) contained reduced stomata size, density, and a smaller stomatic aperture. During drought stress, ftshi3-1(kd) showed lowered stomatal conductance, increased intrinsic water-use efficiency (WUEi), and slower stress acclimation. Expression levels of ABA-responsive genes were higher in leaves of ftshi3-1(kd) than Wt; DREB1A, but not DREB2A, was significantly upregulated during drought. However, although ftshi3-1(kd) displayed a drought-tolerant phenotype in aboveground tissue, the root-associated bacterial community responded to drought.

scholarly journals FASCICLIN-LIKE 18 Is a New Player Regulating Root Elongation in Arabidopsis thaliana

2021 ◽  
Vol 12 ◽  
Author(s):  
Hewot Allelign Ashagre ◽  
David Zaltzman ◽  
Anat Idan-Molakandov ◽  
Hila Romano ◽  
Oren Tzfadia ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Root Elongation ◽  
Genetic Interaction ◽  
Lateral Roots ◽  
Primary Root ◽  
Arabinogalactan Protein ◽  
Wild Type ◽  
Synthesis Inhibitor ◽  
High Sucrose

The plasticity of root development represents a key trait that enables plants to adapt to diverse environmental cues. The pattern of cell wall deposition, alongside other parameters, affects the extent, and direction of root growth. In this study, we report that FASCICLIN-LIKE ARABINOGALACTAN PROTEIN 18 (FLA18) plays a role during root elongation in Arabidopsis thaliana. Using root-specific co-expression analysis, we identified FLA18 to be co-expressed with a sub-set of genes required for root elongation. FLA18 encodes for a putative extra-cellular arabinogalactan protein from the FLA-gene family. Two independent T-DNA insertion lines, named fla18-1 and fla18-2, display short and swollen lateral roots (LRs) when grown on sensitizing condition of high-sucrose containing medium. Unlike fla4/salt overly sensitive 5 (sos5), previously shown to display short and swollen primary root (PR) and LRs under these conditions, the PR of the fla18 mutants is slightly longer compared to the wild-type. Overexpression of the FLA18 CDS complemented the fla18 root phenotype. Genetic interaction between either of the fla18 alleles and sos5 reveals a more severe perturbation of anisotropic growth in both PR and LRs, as compared to the single mutants and the wild-type under restrictive conditions of high sucrose or high-salt containing medium. Additionally, under salt-stress conditions, fla18sos5 had a small, chlorotic shoot phenotype, that was not observed in any of the single mutants or the wild type. As previously shown for sos5, the fla18-1 and fla18-1sos5 root-elongation phenotype is suppressed by abscisic acid (ABA) and display hypersensitivity to the ABA synthesis inhibitor, Fluridon. Last, similar to other cell wall mutants, fla18 root elongation is hypersensitive to the cellulose synthase inhibitor, Isoxaben. Altogether, the presented data assign a new role for FLA18 in the regulation of root elongation. Future studies of the unique vs. redundant roles of FLA proteins during root elongation is anticipated to shed a new light on the regulation of root architecture during plant adaptation to different growth conditions.

Response of primary root to nitrogen-doped carbon dots in Arabidopsis thaliana: Alterations in auxin level and cell division activity

2021 ◽  
Author(s):  
Xiaoyan Yan ◽  
Jianhua Wang ◽  
Dongxia Li ◽  
Jinlin Feng ◽  
qiang Xu ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Carbon Dots ◽  
Growth And Development ◽  
Molecular Mechanisms ◽  
Primary Root ◽  
Auxin Level ◽  
Nitrogen Doped ◽  
Doped Carbon Dots ◽  
Nitrogen Doped Carbon ◽  
Fluorescent Carbon Dots

Fluorescent carbon dots have attracted wide attentions in bioscience and bioimaging. However, the molecular mechanisms of the effects of carbon dots on plants growth and development have not been elucidated....

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