scholarly journals Tissue growth constrains root organ outlines into an isometrically scalable shape

Development ◽  
2021 ◽  
Vol 148 (4) ◽  
pp. dev196253
Author(s):  
Motohiro Fujiwara ◽  
Tatsuaki Goh ◽  
Satoru Tsugawa ◽  
Keiji Nakajima ◽  
Hidehiro Fukaki ◽  
...  
Keyword(s):  
Plant Root ◽  
Lateral Roots ◽  
Time Lapse ◽  
Tissue Growth ◽  
Root Tip ◽  
Root Tips ◽  
Developmental Constraints ◽  
Primary Roots ◽  
Catenary Curve ◽  
Expansion Force

ABSTRACTOrgan morphologies are diverse but also conserved under shared developmental constraints among species. Any geometrical similarities in the shape behind diversity and the underlying developmental constraints remain unclear. Plant root tip outlines commonly exhibit a dome shape, which likely performs physiological functions, despite the diversity in size and cellular organization among distinct root classes and/or species. We carried out morphometric analysis of the primary roots of ten angiosperm species and of the lateral roots (LRs) of Arabidopsis, and found that each root outline was isometrically scaled onto a parameter-free catenary curve, a stable structure adopted for arch bridges. Using the physical model for bridges, we analogized that localized and spatially uniform occurrence of oriented cell division and expansion force the LR primordia (LRP) tip to form a catenary curve. These growth rules for the catenary curve were verified by tissue growth simulation of developing LRP development based on time-lapse imaging. Consistently, LRP outlines of mutants compromised in these rules were found to deviate from catenary curves. Our analyses demonstrate that physics-inspired growth rules constrain plant root tips to form isometrically scalable catenary curves.

Histochemical Examination of Invertase Activities in the Growing Tip of the Plant Root

2017 ◽  
Vol 10 (1) ◽  
pp. 35-45
Author(s):  
N.F. Lunkova ◽  
N.A. Burmistrova ◽  
M.S. Krasavina
Keyword(s):  
Plant Root ◽  
Invertase Activity ◽  
Root Tip ◽  
Elongation Zone ◽  
Root Tips ◽  
Phloem Unloading ◽  
Meristem Cell ◽  
Transition To Elongation ◽  
Different Tissues

Background:A growing part of the root is one of the most active sinks for sucrose coming from source leaves through the phloem. In the root, sucrose is unloaded from conducting bundles and is distributed among the surrounding cells. To be involved in the metabolism, sucrose should disintegrate into hexoses by means of degrading enzymes.Aims:The aim of this research was to explore the possibility of the involvement of one such enzymes, invertase, in phloem unloading as well as distribution of its activity in the functionally different tissues of the plant root tips.Method:To estimate the enzyme activities in root tissues, we applied two techniques: the histochemical method using nitro blue tetrazolium. The localization of phloem unloading was studied with carboxyfluorescein, a fluorescent marker for symplastic transport.Results:Invertase activity was not detected in the apical part of the meristem. It appeared only between the basal part of this zone and the beginning of the elongation zone. There is the root phloem unloading in that area. Invertase activity increased with increasing the distance from the root tip and reached the highest values in the region of cell transition to elongation and in the elongation zone. The activities of the enzyme varied in different tissues of the same zone and sometimes in the neighboring cells of the same tissue. Biochemical determination of invertase activity was made in the maize root segments coincident to the zones of meristem, cell elongation and differentiation. The results of both methods of determination of invertase activity were in agreement.Conclusion:It was concluded that phloem unloading correlated with invertase activity, possibly because of the activation of invertase by unloaded sucrose. Invertase is one of the factors involved in the processes preparing the cells for their transition to elongation because the concentration of osmotically active hexoses increases after cleavage of sucrose, that stimulates water entry into the cells, which is necessary for elongation growth.

Proteomic Analyses of Soybean Root Tips During Germination

2014 ◽  
Vol 21 (12) ◽  
pp. 1308-1319
Author(s):  
Setsuko Komatsu ◽  
Myeong W. Oh ◽  
Hee Y. Jang ◽  
Soo J. Kwon ◽  
Hye R. Kim ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Proteomic Analysis ◽  
Plant Root ◽  
Root Tip ◽  
Root Tips ◽  
Form Complex ◽  
Molecular Weights ◽  
Soybean Seedlings ◽  
2D Gel ◽  
Proteomic Techniques

Plant root systems form complex networks with the surrounding soil environment and are controlled by both internal and external factors. To better understand the function of root tips of soybean during germination, three proteomic techniques were used to analyze the protein profiles of root tip cells. Proteins were extracted from the root tips of 4-dayold soybean seedlings and analyzed using two-dimensional (2D) gel electrophoresis-based proteomics, SDS-gel based proteomics, and gel-free proteomics techniques. A total of 121, 862, and 341 proteins were identified in root tips using the 2D gel-based, SDS gel-based, and gel-free proteomic techniques, respectively. The proteins identified by 2D gel-based proteomic analysis were predominantly localized in the cytoplasm, whereas nuclear-localized proteins were most commonly identified by the SDS gel-based and gel-free proteomics techniques. Of the 862 proteins identified in the SDS gelbased proteomic analysis, 190 were protein synthesis-related proteins. Furthermore, 24 proteins identified using the 2Dgel based proteomic technique shifted between acidic and basic isoelectric points, and 2 proteins, heat shock protein 70.2 and AAA-type ATPase, displayed two different molecular weights at the same isoelectric point. Taken together, these results suggest that a number of proteins related to protein synthesis and modification are activated in the root tips of soybean seedlings during germination.

scholarly journals Expression Studies on AUX1-like Genes in Medicago truncatula Suggest That Auxin Is Required at Two Steps in Early Nodule Development

2001 ◽  
Vol 14 (3) ◽  
pp. 267-277 ◽  
Author(s):  
Françoise de Billy ◽  
Cathy Grosjean ◽  
Sean May ◽  
Malcolm Bennett ◽  
Julie V. Cullimore
Keyword(s):  
Medicago Truncatula ◽  
Lateral Root ◽  
Sequence Similarity ◽  
Lateral Roots ◽  
Peripheral Region ◽  
Nodule Development ◽  
Central Position ◽  
Root Tips ◽  
High Sequence Similarity ◽  
Primary Roots

Medicago truncatula contains a family of at least five genes related to AUX1 of Arabidopsis thaliana (termed MtLAX genes for Medicago truncatula-like AUX1 genes). The high sequence similarity between the encoded proteins and AUX1 implies that the MtLAX genes encode auxin import carriers. The MtLAX genes are expressed in roots and other organs, suggesting that they play pleiotropic roles related to auxin uptake. In primary roots, the MtLAX genes are expressed preferentially in the root tips, particularly in the provascular bundles and root caps. During lateral root and nodule development, the genes are expressed in the primordia, particularly in cells that were probably derived from the pericycle. At slightly later stages, the genes are expressed in the regions of the developing organs where the vasculature arises (central position for lateral roots and peripheral region for nodules). These results are consistent with MtLAX being involved in local auxin transport and suggest that auxin is required at two common stages of lateral root and nodule development: development of the primordia and differentiation of the vasculature.

scholarly journals PIEZO ion channel is required for root mechanotransduction in Arabidopsis thaliana

2020 ◽  
Author(s):  
Seyed A. R. Mousavi ◽  
Adrienne E Dubin ◽  
Wei-Zheng Zeng ◽  
Adam M. Coombs ◽  
Khai Do ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Ion Channels ◽  
Ion Channel ◽  
Mammalian Cells ◽  
Plant Root ◽  
Mechanical Strain ◽  
Root Tip ◽  
Root Tips ◽  
Mechanosensitive Ion Channels ◽  
Mechanical Constraints

SummaryPlant roots adapt to the mechanical constraints of the soil to grow and absorb water and nutrients. As in animal species, mechanosensitive ion channels in plants are proposed to transduce external mechanical forces into biological signals. However, the identity of these plant root ion channels remains unknown. Here, we show that Arabidopsis thaliana PIEZO (AtPIEZO) has preserved the function of its animal relatives and acts as an ion channel. We present evidence that plant PIEZO is highly expressed in the columella and lateral root cap cells of the root tip which experience robust mechanical strain during root growth. Deleting PIEZO from the whole plant significantly reduced the ability of its roots to penetrate denser barriers compared to wild type plants. piezo mutant root tips exhibited diminished calcium transients in response to mechanical stimulation, supporting a role of AtPIEZO in root mechanotransduction. Finally, a chimeric PIEZO channel that includes the C-terminal half of AtPIEZO containing the putative pore region was functional and mechanosensitive when expressed in naive mammalian cells. Collectively, our data suggest that Arabidopsis PIEZO plays an important role in root mechanotransduction and establishes PIEZOs as physiologically relevant mechanosensitive ion channels across animal and plant kingdoms.

scholarly journals Lateral Root Traits of Taxodium Hybrid ‘Zhongshanshan 406’ in Response to Drought Stress

HortScience ◽  
2018 ◽  
Vol 53 (4) ◽  
pp. 547-551
Author(s):  
Qin Shi ◽  
Yunlong Yin ◽  
Zhiquan Wang ◽  
Wencai Fan ◽  
Jinbo Guo ◽  
...  
Keyword(s):  
Drought Stress ◽  
Surface Area ◽  
Root Length ◽  
Lateral Root ◽  
Plant Root ◽  
Lateral Roots ◽  
Specific Root Length ◽  
Root Traits ◽  
Root Tip ◽  
Root Surface Area

Roots are vital organs for resource uptake. However, the knowledge regarding the extent by which responses in roots influence plant resistance is still poorly known. In this study, we examined the morphological and physiological responses of lateral roots of Taxodium hybrid ‘Zhongshanshan 406’ (Taxodium mucronatum♀ and Taxodium distichum♂, T. 406) to 8 (DS-8) and 12 days (DS-12) drought. Control plants (CK-8 and CK-12) were well-watered throughout the experiment. Results indicated that drought resulted in significantly decreased root length, surface area, volume, and biomass and a relatively high death rate of roots (>2 mm). Specific root length (SRL) and specific root surface area (SRA) of drought-stressed T. 406 plants were reduced to enhance resource uptake. Meanwhile, root relative water content (RWC) of T. 406 plants in CK-12 treatment was 5.81 times of those in DS-12 treatment. Under drought stress and root superoxide dismutase and ascorbic acid (ASA) activities, proline and hydrogen peroxide (H2O2) contents consistently increased to benefit the elimination of O2−. At the ultrastructural level, the organelle structure of T. 406 plant root tip was visibly damaged because of dehydration. The nucleus swelled and then exhibited uncommon features of disorganization and disruption. In short, our results provided substantial information about lateral root traits of T. 406 plants in response to drought stress, which is crucial to improve the drought resistance of Taxodium hybrid in the future breeding.

scholarly journals The modification of method of the artificial inoculation of sunflower seedlings with Phoma rot pathogen in the laboratory conditions to identify the colonizing activity of strains-producer of microbiopreparations

2020 ◽  
Vol 4 (184) ◽  
pp. 52-56
Author(s):  
L.V. Maslienko ◽  
◽  
A.Kh. Voronkova ◽  
L.A. Datsenko ◽  
E.A. Efimtseva ◽  
...  
Keyword(s):  
Early Stage ◽  
Lateral Roots ◽  
Artificial Inoculation ◽  
Root Tip ◽  
Root Tips ◽  
Laboratory Conditions ◽  
Oil Crops ◽  
Russian Research Institute ◽  
The Difference ◽  
Intensive Development

We carried the work in the biomethod laboratory of the crop management department of V.S. Pustovoit All-Russian Research Institute of Oil Crops. We modified the method of artificial inoculation of sunflower seedlings with a pathogen in a laboratory conditions for the secondary screening of antagonist strains from the collection of the biomethod laboratory to Phoma rot pathogen. We developed a five-point scale for evaluation of affection degree of sunflower seedlings by Phoma rot pathogen: 0 points – healthy seedlings; 1 point – darkening of the root tip, intensive development of lateral roots; 2 points – darkening of the root by a third or up to the middle, but intensive development of lateral roots; 3 points – necking of rot in the middle of the root or between the hypocotyl and the root, lateral roots are poorly developed; 4 points – root rotting to the middle or necking between the hypocotyl and the root, but intensive development of lateral roots; 5 points – complete rotting of the root, lateral roots are poorly developed or absent; 1-3 – viable seedlings; 4-5 – non-viable seedlings. The optimal period of exposure of the root tips of sunflower seedlings to the pathogen colony equal to 3 hours develops an average background of infection with the pathogen (60.0 %) already on the first day, at which it is possible to evaluate at an early stage the difference between the variants by the colonizing activity of laboratory samples of microbiological preparations.

scholarly journals Growth is required for perception of water availability to pattern plant root branches

2017 ◽  
Author(s):  
Neil E. Robbins ◽  
José R. Dinneny
Keyword(s):  
Water Availability ◽  
Water Movement ◽  
Plant Root ◽  
Growth Dynamics ◽  
Tissue Growth ◽  
Developmental Competence ◽  
Root Tip ◽  
Tissue Water ◽  
Root Branching ◽  
Lateral Branches

Water availability is a potent regulator of development in plants and acts as a positional cue to induce root branching through a process termed hydropatterning. The mechanism by which roots perceive the spatial distribution of water to position lateral branches is unknown. Here we reveal that a root's developmental competence for hydropatterning is limited to the root tip, where tissue growth occurs. Mathematical modeling suggests that water uptake during growth creates spatial biases in tissue water potential, and we show that these gradients predict the position of future lateral branches. By altering growth dynamics with exogenous chemical and environmental treatments, we demonstrate that growth is necessary to allow roots to distinguish environments with relatively high or low water availability and pattern branching accordingly. Furthermore, we show that these cues regulate a number of other physiologically important pathways. Our work supports a sense-by-growth mechanism governing lateral root hydropatterning, in which water availability cues are rendered interpretable through growth-sustained water movement.

Nitrate and glutamate sensing by plant roots

2005 ◽  
Vol 33 (1) ◽  
pp. 283-286 ◽  
Author(s):  
S. Filleur ◽  
P. Walch-Liu ◽  
Y. Gan ◽  
B.G. Forde
Keyword(s):  
Root Growth ◽  
Lateral Root ◽  
Lateral Roots ◽  
Primary Root ◽  
Root Tip ◽  
Root Tips ◽  
Environmental Signals ◽  
Specific Effects ◽  
Large Numbers ◽  
Low Concentrations

The architecture of a root system plays a major role in determining how efficiently a plant can capture water and nutrients from the soil. Growth occurs at the root tips and the process of exploring the soil volume depends on the behaviour of large numbers of individual root tips at different orders of branching. Each root tip is equipped with a battery of sensory mechanisms that enable it to respond to a range of environmental signals, including nutrients, water potential, light, gravity and touch. We have previously identified a MADS (MCM1, agamous, deficiens and SRF) box gene (ANR1) in Arabidopsis thaliana that is involved in modulating the rate of lateral root growth in response to changes in the external NO3− supply. Transgenic plants have been generated in which a constitutively expressed ANR1 protein can be post-translationally activated by treatment with dexamethasone (DEX). When roots of these lines are treated with DEX, lateral root growth is markedly stimulated but there is no effect on primary root growth, suggesting that one or more components of the regulatory pathway that operate in conjunction with ANR1 in lateral roots may be absent in the primary root tip. We have recently observed some very specific effects of low concentrations of glutamate on root growth, resulting in significant changes in root architecture. Experimental evidence suggests that this response involves the sensing of extracellular glutamate by root tip cells. We are currently investigating the possible role of plant ionotropic glutamate receptors in this sensory mechanism.

scholarly journals Asymmetric distribution of cytokinins determines root hydrotropism in Arabidopsis thaliana

Cell Research ◽  
2019 ◽  
Vol 29 (12) ◽  
pp. 984-993 ◽  
Author(s):  
Jinke Chang ◽  
Xiaopeng Li ◽  
Weihao Fu ◽  
Jiawen Wang ◽  
Yueyuan Yong ◽  
...  
Keyword(s):  
Cell Division ◽  
Water Potential ◽  
Molecular Mechanisms ◽  
Plant Root ◽  
Moisture Gradient ◽  
Root Tip ◽  
Asymmetric Distribution ◽  
Root Tips ◽  
Cytokinin Biosynthesis ◽  
Primary Determinant

Abstract The phenomenon of plant root tips sensing moisture gradient in soil and growing towards higher water potential is designated as root hydrotropism, which is critical for plants to survive when water is a limited factor. Molecular mechanisms regulating such a fundamental process, however, are largely unknown. Here we report our identification that cytokinins are key signaling molecules directing root growth orientation in a hydrostimulation (moisture gradient) condition. Lower water potential side of the root tip shows more cytokinin response relative to the higher water potential side. Consequently, two cytokinin downstream type-A response regulators, ARR16 and ARR17, were found to be up-regulated at the lower water potential side, causing increased cell division in the meristem zone, which allows the root to bend towards higher water potential side. Genetic analyses indicated that various cytokinin biosynthesis and signaling mutants, including the arr16 arr17 double mutant, are significantly less responsive to hydrostimulation. Consistently, treatments with chemical inhibitors interfering with either cytokinin biosynthesis or cell division completely abolished root hydrotropic response. Asymmetrically induced expression of ARR16 or ARR17 effectively led to root bending in both wild-type and miz1, a previously known hydrotropism-defective mutant. These data demonstrate that asymmetric cytokinin distribution is a primary determinant governing root hydrotropism.

APPLICATION OF VERTICAL-BEAM IN-AIR PIXE TO SURFACE ANALYSIS OF PLANT ROOT EXPOSED TO ALUMINUM STRESS

1997 ◽  
Vol 07 (01n02) ◽  
pp. 93-100 ◽  
Author(s):  
SATOSHI YOKOTA ◽  
JUN-ICHI INOUE ◽  
KEISUKE MUROZONO ◽  
SIGEO MATSUYAMA ◽  
HIROMICHI YAMAZAKI ◽  
...  
Keyword(s):  
Surface Analysis ◽  
Plant Root ◽  
Living Cells ◽  
Plant Roots ◽  
Root Tip ◽  
Elemental Distribution ◽  
Root Tips ◽  
Aluminum Stress ◽  
Vertical Beam

Elemental composition of living cells and tissues reflects their physiological function and status. However, it has been difficult to know in-situ elemental distribution by conventional analytical methods. In-air PIXE seems suitable for surface analysis of living cells and tissues because any treatment (e.g. freeze drying, digestion) is not required before and during measurement. We applied Via (vertical-beam in-air) PIXE to surface analysis of plant roots exposed to aluminum ( Al ). Aluminum stress is a major factor that limits elongation of plant roots in acid soils. We previously reported decrease in atomic ratio of potassium to phosphorus (K/P ratio) of dried root-tip of alfalfa (Medicago sativa L.) under Al stress using in-vacuum PIXE. In Via PIXE, 5 to 7-minute irradiation by 3 MeV proton beams of 200 pA was sufficient to obtain X-ray spectra without drying root samples. Decrease in K/P ratio in surface cells of root-tips was observed by short-term (6-8 h) exposure of root to Al . Via PIXE is recognized as a powerful tool for in-situ surface analysis of plant material.

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