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 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.

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 STUDIES ON THE GROWTH HORMONE OF PLANTS

1934 ◽  
Vol 18 (1) ◽  
pp. 23-34 ◽  
Author(s):  
Kenneth V. Thimann
Keyword(s):  
Growth Hormone ◽  
Growth Substance ◽  
Root Tip ◽  
Plant Tissues ◽  
Root Tips ◽  
Direct Extraction ◽  
Simple Method ◽  
Avena Coleoptile ◽  
Method Of Extraction

1. It is shown that when plant tissues are ground with water the growth substance contained therein is inactivated by the oxidizing enzymes. 2. A simple method of extraction is described which enables the quantitative determination of growth substance in such tissues. 3. The amount and distribution of growth substance in the Avena coleoptile is determined by this method, and it is shown that while the substance does not diffuse out from the lower parts of the coleoptile, it is nevertheless present in considerable amounts, the concentration decreasing steadily with the distance from the tip. 4. Growth substance is also present in considerable amounts in Avena roots, and here also its concentration decreases steadily with distance from the tip. 5. The amount of growth substance diffusing out of root tips into dextrose agar, even during long periods of time, is not greater than the amount obtainable by direct extraction. Actual production in the root tip therefore either does not take place at all, or else takes place under quite different conditions from the production in the tip of the coleoptile.

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.

scholarly journals Pewarnaan Kromosom dan Pemanfaatannya dalam Penentuan Tingkat Ploidi Eksplan Hasil Kultur Anter Anthurium

2016 ◽  
Vol 21 (2) ◽  
pp. 113 ◽  
Author(s):  
Budi Winarto
Keyword(s):  
Anther Culture ◽  
Ploidy Level ◽  
Staining Method ◽  
Root Tip ◽  
Root Tips ◽  
Staining Methods ◽  
Ornamental Crops ◽  
High Benefit ◽  
Chromosome Staining

Metode pewarnaan Kromosom yang optimal merupakan prasarat penting dalam penentuan level ploidi tanaman hasil kultur anter, termasuk variasi eksplan hasil kultur anter Anthurium. Aplikasi dan modifikasi metode pewarnaan kromosom pada berbagai eksplan dilakukan di Laboratorium Kultur Jaringan Balai Penelitian Tanaman Hias dari bulan Februari sampai dengan Agustus 2009 untuk mengetahui keragaman dan tingkat ploidi regeneran hasil kultur anter Anthurium. Penelitian bertujuan mendapatkan metode pewarnaan kromosom dan modifikasinya, jenis eksplan dan akar yang sesuai untuk mempelajari tingkat ploidi regeneran hasil kultur anter Anthurium. Bahan yang digunakan ialah kalus, pucuk tunas, dan ujung akar udara. Penelitian terdiri atas tiga kegiatan, yaitu (1) modifikasi metode pewarnaan kromosom, (2) seleksi eksplan yang sesuai untuk pewarnaan kromosom, dan (3) optimasi metode pewarnaan kromosom terseleksi. Hasil penelitian menunjukkan bahwa ujung akar dan akar yang ditumbuhkan pada medium yang mengandung 1% arang aktif merupakan jenis eksplan dan akar yang sesuai untuk mendapatkan hasil pewarnaan kromosom yang baik. Modifikasi metode pewarnaan kromosom dengan pemanasan ujung akar pada 1N HCl : asam asetat glasial 45% (3:1, v/v) selama 10 menit pada suhu 60oC dan perlakuan aseto-orcein selama 15 menit merupakan metode pewarnaan kromosom yang lebih baik dalam menghasilkan obyek kromosom yang mudah dihitung. Penerapan metode pewarnaan kromosom pada kultur anter Anthurium dapat memisahkan tingkat ploidi regeneran. Pada penelitian ini rasio ploidi regeneran kultur anter ialah 33,5% haploid, 62,7% diploid, dan 5,7% triploid. Metode pewarnaan kromosom yang berhasil dikembangkan dalam penelitian ini sangat bermanfaat dalam pengembangan teknologi haploid pada jenis Araceae yang lain.<br /><br />Optimal chromosome staining method is important pre-requisite in determination of plant ploidy level derived from anther culture, involving varied explants regenerated from Anthurium anther culture. Application and modification of chromosome staining methods on different explants were conducted at the Tissue Culture Laboratory of  Indonesian Ornamental Crops Research Institute from February to August 2009 for determination of the ploidy level of regenerants derived from anther culture of Anthurium. The aim of this research was to determine the chromosome staining method and its modifications, type of explant and root suitable to study the ploidy level of explants derived from anther culture of Anthurium. Callus, shoot tips, and root tips were utilized in the experiment. The research was consisted of three experiments, i.e. (1) modification of chromosome staining methods (2) selection of explants suitable for chromosome staining, and (3) improvement of the selected chromosome staining method. Results of the study indicated that root tips and roots cultured on medium containing 1% active carchoal were the most appropriate explants and the root type in obtaining better chromosome staining results. The modification method with root tip boiled in 1N HCl : 45% of acetic acid glacial (3:1, v/v) for 10 minutes in 60ºC and aceto-orcein treatment for 15 minutes gave appropriate chromosome staining results exhibited clearer chromosome pictures and was easy to be counted. The  application of chromosome staining on anther culture of Anthurium was able to distinguish the ploidy level of regenerants. Ploidy ratio of regenerants derived from anther culture was 33.5% of haploid, 62.7% of diploid, and 5.7% of triploid. Chromosome staining method resulted from the study give high benefit in developing haploid technologies on other Araceae plants.<br /><br />

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

2021 ◽  
Vol 118 (20) ◽  
pp. e2102188118
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

Plant 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 PIEZO1 (PZO1) has preserved the function of its animal relatives and acts as an ion channel. We present evidence that plant PIEZO1 is expressed in the columella and lateral root cap cells of the root tip, which are known to experience robust mechanical strain during root growth. Deleting PZO1 from the whole plant significantly reduced the ability of its roots to penetrate denser barriers compared to wild-type plants. pzo1 mutant root tips exhibited diminished calcium transients in response to mechanical stimulation, supporting a role of PZO1 in root mechanotransduction. Finally, a chimeric PZO1 channel that includes the C-terminal half of PZO1 containing the putative pore region was functional and mechanosensitive when expressed in naive mammalian cells. Collectively, our data suggest that Arabidopsis PIEZO1 plays an important role in root mechanotransduction and establish PIEZOs as physiologically relevant mechanosensitive ion channels across animal and plant kingdoms.

scholarly journals Cytokinin-Controlled Gradient Distribution of Auxin in Arabidopsis Root Tip

2021 ◽  
Vol 22 (8) ◽  
pp. 3874
Author(s):  
Lei Wu ◽  
Jun-Li Wang ◽  
Xiao-Feng Li ◽  
Guang-Qin Guo
Keyword(s):  
Growth And Development ◽  
Molecular Mechanisms ◽  
Plant Root ◽  
Primary Root ◽  
Root Tip ◽  
Root Tips ◽  
Arabidopsis Root ◽  
Gradient Distribution ◽  
Shed Light ◽  
Auxin Gradient

The plant root is a dynamic system, which is able to respond promptly to external environmental stimuli by constantly adjusting its growth and development. A key component regulating this growth and development is the finely tuned cross-talk between the auxin and cytokinin phytohormones. The gradient distribution of auxin is not only important for the growth and development of roots, but also for root growth in various response. Recent studies have shed light on the molecular mechanisms of cytokinin-mediated regulation of local auxin biosynthesis/metabolism and redistribution in establishing active auxin gradients, resulting in cell division and differentiation in primary root tips. In this review, we focus our attention on the molecular mechanisms underlying the cytokinin-controlled auxin gradient in root tips.

Method development for the determination of textural properties of sugar beet roots

2019 ◽  
pp. 392-400 ◽  
Author(s):  
Gunnar Kleuker ◽  
Christa M. Hoffmann
Keyword(s):  
Sugar Beet ◽  
Compression Test ◽  
Storage Period ◽  
Textural Properties ◽  
Small Sample ◽  
Root Tip ◽  
Flexural Test ◽  
Sample Distribution ◽  
The Impact

The harvest of sugar beet leads to root tip breakage and surface damage through mechanical impacts, which increase storage losses. For the determination of textural properties of sugar beet roots with a texture analyzer a reliable method description is missing. This study aimed to evaluate the impact of washing, soil tare, storage period from washing until measurement, sample distribution and number of roots on puncture and compression measurements. For this purpose, in 2017 comprehensive tests were conducted with sugar beet roots grown in a greenhouse. In a second step these tests were carried out with different Beta varieties from a field trial, and in addition, a flexural test was included. Results show that the storage period after washing and the sample distribution had an influence on the puncture and compression strength. It is suggested to wash the roots by hand before the measurement and to determine the strength no later than 48 h after washing. For reliable and comparable results a radial distribution of measurement points around the widest circumference of the root is recommended for the puncture test. The sample position of the compression test had an influence on the compressive strength and therefore, needs to be clearly defined. For the puncture and the compression test it was possible to achieve stable results with a small sample size, but with increasing heterogeneity of the plant stand a higher number of roots is required. The flexural test showed a high variability and is, therefore, not recommended for the analysis of sugar beet textural properties.

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