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Miki Y, Saito S, Niki T, Gladish DK. Re-Evaluation of Vascular Histogenesis in the Root Tips of Selected Species in the Poaceae Using New Methods: Analysis of the Plerome, Vascular Initials, Pericycle and Late-Maturing Metaxylem Vessels. Plants (Basel) 2024; 13:910. [PMID: 38592924 PMCID: PMC10974141 DOI: 10.3390/plants13060910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 03/05/2024] [Accepted: 03/08/2024] [Indexed: 04/11/2024]
Abstract
Serial sectioning and 3D image reconstruction methods were applied to elucidate the structures of the apices of root vascular cylinders (VCs) in taxa of the Poaceae: Zea mays "Honey Bantam", Z. mays ssp. mexicana, Hordeum vulgare and Oryza sativa. The primary and nodal roots were investigated. Observations were performed using high-quality sectioning and 3D image-processing techniques improved and developed by the authors. We found that a quiescent uniseriate plerome was located at the most distal part of each VC. Vascular initials were located immediately basipetally to the plerome as a specific uniseriate layer that could be classified into central and peripheral initials that produced all the cells in the VC. No supplying of cells from the plerome to the vascular initials was observed. Numerical analysis revealed a "boundary point" along the root axis where the rate of increase of the vascular cell number markedly declined, and the VC diameter, number of vascular cells, and number of late-maturing metaxylem vessels (LMXs) at that point showed a similar relationship among the taxa and the types of roots examined (primary vs. nodal). The plerome and vascular initials layer can be considered independent after seed germination in these taxa. A boundary point at which procambial cell proliferation sharply declined was identified. The diameters of the VCs, number of LMXs, and number of vascular cells at the boundary point were found to be strongly related to each other.
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Affiliation(s)
- Yasushi Miki
- Image Processing Section, MikiOn LLC, 593-1-102 Kunugida, Tokyo 193-0942, Japan; (Y.M.); (S.S.); (T.N.)
| | - Susumu Saito
- Image Processing Section, MikiOn LLC, 593-1-102 Kunugida, Tokyo 193-0942, Japan; (Y.M.); (S.S.); (T.N.)
| | - Teruo Niki
- Image Processing Section, MikiOn LLC, 593-1-102 Kunugida, Tokyo 193-0942, Japan; (Y.M.); (S.S.); (T.N.)
| | - Daniel K. Gladish
- Department of Biological Sciences, Miami University, 1601 University Blvd., Hamilton, OH 45011, USA
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Miki Y, Saito S, Niki T, Gladish DK. Improved image processing for 3D virtual object construction from serial sections reveals tissue patterns in root tips of Zea mays. Appl Plant Sci 2023; 11:e11531. [PMID: 38106532 PMCID: PMC10719874 DOI: 10.1002/aps3.11531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 03/22/2023] [Accepted: 04/07/2023] [Indexed: 12/19/2023]
Abstract
Premise Previously we described methods for generating three-dimensional (3D) virtual reconstructions of plant tissues from transverse thin sections. Here, we report the applicability of longitudinal sections and improved image-processing steps that are simpler to perform and utilize free applications. Methods In order to obtain improved digital images and a virtual 3D object (cuboid), GIMP 2.10 and ImageJ 2.3.0 running on a laptop computer were used. Sectional views of the cuboid and 3D visualization were realized with use of the plug-ins "Volume Viewer" and "3D Viewer" in ImageJ. Results A 3D object was constructed and sectional views along several cutting planes were generated. The 3D object consisted of selected tissues inside the cuboid that were extracted and visualized from the original section data, and an animated video of the 3D construct was also produced. Discussion Virtual cuboids can be constructed by stacking longitudinal images along the transverse depth direction or stacking transverse images vertically along the organ axis, with both generating similar 3D objects. Which to use depends on the purpose of the investigation: if the vertical cell structures need close examination, the former method may be better, but for more general spatial evaluations or for evaluation of organs over longer tissue distances than can be accommodated with longitudinal sectioning, the latter method should be chosen.
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Affiliation(s)
- Yasushi Miki
- Image Processing SectionMikiOn LLC, 103 Ishikawa Heights, 1737 Hazama‐machi, HachiojiTokyo193‐0941Japan
| | - Susumu Saito
- Image Processing SectionMikiOn LLC, 103 Ishikawa Heights, 1737 Hazama‐machi, HachiojiTokyo193‐0941Japan
| | - Teruo Niki
- Image Processing SectionMikiOn LLC, 103 Ishikawa Heights, 1737 Hazama‐machi, HachiojiTokyo193‐0941Japan
| | - Daniel K. Gladish
- Department of BiologyMiami University1601 University Blvd.HamiltonOhio45011USA
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Pegg TJ, Gladish DK, Baker RL. Algae to angiosperms: Autofluorescence for rapid visualization of plant anatomy among diverse taxa. Appl Plant Sci 2021; 9:e11437. [PMID: 34268017 PMCID: PMC8272585 DOI: 10.1002/aps3.11437] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 05/19/2021] [Indexed: 05/22/2023]
Abstract
PREMISE Fluorescence microscopy is an effective tool for viewing plant internal anatomy. However, using fluorescent antibodies or labels hinders throughput. We present a minimal protocol that takes advantage of inherent autofluorescence and aldehyde-induced fluorescence in plant cellular and subcellular structures to markedly increase throughput in cellular and ultrastructural visualization. METHODS AND RESULTS Twelve species distributed across the plant phylogeny were each subjected to five fixative treatments: 1% paraformaldehyde and 2% glutaraldehyde, 2% paraformaldehyde, 2% glutaraldehyde, formalin-acid-alcohol (FAA), and 70% ethanol. Samples were prepared by embedding and mechanically sectioning or via whole mount. A confocal laser scanning system was used to collect micrographs. We evaluated and compared fixative influence on sample structural preservation and tissue autofluorescence. CONCLUSIONS Formaldehyde fixation of Viridiplantae taxa samples generates useful structural data while requiring no additional histological staining or clearing. In addition, a fluorescence-capable microscope is the only specialized equipment required for image acquisition. The minimal protocol developed in this experiment enables high-throughput sample processing by eliminating the need for multi-day preparations.
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Affiliation(s)
- Timothy J. Pegg
- Department of BiologyMiami UniversityOxfordOhio45056USA
- Graduate Program in BotanyMiami UniversityOxfordOhio45056USA
| | - Daniel K. Gladish
- Department of BiologyMiami UniversityOxfordOhio45056USA
- Graduate Program in BotanyMiami UniversityOxfordOhio45056USA
| | - Robert L. Baker
- Department of BiologyMiami UniversityOxfordOhio45056USA
- Graduate Program in BotanyMiami UniversityOxfordOhio45056USA
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Miki Y, Saito S, Niki T, Gladish DK. Three-dimensional digital image construction of metaxylem vessels in root tips of Zea mays subsp. mexicana from thin transverse sections. Appl Plant Sci 2020; 8:e11347. [PMID: 32477843 PMCID: PMC7249274 DOI: 10.1002/aps3.11347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 12/27/2019] [Indexed: 05/12/2023]
Abstract
PREMISE Young plant roots share a common architecture: a central vascular cylinder surrounded by enveloping cylinders of ground and dermal tissue produced by an apical promeristem. Roots with closed apical organization can be studied to explore how ontogeny is managed. The analysis of transverse and longitudinal sections has been the most useful approach for this, but suffers from limitations. We developed a new method that utilizes digital photography of transverse sections and three-dimensional (3D) computer virtual reconstructions to overcome the limitations of other techniques. METHODS Serial transverse sections of teosinte root tips (Zea mays subsp. mexicana) were used to construct longitudinal images, 3D images, and an animated 3D model. The high-resolution, high-contrast, and low-distortion sectioning method developed previously by the authors enabled high-quality virtual image construction with the aid of a standard laptop computer. RESULTS The resulting 3D images allowed greater insight into root tissue ontogeny and organization, especially specific cellular structures such as histogen layers, xylem vessels, pericycle, and meristematic initials. DISCUSSION This new method has advantages over confocal laser scanning microscopy and magnetic resonance imaging for visualizing anatomy, and includes a procedure to correct for sectioning distortion. An additional advantage of this method, developed to produce better knowledge about the developmental anatomy of procambium in roots, is its applicability to a wide range of anatomical subjects.
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Affiliation(s)
- Yasushi Miki
- Image Processing SectionMikiOn LLC103 Ishikawa Heights, 1737 Hazama‐machiHachiojiTokyo193‐0941Japan
| | - Susumu Saito
- Image Processing SectionMikiOn LLC103 Ishikawa Heights, 1737 Hazama‐machiHachiojiTokyo193‐0941Japan
| | - Teruo Niki
- Image Processing SectionMikiOn LLC103 Ishikawa Heights, 1737 Hazama‐machiHachiojiTokyo193‐0941Japan
| | - Daniel K. Gladish
- Department of BiologyMiami University1601 University BoulevardHamiltonOhio45011USA
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Pegg T, Edelmann RR, Gladish DK. Immunoprofiling of Cell Wall Carbohydrate Modifications During Flooding-Induced Aerenchyma Formation in Fabaceae Roots. Front Plant Sci 2020; 10:1805. [PMID: 32117353 PMCID: PMC7008352 DOI: 10.3389/fpls.2019.01805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 12/24/2019] [Indexed: 05/12/2023]
Abstract
Understanding plant adaptation mechanisms to prolonged water immersion provides options for genetic modification of existing crops to create cultivars more tolerant of periodic flooding. An important advancement in understanding flooding adaptation would be to elucidate mechanisms, such as aerenchyma air-space formation induced by hypoxic conditions, consistent with prolonged immersion. Lysigenous aerenchyma formation occurs through programmed cell death (PCD), which may entail the chemical modification of polysaccharides in root tissue cell walls. We investigated if a relationship exists between modification of pectic polysaccharides through de-methyl esterification (DME) and the formation of root aerenchyma in select Fabaceae species. To test this hypothesis, we first characterized the progression of aerenchyma formation within the vascular stele of three different legumes-Pisum sativum, Cicer arietinum, and Phaseolus coccineus-through traditional light microscopy histological staining and scanning electron microscopy. We assessed alterations in stele morphology, cavity dimensions, and cell wall chemistry. Then we conducted an immunolabeling protocol to detect specific degrees of DME among species during a 48-hour flooding time series. Additionally, we performed an enzymatic pretreatment to remove select cell wall polymers prior to immunolabeling for DME pectins. We were able to determine that all species possessed similar aerenchyma formation mechanisms that begin with degradation of root vascular stele metaxylem cells. Immunolabeling results demonstrated DME occurs prior to aerenchyma formation and prepares vascular tissues for the beginning of cavity formation in flooded roots. Furthermore, enzymatic pretreatment demonstrated that removal of cellulose and select hemicellulosic carbohydrates unmasks additional antigen binding sites for DME pectin antibodies. These results suggest that additional carbohydrate modification may be required to permit DME and subsequent enzyme activity to form aerenchyma. By providing a greater understanding of cell wall pectin remodeling among legume species, we encourage further investigation into the mechanism of carbohydrate modifications during aerenchyma formation and possible avenues for flood-tolerance improvement of legume crops.
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Affiliation(s)
- Timothy Pegg
- Department of Biology, Miami University, Oxford, OH, United States
| | - Richard R. Edelmann
- Department of Biology, Miami University, Oxford, OH, United States
- Center for Advance Microscopy & Imaging, Miami University, Oxford, OH, United States
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Saito S, Niki T, Gladish DK. Comparison of Promeristem Structure and Ontogeny of Procambium in Primary Roots of Zea mays ssp. Mexicana and Z. mays 'Honey Bantam' with Emphasis on Metaxylem Vessel Histogenesis. Plants (Basel) 2019; 8:E162. [PMID: 31181793 PMCID: PMC6631287 DOI: 10.3390/plants8060162] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 05/23/2019] [Accepted: 06/04/2019] [Indexed: 12/01/2022]
Abstract
Classical histology describes the histological organization in Zea mays as having a "closed organization" that differs from Arabidopsis with the development of xylem conforming to predictable rules. We speculated that root apical meristem organization in a wild subspecies of Z. mays (a teosinte) would differ from a domestic sweetcorn cultivar ('Honey Bantam'). Careful comparison could contribute to understanding how evolutionary processes and the domestication of maize have affected root development. Root tips of seedlings were prepared and sectioned for light microscopy. Most sections were treated with RNase before staining to increase contrast between the walls and cytoplasm. Longitudinal and serial transverse sections were analyzed using computer imaging to determine the position and timing of key xylem developmental events. Metaxylem development in mexicana teosinte differed from sweetcorn only in that the numbers of late-maturing metaxylem vessels in the latter are typically two-fold greater and the number of cells in the transverse section of procambium were greater in the latter, but parenchymatous cell sizes were not statistically different. Promeristems of both were nearly identical in size and organization, but did not operate quite as previously described. Mitotic activity was rare in the quiescent centers, but occasionally a synchronized pulse of mitoses was observed there. Our reinterpretation of histogen theory and procambium development should be useful for future detailed studies of regulation of development, and perhaps its evolution, in this species.
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Affiliation(s)
- Susumu Saito
- Department of Biotechnology, Takushoku University, Tatemachi 815-1, Hachioji, Tokyo 193-0985, Japan.
| | - Teruo Niki
- Department of Biotechnology, Takushoku University, Tatemachi 815-1, Hachioji, Tokyo 193-0985, Japan.
| | - Daniel K Gladish
- Biological Sciences Department, Miami University, 1601 University Blvd, Hamilton, OH 45011, USA.
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Niki T, Saito S, Gladish DK. A novel thin section preparation and staining protocol to increase contrast and resolution of cell details for light microscopy. Biotech Histochem 2019; 94:522-526. [PMID: 31043085 DOI: 10.1080/10520295.2019.1601769] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
We developed a novel sectioning and staining method to make high contrast, high resolution sections of plant tissue for light microscopy. Specimens of teosinte (Zea mays L., ssp. mexicana) root tips were fixed and embedded in Technovit 7100™ plastic resin. Thin sections, 1-2.5 μm, were cut and mounted on glass slides. The sections were either treated with RNase or not, then stained with 0.1% toluidine blue O and observed through ∞/0 objective lenses. For light microscopy, the enzyme staining procedure increased resolution and contrast. High magnification ∞/0 objective lenses produced high quality images for digital photography without using a coverslip or immersion oil. Our slide preparation and microscopic analysis were less labor intensive and more rapid than previous methods and enabled rapid and precise alignment of serial transverse sections for both tracking cell lineages and tissue measurements.
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Affiliation(s)
- T Niki
- Image Processing Section, MikiOn, LLC , Tokyo , Japan
| | - S Saito
- Image Processing Section, MikiOn, LLC , Tokyo , Japan
| | - D K Gladish
- Department of Biology, Miami University , Hamilton , Ohio , USA
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Niki T, Saito S, Gladish DK. Granular bodies in root primary meristem cells of Zea mays L. var. Cuscoensis K. (Poaceae) that enter young vacuoles by invagination: a novel ribophagy mechanism. Protoplasma 2014; 251:1141-9. [PMID: 24585069 DOI: 10.1007/s00709-014-0622-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 01/29/2014] [Indexed: 05/26/2023]
Abstract
Because it has a very large, very rapidly growing primary root, we evaluated giant maize (Zea mays var. Cuscoensis) as a model organism for root research. Granular inclusions are a common feature of cells in many organisms, but they are not common in root meristems. We here report the presence of granules in root tip cells of giant maize. Seeds were germinated at 20 °C in sterile conditions. Four to 5-day-old primary roots were fixed, embedded, and sectioned for light and electron microscopy. Granules (1-2 μm) were observed in small vacuoles in all cell types of the apical meristem zone and mainly in parenchyma cells of the procambium in the primary meristem zone. Some sections were treated with ribonuclease and/or proteinase and then stained with toluidine blue, methyl green pyronin, or Coomassie brilliant blue. The results were used to determine that the granules were composed primarily of RNA and protein. In electron micrographs, consistent with the enzyme experiment results, granules appeared to be dense aggregates of polyribosomes and rough endoplasmic reticulum. They formed first in the cytosol, then invaginated into an adjacent vacuole. The granules are apparently ephemeral and therefore may not have a function other than being subject to autolysis. We speculate that they are part of a previously undescribed ribophagy system that operates during rapid cell growth and differentiation to regulate translation and recycle granule components.
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Affiliation(s)
- Teruo Niki
- Department of Biotechnology, Takushoku University, Tatemachi 815-1, Hachioji, Tokyo, 193-0985, Japan
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Sarkar P, Gladish DK. Hypoxic stress triggers a programmed cell death pathway to induce vascular cavity formation in Pisum sativum roots. Physiol Plant 2012; 146:413-26. [PMID: 22486732 DOI: 10.1111/j.1399-3054.2012.01632.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Flooding at warm temperatures induces hypoxic stress in Pisum sativum seedling roots. In response, some undifferentiated cells in the primary root vascular cylinder start degenerating and form a longitudinal vascular cavity. Changes in cellular morphology and cell wall ultrastructure detected previously in the late stages of cavity formation suggest possible involvement of programmed cell death (PCD). In this study, cytological events occurring in the early stages of cavity formation were investigated. Systematic DNA fragmentation, a feature of many PCD pathways, was detected in the cavity-forming roots after 3 h of flooding in situ by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay and in isolated total DNA by gel electrophoresis. High molecular weight DNA fragments of about 20-30 kb were detected by pulse-field gel electrophoresis, but no low-molecular weight internucleosomal DNA fragments were detected by conventional gel electrophoresis. Release of mitochondrial cytochrome c protein into the cytosol, an integral part of mitochondria-dependent PCD pathways, was detected in the cavity-forming roots within 2 h of flooding by fluorescence microscopy of immunolabeled cytochrome c in situ and in isolated mitochondrial and cytosolic protein fractions by western blotting. DNA fragmentation and cytochrome c release remained confined to the undifferentiated cells in center of the root vascular cylinders, even after 24 h of flooding, while outer vascular cylinder cells and cortical cells maintained cellular integrity and normal activity. These findings confirm that hypoxia-induced vascular cavity formation in P. sativum roots involves PCD, and provides a chronological model of cytological events involved in this rare and understudied PCD system.
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Affiliation(s)
- Purbasha Sarkar
- Department of Botany, Miami University, Oxford, OH 45056, USA
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Sarkar P, Niki T, Gladish DK. Changes in cell wall ultrastructure induced by sudden flooding at 25{degrees}C in Pisum sativum (Fabaceae) primary roots. Am J Bot 2008; 95:782-792. [PMID: 21632404 DOI: 10.3732/ajb.2007381] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Cellular degeneration is essential for many developmental and stress acclimation processes. Undifferentiated parenchymatous cells in the central vascular cylinder of pea primary roots degenerate under hypoxic conditions created by flooding at temperatures >15°C, forming a long vascular cavity that seems to provide a conduit for longitudinal oxygen transport in the roots. We show that specific changes in the cell wall ultrastructure accompanied previously detected cytoplasmic and organellar degradation in the cavity-forming roots. The degenerating cells had thinner primary cell walls, less electron-dense middle lamellae, and less abundant cell wall homogalacturonans in altered patterns, compared to healthy cells of roots grown under cold, nonflooded conditions. Cellular breakdown and changes in wall ultrastructure, however, remained confined to cells within a 50-μm radius around the root center, even after full development of the cavity. Cells farther away maintained cellular integrity and had signs of wall synthesis, perhaps from tight regulation of wall metabolism over short distances. These observations suggest that the cell degeneration might involve programmed cell death. We also show that warm, nonflooded or cold, flooded conditions that typically do not induce vascular cavity formation can also induce variations in cell wall ultrastructure.
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Affiliation(s)
- Purbasha Sarkar
- Department of Botany, Miami University, Oxford, Ohio 45056 USA
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Gladish DK, Xu J, Niki T. Apoptosis-like programmed cell death occurs in procambium and ground meristem of pea (Pisum sativum) root tips exposed to sudden flooding. Ann Bot 2006; 97:895-902. [PMID: 16533830 PMCID: PMC2803422 DOI: 10.1093/aob/mcl040] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2005] [Revised: 09/19/2005] [Accepted: 01/12/2006] [Indexed: 05/07/2023]
Abstract
BACKGROUND AND AIMS Pea (Pisum sativum) primary roots form long vascular cavities when grown under wet or flooded conditions at 25 degrees C. It is thought that the cavities are a form of aerenchyma. At 25 degrees C short roots continue to grow after flooding. After roots reach 10 cm long flooding causes rapid cessation of growth, and root tips often become curled. In longer roots the cavities do not extend into the base of the roots, perhaps rendering them ineffective as aerenchyma. It was hypothesized that the resulting growth arrest was due to programmed cell death (PCD) rather than necrosis. METHODS AND KEY RESULTS Histological examination by light microscope showed that some cells in the primary meristem (elongation) zone of the primary root tips had morphological abnormalities, including misshapen and fragmented nuclei, and cytoplasmic shrinking and fragmentation. Transmission electron microscopy revealed lobing, invagination and chromatin aggregation in nuclei. The affected cells were positive for terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling. Extracted DNA formed a "DNA ladder" during electrophoresis. Cell death usually began in procambium at one or two protoxylem poles and seemed to spread out to nearby tissues, which asymmetrically inhibited growth and resulted in tip curling. CONCLUSIONS The above are symptoms of apoptosis-like PCD. Programmed root tip death may rapidly reduce oxygen demand and sink strength, allowing more rapid diversion of resources to lateral roots growing in more permissive conditions.
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Affiliation(s)
- Daniel K Gladish
- Department of Botany, Miami University, Hamilton, OH 45011, USA.
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Niki T, Gladish DK. Changes in growth and structure of pea primary roots (Pisum sativum L. cv. Alaska) as a result of sudden flooding. Plant Cell Physiol 2001; 42:694-702. [PMID: 11479375 DOI: 10.1093/pcp/pce086] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Pea (Pisum sativum L. cv. Alaska) primary roots were exposed to flooding after growth for 4 or 5 d at 25 degrees C under relatively dry conditions. Flooding after 4 d growth reduced, but did not stop, primary root growth, and cavities caused by degradation of central vascular cells were typically found from 10-60 mm from the tips. Flooding after 5 d stopped primary root growth and caused cell death in the tips, and vascular cavities formed that typically were 20-60 mm from the tips of the roots. Degradation of root tip cells in 5-day-roots was very rapid and began in the elongation zone and later in the apical zone. Root tips discolored, narrowed or curled before growth arrest. The mitotic indices of 5-day-root tips were suppressed by the flooding treatment. A few mitotic figures were observed in roots treated with flooding after 4 d growth. Affected cells had condensed nuclei, but cytoplasms appeared to be normal in the early stages of cell degradation. Later these cells became very vacuolated. The relationship of flooding to root growth, vascular cavity formation, and the morphology of pea primary roots is described with regard to the ability to resist flooding stress.
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Affiliation(s)
- T Niki
- Department of Cell Technology, Faculty of Engineering, Takushoku University, Hachioji, Tokyo, 193-8585, Japan
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