scholarly journals Radioisotopic studies of DNA biosynthesis in relation to growth of Zea mays roots

2014 ◽  
Vol 55 (1) ◽  
pp. 97-106
Author(s):  
Roman Maksymowych ◽  
Andrew B. Maksymowych ◽  
Joseph A. Orkwiszewski
Keyword(s):  
Zea Mays ◽  
Cell Division ◽  
Dna Synthesis ◽  
Cell Elongation ◽  
Liquid Scintillation ◽  
Primary Root ◽  
Root Region ◽  
Dna Biosynthesis ◽  
Primary Roots ◽  
Meristematic Region

Root growth consists of two basic processes, cell division and cell elongation. An integral part of the first process is the synthesis of deoxyribonucleic acid (DNA). DNA biosynthesis was studied in primary roots of <em>Zea mays</em> through incorporation of <sup>3</sup>H-thymidine by autoradiography and liquid scintillation spectrometry. DNA synthesis was restricted to the meristematic region of the primary root. The curve representing this process was bell-shaped with a peak at 1.5 mm from the tip. Up to 3 mm distance from the tip, the root was growing both by cell division and cell elongation. This was also the region of DNA synthesis. The root region between 3 to 9 mm from the tip. was growing only by cell elongation. The relative elemental rate of elongation had a maximum at 3.5 mm from the tip, or shortly after cessation of DNA synthesis and cell division. Cells stopped elongating at 9 mm distance from the tip.

scholarly journals Impact of soil compaction heterogeneity and moisture on maize (Zea mays L.) root and shoot development

2008 ◽  
Vol 54 (No. 12) ◽  
pp. 509-519 ◽  
Author(s):  
B. Konôpka ◽  
L. Pagès ◽  
C. Doussan
Keyword(s):  
Zea Mays ◽  
Soil Moisture ◽  
Soil Compaction ◽  
Statistical Tests ◽  
Lateral Roots ◽  
Primary Root ◽  
Leaf Biomass ◽  
Fine Soil ◽  
Primary Roots ◽  
Primary And Lateral Roots

Soil compaction heterogeneity and water content are supposed to be decisive factors influencing plant growth. Our experiment focused on simulation of two soil moisture levels (0.16 and 0.19 g/g) plus two levels of clod proportion (30 and 60% volume) and their effects on root and leaf variables of maize (<I>Zea mays</I> L.). We studied number of primary and lateral roots as well as primary root length at the particular soil depths. Statistical tests showed that the decrease rate of the number of roots versus depth was significantly affected by the two studied factors (<I>P</I> < 0.01). Soil moisture and clod occurrence, interactively, affected leaf biomass (<I>P</I> = 0.02). Presence of clods modified root morphological features. Particularly, the diameter of primary roots in the clods was significantly higher than of those grown in fine soil (<I>P</I> < 0.01). For primary roots, which penetrated clods, branching density decreased considerably for the root segments located just after the clods (<I>P</I> = 0.01). Regarding their avoidance to clods and tortuosity, large differences were found between primary roots grown in the contrasting soil environments.

scholarly journals Evaluation of Metaxylem Vessel Histogenesis and the Occurrence of Vessel Collapse during Early Development in Primary Roots of Zea mays ssp. mexicana: A Result of Premature Programmed Cell Death?

Plants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 374
Author(s):  
Susumu Saito ◽  
Teruo Niki ◽  
Daniel K. Gladish
Keyword(s):  
Cell Death ◽  
Zea Mays ◽  
Programmed Cell Death ◽  
Primary Root ◽  
Cell Types ◽  
Root Apical Meristem ◽  
Root Tips ◽  
Primary Roots ◽  
Transmission Electron ◽  
Vessel Elements

Root apical meristem histological organization in Zea mays has been carefully studied previously. Classical histology describes its system as having a “closed organization” and a development of xylem that conforms to predictable rules. Among the first cell types to begin differentiation are late-maturing metaxylem (LMX) vessels. As part of a larger study comparing domestic maize root development to a wild subspecies of Z. mays (teosinte), we encountered a metaxylem development abnormality in a small percentage of our specimens that begged further study, as it interrupted normal maturation of LMX. Primary root tips of young seedlings of Zea mays ssp. mexicana were fixed, embedded in appropriate resins, and sectioned for light and transmission electron microscopy. Longitudinal and serial transverse sections were analyzed using computer imaging to determine the position and timing of key xylem developmental events. We observed a severe abnormality of LMX development among 3.5% of the 227 mexicana seedlings we screened. All LMX vessel elements in these abnormal roots collapsed and probably became non-functional shortly after differentiation began. Cytoplasm and nucleoplasm in the abnormal LMX elements became condensed and subdivided into irregularly-shaped “macrovesicles” as their cell walls collapsed inward. We propose that these seedlings possibly suffered from a mutation that affected the timing of the programmed cell death (PCD) that is required to produce functional xylem vessels, such that autolysis of the cytoplasm was prematurely executed, i.e., prior to the development and lignification of secondary walls.

Pathway of movement of apoplastic fluorescent dye tracers through the endodermis at the site of secondary root formation in corn (Zea mays) and broad bean (Vicia faba)

1981 ◽  
Vol 59 (5) ◽  
pp. 618-625 ◽  
Author(s):  
Carol A. Peterson ◽  
Mary E. Emanuel ◽  
G. B. Humphreys
Keyword(s):  
Zea Mays ◽  
Root Formation ◽  
Broad Bean ◽  
Primary Root ◽  
Root Primordia ◽  
Secondary Root ◽  
Point Of Entry ◽  
Primary Roots ◽  
Apoplastic Pathway ◽  
Root Treatment

The apoplastic dyes disodium 4,4′-bis (2-sulfostyryl) biphenyl (Tinopal CBS), a fabric brightener which is bound by cellulose, and trisodium, 3-hydroxy-5,8,10-pyrene trisulfonate (PTS), which is not bound by the walls, were used to trace an apoplastic pathway into the vascular tissues of corn and broad bean roots. The endodermis prevented dye entry into the stele in most regions of roots. However, if the roots were killed prior to dye treatment both dyes entered the steles, indicating that in healthy roots the dyes were confined to the apoplast and were not toxic in the applied concentrations. The more mobile dye, PTS, appeared in the shoots of the plants following a root treatment, indicating that an apoplastic pathway into the stele does exist in the roots. Neither dye penetrated into the steles at the tips of the primary roots. The point of entry in both corn and broad bean was located along the margin of a secondary root which had recently emerged from the epidermis of the primary root. The dyes did not enter the steles of the primary roots during earlier stages of secondary root development, nor did they enter through the secondary root primordia themselves.

Physiological Responses to Sethoxydim in Tissues of Corn (Zea mays) and Pea (Pisum sativum)

Weed Science ◽  
1987 ◽  
Vol 35 (5) ◽  
pp. 604-611 ◽  
Author(s):  
Hideo Hosaka ◽  
Masae (Kubota) Takagi
Keyword(s):  
Zea Mays ◽  
Cell Division ◽  
Pisum Sativum ◽  
Root Growth ◽  
Dna Synthesis ◽  
Physiological Responses ◽  
Inhibition Mechanism ◽  
Root Tips ◽  
Triphenyltetrazolium Chloride ◽  
Corn Root

The physiological responses of corn (Zea maysL. ‘Goldencrossbantam′) and pea (Pisum sativumL. ‘Alaska′) to sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio) propyl]-3-hydroxy-2-cyclohexen-1-one} were investigated. Sethoxydim did not affect excised pea root growth at 1 × 10−4M but inhibited excised corn root growth at concentrations of 1 × 10−8M and above. Treating corn impeded root growth with 1 × 10−7M sethoxydim within 4 h after treatment; however, little histological change of the roots was observed at 48 h. At 1 × 10−6M, growth nearly stopped within 4 h after treatment, and clear cytological changes of the roots were observed at 24 and 48 h. Sethoxydim inhibited both mitosis and DNA synthesis of excised corn root tips between 4 and 48 h after treatment. Respiration of corn roots measured by oxygen uptake and the TTC (2,3,5-triphenyltetrazolium chloride) test was not affected by the herbicide directly. Sethoxydim (1 × 10−4M) inhibited IAA-induced cell elongation of corn coleoptile and pea epicotyl by 37 and 12%, respectively. Sethoxydim selectively inhibited the growth of excised root tips of susceptible corn by affecting cell division rather than cell enlargement, and the inhibition mechanism of cell division (inhibition of mitosis) by the herbicide was not by direct inhibition of DNA synthesis or by effects on respiration.

Morphological and Histological Effects of Sethoxydim on Corn (Zea mays) Seedlings

Weed Science ◽  
1984 ◽  
Vol 32 (6) ◽  
pp. 711-721 ◽  
Author(s):  
Hideo Hosaka ◽  
Hideo Inaba ◽  
Atsushi Satoh ◽  
Hisao Ishikawa
Keyword(s):  
Zea Mays ◽  
Cell Division ◽  
Foliar Application ◽  
Application Rate ◽  
Hydroponic Culture ◽  
Cytological Investigation ◽  
Primary Roots

The herbicidal action of sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} on corn (Zea maysL. ‘Goldencrossbantam’) was investigated in preemergence and postemergence experiments and hydroponic culture. Soil-applied sethoxydim did not inhibit corn germination. Leaves failed to emerge through the coleoptile with a high herbicide rate (1.6 kg ai/ha), but chlorotic leaves emerged at a lower rate (0.8 kg ai/ha). Growth of corn seedlings treated with a foliar application of 0.2 kg ai/ha was inhibited within 1 day after treatment, but at a lower application rate (0.05 kg ai/ha) growth continued with chlorotic zones on newly expanding leaves. Over the concentration range 3 × 10-5to 1 × 10-6M, sethoxydim inhibited the growth of primary roots of corn in hydroponic culture within 24 h. Cytological investigation showed that sethoxydim inhibited cell division but did not interfere with mitosis.

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