Biochemical Effects of Sethoxydim in Excised Root Tips of Corn (Zea mays)

Weed Science ◽  
1987 ◽  
Vol 35 (5) ◽  
pp. 612-618 ◽  
Author(s):  
Hideo Hosaka ◽  
Masae (Kubota) Takagi
Keyword(s):  
Zea Mays ◽  
Acetic Acid ◽  
Fatty Acid Synthase ◽  
Lipid Fraction ◽  
Lipid Synthesis ◽  
Root Tip ◽  
Root Tips ◽  
Biochemical Effects ◽  
Corn Roots ◽  
Synthase Inhibitor

The effects of sethoxydim {2-[1-(ethoxyimino) butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} on the metabolic activity of excised root tips of corn (Zea mays, L. ‘Goldencrossbantam′) were studied under laboratory conditions. Uptake and incorporation of14C-labeled thymidine, uridine, leucine, glucose, and acetic acid into cell constituents, as well as respiration, increased continuously with time progressions during the incubation period. Sethoxydim did not affect either the uptake of any14C-precursor into or respiration of the root tip tissue. Although RNA and protein syntheses were not affected by the herbicide, DNA and cell wall syntheses were inhibited 120 min after treatment with sethoxydim. Incorporation of14C-acetic acid into lipid fraction was inhibited by sethoxydim in a time- and concentration-dependent fashion. This inhibition was observed at a shorter time after sethoxydim treatment than that of any other14C-precursor. The effect was not observed in the nonproliferative regions of corn roots, whereas cerulenin (a fatty acid synthase inhibitor) inhibited the incorporation of14C-acetic acid both in proliferative and nonproliferative regions. It is suggested that the inhibition of lipid synthesis by sethoxydim does not play a major role in the mode of action of this herbicide. The effects of sethoxydim, including those on lipid metabolism, are closely associated with proliferative conditions of susceptible graminaceous plants.

A biochemical study of BAS 517 using excised corn and soybean root systems

Weed Science ◽  
1999 ◽  
Vol 47 (1) ◽  
pp. 28-36
Author(s):  
Hwei-Yiing Li ◽  
Chester L. Foy
Keyword(s):  
Root System ◽  
Biochemical Study ◽  
Lipid Fraction ◽  
Root Systems ◽  
Water Soluble ◽  
Root Tips ◽  
Soybean Root ◽  
Corn Roots ◽  
Tracer Techniques ◽  
High Degree

The mode of action of BAS 517 in a susceptible plant species, corn, was investigated using an excised root system and14C-tracer techniques. The root system of a tolerant species, soybean, was used for comparison. When UL-14C- glucose was used as a precursor,14C incorporation into lipids was reduced in BAS 517-treated corn roots, although14C incorporation from UL-14C-glucose into lipids was relatively low. Inhibition of14C incorporation into water-soluble compounds was not definite because of a high degree of variability. Using14C-acetate as a precursor, 49, 43, and 34% of the recovered radioactivity was found in the lipid fractions of root tips treated with 0, 1.0, and 10 μM BAS 517, respectively. In nontreated soybean root tips, 47% of the recovered radioactivity was found in the lipid fraction compared to 49% in root tips treated with 10 μM BAS 517. Further analysis of lipids showed that BAS 517 inhibited the incorporation of14C from14C-acetate into phosphatidylethanolamine, a phospholipid, whereas the labeling of sterols in treated corn roots was not adversely affected. Acetyl CoA carboxylase extracted from root systems of corn and soybean showed different sensitivity to BAS 517, suggesting its role as the herbicide target site and as a basis for the selectivity.

Metolachlor and Alachlor Effects on Membrane Permeability and Lipid Synthesis

Weed Science ◽  
1982 ◽  
Vol 30 (4) ◽  
pp. 399-404 ◽  
Author(s):  
Jill M. Mellis ◽  
Parthan Pillai ◽  
Donald E. Davis ◽  
Bryan Truelove
Keyword(s):  
Zea Mays ◽  
Glycine Max ◽  
Choline Chloride ◽  
Lipid Synthesis ◽  
Significant Loss ◽  
Phospholipid Synthesis ◽  
Root Tips ◽  
Naphthalic Anhydride ◽  
Cotton Root ◽  
High Concentrations

Metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] at 1 × 10−5and 1 × 10−4M increased the leakage of previously absorbed,32P-labeled orthophosphate from the roots of onion (Allium cepaL.), a susceptible species, by 14 and 41 times the control values, respectively. A significant amount of32P leaked from the roots of the moderately susceptible species, cotton (Gossypium hirsutumL. ‘DPL 61′) and cucumber (Cucumis sativusL. ‘Ashley′), whereas no significant loss of32P occurred from two tolerant species, soybean [Glycine max(L.) Merr. ‘Bragg′] and corn (Zea maysL. ‘Pioneer 3369A′). At either 1 × 10−7or 1 × 10−6M, 1,8-naphthalic anhydride (NA) prevented32P leakage from onion roots in the presence of 1 × 10−5M metolachlor. High concentrations of NA [0.1% (w/v) suspensions], however, promoted32P leakage and did not protect onion roots from the leakage induced by high concentrations (1 × 10−4M) of metolachlor. Neither metolachlor nor alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], at 1 × 10−4M, inhibited the uptake of acetate-2-14C or malonic acid-2-14C into excised cotton root tips or the incorporation of the precursors into lipids. Similarly, neither herbicide inhibited phospholipid synthesis by cotton root tips. Incorporation of14C-choline chloride into phosphatidylcholine was not significantly inhibited by metolachlor.

Patterns of Incorporation of [3H]Galactose by Cells of Zea Mays Root Tips

1974 ◽  
Vol 14 (1) ◽  
pp. 11-27
Author(s):  
MARIANNE DAUWALDER ◽  
W. G. WHALEY
Keyword(s):  
Zea Mays ◽  
Golgi Apparatus ◽  
Sieve Tube ◽  
Cell Plate ◽  
Root Tip ◽  
Secretory Cells ◽  
Root Tips ◽  
Biochemical Activity ◽  
Apical Portion ◽  
Selective Pattern

[3H]galactose shows a selective pattern of uptake distribution in the apical portion of the root tip of Zea mays. In cells entering division it is incorporated into the Golgi apparatus within 10 min and is transferred from that organelle to the forming cell plate. The pattern of uptake suggests a specific biochemical activity on the part of the Golgi apparatus at the time of division so far as the incorporation of galactose is concerned. Apparently little galactose is converted to glucose in the most apical portion of the root. In normal secretory cells, the heaviest uptake is found in the sieve tube elements, epidermal cells and the outer cells of the root cap.

scholarly journals Polyprenyl phosphate sugars synthesized during slime-polysaccharide production by membranes of the root-cap cells of maize (Zea mays)

1979 ◽  
Vol 178 (3) ◽  
pp. 661-671 ◽  
Author(s):  
J R Green ◽  
D H Northcote
Keyword(s):  
Endoplasmic Reticulum ◽  
Zea Mays ◽  
Neutral Lipids ◽  
Root Tip ◽  
Synthetase Activity ◽  
Root Tips ◽  
Maize Roots ◽  
Glucose Derivatives

Two types of experiments were carried out; either maize roots were incubated in L-[1-3H]fucose or membranes were prepared from root tips and these were incubated with GDP-L-[U-14C]fucose or UDP-D-[U-4C]glucose. The radioactively labelled lipids that were synthesized in vivo and in vitro were extracted and separated into polar and neutral components. The polar lipids had the characteristics of polyprenyl phosphate and diphosphate fucose or glucose derivatives, and the neutral lipids of sterol glycosides (fucose or glucose). A partial separation of the glycolipid synthetase reactions was achieved. Membranes were fractionated into material that sedimented at 20,000g and 100,000g. Most of the polar glycolipid synthetase activity (for the incorporation of both fucose and glucose) was located in the 100,000 g pellet, and this activity was probably located in the endoplasmic reticulum. The neutral lipid, which contained fucose, was synthesized mainly by membranes of the 20,000g pellet, and the activity was probably associated with the dictyosomes, whereas the neutral glucolipids were synthesized by all the membrane fractions. It is suggested that the polar (polyprenyl) lipids labelled with fucose could act as possible intermediates during the synthesis of the glycoproteins and slime in the root tip.

CHROMOSOME ABERRATIONS PRODUCED BY 5-BROMODEOXYURIDINE WITH CONCURRENT EXPOSURE TO LONG WAVELENGTH UV IN ZEA MAYS ROOT TIP CELLS

1977 ◽  
Vol 19 (3) ◽  
pp. 447-459 ◽  
Author(s):  
R. S. Verma ◽  
J. E. Cummins ◽  
D. B. Walden
Keyword(s):  
Zea Mays ◽  
Chromosome Aberrations ◽  
Cesium Chloride ◽  
Root Tip ◽  
Chromosome Damage ◽  
Root Tips ◽  
Long Wavelength ◽  
Small Pool ◽  
Tip Cells ◽  
Root Tip Cells

The influence of bromodeoxyuridine (BrUrdR) on the pattern and level of chromosome damage in Zea mays L. root tip cells is described. In some experiments long wavelength ultraviolet light was employed to convert the bromodeoxyuridine in DNA to its photoproduct. BrUrdR treatment produced a marked decrease in the mitotic index and a high proportion of the mitotic cells bore chromosome damage. Following a BrUrdR treatment of 5 h the proportion of damaged cells increased from 20% to 60% during the 20 h following treatment; then the proportion decreased sharply to less than 20%. Root tips treated as above followed by an exposure to long wavelength ultraviolet radiation (UV) had a proportion of damaged cells (80% at 20 h) only slightly greater than those not exposed to UV up to 20 h after treatment. Unlike the unirradiated BrUrdR substituted root tips, the proportion of damaged cells remained high 25 h after treatment. Furthermore, the spectrum of chromosome aberrations differed between irradiated and unirradiated BrUrdR substituted cells. Root tips exposed to long wavelength UV alone showed some damage that was limited to a stage in the cell cycle of irradiated root tips. Analysis of the BrUrdR treated corn DNA by cesium chloride density centrifugation showed that BrUrdR substitution for thymidine in DNA was extensive. Further experiments demonstrated that a large BrUrdR pool was not carried into the rounds of replication following BrUrdR removal from the medium. Nevertheless a small pool of halogenated pyrimidine was observable after BrUrdR removal from the medium.

scholarly journals Protocorm-like Bodies Initiation from Root Tips of Cyrtopodium paranaense (Orchidaceae)

HortScience ◽  
2010 ◽  
Vol 45 (9) ◽  
pp. 1365-1368 ◽  
Author(s):  
Wei-Ling Guo ◽  
Yao-Chien Alex Chang ◽  
Chien-Yuan Kao
Keyword(s):  
Acetic Acid ◽  
Seed Germination ◽  
Synergistic Effect ◽  
Early Stage ◽  
Root Apex ◽  
Root Tip ◽  
Ms Medium ◽  
Root Tips ◽  
Terrestrial Orchid ◽  
Indole 3 Acetic Acid

Cyrtopodium paranaense is a tropical terrestrial orchid, which propagates mainly through sexual seed germination. In this study, we document the asexual morphogenesis of the root tip to protocorm-like body (PLB) conversion in Cyrtopodium paranaense. Protocorm-like bodies sporadically developed from root tips of flask-grown seedlings in the absence of any exogenous plant growth regulators (PGRs). The compact PLBs ultimately gave rise to normal plantlets. Histological observations revealed that the root cap became dissociated from the root apex at an early stage followed by dispersed extension of root vascular strands into nascent PLBs. Protocorm-like bodies also developed from the root central stele tissue. In root tip segment cultures, PLBs were not formed without providing PGRs but were efficiently formed from root tips in Murashige and Skoog (MS) medium supplemented with 10.2 μM indole-3-acetic acid (IAA) and 9.0 μM thidiazuron (TDZ). Both IAA and TDZ promoted the formation of PLBs; however, TDZ did not induce PLB formation in the absence of IAA, indicating a synergistic effect of the two PGRs. Protocorm-like bodies were proliferated and subsequently plants regenerated in PGR-free MS medium. Root tip culture may be used as an alternative method for the propagation of Cyrtopodium paranaense.

Gross Morphological and Cytological Effects of Nitralin on Corn Roots

Weed Science ◽  
1968 ◽  
Vol 16 (2) ◽  
pp. 259-260 ◽  
Author(s):  
W. A. Gentner ◽  
L. G. Burk
Keyword(s):  
Cell Wall ◽  
Zea Mays ◽  
Cell Division ◽  
Root Tip ◽  
Cell Wall Formation ◽  
Cytological Examination ◽  
Affected Area ◽  
Primary Mechanism ◽  
Corn Roots ◽  
Corn Plants

The gross morphological effects of the herbicide 4-methyl-sulphonyl-2,6-dinitro-N,N-dipropylaniline [nitralin] on roots of corn (Zea mays L., var. U. S. 13) suggested abnormal cytological behavior. Roots of corn plants treated preemergence with nitralin developed digitate to globose swelling in the region of active cell division of the root tip. Cytological examination of the affected area showed that the effects of the herbicide were prevention of cell wall formation, enlargement of cells, and extensive replication of nuclei, and suggests that a primary effect of nitralin is on cell division and that this may be a primary mechanism of action as a herbicide.

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.

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