The regulation of proline biosynthesis in maize roots

1970 ◽  
Vol 48 (12) ◽  
pp. 2249-2258 ◽  
Author(s):  
Ann Oaks ◽  
D. J. Mitchell ◽  
R. A. Barnard ◽  
F. J. Johnson
Keyword(s):  
Product Inhibition ◽  
Maize Root ◽  
Root Tip ◽  
Proline Biosynthesis ◽  
Maize Roots

Proline or the proline analogues hydroxy-L-proline and azetidine-2-COOH inhibit the formation of proline from acetate-2-14C or glutamate-UL-14C in the 5-mm maize root tip. The inhibition of the incorporation of acetate-derived proline into protein is more severe than the inhibition of the total biosynthesis (soluble plus insoluble proline-14C). The results suggest that a portion of the proline biosynthesis, which becomes more prominent as the cells mature, is refractory to end product inhibition. The results also show that simultaneous additions of glucose promote the incorporation of proline-UL-14C into protein, exaggerate its accumulation as soluble proline, and reduce its oxidation.

scholarly journals The relationship of root-cap slimes to proteins

1974 ◽  
Vol 139 (3) ◽  
pp. 525-534 ◽  
Author(s):  
Kenneth Wright ◽  
D. H. Northcote
Keyword(s):  
Chemical Characteristic ◽  
Wheat Root ◽  
Root Cap ◽  
Water Soluble ◽  
Maize Root ◽  
Root Tip ◽  
Root Tips ◽  
Maize Roots ◽  
Neutral Sugars ◽  
Relationship Of

1. The patterns of incorporation of radioactivity from d-[U-14C]glucose into the pectic components of sections of sycamore roots changed so that sections nearer the tip incorporated relatively more label into arabinose and galactose compared with uronic acid. 2. Radioactive maize root-cap slime was prepared and found to contain three water-soluble component polymers which were electrophoretically (i) neutral, (ii) weakly acidic and (iii) strongly acidic at pH6.5. The neutral component was a glucan. The other components, which could be degraded by trans-elimination, consisted of an acidic backbone chain composed of galacturonic acid and glucose, attached to which were different proportions of neutral sugars. Arabinose, galactose and fucose, the main neutral sugars of the weakly and strongly acidic materials, were absent from the neutral fraction. 3. Fucose was a major sugar in maize-root slime and in a slime of similar composition synthesized by a maize callus of shoot origin. Only trace amounts were found in sycamore, pea and wheat root tips, and in pectin prepared from maize roots and coleoptiles. A high proportion of fucose is therefore a chemical characteristic of maize slime, and slime synthesis indicated a state of differentiation of the tissue. 4. The similarity between the slime and pectin is discussed; slime is a form of pectin modified in such a way as to provide a hydrated protective coating around the root tip.

Growth of the maize root tip

1950 ◽  
Author(s):  
Gabriel Baldovinos de la Pena
Keyword(s):  
Maize Root ◽  
Root Tip

scholarly journals Biological nitrification inhibition in maize—isolation and identification of hydrophobic inhibitors from root exudates

2021 ◽  
Author(s):  
Junnosuke Otaka ◽  
Guntur Venkata Subbarao ◽  
Hiroshi Ono ◽  
Tadashi Yoshihashi
Keyword(s):  
Root Exudation ◽  
Root Systems ◽  
Root Surface ◽  
Maize Root ◽  
Nitrification Inhibition ◽  
Isolation And Identification ◽  
N Losses ◽  
Chemical Structures ◽  
Maize Roots ◽  
Biological Nitrification

AbstractTo control agronomic N losses and reduce environmental pollution, biological nitrification inhibition (BNI) is a promising strategy. BNI is an ecological phenomenon by which certain plants release bioactive compounds that can suppress nitrifying soil microbes. Herein, we report on two hydrophobic BNI compounds released from maize root exudation (1 and 2), together with two BNI compounds inside maize roots (3 and 4). On the basis of a bioassay-guided fractionation method using a recombinant nitrifying bacterium Nitrosomonas europaea, 2,7-dimethoxy-1,4-naphthoquinone (1, ED50 = 2 μM) was identified for the first time from dichloromethane (DCM) wash concentrate of maize root surface and named “zeanone.” The benzoxazinoid 2-hydroxy-4,7-dimethoxy-2H-1,4-benzoxazin-3(4H)-one (HDMBOA, 2, ED50 = 13 μM) was isolated from DCM extract of maize roots, and two analogs of compound 2, 2-hydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (HMBOA, 3, ED50 = 91 μM) and HDMBOA-β-glucoside (4, ED50 = 94 μM), were isolated from methanol extract of maize roots. Their chemical structures (1–4) were determined by extensive spectroscopic methods. The contributions of these four isolated BNI compounds (1–4) to the hydrophobic BNI activity in maize roots were 19%, 20%, 2%, and 4%, respectively. A possible biosynthetic pathway for zeanone (1) is proposed. These results provide insights into the strength of hydrophobic BNI activity released from maize root systems, the chemical identities of the isolated BNIs, and their relative contribution to the BNI activity from maize root systems.

scholarly journals The epidermal surface of the maize root tip. I. Development in normal roots

1993 ◽  
Vol 125 (2) ◽  
pp. 413-429 ◽  
Author(s):  
R. M. ABEYSEKERA ◽  
M. E. McCULLY
Keyword(s):  
Maize Root ◽  
Root Tip ◽  
Epidermal Surface

The influence of nitrate on the induction of nitrate reductase in maize roots

1973 ◽  
Vol 51 (6) ◽  
pp. 1255-1258 ◽  
Author(s):  
D. L. Stevens ◽  
Ann Oaks
Keyword(s):  
Nitrate Reductase ◽  
Maize Root ◽  
Lag Phase ◽  
Root Tips ◽  
Final Level ◽  
Maize Roots ◽  
Mature Root

A concentration of 10 mM NO3 saturates the induction of nitrate reductase in maize root tips whereas concentrations up to 100 mM do not saturate the induction in mature root sections. Increasing concentrations of nitrate from 1 to 25 mM have no effect on either the lag phase, or the phase of rapid increase of the enzyme. They do influence the final level of enzyme obtained at 8 h.

The effect of cycloheximide on amide formation in maize roots

1973 ◽  
Vol 51 (1) ◽  
pp. 91-95 ◽  
Author(s):  
Ann Oaks ◽  
F. J. Johnson
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Root Tip ◽  
Minor Effect ◽  
Root Tips ◽  
Corn Root ◽  
Basic Amino Acids ◽  
Maize Roots ◽  
A Minor ◽  
Mature Root

Cycloheximide inhibits the incorporation of acetate-2-14C into protein and into asparagine in corn root tips. It also causes an accumulation of glutamine and, over a concentration range of 0.4 to 5.0 μg/ml, a transient accumulation of the neutral and basic amino acids. In mature sections, cycloheximide inhibits protein synthesis but causes an increase in the incorporation of radioactivity into both glutamine and asparagine. Azaserine, a glutamine analogue, also inhibits the formation of asparagine in root-tip sections but has only a minor effect on protein synthesis. In mature root sections, there is an accumulation of glutamine but no effect on asparagine formation when azaserine is used. Glutamine additions to root tips or mature root sections affect neither asparagine formation nor protein synthesis. We conclude that cycloheximide is behaving as a glutamine analogue in its effect on asparagine biosynthesis, and that its effect as a glutamine analogue is lost as cells mature.

Cell synchronization and isolation of metaphase chromosomes from maize (Zea mays L.) root tips for flow cytometric analysis and sorting

Genome ◽  
1996 ◽  
Vol 39 (4) ◽  
pp. 697-703 ◽  
Author(s):  
Jai-Heon Lee ◽  
K. Arumuganathan ◽  
S. M. Kaeppler ◽  
C. M. Papa ◽  
H. F. Kaeppler
Keyword(s):  
Cell Cycle ◽  
Flow Cytometric Analysis ◽  
Maize Root ◽  
Root Tip ◽  
Root Tips ◽  
Chromosome Sorting ◽  
Synthesis Inhibitor ◽  
Metaphase Chromosomes ◽  
Flow Karyotype ◽  
Flow Cytometric

Accumulation of cells containing metaphase chromosomes is an important step in cytological analyses and chromosome sorting procedures. The goal of this research was to optimize treatment parameters to synchronize the cell cycle of maize root tip meristem cells. Levels of hydroxyurea, a DNA synthesis inhibitor, were assessed for their utility in accumulating cells at the G1 phase of the cell cycle. Trifluralin, amiprophos-methyl, and colchicine were used to accumulate cells containing metaphase chromosomes upon release from hydroxyurea inhibition. Optimal mitotic indices were achieved by treating seedlings with 5 mM hydroxyurea for 18 h, incubating for 1 h without chemical treatment to release the hydroxyurea block, and then treating emerging roots with 1 μM trifluralin for 4 h. The mitotic index of synchronized maize root tips was over 70%. Uniformity of synchronization depended upon selection of seeds with emerging radicles that were similar in length at the time of treatment. Suspensions of intact chromosomes were prepared by a simple slicing procedure. The chromosome preparations were found to be suitable for flow cytometric characterization and sorting. Chromosome peaks of the observed flow karyotype resembled the predicted flow karyotype calculated on the basis of maize chromosome size. Key words : flow karyotype, hydroxyurea, plant chromosome sorting, trifluralin.

scholarly journals AFFINITY DISTANCE VALUES AMONG SOMATIC METAPHASE CHROMOSOMES IN MAIZE

Genetics ◽  
1978 ◽  
Vol 88 (1) ◽  
pp. 181-199
Author(s):  
J D Horn ◽  
D B Walden
Keyword(s):  
Random Distribution ◽  
Maize Root ◽  
Root Tip ◽  
Metaphase Arrest ◽  
Metaphase Chromosomes ◽  
Somatic Metaphase ◽  
Chemical Agents ◽  
Differential Responses

ABSTRACT In maize root-tip metaphase preparations, all distances between two chromosomes were measured in 50 cells from each of seven stocks and in 30 from one stock; four were arrested with cold, two with 8-hydroxyquinoline, one with colchicine and one with monobromonaphthalene Standardized, affinity-distance values were calculated for all pairs of homologues and pairs of nonhomologues from each preparation. The homologues of pair X were the least separated, those of pair I the most separated in the cold-arrested stocks. All but pairs I and VIII were shown to be significantly different from the observed mean. The observed mean was less than but not significantly different from the theoretical value for a random distribution. The use of chemical agents for metaphase arrest increased the separation of homologues, except for pair I.—Eleven percent of the comparisons of nonhomologues from cold-arrested, as contrasted to none of the comparisons from the c-metaphase treatments, were significantly different from the theoretical talue for a random distribution. This was considered evidence for limited primary nonhomologue association in maize. Although there were specific, differential responses to the two arrest agents, the population of homologous pairs approached a random distribution only in chemically arrested stocks.—Primary homologue association was considered to be maintained by two mechanisms. the more common involving the micro-tubules and the second involving the nucleolus.—Interpretations are offered regarding the claims of somatic association in other species, especially man. The opportunity in maize for experimentally modifying distance values by cytogenetic techniques is discussed.

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