Growth of the maize root tip

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.

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The Enzymatic Oxidation of Reduced Diphosphopyridine Nucleotide in the Maize Root Tip by an Oxidation Product of Ascorbic Acid

Physiologia Plantarum ◽

10.1111/j.1399-3054.1961.tb07862.x ◽

1961 ◽

Vol 14 (2) ◽

pp. 266-274 ◽

Cited By ~ 2

Author(s):

Dan Mertz

Keyword(s):

Ascorbic Acid ◽

Oxidation Product ◽

Maize Root ◽

Enzymatic Oxidation ◽

Root Tip

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The epidermal surface of the maize root tip. III. Isolation of the surface and characterization of some of its structural and mechanical properties

New Phytologist ◽

10.1111/j.1469-8137.1994.tb04283.x ◽

1994 ◽

Vol 127 (2) ◽

pp. 321-333 ◽

Cited By ~ 8

Author(s):

R. M. ABEYSEKERA ◽

M.E. MCCULLY

Keyword(s):

Mechanical Properties ◽

Maize Root ◽

Root Tip ◽

Epidermal Surface

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AFFINITY DISTANCE VALUES AMONG SOMATIC METAPHASE CHROMOSOMES IN MAIZE

Genetics ◽

10.1093/genetics/88.1.181 ◽

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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Cytological and Molecular Characterization of Quantitative Trait Locus qRfg1, Which Confers Resistance to Gibberella Stalk Rot in Maize

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-06-13-0161-r ◽

2013 ◽

Vol 26 (12) ◽

pp. 1417-1428 ◽

Cited By ~ 19

Author(s):

Jianrong Ye ◽

Yanling Guo ◽

Dongfeng Zhang ◽

Nan Zhang ◽

Chao Wang ◽

...

Keyword(s):

Molecular Mechanisms ◽

Microscopic Analysis ◽

Hyphal Growth ◽

Maize Root ◽

Root Tip ◽

Basal Resistance ◽

Stalk Rot ◽

Primary Roots ◽

Tremendous Progress ◽

Trait Locus

Tremendous progress has been made recently in understanding plant response to Fusarium graminearum infection. Here, the cytological aspect and molecular mechanism of maize defense to F. graminearum infection were characterized using a pair of near-isogenic lines (NIL), the resistant and the susceptible NIL. F. graminearum primarily penetrated the maize root tip and no penetration structure was found. The fungal biomass within the root correlated well with root-disease severity. Following inoculation, R-NIL and S-NIL plants significantly differed in percentage of diseased primary roots. In R-NIL roots, a fraction of exodermal cells collapsed to form cavities, and hyphae were confined to the outer exodermal cells. However, most exodermal cells shrank and turned brown, and fungi colonized the entire S-NIL root. In the R-NIL roots, the exodermal cells exhibited plasmolysis and atropous hyphal growth whereas, in the exodermal cells of the S-NIL roots, severe cellular degradation and membrane-coated, lushly grown hyphae were found. Transcriptome sequencing revealed comprehensive transcription reprogramming, reinforcement of a complex defense network, to enhance the systemic and basal resistance. This study reports a detailed microscopic analysis of F. graminearum infection on maize root, and provides insights into the molecular mechanisms underlying maize resistance to the pathogen.

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