NULLISOMIC ANALYSIS OF NUCLEOLAR FORMATION IN ZEA MAYS

1978 ◽  
Vol 20 (1) ◽  
pp. 97-100 ◽  
Author(s):  
David F. Weber
Keyword(s):  
Zea Mays ◽  
Chromosome Number ◽  
Zea Mays L ◽  
Diploid Species ◽  
5S Rrna ◽  
Chromosome 6 ◽  
Chromosome 2 ◽  
Nucleolar Organizing Region

When a monosomic plant of a diploid species undergoes meiosis, two haploid and two nullisomic cells are produced. Zea mays L. microspore quartet cells nullisomic for chromosome number 1, 2, 4, 6, 7, 8, 9, or 10 produced by monosomics were analyzed. Cells nullisomic for chromosome 6, as expected, do not contain a nucleolus because chromosome 6 bears the nucleolar organizing region. Cells nullisomic for chromosome 2 contain nucleoli; therefore, the 5S rRNA template on chromosome 2 is not necessary for nucleolar formation. Cells nullisomic for chromosomes 1, 4, 7, 8, 9, or 10 also contain nucleoli; thus, no factors located on these chromosomes are necessary for nulceolar formation at the quartet stage.

Genetic and physical fine mapping of the novel brown midrib gene bm6 in maize (Zea mays L.) to a 180 kb region on chromosome 2

2012 ◽  
Vol 125 (6) ◽  
pp. 1223-1235 ◽  
Author(s):  
Yongsheng Chen ◽  
Hongjun Liu ◽  
Farhad Ali ◽  
M. Paul Scott ◽  
Qing Ji ◽  
...  
Keyword(s):  
Zea Mays ◽  
Fine Mapping ◽  
Zea Mays L ◽  
Brown Midrib ◽  
Chromosome 2 ◽  
The Novel

Analysis of Nondisjunction Induced by the R-X1 Deficiency during Microsporogenesis in Zea Mays L.

Genetics ◽  
1988 ◽  
Vol 119 (4) ◽  
pp. 975-980
Author(s):  
Z Y Zhao ◽  
D F Weber
Keyword(s):  
Zea Mays L ◽  
Embryo Sac ◽  
Mitotic Division ◽  
The Other ◽  
Chromosome 6 ◽  
Nucleolar Organizing Region ◽  
Sperm Nuclei ◽  
Embryo Sac Formation ◽  
And Control ◽  
Generative Nuclei

Abstract The r-X1 deficiency in maize induces nondisjunction at the second mitotic division during embryo sac formation. However, it was not known if this deficiency also induces nondisjunction during the microspore divisions. Microsporogenesis in plants lacking or containing this deficiency was compared using two approaches. First, chromosome numbers were determined in generative nuclei. Many (8.3%) of the generative nuclei in r-X1-containing plants were aneuploid; however, those from control plants were all haploid. Thus, this deficiency induces nondisjunction during the first microspore division. Second, nucleoli were analyzed in microspores. The only nucleolar organizing region in maize is on chromosome 6. If chromosome 6 underwent nondisjunction during the first microspore division, one nucleus in binucleate microspores would contain no nucleolus and the other would contain two nucleoli (or one nucleolus if the nucleoli fused). Only one (0.03%) microspore of this type was observed in control plants while 1.12% were found in r-X1-containing plants. Thus, the r-X1 deficiency induces nondisjunction of chromosome 6 during the first microspore division. However, both of the sperm nuclei in trinucleate microspores contained one nucleolus in r-X1-containing and control plants; thus, this deficiency does not induce nondisjunction of chromosome 6 (and presumably other chromosomes) during the second microspore division.

Detection of the time of occurrence of nondisjunction induced by the r-X1 deficiency in Zea mays L.

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 782-785 ◽  
Author(s):  
Kevin D. Simcox ◽  
Jeffery D. Shadley ◽  
David F. Weber
Keyword(s):  
Zea Mays ◽  
Key Words ◽  
Zea Mays L ◽  
Embryo Sac ◽  
Mitotic Division ◽  
Polar Nucleus ◽  
Chromosome 6 ◽  
High Frequencies ◽  
The Third ◽  
Β Carotene

The r-X1 deficiency in maize produces high frequencies of aneuploid progeny by inducing nondisjunction during embryo sac development. The purpose of this investigation was to determine the embryo sac division at which the nondisjunctive event takes place. Monosomic-6 individuals were generated by crossing r-X1 containing plants by those carrying the y-pastel-8549 allele of the Y locus on chromosome 6. A strict dosage relationship exists between the number of dominant alleles of the Y locus and the level of β-carotene in the endosperm. We found that the level of β-carotene in the endosperm of kernels containing monosomic-6 embryos was comparable with that found in endosperms with one Y allele. This indicated that they contained only one maternally contributed chromosome 6. Only nondisjunction at the second postmeiotic division could have produced such an endosperm; thus, the nondisjunctive event occurs at this division. Another endosperm type expected from nondisjunction at this same division, with three dominant Y alleles, was not found. The absence of this endosperm type suggests that the egg nucleus and the polar nucleus originating at the micropylar pole are sister nuclei that arose from the same cell at the third embryo sac mitotic division. Key words: aneuploidy, embryo sac, nondisjunction, r-X1 deficiency, Zea.

scholarly journals Mapping of a novel viviparous unstable mutant of maize (vp 12)

1997 ◽  
Vol 20 (1) ◽  
pp. 71-74 ◽  
Author(s):  
Paula G. Araujo ◽  
William J. da Silva ◽  
Mirian P. Maluf ◽  
Laudenir M. Prioli
Keyword(s):  
Zea Mays ◽  
Linkage Group ◽  
Inbred Line ◽  
Reciprocal Translocation ◽  
Genetic Instability ◽  
Zea Mays L ◽  
Chromosome 6 ◽  
Tropical Regions

A new viviparous mutant of maize (Zea mays L.), associated with genetic instability and designated viviparous-12 (vp12), was identified in a synthetic Tuxpeño adapted to tropical regions. In the present work, the linkage group of this new locus was determined. Progenies of inbred line L477 segregating for the vp12 mutant were crossed with waxy-marked reciprocal translocation stocks. The phenotypic frequencies of the wx and vp12 mutants were analyzed in F2 progenies. The results demonstrated that the Viviparous-12 locus of maize is located on the long arm of chromosome 6.

A CYTOLOGICAL SURVEY OF ZEA-TRIPSACUM HYBRIDS

1973 ◽  
Vol 15 (4) ◽  
pp. 763-778 ◽  
Author(s):  
C. A. Newell ◽  
J. M. J. de Wet
Keyword(s):  
Zea Mays ◽  
Chromosome Number ◽  
Zea Mays L ◽  
Homologous Pairing ◽  
Tripsacum Dactyloides ◽  
Chromosome Behavior ◽  
Chromosomal Homology ◽  
Cytological Data ◽  
Chromosomal Association ◽  
Bivalent Formation

Reciprocal crosses involving various combinations of diploid (2n = 20) and tetraploid (2n = 40) Zea mays L. (maize), diploid (2n = 20) Zea mexicana (Schrad.) Kuntze (annual teosinte), and tetraploid (2n = 40) Zea perennis (Hitchc.) Reeves and Mangelsdorf (perennial teosinte) were studied cytologically. Observations of chromosome behavior during meiosis indicated that chromosomes of Z. perennis were more compatible with those of Zea mays than with those of Z. mexicana. Hybrids between Z. mays and diploid (2n = 36) or tetraploid (2n = 72) Tripsacum dactyloides (L.) L, incorporating different numbers of genomes from each parent and ranging in chromosome number from 2n = 28 28 to 2n = 82, were also examined at meiosis. Allodiploids (2n = 28) combining one Zea genome with one Tripsacum genome showed a low level of synaptic bivalent formation, indicating limited chromosomal homology between the two genera. Almost without exception, maize-Tripsacum hybrids exhibited more chromosomal association than expected on the basis of strictly homologous pairing; however, only a few plants possessed configurations stable enough to be taken as evidence of possible intergeneric segmental exchange. Triple hybrids involving maize, teosinte, and Tripsacum were produced in several combinations by pollinating maize-Tripsacum hybrids with annual or perennial teosinte. These showed chromosomal associations in accordance with the expected, on the basis of cytological data from maize-Tripsacum and maize-teosinte hybrids. These cytological observations suggest that teosinte and maize are conspecific, and that teosinte could not have originated as a by-product of Zea-Tripsacum introgression.

scholarly journals Karyotypic diversity among eight Zea mays L. varieties

2020 ◽  
Vol 49 (4) ◽  
pp. 1157-1161
Author(s):  
Chandan Kumar Dash ◽  
Kazi Nahida Begum ◽  
Syeda Sharmeen Sultana
Keyword(s):  
Zea Mays ◽  
Chromosome Number ◽  
Significant Variation ◽  
Zea Mays L ◽  
Chromosome Length ◽  
Diploid Chromosome Number ◽  
Genetic Identification ◽  
Interphase Nuclei ◽  
Maize Varieties ◽  
Karyotypic Diversity

Staining property of interphase nuclei and prophase chromosomes, diploid chromosome number, total chromosome length (TCL), symmetric and asymmetric indices of karyotype were studied in eight maize varieties released by BARI. 2n = 20 chromosomes were found in Barnali, Mohor, Khoi Vhutta, BS-1, B-5 and BM-7 whereas 2n = 22 chromosomes in China and 2n = 24 chromosomes in B-73 were observed. TCL was highest in Mohor (190.49 ± 5.61 μm) and lowest in B-73 (69.30 ± 2.51 μm). These varieties showed significant variation in cytogenetical parameters. Results obtained are expected to supplement genetic identification of maize varieties in variety conservation efforts.

Influence de l'âge sur les caractéristiques photosynthétiques de la feuille de maïs, Zea mays L

Agronomie ◽  
1982 ◽  
Vol 2 (2) ◽  
pp. 159-166 ◽  
Author(s):  
Olivier BETHENOD ◽  
Christine JACOB ◽  
Jean-Claude RODE ◽  
Jean-François MOROT-GAUDRY
Keyword(s):  
Zea Mays ◽  
Zea Mays L

PRODUKTIVITAS PUPUK ORGANIK TERHADAP HASIL TANAMAN JAGUNG (Zea mays L) DI TANAH MINERAL

1970 ◽  
Vol 3 (2) ◽  
pp. 318-326
Author(s):  
Yoyon Riono.
Keyword(s):  
Zea Mays ◽  
Zea Mays L

Penelitian tentang pengaruh pemberian produktivitas pupuk organik terhadap hasil Tanaman Jagung (Zea mays L) di tanah mineral penelitian ini di laksanakan pada bulan Februari sampai Mei, yang bertempat di Sungai Salak Kecsmstsn Tempuling Kabupaten Indragiri Hilir Provinsi Riau. Penelitian ini menggunakan Rancangan Acak Kelompok (RAK) yang disusun secara faktorial yang terdiri dari 2 faktor dan 3 ulangan. Faktor B adalah bokashi pupuk kandang yang terdiri dari 4 taraf yaitu B0 (tanpa pemberianpupuk kandang), B1 (5 ton/ha) dan B2 (10 tom/ ha), serta B3 (15 ton/ha) Parameter yang di amati adalah tinggi tanaman, panjang daun ke tujuh, berat brangkasan basah, berat berangkasan kering, berat tongkol pertanaman sampel, diameter tongkol , produksi per plot, dan berat 100 biji. Selanjutnya data yang di peroleh di olah secara statistik, apabila F hitung lebih besar dari F tabel di lanjutkan dengan uji lanjut Tukey HSD pada taraf 5%. Hasil penelitian menunjukan bahwa interaksi bokashi pupuk kandang dan varietas berpengaruh nyata terhadap berat tongkol dan produksi dan produksi per plot, akan tetapi tidak berpengaruh nyata terhadap tinggi tanaman, panjang daun ke tujuh, berat brangkasan basah, berat brangkasan kering , diameter tongkol dan berat 1000 biji. Untuk perlakuan bokashi pupuk kandang secara tunggal berpengaruh nyata terhadap terhadap diameter tongkol , akan tetapi tidak berpengaruh nyata terhadap tinggi tanaman, panjang daun ke tujuh, berat brangkasan basah, berat brangkasan kering, berat tongkol, produksi per plot, dan berat 1000 biji, perlakuan bokashi terbaik terdapat pada pemberian 15 ton/ha. Sedangkan perlakuan varietas secara tunggal berpengaruh nyata terhadap berat brangkasan basah, berat tongkol, dan produksi per plot seta berat 1000 biji, akan tetapi tidak berbeda nyata dengan tinggi tanaman, panjang daun ke tujuh, berat brangkasan kering, dan diameter tongkol. Varietass terbaik adalah NT 10

Relaciones genéticas en muestras de razas mexicanas de maíz (Zea mays L.)

2020 ◽  
Vol 13 (3) ◽  
Author(s):  
Luis Angel Barrera Guzman ◽  
Juan Porfirio Legaria Solano
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
Palabras Clave

Objetivo: Caracterizar muestras representativas de razas mexicanas de maíz con marcadores moleculares ISSR, que ayuden a inferir relaciones genéticas vinculadas a su origen, morfología, aspectos ecogeográficos, distribución y usos. Diseño/metodología/aproximación: Se emplearon 54 muestras representativas de razas mexicanas de maíz caracterizadas con diez marcadores moleculares ISSR. Las distancias genéticas se calcularon con el coeficiente Dice y se generó un dendrograma con el método de agrupamiento jerárquico de varianza mínima de Ward. Para visualizar las muestras en dos dimensiones se efectúo un Análisis de Coordenadas Principales con el método de varianza mínima estandarizada. Resultados: En 76 loci detectados, el análisis de agrupamiento con una R2 semiparcial de 0.04 formó cinco grupos que compartieron características filogenéticas, ecogeográficas, morfoagronómicas, de distribución y usos especiales. El análisis de coordenadas principales mostró 21.2 % de la variación total para las dos primeras coordenadas. La primera coordenada principal explicó el 12.43 % de la variación total y separó las muestras por ubicación geográfica y usos especiales; la segunda coordenada principal explicó el 8.77 % de la variación total y separó las muestras por rangos altitudinales y ciclo biológico. Limitaciones del estudio/implicaciones: Se empleó únicamente una muestra representativa por cada raza de maíz, considerando la variabilidad genética de este cultivo se deben incluir más muestras de la misma raza. Hallazgos/conclusiones: Las relaciones genéticas entre las muestras de razas de maíz obedecen a patrones altitudinales y geográficos; aunque algunos agrupamientos compartieron aspectos filogenéticos, morfoagronómicos, de distribución y usos. Palabras clave: Variabilidad genética, recursos fitogenéticos, caracterización molecular, clasificación integral.

Sustentabilidad económica del cultivo de maíz (Zea mays L.) en Acambay, México

2019 ◽  
Vol 12 (11) ◽  
Author(s):  
Liliana Urbano-Castillo ◽  
Noe Flores-Hernández ◽  
Augusto Montiel-Castro ◽  
Rosy G. Cruz-Monterrosa ◽  
Mayra Díaz-Ramírez ◽  
...  
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
San Pedro

Objetivo: evaluar la sustentabilidad económica del cultivo de maíz criollo (Zea mays L.) en Acambay, Estado de México. Diseño/metodología/aproximación: El área de estudio fue el municipio de Acambay, del estado de México. Se aplicó un cuestionario a 50 productores de maíz de los ejidos y comunidades agrarias de la Soledad, Pueblo Nuevo, Loma Linda, Dateje, San Pedro de los Metales, Dongú y Tixmadeje. El cuestionario se basó en el método de Indicadores de Sustentabilidad de Explotaciones Agropecuarias (IDEA). La selección de cada productor encuestado se realizó mediante el muestreo tipo bola de nieve, escogiendo el primer encuestado al azar. Resultados: El valor obtenido para el indicador “viabilidad económica” (C1) fue 1 de 20 puntos, indicando que la ganancia derivada del cultivo de maíz representa un salario mínimo. El indicador “tasa de especialización económica” (C2) obtuvo 0 puntos ya que solo se cultiva maíz, por lo tanto, representa una fuente de ingreso para los productores. En el indicador “autonomía financiera” (C3) el valor promedio obtenido fue 12 explicando que no existe una dependencia marcada en la compra de insumos externos para cultivar maíz. El indicador “sensibilidad a las ayudas del primer pilar de la política agrícola común” (C4) obtuvo 0 en promedio ya que la mayoría de los productores no reciben apoyos gubernamentales para cultivar maíz.  Limitaciones del estudio/implicaciones: los resultados presentados son avances de un análisis con más encuestados, por lo tanto, se sugiere tomar con cautela los resultados. Los indicadores “transmisión del capital” (C5) y “eficiencia de los procesos productivos” (C6) no se evaluaron adecuadamente ya que durante la aplicación de las encuestas los productores se negaron a proporcionar información detallada para evaluar estos indicadores. Hallazgos/conclusiones: la sustentabilidad económica calculada para los productores encuestados fue de 13% lo cual es muy baja, esto se debe principalmente a que éstos no siempre cuentan con el acceso a apoyos aplicables a la producción de maíz, otro factor que contribuye a la baja sustentabilidad es que el grano de maíz y los subproductos no se venden debido a bajos precios del mercado, por lo tanto, prefieren sembrar para autoconsumo, o para que los terrenos de cultivo heredados no estén ociosos.

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