Variability in Length and Arm Ratio of the Pachytene Chromosomes of Corn

Maguire, Marjorie P.

doi:10.1508/cytologia.27.248

Cited by 14 publications

(4 citation statements)

References 22 publications

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“…In pachytene cells only a few chromosomes can usually be traced completely. Maguire (1962) needed 89 anthers to find 27 1 microsporocytes at pachytene in which lengths of all chromosomes could be measured. In even fewer cells the centromere position could be distinguished.…”

Section: Discussionmentioning

confidence: 99%

Chromosome C-banding of Zea mays and its closest relatives

Mastenbroek¹,

Wet²

1983

Can. J. Genet. Cytol.

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MASTENBROEK, I., and J . M. J . DE WET. 1983. Chromosome C-banding of Zecl mays and its closest relatives. Can. J . . An established C-banding technique was modified to consistently yield complete sets of distinct, sharply banded chromosomes in Zea. It was used to demonstrate similarities and differences among heterochromatin patterns of different Zea taxa. The C-banding patterns showed a general agreement with heterochromatic knob positions known from pachytene studies. Two groups of banding patterns could be distinguished. Those taxa with bands that were almost exclusively terminally positioned included Z . mays ssp. pnrviglumis var. huehuerennngensis, Z . diploperennis, Z . perennis, and Z . luxurians. In the last mentioned, previously unknown heterochromatic regions were found. Both terminal and subterminal band positions were found in Z . mays, Z . mays ssp. mexicana, and Z . mays ssp. parvig1umi.s var. parviglurnis. On the basis of these results, and those of other workers, the taxonomic treatments of Z . mays ssp. parviglumis var. huehuerennngensis, and of Z . diploperennis and its autotetraploid derivative Z . perennis are questioned. MASTENBROEK, I., et J. M. J. DE WET. 1983. Chromosome C-banding of Zea mc1y.s and its closest relatives. Can. J. Genet. Cytol. 25: 203-209. Une technique connue d'application des bandes C etait modifie jusque c'dtait capable de produire consistant un ensemble complet et distinct des chromosomes avec des bandes nette. Elle dtait utilisk pour demonstrer des similarites et des differences parmi les arrangements de h6terochromatine des taxons differentes de Zecl. Les arrangements de band C revelaient une concordance genkrale avec les positions des blocs d'heterochromatine connu des etudes pachytenique. Deux groups d'arrangements des bandes etaient distingue. Les taxons avec bandes presque exclusivement aux positions terminales sont Z . mays ssp. parviglumis var. huehuerennngen.si.s, Z . dip1operenni.s. Z . perennis et Z . 1u.uurinns. Dans la derniere des regions d'heterochromatine etait decouvert qui etaient inconnue. A la fois des bandes terminales et subterminales etaient decouvert en Z . mays, Z. mays ssp. me-uicann et Z . mays ssp. pnr\iglumis var. huehue~enc~izgensis. A cause de nos resultats, et ceux d'autre chercheurs, le traitement taxonomic de Z . mays ssp. par\~i~lumi.s var. huehuerenc~ngen.si.s, et de Z . diploperennis et son derive autotetraploid Z . perennis sont mis en question.

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Section: Discussionmentioning

confidence: 99%

Chromosome C-banding of Zea mays and its closest relatives

Mastenbroek¹,

Wet²

1983

Can. J. Genet. Cytol.

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“…Further, the amount of variation in the arm ratio appears to be chromosome specific. Reports (Filion, 1970;Lighty and Plaisted, 1960;Maguire, 1962) indicate that the amount of variation in arm ratio increases with increasing arm ratio. Filion (19'70) noted that the amount of variation, calculated from short and long arm mensuration data, showed consistently higher values for the short arms of chromosomes.…”

Section: Resultsmentioning

confidence: 99%

An Examination of Chromosomal Indices

Filion¹

1972

Can. J. Genet. Cytol.

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Equations relating the effects of an increment and a decrement of a chromosome arm on arm ratio, centromeric index and morphological index were derived. These equations demonstrate that an increment and decrement of the same magnitude alter specific indices by differing amounts. Further, the equations for centromeric index and morphological index with one exception were chromosome dependent. The use of these indices in applied cytogenetics may require reconsideration.

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“…It is possible that the chromosomes may have inherent variability in their length patterns. Maguire (1962) suggested that the chromosomes may have two kinds of variability, one which apparently contributes uniformly per unit length throughout the genome and the other, which is, possibly a characteristic property of each chro mosome, unrelated to length in any way. She also further observed that the chro mosomes of a cell would tend to be either consistently longer or shorter than the average.…”

Section: Variation Within Maizementioning

confidence: 99%