scholarly journals The Development and Meiotic Behavior of Asymmetrical Isochromosomes in Wheat

Genetics ◽  
1997 ◽  
Vol 145 (4) ◽  
pp. 1155-1160
Author(s):  
Adam J Lukaszewski
Keyword(s):  
Triticum Aestivum ◽  
Hexaploid Wheat ◽  
Triticum Aestivum L ◽  
Meiotic Metaphase ◽  
Meiotic Behavior ◽  
Pollen Mother Cells ◽  
Chromosome Arm ◽  
Mother Cells ◽  
Metaphase I

To determine which segments of a chromosome arm are responsible for the initiation of chiasmate pairing in meiosis, a series of novel isochromosomes was developed in hexaploid wheat (Triticum aestivum L.). These isochromosomes are deficient for different terminal segments in the two arms. It is proposed to call them “asymmetrical.” Meiotic metaphase I pairing of these asymmetrical isochromosomes was observed in plants with various doses of normal and deficient arms. The two arms of an asymmetrical isochromosome were bound by a chiasma in only two of the 1134 pollen mother cells analyzed. Pairing was between arms of identical length whenever such were available; otherwise, there was no pairing. However, two arms deficient for the same segment paired with a frequency similar to that of normal arms, indicating that the deficient arms retained normal capacity for pairing. Pairing of arms of different length was prevented not by the deficiency itself, but rather, by the heterozygosity for the deficiency. Whether two arms were connected via a centromere in an isochromosome or were present in two different chromosomes had no effect on pairing. This demonstrates that in the absence of homology in the distal regions of chromosome arms, even if relatively short, very long homologous segments may remain unrecognized in meiosis and will not be involved in chiasmate pairing.

The three-dimensional arrangement of chromosomes at meiotic metaphase I in normal and interchange heterozygotes of Briza humilis

1990 ◽  
Vol 97 (3) ◽  
pp. 565-570
Author(s):  
JANET M. MOSS ◽  
BRIAN G. MURRAY
Keyword(s):  
Mother Cell ◽  
Three Dimensional ◽  
Meiotic Metaphase ◽  
Central Position ◽  
Normal Plant ◽  
Serial Sections ◽  
Pollen Mother Cells ◽  
Sector Analysis ◽  
Mother Cells ◽  
Metaphase I

Pollen mother cells at metaphase I have been reconstructed from serial sections in normal and interchange heterozygotes of Briza humilis. The pollen mother cells have an irregular shape with a prominent projection from the tangential face into the anther loculus. The seven bivalents of the normal plant are usually arranged with one bivalent in a central position surrounded by a ring of the remaining six or as a ring of all seven bivalents. The central:peripheral distribution of quadrivalents is different in two different interchange plants; in a sector analysis, where cells are divided into four quarters relative to the tangential face of the pollen mother cell, the two plants also show differences in quadrivalent distribution, indicating that individual chromosomes occupy different positions in the cell. The relevance of these results to the positioning of quadrivalents in lateral squashes of meiotic metaphase I are discussed.

scholarly journals CHROMOSOMAL LOCATION OF GENES CONTROLLING FLAVONOID PRODUCTION IN HEXAPLOID WHEAT

Genetics ◽  
1983 ◽  
Vol 103 (2) ◽  
pp. 313-321
Author(s):  
Paula R Neuman ◽  
J G Waines ◽  
K W Hilu ◽  
D Barnhart
Keyword(s):  
Triticum Aestivum ◽  
Hexaploid Wheat ◽  
Chinese Spring ◽  
Chromosomal Location ◽  
Triticum Aestivum L ◽  
Phenolic Glycoside ◽  
Two Dimensional ◽  
Chromosome Arm ◽  
The Individual ◽  
Homoeologous Chromosomes

ABSTRACT Two-dimensional paper chromatography was performed on methanol extracts of leaves of hexaploid bread wheat, Triticum aestivum L. em. Thell. cultivar Chinese Spring, and of the available nullisomic-tetrasomic compensating lines, the tetrasomic lines and the ditelocentric lines. The chromatograms had 27 spots identified as flavonoids and six representing phenolic acids. Some of the areas were complex and contained more than one compound. Four flavonoids were identified as under the control of gene(s) on chromosome arms 1DS, 4DL, 5AS and 6BS. A phenolic glycoside was concluded to be controlled by a gene(s) on chromosome arm 7BL. Gene(s) on chromosome arm 4DL affected the amount of compounds in two other spots, and gene(s) on chromosome arm 4BS reduced the level of all flavonoid compounds. The individual compounds in some of the complex spots may be under the control of gene(s) on homoeologous chromosomes.

The chromosomal location of a gene (msg) affecting megasporogenesis in durum wheat

Genome ◽  
1987 ◽  
Vol 29 (4) ◽  
pp. 578-581 ◽  
Author(s):  
L. R. Joppa ◽  
N. D. Williams ◽  
S. S. Maan
Keyword(s):  
Durum Wheat ◽  
Key Words ◽  
Chromosomal Location ◽  
Triticum Turgidum ◽  
Wheat Line ◽  
Pollen Mother Cells ◽  
Chromosome Arm ◽  
Pollen Nucleus ◽  
Mother Cells ◽  
Metaphase I

An aneuploid durum wheat line (Triticum turgidum L. var. durum) having 13 chromosome pairs and 2 unpaired chromosomes at metaphase I of meiosis in pollen mother cells (i.e., monosomic for chromosomes 7A and 7D) was observed to produce some progeny plants with 2n = 40 chromosomes. These aneuploid (triploid) plants were usually weak and sterile. Triploid plants also occurred in the progeny of durum plants monosomic for chromosome 7A, or in progeny of plants that were mono-telodisomic or ditelomonotelosomic for chromosome 7Aq (13 II + 1 t II or 13 II + t II + t I) but not in the progeny of plants ditelomonotelosomic for chromosome 7Ap (13 II + t II + t 1). Therefore, there is a gene(s) on chromosome arm 7Ap that prevents the production of diploid (2n) egg cells in wheat. In the absence of 7Ap, a portion of the egg cells have 26 chromosomes, which when fertilized with a pollen nucleus with 14 chromosomes, produces progeny plants with 2n = 40 chromosomes. The data also indicated that chromosome arm 7Dp probably contains a second gene that is capable of preventing the production of triploid plants. Key words: Triticum turgidum L. var. durum, polyploidy, aneuploid, triploid, monosomic.

scholarly journals Cytogenetics and immature embryo culture at Embrapa Trigo breeding program: transfer of disease resistance from related species by artificial resynthesis of hexaploid wheat (Triticum aestivum L. em. Thell)

2000 ◽  
Vol 23 (4) ◽  
pp. 1051-1062 ◽  
Author(s):  
Maria Irene Baggio de Moraes Fernandes ◽  
Ana Christina A. Zanatta ◽  
Ariano Moraes Prestes ◽  
Vanderlei da Rosa Caetano ◽  
Amarilis Labes Barcellos ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
Disease Resistance ◽  
Embryo Culture ◽  
Related Species ◽  
Hexaploid Wheat ◽  
Immature Embryo ◽  
Triticum Aestivum L ◽  
Breeding Program ◽  
Immature Embryo Culture ◽  
Program Transfer

The biology and ecology of hexaploid wheat (Triticum aestivum L.) and its implications for trait confinement

2008 ◽  
Vol 88 (5) ◽  
pp. 997-1013 ◽  
Author(s):  
C. J. Willenborg ◽  
R. C. Van Acker
Keyword(s):  
Triticum Aestivum ◽  
Gene Flow ◽  
Hexaploid Wheat ◽  
Triticum Turgidum ◽  
Cropping Systems ◽  
Pollen Viability ◽  
Triticum Aestivum L ◽  
Genetically Engineered ◽  
Wide Range ◽  
Trait Confinement

This review summarizes the biological and ecological factors of hexaploid wheat (Triticum aestivum L.) that contribute to trait movement including the ability to volunteer, germination and establishment characteristics, breeding system, pollen movement, and hybridization potential. Although wheat has a short-lived seedbank with a wide range of temperature and moisture requirements for germination and no evidence of secondary dormancy, volunteer wheat populations are increasing in relative abundance and some level of seed persistence in the soil has been observed. Hexaploid wheat is predominantly self-pollinating with cleistogamous flowers and pollen viability under optimal conditions of only 0.5 h, yet observations indicate that pollen-mediated gene flow can and will occur at distances up to 3 km and is highly dependent on prevailing wind patterns. Hybridization with wild relatives such as A. cylindrica Host., Secale cereale L., and Triticum turgidum L. is a serious concern in regions where these species grow in field margins and unmanaged lands, regardless of which genome the transgene is located on. More research is needed to determine the long-term population dynamics of volunteer wheat populations before conclusions can be drawn with regard to their role in trait movement. Seed movement has the potential to create adventitious presence (AP) on a larger scale than pollen, and studies tracing the movement of wheat seed in the grain handling system are needed. Finally, the development of mechanistic models that predict landscape-level trait movement are required to identify transgene escape routes and critical points for gene containment in various cropping systems. Key words: Triticum, coexistence, gene flow, genetically-engineered, herbicide-resistant, trait confinement

Chromosome localization of genes for soluble proteins in hexaploid wheat (triticum aestivum L.)

1991 ◽  
Vol 33 (2) ◽  
pp. 145-149
Author(s):  
Ts. Stoilova ◽  
G. Ganeva ◽  
B. Bochev ◽  
K. Petkolicheva
Keyword(s):  
Triticum Aestivum ◽  
Hexaploid Wheat ◽  
Triticum Aestivum L ◽  
Soluble Proteins ◽  
Chromosome Localization
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