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SOMATIC CHROMOSOME MORPHOLOGY OF SOME CULTIVATED MEMBERS OF TRITICEAE

Jahan, Qamar (1994) SOMATIC CHROMOSOME MORPHOLOGY OF SOME CULTIVATED MEMBERS OF TRITICEAE. PhD thesis, University of Karachi, Karachi.

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Abstract

The present study was undertaken to perform karyotype analysis by conventional, C-and N-banding methods in some cultivated of Triticeae like wheat, Triticum aestivum L., macaroni wheat, T. turgidum L., Eincorn, T. monococcum L., rye, Secale cereale L., titicale X Triticosecale (hexaploid and octoploid) and barley Hordeum vulgare L. Chromosomes were identified on the basis of total length, arm ratio and satellites when acetoorcein was used for staining. Four wheat chromosomes viz., 6A, 7A, 4B and 6D were met centric while the rest submetacentric. The chromosomes 1B, 6B and 5D were satellited. An idogram and a nomenclature system were developed for the description of individual N-bands. Nomenclature rules were proposed for the description of chromosomal structural aberrations and polymorphic bands in different wheat cultivars. As a rule each short arm (S) and long arm (L) consisted of a series of dark bands. The region number was separated from the band number by a decimal point for example in 4AL1.3, the region number 1 is separated from band number 3 by the decimal point. All wheat chromosome arms have one or more interstitial C- and N-bands, whereas 1AS, 3AL, 4AS, 5AS, 6AS, 1DL and 7DL have no such bands. Polymorphism in banding patterns of somatic chromosomes in several cultivars of wheat was studied by Giemsa N-banding technique. Sixteen out of twenty one chromosomes exhibited distinct banding patterns, while no bands were observed in 1A and 3D to 6D. The banding polymorphism was observed mainly in the B-genome chromosomes, whereas the D-genome chromosomes revealed the maximum consistency. N-banding polymorphism was analyzed through SPSS/PC+ (Statistical Package for Social Sciences) Ver. 3 utilizing the command Hierarchical clustering analysis.The 1B/1R translocated chromosome in T. aestivum cvs. Seri-82’, ‘Pak-81’ and several accessions of National Uniform Wheat yield Trials was confirmed through C- and N-banding technique In rye, S. cereale 3 and 4 chromosomes were met centric and submetacentric respectively, out of which only 1R was satellited. Mean and standard error for total length, relative length and arm ratio in each cultivar of rye was statistically analyzed through SPSS/PC+ using the command Manova. All the chromosome arms exhibited a terminal and one or more interstitial C-bands. By the N-banding only one interstitial band was observed in 2R, 3R and 6R chromosomes. Polymorphism was studied in five rye, by their distinctive heterochromatin pattern through the Giemsa C-banding technique as well. The strength of telomeric heterochromatin was different among the cultivars as observed through the thickness of the dark band. Variation in the banding pattern was observed even in between homologous chromosomes in certain cultivars. The 6X and 8X triticales (2n=42 and 56), were studied through conventional cytology and keryotyping on the basis of total length, arm ratios and presence of satellite as well as by N-banding technique. In barley, H. vulgare 5 chromosomes were metacentric and 2 submetacentric, out of which 6H and 7H (now recognized as 5H) were satellited chromosomes. Arms had one or more interstitial N-bands and were divisible into two or more bands. Characteristic N-banding polymorphism was observed in the interstitial regions of chromosomes 1,2,3 and 6. Intergeneric amphipod between T. aestivum cv. ‘Sarsabz’ and salt tolerance, Karnal bunt resistant accession of Aegilops ovata was produced and a few shriveled seeds with normal endosperm were obtained. These were confirmed to have 2n=5X=35; ABDUM chromosomes. The pentaploid F1 hybrids had a range of 0-4 rod bivalents and 26-35 univalents with a frequency of 2.32 chiasmata cell. T. aestivum – Ae. Ovata amphiploids were synthesized by chromosome doubling of sterile pentaploid F1 hybrids through a treatment of 0.01 percent colchicines. Cytologically amphiploids were confirmed to possess 2n=10X=70; AABBDDUUMM chromosomes and had a range of 0-10 univalents, 7-29 ring bivalents, 6-23 rod bivalents, 0-4 trivalents and 0-1 quadrivalent in 50 PMCs. This germplasm offers avenues of alien addition line development

Item Type:Thesis (PhD)
Uncontrolled Keywords:triticeae, karyotype analysis, wheat, wheat breeding, amphiloid, rye, barley, germplasm, triticum aestivum l., macaroni wheat, t. turgidum l., eincorn, t. monococcum l., secale cereale l., titicale x triticosecale
Subjects:Biological & Medical Sciences (c) > Biological Sciences(c1) > Evolution & genetics (c1.6)
ID Code:1211
Deposited By:Mr. Muhammad Asif
Deposited On:04 Jan 2007
Last Modified:04 Oct 2007 21:05

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