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Öğe C-banding analyses of Bromus inermis genomes(Wiley, 2004) Tuna, M; Vogel, KP; Gill, KS; Arumuganathan, KSmoothbromegrass (Bromus inermis Leyss.) has both tetraploid (2n = 28) and octaploid (2n = 56) ploidy levels that have been difficult to characterize cytogenetically because of similar chromosome morphology. Objectives of this study were to identify individual chromosomes of tetraploid and octaploid B. inermis with C-banding procedures along with chromosome length and arm length ratios, develop more detailed karyotypes than those previously available, and use the karyotypes to examine the genomic relationship of tetraploid and octaploid B. inermis. Root tips of the plants from four tetraploid and three octaploid accessions were used to produce chromosome squash preparations for cytogenetic analysis. The tetraploid B. inermis genome consisted of 12 chromosomes with a telomeric band on each arm and sixteen chromosomes with only one telomeric band on one arm. All of the chromosomes of the tetraploid form, except for four chromosomes, were identified by C-banding patterns, chromosome length, and arm length ratio. The octaploid B. inermis genome consisted of four chromosomes with no C-bands, approximate to14 chromosomes with two telomeric bands, and approximate to38 chromosomes with only one telomeric band on either the short or long arm. The combined use of C-banding, chromosome size, and arm length ratio only enabled groups of 2, 4, 6, or 8 similar chromosomes to be identified because of similarities in chromosome morphology of the octaploids. Results indicate that tetraploid B. inermis is an allotetraploid since all chromosomes except four could be separated into identifiable pairs. Because of differences between expected and actual numbers of satellite chromosomes and chromosomes with specific C-banding patterns, octaploid B. inermis is probably not a doubled form of the tetraploid B. inermis.Öğe Characterization of natural orchardgrass (Dactylis glomerata L.) populations of the Thrace Region of Turkey based on ploidy and DNA polymorphisms(Kluwer Academic Publ, 2004) Tuna, M; Khadka, DK; Shrestha, MK; Arumuganathan, K; Golan-Goldhirsh, ADetermining the ploidy and genetic diversity of a germplasm is necessary before initiating breeding or genetic studies. This study was conducted to characterize the ploidy level of 57 natural populations of orchardgrass (Dactylis glomerata L.) collected from the ranges of Thrace region of Turkey and the diversity among populations based on RAPD (Random Amplified Polymorphic DNA) markers. Flow cytometry was used to determine nuclear DNA content (pg 2C(-1) = DNA content of a diploid somatic nucleus) of 6 plants for each population. Nuclear DNA contents were correlated to ploidy level with root tip chromosome counts on selected plants. On the basis of this study, mean nuclear DNA content of orchardgrass was determined as 9.5 pg +/- 0.33 (with 95% confidence interval) while all the plants used in chromosome counting were determined to be tetraploid, with 2n=28 mitotic chromosomes, suggesting that diploid orchardgrass plants are likely very rare or absent in ranges of Thrace region of Turkey. In the RAPD assay, over 40 polymorphic fragments were generated which allowed some populations to be distinguished from the rest by unique markers. A cluster analysis was performed using Nei's (1972) genetic distance index with an unweighted pair group method with arithmetic mean (UPGMA). The cluster analysis indicated that there is a high level of gene flow among natural orchardgrass populations and therefore genes distributed quite homogeneously through out the region. The results of this study can be useful in the development of Dactylis germ plasm collection strategies in Thrace region for breeding purpose.Öğe Cytogenetic and nuclear DNA content characterization of diploid Bromus erectus and Bromus variegatus(Crop Science Soc Amer, 2006) Tuna, M; Vogel, KP; Arumuganathan, KBromus erectus Huds. (erect brome) and B. variegatus M. Bieb. are Eurasian Bromus species that have been tentatively identified as potential progenitors of smooth bromegrass (B. inermis Leyss) which is the principal cultivated bromegrass in North America. The objective of this study was to characterize the genome of diploid accessions of B. erectus (2n = 2x = 14) and R variegatus (2n = 2x = 14) using nuclear DNA content and cytogenetic analysis using Giemsa C-banding. The nuclear DNA content for B. erectus (6.19 +/- 0.08 pg 2C(-1)) was less than that of B. variegatus (6.76 +/- 0.05 pg 2C(-1)). These two species can be distinguished cytogenetically with the karyotypes that were developed. Complete karyotypes were not developed for both species because within species, multiple chromosomes were similar in size and C-banding. Both species had two pairs of chromosomes with satellites but the size of the satellites and the number and position of C-bands on these chromosomes differed between species. Bromus variegatus had five pairs of chromosomes with telomeric C-bands on both arms, while R erectus had four pairs of chromosomes with a single telomeric band on the long arm and a single pair with telomeric bands on both arms. Comparison with the previously reported karyotypes and nuclear DNA contents for tetraploid and octaploid B. inermis suggest that if the diploid species R erectus and B. variegatus were the donor species for these polyploids, significant evolutionary changes have occurred since the initial formation of these species including chromosome loss and re-arrangement.Öğe DNA content and ploidy determination of bromegrass germplasm accessions by flow cytometry(Wiley, 2001) Tuna, M; Vogel, KP; Arumuganathan, K; Gill, KSSpecies of the genus Bromus represent ploidy states from diploid to decaploid. Ploidy determination of Bromus germplasm is necessary before it can be effectively used in breeding or genetic studies. The objective of this study was to characterize the ploidy of 322 accessions of four Bromus species [Bromus inermis Leyss, B. riparius Rehm, B. biebersteinii Roem and Schult., and B. inermis ssp. pumpellianus (Scribn) Wagnon] that are in the USDA National Plant Germplasm System (NPGS). Flow cytometry was used to determine DNA content of 10 plants of each accession. Mean DNA contents were correlated to ploidy level with root tip chromosome counts on selected accessions whose DNA content indicated that they represented different ploidy levels. On the basis of DNA content (pg 2C(-1) = DNA content of a diploid somatic nucleus) and chromosome counts, mean DNA content and chromosome number was 22.62 pg 2C(-1) for octaplold B. biebersteinii (2n = 8x = 56), 26.07 pg 2C(-1) for decaploid B. biebersteinii (2n = 10x 70), 11.74 pg 2C(-1) for tetraploid B. inermis (2n = 4x = 28), 22.28 pg 2C(-1) for octaploid B. inerm is (2n = 8x 56). 22.72 pg 2C(-1) for octaploid B. inermis ssp. pumpellianus (2n 8x = 56). 26.5 pg 2C(-1) for decaploid B. inermis ssp.pumpellianus (2n = 10x = 70), 6.14 pg 2C(-1) for diploid B. riparius (2n = 2x = 14), 22.15 pg 2C(-1) for octaploid B. riparius (2n = 8x = 56), and 26.64 pg 2C(-1) for decaploid B. riparius (2n = 10x = 70). Standard deviations of the mean values were 0.88 pg 2C(-1) or less. Most B. inermis and B. inermis ssp. pumpellianus accessions were octaploid (93.75%), while the majority of the B. riparius and B. biebersteinii were decaploid (92.30%). The B. inermis and related species in the USDA NPGS were collected primarily from areas in the former USSR. The NPGS bromegrass germplasm could be enhanced by collections from western and central Europe, the Middle East, and China.Öğe Genome size and Giemsa C-banded karyotype of tetraploid Bromus ciliatus L.(Springer, 2005) Tuna, M; Vogel, KP; Arumuganathan, KTetraploid Bromus ciliatus L. is a North American bromegrass that has been placed in the Pnigma section of Bromus. The objective of this study was to characterize the genome of tetraploid B. ciliatus by cytogenetic methods and compare it to the genomes of other species included in the section Pnigma. All the plants of the accession (USDA PI 232214) selected for chromosome counting were tetraploids (2n = 28). The mean 2C nuclear DNA content for tetraploid B. ciliatus was 19.13 +/- 0.07 pg as determined by flow cytometry which is significantly greater than the tetraploid DNA content of B. inermis Leyss. (11.74 +/- 0.16 pg). C-banding procedures were used to identify individual mitotic chromosomes and to develop a karyotype for B. ciliatus. The genome of the tetraploid B. ciliatus consisted of 16 median chromosomes, eight submedian chromosomes, and four chromosomes with satellites which included one pair with a large satellite and one pair with a small satellite. The general pattern of the distribution of constitutive heterochromatin in B. ciliatus was quite different than the other bromegrasses that have been analyzed to date. Except for two pairs of chromosomes, all chromosomes in tetraploid B. ciliatus had telomeric bands on one or both arms. Some of the chromosomes with telomeric bands had centromeric bands that were located at one or both sides of the centromere and intercalary bands which were generally absent in the other bromegrass species. It was possible to identify all chromosomes of tetraploid B. ciliatus and to match the pairs of homologous chromosomes by using chromosome lengths, arm length ratios and C-banding patterns. The results of this study indicate that tetraploid B. ciliatus has different genomes than the European species evaluated to date in the section Pnigma.Öğe Karyotype and C-banding patterns of mitotic chromosomes in diploid bromegrass (Bromus riparius Rehm)(Wiley, 2001) Tuna, M; Gill, KS; Vogel, KPPrevious cytogenetic studies of the genus Bromus L. were limited to chromosome counts and construction of karyotypes on the basis of Feulgen staining. Since the chromosomes of Bromus are similar in morphology, these karyotypes are of limited use for chromosome identification and genome analysis. The objectives of this study were to develop and evaluate a Giemsa C-banding procedure to use in identification of individual bromegrass chromosomes and to develop a karyotype for diploid Bromus riparius Rehm. (2n = 14; PI 440215). All chromosomes had one or more C-bands which were located mainly at telomeric regions. A group (I) of four pairs of chromosomes had telomeric bands on only one arm and could be differentiated. In this group, one pair had an interstitial C-band along with a telomeric band, one pair had a nucleolus organizer region (NOR) at a subtelomeric location on the short arm, and the other two pair could be distinguished by centromere location. The other group (II) of three pairs or chromosomes had telomeric bands on both arms. The unequivocal identification of specific chromosomes of Group II was not possible in all cells because of their similarity and differential condensation of chromosomes. Chromosomes of both groups were either metacentric or submetacentric. The total length of individual chromosomes ranged from 5.58 to 6.87 mum and the arm ratios ranged from 1.02 to 1.5. The homologous chromosomes were paired and assigned numbers I to VII in decreasing length. A karyotype was constructed by means of the C-bands, mean chromosome lengths, and arm ratios. The C-banding procedure used in this study could be used to developed karyotypes for the other species of the genus Bromus and these C-banded karyotypes could be used to compare genomes within the genus.Öğe Nonadditive changes in genome size during allopolyploidization in the wheat (Aegilops-Triticum) group(Oxford Univ Press Inc, 2003) Ozkan, H; Tuna, M; Arumuganathan, K[Abstract Not Available]
