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1.
Pulak Mukherjee 《Euphytica》1975,24(2):483-486
Summary Karyomorphological studies on ten cultivated strains of Brassica juncea Coss. (Indian mustard) have been made. All of them were found to possess 2n=36 chromosomes and meiotic studies revealed 18 regular bivalents. A great many structural differences between chromosome complements have been recorded. It has been shown that though homogeneous in gross morphology, minute structural differences between the strains are noted in relation to the number of secondary constrictions, the position of primary constrictions as well as the changes in the arm ratio. A histogram of the haploid chromatin complement of the somatic set of ten strains illustrates the differences. 相似文献
2.
D. J. Cox 《Euphytica》1991,55(1):57-63
Summary Monosomic alien addition lines combining individual F. drymeja chromosomes and the L. multiflorum complement were isolated from the cross between the triploid hybrid L. multiflorum (4x) × F. drymeja (2x) and diploid L. multiflorum (2x). Chromosome pairing in the addition lines was studied at metaphase 1 of meiosis and the relationship between single F. drymeja chromosomes and the corresponding homologous pair in L. multiflorum is discussed. Trivalent frequency in the addition lines was higher than expected from observations of chromosome pairing in the triploid hybrid and there were differences between lines in the number of trivalent associations formed. There is some evidence to suggest that trivalent frequency is not entirely dependent on chromosome length and that transmission of the alien chromosome in the female is dependent on the size of the added chromosome. Morphological studies were made to assess the phenotypic effects of the addition of single F. drymeja chromosomes to the L. multiflorum complement. Two plants (2n=14) with recombination between a L. multiflorum and a F. drymeja chromosome were identified. 相似文献
3.
4.
Chromosome morphology was studied in diploid cultivars of Tulipa fosteriana and T. gesneriana (2n = 2x = 24) and triploid Darwin hybrids (2n = 3x = 36) developed from interspecific crosses of T. gesneriana and T. fosteriana. Chromosomes were arranged in the karyotype according to decreasing total length. Based on our karyotypic analysis, we propose that median chromosomes may serve as markers for diploid genotypes. Discriminant analysis with respect to total chromosome length and short arm length showed a significant difference between the size of the larger median chromosomes of T. gesneriana and T. fosteriana Comparison of median chromosome length in Darwin hybrid tulips showed that two larger chromosomes and one smaller chromosome were derived from T. gesneriana and T. fosteriana, respectively. This finding was clearly and unambiguously confirmed by simultaneous hybridization of differentially labeled genomic probes of T. fosteriana and T. gesneriana to metaphase chromosomes of the triploid cultivar ‘Yellow Dover’, thereby enabling us to distinguish between the 24 chromosomes derived from T. gesneriana and 12 chromosomes derived from T. fosteriana. Thus, genomic in situ hybridization and median chromosome analyses can be useful to identify the genome constitution of triploid Darwin hybrid tulips. In addition, their hybridity was readily verified by flow cytometry using vegetative tissue of Darwin hybrid tulips. Our results clarify the process of Tulipa cultivar formation and will be useful for interspecific hybridization breeding.The first and second author have contributed equally to this paper 相似文献
5.
G. Bremer 《Euphytica》1961,10(3):325-342
In connection with the increase of chromosome number found in species hybrids of Saccharum the author studied embryo-sac development within several Saccharum froms from early stages of meiosis in the embryo-sac mother cells to stages where fertilization already had taken place.Normally by meiosis within E M C's a row of four haploid megaspores is formed from which the innermost, the chalazal megaspore, develops into an embryo-sac and the other three degenerate.Haploid embryo-sacs, thus formed, may occur in Saccharum. Frequently however, in Saccharum endo-duplication takes place, that is splitting of the chromosomes within the nucleus of the chalazal megaspore, through which the chromosome number is increased.It is described how within Saccharum by this phenomenon embryo-sacs may be formed with diploid and tetraploid chromosome numbers and with numbers between haploid and diploid.The increase of chromosome number, observed in the young megaspore after meiosis, could be confirmed by counting the chromosomes of dividing nuclei within young embryo-sacs.Chromosome numbers found in dividing zygotes and endosperm nuclei within fertilised embryo-sacs also pointed to the occurrence of egg-cells and polar nuclei that must be haploid, diploid and tetraploid.The significance of this research in relation to plant breeding will be discussed in Part V. 相似文献
6.
Summary The meiotic pairing behaviour at metaphase I of a Triticum aestivum×Triticum monococcum hybrid has been studied by means of the C-banding technique to ascertain the homology between the chromosomes in the A genome of the two species. The technique allowed the A and B genome chromosomes and the 2D, 3D and 5D chromosomes to be identified. Differences in the level of chromosome pairing in the A genome were noted. The T. monococcum 4A chromosome did not pair with any of the T. aestivum chromosomes in any of the metaphase I cells analysed. Two reciprocal translocations between the 2B and 2D chromosomes on one side and the 2A and 3D on the other side have been identified. The usefulness of the C-banding technique in the study of chromosome homology among species related to wheat is discussed. 相似文献
7.
A synthetic amphidiploid species Cucumis hyriviis Chen & Kirkbride (2n = 4x = 38; genome designated as HHCC) has recently been created from an interspecific mating between C. sativus L. (2n = 2x = 14: genome designated as CC) and C. hystrx. Chakr. (2n = 2x = 24; genome designated as HH). This amphidiploid is resistant to root knot nematode, tolerant to low irradiance, and has higher nutritional value than standard processing cucumber cultivars. An allotriploid (2n = 3x = 26; HCC) was derived from a cross between C. sativus L. and C. hytivus Chen & Kirkbride. Diploid meiotic behaviour in C. sativus and C. hystrix involves the development of seven and 12 metaphase bivalents respectively. In the derived allotriploid. univalents. bivalents, and trivalents (at relatively low frequency) were observed at metaphase I indicating that some homeologues from the C and H genomes can synapse. Based on a comparative karyotype analysis of cucumber (i.e. chromosome size and pairing behaviour) and aliotriploid plants, the seven bivalents observed at metaphase I were ascertained to be cucumber homologues, while the 12 univalents were of C. hystrix origin thus confirming the allotriploid karyotypic constitution to be HCC. On average, the frequency of trivalents was 0.24 at diakinesis and 0.22 in 100 meiocytes at metaphase I. indicating the possibility of genetic exchange due to the homoeology between the C and H genomes. After simultaneous cytokinesis, only polyads were observed in pollen mother cells (PMCs) at telophase II, which led to the production of sterile pollen grains. Multi‐polarization of chromosomes was dominant at anaphase II. However. in about 20% PMCs. chromosomes separated to form a 7C + 1‐2H complement, suggesting a possible method for the production of alien addition cucumber‐C hystrix lines through further backcrossing of the allotriploid to diploid cucumber. 相似文献
8.
中国种诸葛菜变种群的核型研究 总被引：2，自引：0，他引：2
对中国种诸葛菜变种群（色括原变种及三个变种）作了大样本核型分析，结果显示：染色体相对长度从长到短呈渐缓梯度变化，次缢痕位置大多出现在第11对染色体上，一部分次缢痕变化不定。臂比指数极端变幅大，按众数求得的染色体类型是：2n=24(2st)+6sm(2st)。核型对称性分析结果是1A-2A，属于最对称性。核中有较高频率的B染色 相似文献
9.
分析rDNA基因位点在染色体上的分布可以对新麦草染色体进行识别和分析其基因组特征。利用FISH和顺序C-分带-FISH技术将45S rDNA定位于新麦草细胞分裂中期染色体上,结果表明,45S rDNA在二倍体新麦草染色体上有6个主要分布位点,另外几条染色体在两臂中部或长臂末端还显示出较弱的杂交信号,信号强度显示蒙农4号新麦草基因组具有一定杂合性。分析确定新麦草的45S rDNA基因主位点分别位于N1染色体短臂末端、N3染色体短臂末端以及N5染色体短臂末端,推测这3对染色体是NOR染色体。 相似文献
10.
Karyotype of Canada wildrye (Elymus canadenisis L.) was described using giemsa C-banding techniques. Most of the chromosomes showed dome banding pattern polymorphism. Small to large terminal and centormere bands were observed in most of the chromosomes. A faint satellite was observed in one chromosome. Tow chromosomes had a large interstitial band near the centromeres in the long arms. The Giemsa C-banding pattern of E. Canadensis is compared to that of Pseudoroegneria spicata and Critesion boddanii to illustrate species relationship. 相似文献
11.
Development of tall fescue (Festuca arundinacea Schreb., 2n = 6x - 42) × Italian rye-grass (Lolium multiflorum Lam., 2n = 2 ×= 14) hybrids would enhance efforts to improve the quality of tall fescue. Two ‘Kentucky 31’ tall fescue בLemtal Italian ryegrass hybrids were obtained via embryo rescue on MS media containing casein hydrolysate, ascorbic acid and sucrose. Chromosome pairing at metaphase I had an average of more than 12 bivalents per cell. Since Festuca-Lolium pairing can account only for seven of the paired chromosomes, intergenomic as well as interspecific chromosome pairing is indicated. There was no cytoplasmic effect on chromosome pairing. To determine if enzymes could be used as genetic markers for distinguishing hybrids from self-contaminants in crosses, zymograms of PGI, 6-PGD, MDH, GOT and ACPH were obtained from parents and hybrids using starch gel etectrophoresis. PGI, 6-PGD and MDH had fewer bands in the diploid ryegrass, as compared with the hexaploid tall fescue and the tetraploid hybrid. 相似文献
12.
Summary Tetraploid 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. 相似文献
13.
Summary Some haploids isolated among the progeny from crosses involving several genotypically different motherplants of Beta vulgaris L., were used for an investigation on chromosome morphology of the genus Beta.The length of both the long and short arms proved to vary considerably for each chromosome, so that a representative idiogram of the 9 chromosomes could not be made. Staining the chromosomes according to the BSG-technique revealed only bands in the centromere regions. However, one chromosome with a narrow band in the short arm could be identified, which was supposed to be the nucleolar chromosome. The C-bands presumably correlate with the heterochromatic blocks as observed in mitotic and meiotic (pachytene) prophase.This study was part of a project on cytogenetics of interspecific hybrids resistent to beet cyst eelworm, supported by the Institute of Rational Sugar Production,Bergen op Zoom, the Netherlands. 相似文献
14.
Three tetraploid (2n= 4x= 28) wheat Triticum turgidum L. landrace morphotypes (= genotypes) from Ethiopia were found to carry a variant karyotype directly discernible under the microscope. This was possible because the rearrangement involved one of the satellited chromosomes. Giemsa C-banding revealed that the rearrangement resulted from a 5BS.6BS(5BL.6BL) centric reciprocal translation. The banding pattern on 5BL was polymorphic, suggesting that this translocation might have occurred more than once. There was little C-band polymorphism for the remaining chromosomes, except for 2A. As pure lines, all three morphotypes showed normal chromosome pairing at metaphase I (MI) in pollen mother cells (PMCs). indicating that they are genomically stable. Meiotic analyses of F1 hybrids and F2 segregates derived from crosses with tester varieties clearly indicated that one of them (B-l–9) carried another translocation. However, we were not successful in delecting the chromosomes involved, presumably the interchanged segments did nol include C-banding regions. By using T5BS.6BS, direct evidence for segregation distortion against translocation homozygotes in intervarietal hybrids was obtained. The distorted segregation was attributed lo zygotic selection. No aneuploid plants were obtained from the F2 segregates. However, translocation heterozygotes resulting in unstable meiosis were abundant in the F2 generation. The implications of the results in using the indigenous landraces in hybridization breeding are discussed. 相似文献
15.
Detailed karyotypes of Hydrangea macrophylla, Hydrangea paniculata and Hydrangea quercifolia were constructed on the basis of arm lengths and centromeric index, together with 45S rDNA fluorescence in situ hybridization. Although the chromosomes were small, they were well distinguishable for all species. Chromosome morphology and karyotypes were different for the three species. H. macrophylla had six metacentric (M), eight submetacentric (SM) and four subtelocentric (ST) chromosomes. The karyotype of H. paniculata contained seven M, 10 SM and one ST chromosomes and H. quercifolia had six M, 10 SM and two ST chromosomes. The variability among three species also was expressed by 45S rDNA signals. H. macrophylla had a nucleolar organizing region on chromosome 2, H. paniculata had 45S rDNA signals on chromosomes 2, 5 and 11 and H. quercifolia on chromosomes 3 and 8. Hybridization signal always was distally on the short arm but the strength of the signals was different for the three species. The chromosome portraits made in this study will be used to trace chromosome behaviour in interspecific hybrids resulting from breeding work between the three species. 相似文献
16.
Summary Metaphase I chromosome association of the monosomic F1 and the backcross progenies made to develop a monosomic line in the Spanish common wheat Pané-247 was analyzed using a Giemsa C-banding technique. This permits the unequivocal identification of nine meiotic chromosomes (4A, 7A and the seven chromosomes of the B genome). The average frequencies of pairing per arm and of univalents for these nine pairs per arm and of univalents for these nine pairs indicate a difference between arms. The F1 showed asynapsis with univalents in 18.5 per cent of PMC's in intervarietal hybrids. This mainly involved chromosomes 4A, 1B and 6B which also have the largest amount of constitutive heterochromatin. The possible causes of reduced metaphase I association and its rapid decrease during backcrossing are discussed in relation to polymorphism between heterozygous homologous chromosomes. 相似文献
17.
Bronco 90 is an advanced line of hexaploid triticale and was reported to be a 2D(2R) chromosome substitution type. In F1 hybrids of this triticale with bread wheat, however, a meiotic configuration of 16 bivalents and 10 univalents was frequently
observed indicating the presence of an additional D(R) chromosome substitution or D/R translocation. To determine the chromosome
constitution of Bronco 90, C-banding and fluorescent in situ hybridization techniques were applied to somatic and meiotic
metaphase chromosomes. These analyses revealed that in Bronco 90, the terminal 7% of the long arm of rye chromosome 5R is
derived from the long arm of chromosome 4D. This translocated chromosome (5RS.5RL-4DL) and telosome 4DL formed metaphase I
bonds at a frequency of 71%, demonstrating the significance of small terminal chromosome segments for pairing. This novel
rye-wheat translocation is probably generated by homoeologous crossing-over because the distal region of 5RL is known to be
homoeologous to that of 4DL. Possible association of this translocation with the absence of hairy peduncle character in Bronco
90 is discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
S. E. Zorinyants A. V. Nosov E. D. Badaeva I. N. Smolenskaya N. S. Badaev 《Plant Breeding》1995,114(3):219-225
In vitro culturing of plant cells can cause changes in karyotype. Chromosome variations following long-term propagation in suspension culture of Triticum timopheevii (Zhuk.) Zhuk. were studied by routine staining and C-banding. The culture was highly heterogeneous with respect to the number and structure of chromosomes. The modal class cells had a lower chromosome number than T. timopheevii (2n= 28). This data was confirmed by cytophotometric analysis of nuclear-DNA content. Frequencies of chromosome loss varied for different homoeologous groups. At genome chromosomes tended to be preferentially eliminated in cells of different ploidy levels. Deletions, insertions, translocations, telocentric chromosomes, isochromosomes and dicentrics and their derivatives were observed in cultured cells. Chromosomes of various homoeologous groups differed in the frequencies and spectra of re—arrangements, but most aberrations occurred in the G-genome chromosomes. In vitro chromosome modifications did not correspond to in vivo variation. Presumably, this difference was caused by differences in the mechanisms of adaptation to the environment at the levels of the cell and the whole organism. G-genome chromosomes were more frequently involved in this process, both in vivo and in vitro. 相似文献
19.
Summary Giemsa C-banding allows for the identification of all 21 chromosome pairs of hexaploid wheat. However, variation in banding patterns of individual chromosomes and structural rearrangements exist between different cultivars making chromosome identification more difficult. The paper summarizes the available data on C-band polymorphism and structural rearrangement present in wheat cultivars and germplasms. 相似文献
20.
西藏小麦及半野生小麦异染色质分化的C-带研究 总被引：2，自引：0，他引：2
以Giemsa C-带技术研究了西藏小麦、西藏半野生小麦和中国春的异染色质分化。它们之间的带型没有很大的差异,但出现了C-带多态性。多态性主要表现在A、B组染色体和分布于染色体臂的中部及端部。以中国春C-带为标准的比较表明,半野生小麦的多态性所属染色体主要为A组的2A、6A和7A,B组的2B、3B、4B和7B,西藏小麦为2A、7A和7B。推测它们同属一个类群,西藏半野生小麦比西藏小麦和中国春原始,并非是来自栽培小麦的杂交后裔。 相似文献