CYTOGENETICS OF 6X-AMPHIPLOID × AVENA SATIVA L. F1 HYBRIDS

1971 ◽  
Vol 13 (2) ◽  
pp. 292-297 ◽  
Author(s):  
R. A. Forsberg ◽  
S. Wang
Keyword(s):  
Avena Sativa ◽  
Seed Set ◽  
Pollen Grains ◽  
F1 Hybrids ◽  
Root Tip ◽  
Ploidy Levels ◽  
Sperm Nuclei ◽  
Mother Cells ◽  
Tip Cells ◽  
Root Tip Cells

Avena abyssinica (2n=28) × A. strigosa (2n=14) 6x amphiploids were crossed with 13 different A. sativa (2n=42) varieties or selections. There was considerable variation in chromosome number within and among F1 plants. The mode was 40 in root tip cells and 41 in pollen mother cells (PMC's). The number of univalents in PMC's ranged from 10 to 27 with a mean of 18.9. The average number of bivalents was 7.1, ranging from 2 to 13. Multiple associations were common. Only 10.8% of the pollen grains contained normally developed nuclei, i.e. one vegetative and two elongated sperm nuclei. Forty of 41 F1 plants were completely self-sterile and only one seed was obtained from 16,950 florets. Seed set in backcross pollinations with A. sativa was 1.25%, providing some opportunity for perpetuation of desirable genes from lower ploidy levels.

scholarly journals Cytogenetics of Mimosa bimucronata (DC.) O. Kuntze (Mimosoideae, Leguminosae): chromosome number, polysomaty and meiosis

2011 ◽  
Vol 11 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Denise Olkoski ◽  
Maria Teresa Schifino Wittmann
Keyword(s):  
Seed Set ◽  
Pollen Grains ◽  
Root Tip ◽  
Rio Grande Do Sul ◽  
Root Tips ◽  
Pollen Mother Cells ◽  
Species Area ◽  
Mother Cells ◽  
Tip Cells ◽  
Root Tip Cells

Chromosome numbers (somatic and/or gametic) were determined in 50 populations of M. bimucronata (DC.) O. Kuntze collected in the species area of distribution in Rio Grande do Sul, south Brazil. All populations were diploid (2n = 2x = 26, n = 13). Polysomatic (mostly tetraploid) cells were detected in the seedlings root-tip cells in 39 out of the 41 populations examined, ranging from 3.0 to 28.2 % among populations, but were absent in the root-tips of grown plants. Polysomaty was as well absent in pollen-mother cells. In M. bimucronata pollen-mother cells are joined two-by-two before the onset of meiosis, remaining attached during all the meiotic division until the formation of pollen grain polyads, composed of two sets of four pollen grains each, that are dispersed in this way, which, according to previous suggestions would be an adaptation to ensure high seed set after a single pollination event.

scholarly journals PROGRESS IN THE DEVELOPMENT OF A MENTHA GERMPLASM COLLECTION

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 774D-774
Author(s):  
Henrietta L. Chambers ◽  
Barbara M. Reed ◽  
Joseph D. Postman ◽  
Kim Hummer
Keyword(s):  
Bacterial Contamination ◽  
Germplasm Collection ◽  
In Vitro Cultures ◽  
F1 Hybrids ◽  
Root Tip ◽  
Meristem Culture ◽  
Mother Cells ◽  
Tip Cells ◽  
Root Tip Cells

Approximately 450 accessions representing 40 taxa from around the world, including 77 advanced breeder selections and 54 F1 hybrids are maintained at the repository in Corvallis. Most of the clones came from the collection of M. J. Murray of the A. M. Todd Company, Kalamazoo, MI. Others were received from the former USDA/ARS mint breeding program in Corvallis which ended in 1981. Data on origin, morphology, pedigree, oil analysis, fertility and chromosome number was provided with many of the accessions. We have confirmed the identity of the clones utilizing many of these features. We are actively seeking unrepresented germplasm. Chromosomes from pollen mother cells or root-tip cells are currently being counted. Nomenclature changes reflecting recent research have been made. Many clones have been indexed for viruses. Infected clones are treated with thermotherapy and meristem culture to produce virus-negative replacements. An in vitro backup collection is maintained in cold storage. Iniation of in vitro cultures has been complicated by internal bacterial contamination in some clones. Research to eliminate this problem is in progress. Cuttings and in vitro cultures of Mentha germplasm are available to researchers worldwide.

scholarly journals Ploidy Levels of Hardy Actinidia Accessions in the U.S. Determined by Flow Cytometry

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 439D-439 ◽  
Author(s):  
Mary Ann Start ◽  
James Luby ◽  
Robert Guthrie ◽  
Debby Filler
Keyword(s):  
Flow Cytometry ◽  
Ploidy Level ◽  
Interspecific Variation ◽  
Root Tip ◽  
Interspecific Crosses ◽  
Ploidy Levels ◽  
Haploid Chromosome Number ◽  
Tip Cells ◽  
Root Tip Cells ◽  
The U.S

The hardy Actinidia species represent a source of genetic diversity for improving A. deliciosa (kiwifruit) as well as for creating new economically important cultivars through intra- and interspecific crosses. Attempts at breeding in Actinidia have been complicated by the existence of intraspecific as well as interspecific variation in ploidy. The haploid chromosome number in Actinidia is 29 and diploid (2n=2x=58), tetraploid (2n=4x=116), and hexaploid (2n=6x=174) levels have been identified. Because of the problems encountered when crossing parents differing in ploidy level, it is desirable to know the ploidy levels of plants to be used in breeding. We determined the ploidy levels of 61 Actinidia accessions currently available in the U.S., including primarily accessions of relatively winter-hardy species. The 61 accessions, representing eight species and three interspecific hybrids, were screened for ploidy using flow cytometry. Mitotic root tip cells from one plant from each putative ploidy level were examined microscopically to confirm the ploidy level derived from flow cytometry. There were 17 diploids, 40 tetraploids, and 4 hexaploids. Intraspecific variation was not found among accessions of the species arguta, callosa, deliciosa, kolomikta, melanandra, polygama, or purpurea. All kolomikta and polygama accessions were diploid. All arguta, callosa, melanandra, and purpurea accessions were tetraploid. Actinidia deliciosa was hexaploid. One chinensis accession was tetraploid. Two accessions (NGPR 0021.14 and 0021.3), acquired as chinensis, were hexaploid and may, in fact, be A. deliciosa based on their morphology. `Issai' (arguta × polygama) was hexaploid and `Ken's Red' and `Red Princess' (both melanandra × arguta) were tetraploid.

scholarly journals Study of crossability and F1 of interspecific hybridization between Brassica rapa (B. campestris) and B. nigra

2008 ◽  
Vol 32 (3) ◽  
pp. 445-449
Author(s):  
MA Malik
Keyword(s):  
Chromosome Number ◽  
Interspecific Hybridization ◽  
Female Parent ◽  
Pollen Sterility ◽  
F1 Hybrids ◽  
Root Tip ◽  
Intermediate Morphology ◽  
Pale Colour ◽  
Tip Cells ◽  
Root Tip Cells

Interspecific hybridization between yellow seeded variety, Binasarisha-6 of B. rapa var. Yellow Sarson (2n=20; AA) and Nigra-1 of B. nigra (2n=16; BB) were made. The crosses with Binasarisha-6 of B. rapa var. Yellow Sarson as a female parent were only successful. Chromosome number in root tip cells of the F1 hybrids was 18, which was half of the sum total of the somatic chromosome number of the parents and indicated hybrid nature. Hybrids exhibited intermediate morphology between the parents. All the hybrids showed complete pollen sterility with shrivelled, pointed tip, and pale colour anthers and reduced filaments and failed to set siliquae and seeds.DOI: http://dx.doi.org/10.3329/bjar.v32i3.546Bangladesh J. Agril. Res. 32(3) : 445-449, September 2007

An advanced generation of Aranda orchids

Genome ◽  
1988 ◽  
Vol 30 (4) ◽  
pp. 608-611 ◽  
Author(s):  
Y. H. Lee ◽  
F. Y. Tham
Keyword(s):  
Somatic Chromosome ◽  
Intergeneric Hybrids ◽  
Root Tip ◽  
Chromosome Counts ◽  
Pollen Mother Cells ◽  
Mother Cells ◽  
Tip Cells ◽  
Somatic Chromosome Numbers ◽  
Root Tip Cells ◽  
Advanced Generation

Aranda orchids are a group of artificially bred intergeneric hybrids between member species (2n = 38) of two natural genera, Vanda and Arachnis, of Orchidaceae. Nine second generation Aranda cultivars were selected for analysis of somatic chromosome numbers, meiotic behaviour, and sporad formation. Eight of the cultivars were derived from Aranda × Vanda crosses and one from an Aranda × Aranda cross. Chromosome counts of their root tip cells showed that eight of them contained 2n = 3x = 57 chromosomes each, presumably resulting from unreduced eggs of the Aranda parent fertilized by haploid Vanda pollen. The ninth revealed 2n = 2x = 38 chromosomes. Pollen mother cells of eight of the cultivars (2n = 3x = 57) commonly formed more than 10 bivalents, presumably between homologous Vanda chromosomes, as well as many univalents, mainly of Arachnis chromosomes. Only 8–10 bivalents were observed in pollen mother cells of the ninth cultivar (2n = 2x = 38). All the cultivars formed a range of dyads containing unreduced microspores. Two mechanisms are proposed for the origin of these dyad sporads.Key words: Aranda orchids, intergeneric hybrids, cytology.

Identification of a barley chromosomal interchange using N-banding and in situ hybridization techniques

Genome ◽  
1992 ◽  
Vol 35 (3) ◽  
pp. 392-397 ◽  
Author(s):  
Jie Xu ◽  
K. J. Kasha
Keyword(s):  
In Situ Hybridization ◽  
Rapid Identification ◽  
Root Tip ◽  
Chromosome 4 ◽  
Chromosome Identification ◽  
Chromosomal Interchange ◽  
Mother Cells ◽  
Tip Cells ◽  
Root Tip Cells

The combination of N-banding and in situ hybridization was used to illustrate the rapid identification of the chromosomes involved in a newly formed chromosomal interchange (reciprocal translocation) in barley. The plant heterozygous for the interchange was derived from the backcross of 'Su Pie', a two-rowed Chinese winter barley cultivar (2n = 2x = 14), with pollen from a triploid interspecific F1 hybrid (2n = 3x = 21) obtained from the cross of 'Su Pie' × tetraploid Hordeum bulbosum accession GBC141 (2n = 4x = 28). Pollen mother cells of the interchanged plant exhibited one quadrivalent and five bivalents in 97.8% of cells. Partial sterility of florets was observed in spikes obtained from self-pollination and the plants morphologically resembled barley. Barley chromosomes were readily identified by N-banding from root-tip cells with one band missing from the short arm of one of the pair of chromosome 4. N-banding of metaphase I of meiosis revealed that chromosomes 1, 2, and 5 were not involved in the interchange. In situ hybridization with a rDNA probe showed that chromosomes 6 and 7 were paired as bivalents. In conclusion, chromosomes 3 and 4 are involved in the interchange with the breakpoint in the short arm of chromosome 4 between the two proximal N-bands. The use of chromosome-specific DNA probes for chromosome identification using in situ hybridization is proposed.Key words: barley, chromosomal interchange, N-banding, in situ hybridization, rDNA.

SPONTANEOUS CHROMOSOME ABERRATIONS IN MELANDRIUM

1968 ◽  
Vol 10 (1) ◽  
pp. 143-147 ◽  
Author(s):  
Hiran C. Choudhuri
Keyword(s):  
Chromosome Aberrations ◽  
Pollen Grains ◽  
Root Tip ◽  
Dicentric Chromosomes ◽  
Ring Chromosomes ◽  
Melandrium Album ◽  
Spontaneous Chromosome ◽  
First And Second Generation ◽  
Tip Cells ◽  
Root Tip Cells

Chromosome aberrations were observed in root tip cells of Melandrium album. These aberrations were generally in the form of dicentric chromosomes involving bridge formation, ring chromosomes, fragments and elimination of acentric fragments from daughter nuclei. All the aberrations varied from 19.6 to 10.7 per cent in the first and second generation seedlings respectively. The chromosome irregularities and abortion of pollen grains (4.0 to 5.0%) are presumably due to gene mutation which has been enhanced in aged seeds.

Cytological investigation of the Achillea millefolium complex (Compositae) in Quebec

1977 ◽  
Vol 55 (7) ◽  
pp. 796-808 ◽  
Author(s):  
Camille Gervais
Keyword(s):  
Chromosome Numbers ◽  
Pollen Grains ◽  
Achillea Millefolium ◽  
Root Tip ◽  
Herbarium Specimens ◽  
Cytological Investigation ◽  
Mitotic Abnormalities ◽  
Small Pollen ◽  
Tip Cells ◽  
Root Tip Cells

The study of the chromosome numbers of over 112 individuals belonging to the Achillea millefolium L. complex (Compositae) and the examination of the pollen of about 200 herbarium specimens have led to the following conclusions; the A. millefolium complex, in Quebec, includes tetraploids (2n = 36), hexaploids (2n = 54), and various hybrid types. Tetraploids could be divided into two taxa: the southernmost is A. lanulosa Nutt. with small pollen grains and light brown or yellowish-margined phyllaries while the northern or alpine plants, corresponding to A. nigrescens (E. Mey.) Rydb., possess large pollen grains and dark-margined phyllaries. The two species, in contact zones, seem to hybridize freely. Hexaploids comprise purple-flowered introduced individuals escaping from cultivation, white or pink individuals, also introduced, and possibly a native taxon. The introduced hexaploids belong to A. millefolium s.str. and the purple-flowered variety frequently hybridizes with A. lanulosa giving rise to pentaploids (2n = 45) apparently almost sterile. A few plants from Maine (U.S.A.) have also been studied. This paper finally reports cytological observations related particularly to spontaneous mitotic abnormalities (fragmentation, fusion of chromosomes) affecting root tip cells of seedlings.

scholarly journals Morphological Characterization of Three Intergeneric Hybrids Among Gloriosa superba ‘Lutea’, Littonia modesta, and Sandersonia aurantiaca (Colchicaceae)

HortScience ◽  
2008 ◽  
Vol 43 (1) ◽  
pp. 115-118 ◽  
Author(s):  
Junji Amano ◽  
Sachiko Kuwayama ◽  
Yoko Mizuta ◽  
Masaru Nakano ◽  
Toshinari Godo ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Pollen Grains ◽  
Morphological Characterization ◽  
Intergeneric Hybrids ◽  
Root Tip ◽  
Gloriosa Superba ◽  
Hybrid Plants ◽  
Tip Cells ◽  
Root Tip Cells

Three intergeneric hybrids among colchicaceous ornamentals, Gloriosa superba ‘Lutea’ (2n = 2x = 22), Littonia modesta (2n = 2x = 22), and Sandersonia aurantiaca (2n = 2x = 24), were subjected to morphological characterization and chromosome observation. Hybrid plants produced flowers 2 to 3 years after transplantation of ovule culture-derived plantlets to the greenhouse. All the hybrid plants, L. modesta × S. aurantiaca, L. modesta × G. superba ‘Lutea’, and S. aurantiaca × G. superba ‘Lutea’, showed a climbing habit like those of L. modesta and G. superba ‘Lutea’. Plants of L. modesta × S. aurantiaca and L. modesta × G. superba ‘Lutea’ were taller and shorter than their respective parents, whereas plant height of S. aurantiaca × G. superba ‘Lutea’ was nearly intermediate between the parents. Leaves of all the hybrids had a tendril at the tip like those of L. modesta and G. superba ‘Lutea’. Flower morphologies of all the hybrids were nearly intermediate between the parents. Flower colors of all the hybrids were similar to the seed or pollen parent. Although hybrids of L. modesta × G. superba ‘Lutea’ showed low pollen fertility as assessed with acetocarmine staining, the other two kinds of hybrids had nondehiscent anthers or no fertile pollen grains. Chromosome observation in root tip cells revealed that all the hybrids had a diploid number of chromosomes: L. modesta × S. aurantiaca (2n = 2x = 23), L. modesta × G. superba ‘Lutea’ (2n = 2x = 22), and S. aurantiaca × G. superba ‘Lutea’ (2n = 2x = 23). Novel morphological characteristics of the hybrids may be valuable for future breeding of colchicaceous ornamentals.

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