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.

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.

Diploid perennial intergeneric hybrids in the tribe Triticeae. III. Hybrids among Secale montanum, Pseudoroegneria spicata, and Agropyron mongolicum

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 80-84 ◽  
Author(s):  
Richard R.-C. Wang
Keyword(s):  
Key Words ◽  
Embryo Culture ◽  
Intergeneric Hybrids ◽  
Root Tip ◽  
Pseudoroegneria Spicata ◽  
Chromosome Homology ◽  
Tip Cells ◽  
Root Tip Cells ◽  
Secale Montanum ◽  
Tribe Triticeae

Four new intergeneric diploid hybrids were synthesized in the greenhouse with the aid of embryo culture. Hybrids of Pseudoroegneria spicata × Secale montanum and P. spicata ssp. inermis × S. montanum, both having the genome formula SR, averaged 12.97 I + 0.49 II + 0.01 III at metaphase I. The hybrids of Agropyron mongolicum × S. montanum, which have the PR genomes, had an average of 12.86 I + 0.51 II + 0.03 III + 0.004 IV. The hybrid (SP) between P. spicata ssp. inermis and Agropyron mongolicum had a mean configuration of 8.05 I + 2.86 II + 0.07 III + 0.01 IV. All hybrids had intermediate spike morphology, respective to their parents, and were sterile. Mitotic preparations of root-tip cells of these hybrids suggested that the chromosomes of different genomes were spatially separated. The meiotic pairings of these hybrids indicated that chromosome homology between the S and P genomes is higher than either the S and R or the P and R. Both SR and PR hybrids represent new genomic combinations. The SP hybrid is equivalent to the dihaploid of P. tauri. All of these hybrids should be of value for breeding and taxonomy. Key words: intergeneric hybrids, genome, Secale, Pseudoroegneria, Agropyron.

scholarly journals New chromosome numbers in Pilocarpus Vahl (Rutaceae)

2000 ◽  
Vol 14 (1) ◽  
pp. 11-24
Author(s):  
Ladislau A. Skorupa
Keyword(s):  
Chromosome Numbers ◽  
Room Temperature ◽  
Basic Number ◽  
Root Tip ◽  
Root Tips ◽  
Chromosome Counts ◽  
Pre Treatment ◽  
First Time ◽  
Tip Cells ◽  
Root Tip Cells

Chromosome counts for eight species of Pilocarpus Vahl (Rutaceae) a native of Brazil are reported for the first time. Chromosome numbers were determined from mitotic root tip cells of seedlings derived from field collections and grown in the greenhouse. Feulgen staining was used. Initial pre-treatment of root tips was done by using a saturated aqueous solution of alpha-bromonapthalene for two hours at room temperature (20-25ºC). Chromosome numbers of 2n=44 and 2n=88 were determined for the examined taxa. The present results suggest the occurrence of tetraploidy in P. spicatus St.-Hil. and P. carajaensis Skorupa, and a possible basic number x=22 to the genus Pilocarpus.

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.

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.

Cytogenetic characteristics of wheat plants regenerated from anther calli of 'Centurk'

1983 ◽  
Vol 25 (5) ◽  
pp. 513-517 ◽  
Author(s):  
Dalia T. Kudirka ◽  
Gideon W. Schaeffer ◽  
P. Stephen Baenziger
Keyword(s):  
Chromosome Doubling ◽  
Doubled Haploids ◽  
Triticum Aestivum L ◽  
Root Tip ◽  
Anther Wall ◽  
Root Tips ◽  
Chromosome Counts ◽  
Spontaneous Chromosome ◽  
Tip Cells ◽  
Root Tip Cells

Plants were recovered from 10 different calli derived through anther culture of Triticum aestivum L. em Thell (cv. 'Centurk'). Chromosome counts and estimates of ploidy level were made on cells from roots of these developing plants. Plants with polyhaploid cells were regenerated from all calli indicating that they were of microspore origin. Three populations of plants were recognized: first, those that were polyhaploid and euploid; second, those that were almost totally polyhaploid but aneuploid; and third, those plants which were largely hexaploid with some cells reflecting spontaneous chromosome doubling. Aneuploid cells with corresponding polyhaploid and hexaploid chromosome numbers in root-tip cells among plants regenerated from a number of calli were taken to indicate that these cells were doubled haploids and not hexaploid cells of the anther wall. Mixoploid plants were regenerated from secondary calli in which chromosome doubling was known to have been induced at the callus stage. The presence of individual mixoploid root tips in these plants was assumed to indicate that individual organs of a plant may arise from several cells of a callus.

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 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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