Coenocytism, ameiosis, and chromosome diminution in intergeneric hybrids in the perennial Triticeae

Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 766-775 ◽  
Author(s):  
Richard R.-C. Wang
Keyword(s):  
Intergeneric Hybrid ◽  
Chromosome Elimination ◽  
Intergeneric Hybrids ◽  
Pollen Grain ◽  
Unreduced Gamete ◽  
Pollen Mother Cells ◽  
Psathyrostachys Juncea ◽  
Hybrid Plants ◽  
Mother Cells ◽  
Pollen Grain Wall

Three different pathways of ameiotic microsporogenesis were observed in some intergeneric hybrids of the perennial Triticeae grasses. In one of the hybrids between Pseudoroegneria spicata ssp. inermis and Psathyrostachys juncea, pollen mother cells remained as premeiotic interphase cells when the pollen grain wall started to form. The microspores in such an ameiotic plant are presumably unreduced. Coenocyte formation coupled with ameiosis occurred in two hybrid plants of Psathyrostachys huashanica × Secale montanum. Less than 10% of the pollen mother cells had one nucleus. An average of 4.44 nuclei, ranging from 1 to 25 per pollen mother cell, was observed. The nuclei in coenocytes remained unfused when the pollen grain wall was formed. Nucleus splitting followed by cytoplasmic budding or cleavage, possibly a process of chromosome diminution or elimination, replaced meiotic divisions in most of the pollen mother cells in one plant of Leymus angustus × Hordeum bulbosum and two plants of Thinopyrum elongatum × Psathyrostachys juncea. It is evident that these meiotic abnormalities are under genetic control. Probable locations for these genes controlling these phenomena are suggested.Key words: coenocyte, ameiosis, chromosome diminution, chromosome elimination, microsporogenesis, unreduced gamete, polyploidy, intergeneric hybrid.

Genome constitution of the Australian hexaploid grass Elymus scabrus (Poaceae: Triticeae)

Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 147-151 ◽  
Author(s):  
J. Torabinejad ◽  
R. J. Mueller
Keyword(s):  
Chromosome Pairing ◽  
Interspecific Hybrids ◽  
Intergeneric Hybrid ◽  
Meiotic Pairing ◽  
Genome Constitution ◽  
Psathyrostachys Juncea ◽  
Hybrid Plants ◽  
Thinopyrum Bessarabicum ◽  
Mother Cells ◽  
Metaphase I

Eight intergeneric hybrid plants were obtained between Elymus scabrus (2n = 6x = 42, SSYY??) and Australopyrum pectinatum ssp. retrofractum (2n = 2x = 14, WW). The hybrids were vegetatively vigorous but reproductively sterile. Examination of pollen mother cells at metaphase I revealed an average of 16.63 I, 5.29 II, 0.19 III, and 0.05 IV per cell for the eight hybrids. The average chiasma frequency of 6.77 per cell in the above hybrids strongly supports the presence of a W genome from A. pectinatum ssp. retrofractum in E. scabrus. Meiotic pairing data of some other interspecific hybrids suggest the existence of the SY genomes in E. scabrus. Therefore, the genome constitution of E. scabrus should be written as SSYYWW. Two other hybrid plants resulted from Elymus yezoensis (2n = 4x = 28, SSYY) crosses with A. pectinatum ssp. pectinatum (2n = 2x = 14, WW). Both were weak and sterile. An average of 0.45 bivalents per cell were observed at metaphase I. This clearly indicates a lack of pairing between W genome of Australopyrum and S or Y genomes of E. yezoensis. In addition, six hybrid plants of E. scabrus with Psathyrostachys juncea (2n = 2x = 14, NN) and one with Thinopyrum bessarabicum (2n = 2x = 14, JJ) were also obtained. The average bivalents per cell formed in both combinations were 2.84 and 0.70, respectively. The results of the latter two combinations showed that there is no N or J genome in E. scabrus.Key words: wide hybridization, chromosome pairing, genome analysis, Australopyrum, Elymus.

Genetically controlled desynapsis in diploid Critesion violaceum and its hybrids with autotetraploid Psathyrostachys juncea

1984 ◽  
Vol 26 (5) ◽  
pp. 532-537 ◽  
Author(s):  
Richard R-C. Wang
Keyword(s):  
Chromosome Pairing ◽  
Chiasma Frequency ◽  
Intergeneric Hybrid ◽  
Dosage Effect ◽  
The Other ◽  
Pollen Mother Cells ◽  
Psathyrostachys Juncea ◽  
Self Pollination ◽  
Meiotic Irregularities ◽  
Mother Cells

Segregation for chiasma frequency was observed in the progeny of a diploid (2n = 14) Critesion violaceum strain following self-pollination. One S1 plant had normal metaphase pairing with an average of 0.43I + 6.78II, giving a high chiasma frequency, 12.03 per cell. The other S1 plant averaged 7.89I + 3.08II and a low chiasma frequency, 3.47 per cell. Examination of pollen mother cells at early prophases revealed that chromosome pairing was not totally prevented. It was concluded that desynapsis was responsible for the meiotic irregularities observed in the variant progeny. The same phenomena were observed in F1 hybrids of the cross between diploid C. violaceum and an induced autotetraploid (2n = 28), Psathyrostachys juncea. The normal F1 hybrid had a chiasma frequency of 12.81, but the desynaptic hybrid had a chiasma frequency of 6.94. A dosage effect of the desynaptic gene, which was probably recessive, was suggested. The implications and significance of this discovery are discussed.Key words: asynapsis, chiasma, meiosis, intergeneric hybrid.

scholarly journals VARIATION AMONG PERENNIAL RYEGRASS x TALL FESCUE PLANTS FROM TISSUE CULTURE

1988 ◽  
pp. 81-86
Author(s):  
A.G. Scott ◽  
D.W.R. White
Keyword(s):  
Tissue Culture ◽  
Lolium Perenne ◽  
Perennial Ryegrass ◽  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Chromosome Doubling ◽  
Chromosome Elimination ◽  
Intergeneric Hybrids ◽  
Hybrid Plants ◽  
Spontaneous Chromosome

Tissue culture was used in an attempt to obtain a fertile perennial ryegrass x tall fescue hybrid. Regenerated hybrid plants were found to be morphologically variable and contain extensive chromosome rearrangements. Spontaneous chromosome doubling had occurred as well as chromosome elimination. though no fertile hybrid plants have been obtained to date. Keywords: somaclonal variation, Lolium perenne, Festuca arundinacea, intergeneric hybrids

Low glucosinolate Brassica juncea breeding line revealed to be nullisomic

Genome ◽  
2001 ◽  
Vol 44 (4) ◽  
pp. 738-741 ◽  
Author(s):  
B F Cheng ◽  
G Séguin-Swartz ◽  
D J Somers ◽  
G Rakow
Keyword(s):  
Brassica Juncea ◽  
Interspecific Cross ◽  
Meiotic Behaviour ◽  
Breeding Line ◽  
Pollen Mother Cells ◽  
Chromosomal Segregation ◽  
B Genome ◽  
Hybrid Plants ◽  
Mother Cells ◽  
Metaphase I

The low glucosinolate Brassica juncea breeding line 1058 was derived from a BC1F3 plant of an interspecific cross between high glucosinolate Indian B. juncea (genome AABB, 2n = 36) line 60143 and B. rapa (genome AA, 2n = 20) canola strain CZY. Line 60143 had 2n = 36 chromosomes (18 bivalents at metaphase I) and strain CZY had 2n = 20 chromosomes (10 bivalents). Line 1058 was nullisomic, with 2n - 2 = 34 chromosomes, with 17 bivalents formed at metaphase I and an even chromosomal segregation of 17:17 at anaphase I. In F1 hybrid plants of the cross 1058 × CZY, 98.3% of the pollen mother cells had 10 bivalents and seven univalents. This is evidence that plants of line 1058 are nullisomic, missing one pair of B-genome chromosomes.Key words: low glucosinolate mustard, meiotic behaviour, cytogenetics.

Progenies of Thinopyrum elongatum × Agropyron mongolicum

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 738-743 ◽  
Author(s):  
Richard R-C. Wang
Keyword(s):  
Embryo Rescue ◽  
Chromosome Elimination ◽  
Root Tip ◽  
Hybrid Necrosis ◽  
Genome Chromosome ◽  
Pollen Mother Cells ◽  
Close Phylogenetic Relationship ◽  
Mother Cells ◽  
Thinopyrum Elongatum ◽  
High Degree

With the aid of embryo rescue, both a monoploid and several hybrids were obtained from the cross Thinopyrum elongatum × Agropyron mongolicum. The monoploid was a result of gradual and eventually complete elimination of A. mongolicum chromosomes in the hybrid. About 95% of the root-tip cells, and nearly all of the pollen mother cells, had only the seven chromosomes of the Je genome of the maternal parent. Very little autosyndesis occurred between chromosomes within the Je genome. Extensive chromosome pairings were observed in one headed hybrid, averaging 6.42 I + 2.53 rod II + 0.85 ring II + 0.25 III + 0.02 IV at metaphase I in pollen mother cells, which revealed a high degree of chromosome homology between the two genomes and thus justifying the close phylogenetic relationship between the two species. All plants died from hybrid necrosis, some as seedlings and some after heading. The Je and P genomes in the accessions used in this study carry complementary genes for hybrid necrosis. Key words: hybrid (intergeneric), haploid, genome, chromosome elimination, meiosis.

Genome doubling and chromosome elimination with fragment recombination leading to the formation of Brassica rapa–type plants with genomic alterations in crosses with Orychophragmus violaceus

Genome ◽  
2007 ◽  
Vol 50 (11) ◽  
pp. 985-993 ◽  
Author(s):  
Min Liu ◽  
Zai-Yun Li
Keyword(s):  
Brassica Rapa ◽  
Embryo Rescue ◽  
Chromosome Elimination ◽  
Intergeneric Hybrids ◽  
Aflp Analysis ◽  
Genetic Introgression ◽  
Orychophragmus Violaceus ◽  
Distant Hybridization ◽  
Genome Doubling ◽  
Mother Cells

In distant hybridization of plants, nonclassical hybrids with unexpected chromosome complements, chromosome elimination, and genetic introgression have been well documented. We obtained intergeneric hybrids between Brassica rapa , B. rapa var. chinensis, and another cruciferous species, Orychophragmus violaceus , following embryo rescue. Hybrids mainly displayed phenotypes of B. rapa, although certain O. violaceus or novel characteristics also appeared. Variable numbers of chromosomes were observed in somatic cells in the roots of plantlets on medium and in ovaries and pollen mother cells (PMCs). However, higher numbers were recorded in the roots. GISH revealed that the majority of ovary cells and PMCs contained 20 chromosomes of B. rapa with or without individual O. violaceus chromosomes or fragments added or introgressed. AFLP analysis showed that fragments deleted from the B. rapa genome were much more frequent than novel and O. violaceus fragments. The mechanisms involved genome doubling and successive elimination of O. violaceus chromosomes accompanied by fragment recombination and introgression, producing B. rapa–type plants with modified genetic constitutions and phenotypes.

scholarly journals Radioautographic visualization of incorporation of lipid precursors into anthers of Muscari comosum (L.) Mili.

2015 ◽  
Vol 46 (2) ◽  
pp. 295-302 ◽  
Author(s):  
Barbara Gabara
Keyword(s):  
Acetic Acid ◽  
Palmitic Acid ◽  
Developmental Stages ◽  
Mevalonic Acid ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Tetrad Stage ◽  
Lipid Precursor ◽  
Mother Cells ◽  
Pollen Grain Wall

Incorporation of the following lipid precursors: DL-mevalonic acid-2 <sup>3</sup>H, <sup>3</sup>H palmitic acid and acetic acid-<sup>3</sup>H sodium salt, into the anther cells of <i>Muscari comosum</i> (L.) Mili. has been investigated. These lipid precursors have been demonstrated to incorporate into pollen mother cells, pollen grains and the tapetum at the consecutive developmental stages. Ali used isotopes are incorporated into the cytoplasm of these cells and in the case of pollen grain the radioactivity of pollen grain wall (mainly composed of sporopellenin) is noticed. The highest radioactivity of pollen grain wall is observed after acetic acid, the lower one after palmitic acid, whereas the lowest uptake of lipid precursor occurs after mevalonic acid. In comparison with tetrad stage the distinct inrease of the cytoplasmic radioactivity of tapetum, which appears to1 accompany the labelling of pollen grain wall, seems to indicate the participation of tapetum in the formation of exine. A possible role of Ubisch bodies in the formation of pollen grain wall is discussed.

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.

New intergeneric diploid hybrids among Agropyron, Thinopyrum, Pseudoroegneria, Psathyrostachys, Hordeum, and Secale

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 545-550 ◽  
Author(s):  
Richard R.-C. Wang
Keyword(s):  
Diploid Species ◽  
Intergeneric Hybrids ◽  
Meiotic Pairing ◽  
Genome Chromosome ◽  
Psathyrostachys Juncea ◽  
Hybrid Plants ◽  
Hybrid Genome ◽  
Genomic Relationships ◽  
The Mean ◽  
Thinopyrum Bessarabicum

Eight diploid intergeneric hybrids representing six genomic combinations were synthesized and meiotically analyzed. The SN hybrids of Pseudoroegneria spicata and P. spicata spp. inermis with Psathyrostachys juncea resembled the Pseudoroegneria species in that the spikes had a single spikelet per node. The spikes of all other hybrids were intermediate to those of their respective parents. The mean meiotic pairing pattern for two SN hybrids was 9.90 I + 1.74 rod II + 0.16 ring II + 0.07 III + 0.02 IV, which was equivalent to a mean arm-pairing frequency (c) of 0.16. When the results were averaged with a previously reported hybrid, the mean pairing in two hybrid plants of P. spicata × Thinopyrum bessarabicum (SJ genome combination) was 4.79 I + 3.24 rod II + 0.91 ring II + 0.18 III + 0.09 IV and c = 0.41. Of the JeS hybrids, mean pairing was 8.40 I + 2.30 rod II + 0.25 ring II + 0.13 III + 0.03 IV (c = 0.28) for T. elongatum × P. spicata and 6.98 I + 2.90 rod II + 0.39 ring II + 0.12 III + 0.02 IV (c = 0.28) for T. elongatum × P. spicata ssp. inermis. The JP hybrid of T. bessarabicum × Agropyron cristatum had 8.99 I + 2.11 rod II + 0.14 ring II + 0.13 III + 0.03 IV and c = 0.20. Pairing was lower in the new PH hybrids A. mongolicum × Hordeum californicum and HR hybrids H. californicum × Secale montanum: 12.20 I + 0.82 rod II + 0.05 III (c = 0.06) and 13.04 I + 0.44 rod II + 0.01 III (c = 0.03), respectively. These data contribute to the elucidation of the genomic relationships among diploid species of the perennial Triticeae.Key words: hybrid, genome, chromosome pairing, Triticeae.

Chromosomal and flavonoid chemical confirmation of intergeneric hybridization between Tolmiea and Tellima (Saxifragaceae)

1985 ◽  
Vol 63 (7) ◽  
pp. 1309-1312 ◽  
Author(s):  
Douglas E. Soltis ◽  
Bruce A. Bohm
Keyword(s):  
Intergeneric Hybrid ◽  
Intergeneric Hybrids ◽  
Hybrid Plant ◽  
Hybrid Origin ◽  
Intergeneric Hybridization ◽  
Hybrid Plants ◽  
Quercetin Glycoside ◽  
Flavonoid Chemistry

Two putative intergeneric hybrids between Tolmiea menziesii and Tellima grandiflora were discovered in Oregon and Washington. These plants are morphologically intermediate in several floral features between the presumed parental taxa. Evidence from flavonoid chemistry and karyology support the contention that these plants are of intergeneric hybrid origin. Cytological studies demonstrated that the hybrid plant from Oregon has 2n = 14 and involves diploid (2n = 14) Tolmiea menziesii and Tellima grandiflora. The hybrid plant from Washington has 2n = 21 and has tetraploid T. menziesii (2n = 28) and diploid T. grandiflora as parents. Tolmiea menziesii and Tellima grandiflora have distinctive karyotypes and both hybrid plants were found to combine these chromosomal complements. The hybrids also combine the flavonoid constituents of Tolmiea and Tellima. In addition to exhibiting kaempferol, quercetin, and myricetin glycosides found in both species, the hybrid plants have kaempferol and quercetin glycoside gallates characteristic of Tellima grandiflora, and isorhamnetin glycosides found in Tolmiea menziesii.

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