CYTOGENETIC ANALYSIS OF PLANTS REGENERATED FROM OAT (AVENA SATIVA) TISSUE CULTURES; HIGH FREQUENCY OF PARTIAL CHROMOSOME LOSS

1982 ◽  
Vol 24 (1) ◽  
pp. 37-50 ◽  
Author(s):  
T. J. McCoy ◽  
R. L. Phillips ◽  
H. W. Rines
Keyword(s):  
Avena Sativa ◽  
High Frequency ◽  
Chromosome Instability ◽  
Chromosome Breakage ◽  
Chromosome Loss ◽  
Tissue Cultures ◽  
Meiotic Analysis ◽  
Regenerated Plants ◽  
Chromosomal Variability ◽  
Regeneration Cycle

The frequency and types of chromosomal variability in regenerated Avena sativa L. plants were assessed by detailed meiotic analysis on 655 regenerated plants. Tissue cultures were initiated from immature embryos of the varieties Lodi and Tippecanoe and maintained by monthly subculturing. Plants were regenerated from 4-, 8-, 12-, 16- and 20- month-old cultures. Regenerated plants with cytogenetic alterations were common, although Lodi cultures produced a higher frequency of cytogenetically abnormal plants at each regeneration cycle than Tippecanoe cultures. After four months in culture, 49% of Lodi regenerated plants were cytogenetically abnormal, whereas only 12% of Tippecanoe regenerated plants were abnormal. The frequency of cytogenetically abnormal, regenerated plants increased with culture age. After 20 months in culture 88% of Lodi regenerated plants and 48% of Tippecanoe regenerated plants were cytogenetically abnormal. The most common cytogenetic alteration was chromosome breakage, followed by loss of a chromosome segment resulting in a heteromorphic pair at diakinesis. Of the regenerated plants classified as cytogenetically abnormal, 41% of Lodi plants and 66% of Tippecanoe plants had lost a portion of one or more chromosomes. Other alterations included trisomy, monosomy and interchanges. Chromosome instability associated with oat tissue cultures has several possible uses.

Genomic rearrangements in maize induced by tissue culture

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 122-128 ◽  
Author(s):  
Michael Lee ◽  
R. L. Phillips
Keyword(s):  
Tissue Culture ◽  
Zea Mays ◽  
Zea Mays L ◽  
Chromosome Instability ◽  
Chromosome Breakage ◽  
Callus Cultures ◽  
Tissue Cultures ◽  
Meiotic Analysis ◽  
Regenerated Plants

Chromosomal instability is a common occurrence in plant tissue cultures and has been documented in plants regenerated from several genotypes of maize (Zea mays L.) tissue cultures. The objective of this research was to evaluate the frequency and types of chromosomal aberrations in regenerated plants of an Oh43–A188 genetic background, which had not been examined previously for chromosome stability in culture. Organogenic callus cultures were intitated from immature embryos of F2 plants for several Oh43 ms isoline × A188 crosses. The chromosome constitution of 267 plants was investigated through meiotic analysis of plants regenerated either 3 to 4 or 8 to 9 months after culture initiation. No abnormalities were detected in 78 plants regenerated during the first period. During the second period, however, 91 of the 189 plants were cytologically abnormal. One hundred and eight aberrations were detected and most (96%) involved changes in chromosome structure such as interchanges (42%), deficiencies (35%), and heteromorphic pairs (19%). All deficiencies were intercalary. Also, most (51%) interchanges involved chromosome 6. An association between male-sterility factors and chromosome instability was not observed. Breakpoints were primarily on chromosome arms containing large blocks of heterochromatin such as knobs. Several abnormal plants from the same culture appeared to contain identical aberrations indicating the aberrations may trace to a single event. A hypothesis for the involvement of heterochromatin in chromosome breakage during in vitro culture is supported. Key words: Zea mays L., tissue culture, somaclonal variation, chromosome breakage, heterochromatin.

Cytogenetic stability of aneuploid maize tissue cultures

1986 ◽  
Vol 28 (3) ◽  
pp. 374-384 ◽  
Author(s):  
C. A. Rhodes ◽  
R. L. Phillips ◽  
C. E. Green
Keyword(s):  
Cell Walls ◽  
Chromosome Breakage ◽  
Pollen Sterility ◽  
Tissue Cultures ◽  
Culture Initiation ◽  
Single Chromosome ◽  
Recessive Mutations ◽  
Regenerated Plants ◽  
Genetic Stocks ◽  
Common Cell

Monosomic maize tissue cultures might be used to select recessive mutations of cellular traits. This strategy would avoid some of the problems encountered with haploid cultures such as lack of vigor, sterility of regenerated plants, and uncontrolled diploidization. Monosomic and other aneuploid plants were selected among progeny of W22 R/r-x1 crossed with genetic stocks containing recessive markers. The r-x1 allele induces aneuploidy at a frequency of about 15%. Immature tassels of selected plants were used to initiate totipotent tissue cultures. Plants were regenerated from the cultures over a period of 3 to 17 months after culture initiation. Meiotic karyotypes of microsporocytes and pollen sterility were analyzed in regenerated plants. At least 40% of the 161 plants regenerated from aneuploid cultures had altered karyotypes. This frequency was not related to culture age. Most alterations involved chromosome breakage rather than changes in chromosome number. Types of alterations included heteromorphic pairs (18.1%), translocations (12.5%), addition (10.6%) or loss (1.4%) of chromosomes, and genomic doubling (2.8%). Four euploid cultures, including one with a translocation, were equally unstable (49% with alterations among 115 plants). Euploid cultures gave rise to plants with translocations (12.3%), heteromorphic pairs (8.8%), and genomic doubling (29.2%), but no single chromosome additions or losses. Plants that shared a common distinctive karyotype, such as a specific translocation, were probably derived from a common cell line. Tassels with sectors of two different karyotypes were frequent in plants regenerated from aneuploid (20%) or euploid (33%) cultures. Coenocytic microsporocytes, which lacked cell walls between nuclei, were found in plants from monosomic-2, deficient-2L, and monosomic-6 cultures. Another aberration (23% of 144 regenerants) was lack of cell wall formation after the first and (or) second meiotic division, which was often followed by nuclear fusion. Karyotypic changes observed in this study rarely involved the monosomic chromosome, which means that monosomic tissue cultures could be used to select recessive mutants. Further tests would be needed to demonstrate that the selected gene resides in the monosomic chromosome.Key words: Zea mays, monosomic, trisomic, chromosome, somaclonal variation, karyotype.

Chromosome instability in cell and tissue cultures and regenerated plants

1981 ◽  
Vol 21 (3-4) ◽  
pp. 359-368 ◽  
Author(s):  
Milton J. Constantin
Keyword(s):  
Chromosome Instability ◽  
Tissue Cultures ◽  
Regenerated Plants

Chromosomal variability in tissue cultures and regenerated plants of Hordeum

1980 ◽  
Vol 56 (3) ◽  
pp. 101-112 ◽  
Author(s):  
T. J. Orton
Keyword(s):  
Tissue Cultures ◽  
Regenerated Plants ◽  
Chromosomal Variability

CHROMOSOME STABILITY IN MAIZE (ZEA MAYS) TISSUE CULTURES AND SECTORING IN SOME REGENERATED PLANTS

1982 ◽  
Vol 24 (5) ◽  
pp. 559-565 ◽  
Author(s):  
T. J. McCoy ◽  
R. L. Phillips
Keyword(s):  
Zea Mays ◽  
Cultured Cells ◽  
Chromosome Complement ◽  
Recessive Mutation ◽  
Chromosome Stability ◽  
Tissue Cultures ◽  
Meiotic Analysis ◽  
Recessive Mutations ◽  
Regenerated Plants

Cytogenetic stability of maize (Zea mays L.) tissue cultures was assessed by meiotic analysis of plants regenerated from 4- and 8-month-old tissue cultures and by mitotic analysis of cultured cells 4 and 8 months after culture initiation. Cultures initiated from four embryos each of W22 R-nj R-nj × A188 and A188 × W22 R-nj R-nj were examined. After four months in culture, only one of 65 regenerated plants was abnormal; after eight months, only four of 59 regenerated plants were abnormal. Three of the five abnormal plants had normal and cytogenetically abnormal sectors in the tassels. Inheritance studies were conducted on 51 regenerated plants. Eight plants segregated in the S1 for recessive mutations resulting in defective kernels, and one plant segregated for a recessive mutation resulting in a wilted phenotype. Eight different plants that produced normal S1 progeny segregated for defective kernel mutations in some S1 families, indicating a lack of concordance between male and female reproductive cells in the original regenerated plant. The cytogenetic stability observed in regenerated plants also was observed in vitro, indicating that selection at the time of regeneration did not occur. Four hundred and thirty-four (97%) of the 449 cells analyzed in 4-month-old cultures had the normal 20-chromosome complement; 377 (95%) of the 398 cells analyzed in 8-month-old cultures were normal. These results indicate that chromosome stability is maintained in tissue cultures of A188 × W22 R-nj R-nj maize.

scholarly journals THE UTILIZATION DURING MITOTIC CELL DIVISION OF LOCI CONTROLLING MEIOTIC RECOMBINATION AND DISJUNCTION IN DROSOPHILA MELANOGASTER

Genetics ◽  
1978 ◽  
Vol 90 (3) ◽  
pp. 531-578 ◽  
Author(s):  
Bruce S Baker ◽  
Adelaide T C Carpenter ◽  
P Ripoll
Keyword(s):  
Chromosome Segregation ◽  
Meiotic Recombination ◽  
Mitotic Chromosome ◽  
Chromosome Instability ◽  
Chromosome Breakage ◽  
Mitotic Cell ◽  
Mitotic Recombination ◽  
Chromosome Stability ◽  
Chromosome Loss ◽  
Meiotic Mutants

ABSTRACT To inquire whether the loci identified by recombination-defective and disjunction-defective meiotic mutants in Drosophila are also utilized during mitotic cell division, the effects of 18 meiotic mutants (representing 13 loci) on mitotic chromosome stability have been examined genetically. To do this, meiotic-mutant-bearing flies heterozygous for recessive somatic cell markers were examined for the frequencies and types of spontaneous clones expressing the cell markers. In such flies, marked clones can arise via mitotic recombination, mutation, chromosome breakage, nondisjunction or chromosome loss, and clones from these different origins can be distinguished. In addition, meiotic mutants at nine loci have been examined for their effects on sensitivity to killing by UV and X rays.—Mutants at six of the seven recombination-defective loci examined (mei-9, mei-41, c(3)G, mei-W68, mei-S282, mei-352, mei-218) cause mitotic chromosome instability in both sexes, whereas mutants at one locus (mei-218) do not affect mitotic chromosome stability. Thus many of the loci utilized during meiotic recombination also function in the chromosomal economy of mitotic cells.—The chromosome instability produced by mei-41 alleles is the consequence of chromosome breakage, that of mei-9 alleles is primarily due to chromosome breakage and, to a lesser extent, to an elevated frequency of mitotic recombination, whereas no predominant mechanism responsible for the instability caused by c(3)G alleles is discernible. Since these three loci are defective in their responses to mutagen damage, their effects on chromosome stability in nonmutagenized cells are interpreted as resulting from an inability to repair spontaneous lesions. Both mei-W68 and mei-S282 increase mitotic recombination (and in mei-W68, to a lesser extent, chromosome loss) in the abdomen but not the wing. In the abdomen, the primary effect on chromosome stability occurs during the larval period when the abdominal histoblasts are in a nondividing (G2) state.—Mitotic recombination is at or above control levels in the presence of each of the recombination-defective meiotic mutants examined, suggesting that meiotic and mitotic recombination are under separate genetic control in Drosophila.—Of the six mutants examined that are defective in processes required for regular meiotic chromosome segregation, four (l(1)TW-6cs, cand, mei-S332, ord) affect mitotic chromosome behavior. At semi-restrictive temperatures, the cold sensitive lethal l(1)TW-6cs causes very frequent somatic spots, a substantial proportion of which are attributable to nondisjunction or loss. Thus, this locus specifies a function essential for chromosome segregation at mitosis as well as at the first meiotic division in females. The patterns of mitotic effects caused by cand, mei-S332, and ord suggest that they may be leaky alleles at essential loci that specify functions common to meiosis and mitosis. Mutants at the two remaining loci (nod, pal) do not affect mitotic chromosome stability.

Stability at the phosphoglucoisomerase (PGI/2) locus in Lolium multiflorum (2n = 4x = 28) × Festuca arundinacea (2n = 6x = 42) plants regenerated from cell suspension

Genome ◽  
1992 ◽  
Vol 35 (3) ◽  
pp. 461-467 ◽  
Author(s):  
M. W. Humphreys ◽  
S. J. Dalton
Keyword(s):  
Cell Suspension ◽  
Festuca Arundinacea ◽  
Lolium Multiflorum ◽  
Chromosome Instability ◽  
Chromosome Loss ◽  
Somatic Recombination ◽  
Regenerated Plants ◽  
A Cell ◽  
Homoeologous Chromosomes ◽  
Culture Phase

Plants were regenerated from a cell suspension from shoot-tip derived callus of a pentaploid Lolium multiflorum (2n = 4x = 28) × Festuca arundinacea (2n = 6x = 42) in which a set of five homologous and homoeologous chromosomes were marked at the PGI/2 locus by distinct alleles. A direct relationship was found in regenerated plants between time in cell suspension and the number of aberrations at the PGI/2 locus. These included deletion of any one, and in a few cases two, of the five PGI/2 alleles, but these were not always related to chromosome loss. In addition three different PGI/2 alleles were each rendered null in some somaclones regenerated last from the cell suspension. While bivalent and trivalent frequency remained unaltered in the regenerated plants compared with the original hybrid, univalent frequency decreased. Chromosome configurations of four or more chromosomes, which probably represent intergeneric chromosome pairing, were significantly increased in the regenerated plants compared with the original hybrid and were negatively correlated with univalents. The possible incorporation of a cell culture phase as a way of increasing intergeneric recombination between L. multiflorum and F. arundinacea chromosomes in a conventional breeding program is discussed.Key words: Festuca–Lolium, somaclonal variation, phosphoglucoisomerase (PGI/2), chromosome instability, somatic recombination.

scholarly journals Extraordinary genome instability and widespread chromosome rearrangements during vegetative growth

2018 ◽  
Author(s):  
Mareike Möller ◽  
Michael Habig ◽  
Michael Freitag ◽  
Eva H. Stukenbrock
Keyword(s):  
Incubation Temperature ◽  
Genome Instability ◽  
Pathogenic Fungus ◽  
Chromosome Instability ◽  
Chromosome Breakage ◽  
Chromosome Loss ◽  
In Planta ◽  
Zymoseptoria Tritici ◽  
Accessory Chromosomes

AbstractThe haploid genome of the pathogenic fungusZymoseptoria triticiis contained on “core” and “accessory” chromosomes. While 13 core chromosomes are found in all strains, as many as eight accessory chromosomes show presence/absence variation and rearrangements among field isolates. We investigated chromosome stability using experimental evolution, karyotyping and genome sequencing. We report extremely high and variable rates of accessory chromosome loss during mitotic propagationin vitroandin planta. Spontaneous chromosome loss was observed in 2 to >50 % of cells during four weeks of incubation. Similar rates of chromosome loss in the closely relatedZ. ardabiliaesuggest that this extreme chromosome dynamic is a conserved phenomenon in the genus. Elevating the incubation temperature greatly increases instability of accessory and even core chromosomes, causing severe rearrangements involving telomere fusion and chromosome breakage. Chromosome losses do not impact the fitness ofZ. tritici in vitro, but some lead to increased virulence suggesting an adaptive role of this extraordinary chromosome instability.

scholarly journals Multivariate analysis as a tool for measuring the stability of morphometric traits in Lycopersicon plants from in vitro culture

2000 ◽  
Vol 23 (2) ◽  
pp. 479-493 ◽  
Author(s):  
Guillermo Pratta ◽  
Roxana Zorzoli ◽  
Liliana Amelia Picardi
Keyword(s):  
Multivariate Analysis ◽  
In Vitro Culture ◽  
Principal Component ◽  
Eigenvalues And Eigenvectors ◽  
Morphometric Traits ◽  
Regenerated Plants ◽  
Phenotypic Structure ◽  
Regeneration Cycle ◽  
The Stability

The phenotypic stability of morphometric traits in Lycopersicon spp. (stem perimeter at the base, middle and top, and number of flowers per cluster) was measured by multivariate analysis through a progeny test in order to estimate the genetic stability of these traits. Principal components were calculated for two groups of Lycopersicon spp., non-regenerated plants and the progeny of regenerated plants. Analysis of variance was performed to support principal component analysis. Both groups presented similar eigenvalues and eigenvectors, while no significant differences were found between any of the traits studied. These results indicated that the phenotypic structure was the same among the progeny of regenerated and non-regenerated plants, so that no variation would occur in in vitro culture. Multivariate analysis proved to be an appropriate methodology for the measurement of the stability of morphometric traits after one regeneration cycle.

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