Interstitial chiasmata and centromere orientation in heterozygotes for a translocation in rye

Genome ◽  
1987 ◽  
Vol 29 (4) ◽  
pp. 647-657 ◽  
Author(s):  
P. G. Goicoechea ◽  
A. Roca ◽  
T. Naranjo ◽  
R. Giraldez
Keyword(s):  
Key Words ◽  
Secale Cereale ◽  
Chiasma Frequency ◽  
Recombination Fraction ◽  
Translocation Breakpoint ◽  
Meiotic Behaviour ◽  
Significant Excess ◽  
Alternate Orientation ◽  
Chiasma Interference ◽  
Metaphase I

The meiotic behaviour of plants heterozygous for translocation T242W of rye (involving 2RL and 6RL) and an interstitial C-band in 2RL has been analyzed. Chain and frying pan quadrivalents predominate. The following results have further been obtained: (i) double chiasmata occur in the interstitial segment carrying the C-band; (ii) from the frequency of being bound at metaphase I and the frequency of recombinant chromosomes at anaphase I, estimates of chiasma frequencies (and chiasma interference) in interstitial segments have been derived; (iii) estimates of the recombination fraction between the interstitial C-band and the translocation breakpoint have been obtained from offspring analysis; (iv) there is a difference in the frequency of alternate orientation between configurations with and without interstitial chiasmata (adjacent-2 has not been observed and a small but significant excess of alternate vs. adjacent-1 coorientation appears). Without intersitial chiasmata, alternate orientation predominates. The possible reasons for these differences are discussed. Key words: Secale cereale, translocations, chiasma frequency, centromere orientation.

Relation between loss of chromosome associations at metaphase I and interference estimates in rye

Genome ◽  
1988 ◽  
Vol 30 (1) ◽  
pp. 19-24
Author(s):  
A. Roca ◽  
T. Naranjo ◽  
P. G. Goicoechea ◽  
R. Giraldez
Keyword(s):  
Secale Cereale ◽  
Translocation Breakpoint ◽  
Negative Interference ◽  
Secale Cereale L ◽  
Chromosome Associations ◽  
I Cells ◽  
Chiasma Interference ◽  
Metaphase I

Interference between metaphase I associations (bonds) in specific segments of the chromosomes involved in translocation T242W of rye has been studied. Different values of coincidence were obtained at mid- and late metaphase I for all segment pairs analyzed. At mid-metaphase I there is negative interference between segments opposite to the translocation breakpoint and there is no cross-centromere interference. At late metaphase I there is negative interference in all these segment pairs. The comparison between mid- and late metaphase I cells also indicated that the frequency with which some of these segments are associated decreases along this stage. The possible causes of this decrease and its relation to the differences in coincidence estimates are discussed.Key words: Secale cereale L., translocations, chiasma interference.

Evidence of nonchiasmate bonds at metaphase I in inbred rye

1984 ◽  
Vol 26 (4) ◽  
pp. 409-414 ◽  
Author(s):  
M. C. Cermeño ◽  
J. Orellana ◽  
J. R. Lacadena
Keyword(s):  
Secale Cereale ◽  
Chiasma Frequency ◽  
Meiotic Pairing ◽  
Secale Cereale L ◽  
Chromosome 1R ◽  
Metaphase I

The loss of bound chromosome arms through early, middle, and late metaphase I has been analyzed in a plant of inbred rye (Secale cereale L.) heterozygous for a terminal heterochromatic C-band of the long arm of chromosome 1R. From the increase in the number of univalent pairs due to bound arm loss, and from the comparison between the frequencies of bound arms at metaphase I and recombinant chromosomes at anaphase I, it is concluded that some of the chromosome bonds appearing at metaphase I are actually nonchiasmate associations that can be considered as remnants of prophase pairing. Conclusions concerning recombination obtained solely from the analysis of chiasma frequency measured as bound arms may be invalid.Key words: inbred rye, C-heterochromatin, meiotic pairing, nonchiasmate bonds.

Relationship between pachytene synapsis, metaphase I associations, and transmission of 2B and 4B chromosomes in rye

Genome ◽  
2000 ◽  
Vol 43 (2) ◽  
pp. 232-239 ◽  
Author(s):  
Guillermo Jiménez ◽  
Silvia Manzanero ◽  
María J Puertas
Keyword(s):  
Secale Cereale ◽  
Maternal Effect ◽  
Chiasma Frequency ◽  
Transmission Rate ◽  
Chiasma Formation ◽  
B Chromosomes ◽  
Bivalent Formation ◽  
The Relationship ◽  
Variable Efficiency ◽  
Metaphase I

2B rye plants selected for high (H) or low (L) B transmission rate were studied at pachytene and metaphase I of meiosis to determine the relationship between synapsis, bivalents at metaphase I, and B transmission rate. The results show that the 2 B chromosomes (Bs) form bivalents at pachytene in both the H and L lines, whereas the frequency of bivalents at metaphase I is much higher in the H than in the L line. This demonstrates that B transmission is mainly related to the proper association of Bs at metaphase I, as well as that synapsis of the 2 Bs in the L line is normal, but the bivalent is not consolidated by a chiasma in most cases. Crosses were made between 2B plants of the H and L lines in all combinations (H × H, H × L, L × H, and L × L) to obtain 4B plants. Similarly, bivalent formation at pachytene and metaphase I was studied. The results show that 4B plants of the H × H and L × L classes differ significantly at pachytene and metaphase I since the former forms more bivalents. The heterozygous 4 Bs of the H × L and L × H classes show intermediate values. The relation H × H > H × L > L × H > L × L was consistently found for the variables transmission rate, bivalents at pachytene, bivalents at metaphase I, and B mean chiasma frequency. A maternal effect was also found. Our data suggest that there are two separate mechanisms acting upon synapsis and chiasma formation in H and L B chromosomes: (i) there is variable efficiency of the control of synapsis at early stages of meiosis; and (ii) there is variable efficiency of the control of the number of chiasmata. Key words: B chromosomes, synaptonemal complex, Secale cereale.

Synaptic abnormalities in spread nuclei of Secale. I. Inbred lines

Genome ◽  
1995 ◽  
Vol 38 (4) ◽  
pp. 764-771 ◽  
Author(s):  
M. Martínez ◽  
C. Cuadrado ◽  
C. Romero
Keyword(s):  
Complex Formation ◽  
Synaptonemal Complex ◽  
Secale Cereale ◽  
Inbred Lines ◽  
Meiotic Behaviour ◽  
Synaptonemal Complex Formation ◽  
Metaphase I

The meiotic behaviour at metaphase I of two inbred lines of Secale cereale showed a decrease in the frequency of bound arms and the presence of univalents. The study of synaptonemal complex formation revealed that these inbred lines had asynapsis and many nuclei did not complete the pairing process. Synaptic abnormalities such as fold-back loops, short pairing partner switches, interstitial nonhomologous pairing regions, and asynchrony between bivalents were associated and correlated with interlocking. It is suggested that the asynapsis is due to a failure in the interlocking repair. All these abnormalities could affect the formation and maintenance of chiasmata and so could explain the metaphase I behaviour of these inbred lines and the differences between them.Key words: inbred lines, Secale cereale, synaptonemal complex, spreading, synaptic abnormalities.

Genetics and cytology of unreduced gametes in cultivated rye (Secale cereale L.)

Genome ◽  
1987 ◽  
Vol 29 (4) ◽  
pp. 635-638 ◽  
Author(s):  
T. Lelley ◽  
A. A. Mahmoud ◽  
V. Lein
Keyword(s):  
Key Words ◽  
Genetic Control ◽  
Inbred Line ◽  
Secale Cereale ◽  
Chiasma Frequency ◽  
Unreduced Gametes ◽  
Recessive Trait ◽  
Secale Cereale L ◽  
The Cross

An inbred genotype of cultivated rye was found that produces unreduced gametes in a very regular fashion. In the cross progeny of this line with another inbred line, which did not show unreduced gametes, the inheritance of this phenomenon was studied. The formation of unreduced gametes appears to be a recessive trait controlled by more than one gene. Chiasma frequency in 4n PMCs is exactly twice that in 2n PMCs. In first metaphase of 4n PMCs only bivalents (no multivalents) were seen. The possible mechanism leading to unreduced gametes and its evolutionary implications are discussed. Key words: rye, unreduced gametes, polyploidy, genetic control, chiasma frequency.

Rye C-banding patterns and meiotic stability of hexaploid triticale (× Triticosecale) selections differing in kernel shriveling

Genome ◽  
1990 ◽  
Vol 33 (5) ◽  
pp. 686-689 ◽  
Author(s):  
Charles M. Papa ◽  
R. Morris ◽  
J. W. Schmidt
Keyword(s):  
Secale Cereale ◽  
Chromosome Banding ◽  
Agronomic Performance ◽  
Hexaploid Triticale ◽  
Kernel Development ◽  
Banding Patterns ◽  
C Banding ◽  
Meiotic Stability ◽  
Metaphase I

Two winter hexaploid triticale populations derived from the same cross were selected on the basis of grain appearance and agronomic performance. The five lines from 84LT402 showed more kernel shriveling than the four lines from 84LT401. The derived lines were analyzed for aneuploid frequencies, rye chromosome banding patterns, and meiotic stability to detect associations with kernel development. The aneuploid frequencies were 16% in 84LT401 and 18% in 84LT402. C-banding showed that both selection groups had all the rye chromosomes except 2R. The two groups had similar telomeric patterns but differed in the long-arm interstitial patterns of 4R and 5R. Compared with lines from 84LT402, those from 84LT401 had significantly fewer univalents and rod bivalents, and more paired arms at metaphase I; fewer laggards and bridges at anaphase I; and a higher frequency of normal tetrads. There were no significant differences among lines within each group for any meiotic character. Since there were no differences within or between groups in telomeric banding patterns, the differences in kernel shriveling and meiotic stability might be due to genotypic factors and (or) differences in the interstitial patterns of 4R and 5R. By selecting plump grains, lines with improved kernel characteristics along with improved meiotic stability are obtainable.Key words: triticale, meiotic stability, C-banding, Secale cereale, heterochromatin.

Persisting demibivalents: a unique meiotic behaviour in Cuscuta babylonica Choisy

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 63-66 ◽  
Author(s):  
Batia Pazy ◽  
Uzi Plitmann
Keyword(s):  
Key Words ◽  
Chromosome Segregation ◽  
Meiotic Behaviour ◽  
Chromosome Behaviour ◽  
Chromosome Movement ◽  
Pollen Mother Cells ◽  
Key Words Meiosis ◽  
Mother Cells ◽  
Telomeric Association

Idiosyncratic chromosome behaviour during meiosis was found in pollen mother cells of Cuscuta babylonica Choisy, a thread-like holoparasitic herb. Its main features are among the following: (i) telomeric association between homologues through most stages of the process, which leads to persisting chromatid bivalents (= "demibivalents"); (ii) uncommon chromosome segregation in first and second anaphase; and (iii) prolonged intensified heterochromatinization. Although "regular" in its own way, this process leads to the formation of unviable products. Its further investigation might contribute to our understanding of the role of the spindle and chromosome movement in the ordinary process of meiosis. Key words: meiosis (abnormal), persisting demibivalents, Cuscuta babylonica.

The orientation behaviour of multiple chromosome configurations in acridid grasshoppers

Genome ◽  
1987 ◽  
Vol 29 (2) ◽  
pp. 292-308 ◽  
Author(s):  
B. John
Keyword(s):  
Key Words ◽  
Reciprocal Translocation ◽  
Chiasma Frequency ◽  
The Other ◽  
Robertsonian Fusion ◽  
Orientation Behaviour ◽  
Chiasma Distribution ◽  
First Time ◽  
Existing Data ◽  
Combined Data

The existing data on the behaviour of multiple chromosome configurations arising from single interchanges between either metacentric–telocentric or telocentric–telocentric nonhomologues in 10 species of acridid grasshoppers are compared with data from four new cases. Two of these new cases involve metacentric–telocentric exchanges but the other two, for the first time in acridids, deal with a reciprocal translocation between two nonhomologous metacentrics. The combined data are used to evaluate the factors that influence multiple orientation in this family of grasshoppers and reemphasize the importance of chiasma frequency and chiasma distribution for multiple behaviour. This conclusion is reinforced by a consideration of the known cases of chain of three multiples originating from the Robertsonian fusion of nonhomologous telocentrics in acridoids. Key words: acridid grasshoppers, multiple chromosome configurations, chiasma distribution, orientation behaviour.

The effect of genotype × cytoplasm interaction on meiotic behaviour of maize chromosomes

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 653-658 ◽  
Author(s):  
M. M. Kruleva ◽  
A. B. Korol ◽  
T. G. Dankov ◽  
V. G. Skorpan ◽  
I. A. Preygel
Keyword(s):  
Cytoplasmic Male Sterility ◽  
Male Sterility ◽  
Relative Stability ◽  
Chiasma Frequency ◽  
Chiasma Formation ◽  
Meiotic Behaviour ◽  
Male Sterile ◽  
Maize Hybrids ◽  
Male Sterile Cytoplasm ◽  
Cytoplasmic Sterility

The effect of four isogenic cytoplasmic types, normal, Salvador, Texas, and Charrua (the latter three causing male sterility), on the process of chiasma formation has been studied using two different maize hybrids. The cytoplasmic male sterility determinants have been shown to reduce the rate of interstitial exchanges per nucleus and per bivalent and the frequency of univalents. Increased variation between plants and relative stability of the intercellular variation within a plant have been observed for the parameters studied. It is concluded that the determinants of cytoplasmic sterility lower the probability of additional exchanges (relative to the obligate one) and reduce the frequency of premature disruption of one-exchange chromosome associations.Key words: maize, chiasma frequency, male sterile cytoplasm, univalent formation, genotype × cytoplasm interaction.

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