Fig 3 - uploaded by Olga G Silkova
Content may be subject to copyright.
A behavior of chromosomes 6R and 6A at the late anaphase II of meiosis. (a)-single chromatids nonnincluded into nuclei. (b)-chromatid located across the equator during the fragmoplast formation.
Source publication
The effect of wheat-rye chromosome 1Rv/1A, 2R/2D and 6R/6A substitutions characterized by differences in the expression of the equational division of sister centromeres in anaphase I on segregation and the elimination of wheat and rye univalents was investigated. To determine the individual effect of each of the studied chromosomal pairs, a compara...
Contexts in source publication
Context 1
... reveal the individual impact of each of the inves tigated chromosomal pairs, a comparison of the univa lent chromosomal behavior in the meiosis of dii and tetramonosomics was conducted. Univalent chromosomal behavior in the meiosis of dimonosomics 1Rvv1A, 2RR2D, 6RR6A. Each PMC analyzed at the MI stage was characterized by the presence of two univalents in dimonosomics: rye and wheat chromosomes. Univalent chromosomes were located randomly near the cell poles or on the equatoo rial plane, together with bivalents ( Fig. 2a). Subsee quently, both univalents segregated simultaneously with bivalents at stage AI (Fig. 2b) or were detained on the cell equator (Fig. 2c). The last ones divided on the siss ter chromatids and segregated to opposite poles (Fig. 2d). Such univalent behavior was unobserved in all meioo cytes. An equatorial delay did not always result in the division into sister chromatids, the segregation of divided chromatids to the poles (Fig. 2e) or transversal division of one of chromatids (Fig. 2f). The second division was characterized by chromatid delay on the equator after the segregation of all chromosomes until late anaphase II (Fig. 3a) and the presence of single chromatids across the equator during fragmoplast forr mation (Fig. 3b). Such behavior resulted in their nonn inclusion into microspores nuclei. In the present experiment, we considered meiocytes in AI with unii valent chromosomes divided into sister chromatids and with chromatids segregated to the poles, i.e. an equational division ...
Context 2
... reveal the individual impact of each of the inves tigated chromosomal pairs, a comparison of the univa lent chromosomal behavior in the meiosis of dii and tetramonosomics was conducted. Univalent chromosomal behavior in the meiosis of dimonosomics 1Rvv1A, 2RR2D, 6RR6A. Each PMC analyzed at the MI stage was characterized by the presence of two univalents in dimonosomics: rye and wheat chromosomes. Univalent chromosomes were located randomly near the cell poles or on the equatoo rial plane, together with bivalents ( Fig. 2a). Subsee quently, both univalents segregated simultaneously with bivalents at stage AI (Fig. 2b) or were detained on the cell equator (Fig. 2c). The last ones divided on the siss ter chromatids and segregated to opposite poles (Fig. 2d). Such univalent behavior was unobserved in all meioo cytes. An equatorial delay did not always result in the division into sister chromatids, the segregation of divided chromatids to the poles (Fig. 2e) or transversal division of one of chromatids (Fig. 2f). The second division was characterized by chromatid delay on the equator after the segregation of all chromosomes until late anaphase II (Fig. 3a) and the presence of single chromatids across the equator during fragmoplast forr mation (Fig. 3b). Such behavior resulted in their nonn inclusion into microspores nuclei. In the present experiment, we considered meiocytes in AI with unii valent chromosomes divided into sister chromatids and with chromatids segregated to the poles, i.e. an equational division ...
Similar publications
An original cytogenetic study combining classical karyotype analysis and modern fluorescence in situ hybridization using telomeric (TTAGGG)n and ribosomal sequences (18S rDNA) was performed in Khawia abbottinae (Cestoda, Caryophyllidea), a parasite of Chinese false gudgeon (Abbottina rivularis) from China. Analyses based on conventional Giemsa stai...
Citations
... Most of the studies performed during meiosis in wheat plants carrying alien chromosomes are focused on meiosis metaphase I or later stages [35,46,47]. Previously, we studied interspecific chromosome associations in early meiosis stages (pachytene) and we managed to track simultaneously extra wild and cultivated barley chromosomes (for the same and for different homoeology groups) in the wheat background using in situ hybridization [21]. ...
Bread wheat is an allohexaploid that behaves as a diploid during meiosis, the cell division process to produce the gametes occurring in organisms with sexual reproduction. Knowledge of the mechanisms implicated in meiosis can contribute to facilitating the transfer of desirable traits from related species into a crop like wheat in the framework of breeding. It is particularly interesting to shed light on the mechanisms controlling correct pairing between homologous (equivalent) chromosomes and recombination, even more in polyploid species. The Ph1 (Pairing homoeologous 1) locus is implicated in recombination. In this work, we aimed to study whether homoeologous (equivalent chromosomes from different genomes) Hordeum chilense (wild barley) and H. vulgare (cultivated barley) chromosomes can associate and recombine during meiosis in the wheat background in the absence of the Ph1 locus. For this, we have developed H. chilense and H. vulgare double monosomic addition lines for the same and for different homoeology group in wheat in the ph1b mutant background. Using genomic in situ hybridization, we visualized the two (wild and cultivated) barley chromosomes during meiosis and we studied the processes of recognition, association, and recombination between homoeologous chromosomes in the absence of the Ph1 locus. Our results showed that the Ph1 locus does not prevent homoeologous chromosome pairing but it can regulate recombination.
... These double monosomic addition lines can contribute to go deeper into the knowledge of how chromosomes recognize and associate in pairs in the wheat background in the presence of the Ph1 locus. In addition, most of the works carrying alien chromosomes in the wheat background are focused in meiosis metaphase I or later stages (Molnár-Láng et al., 2000;Silkova et al., 2014). The analysis of chromosome pairing focused only in metaphase I can result in an underestimation of homoeologous associations that might occur earlier in meiosis, as chromosomes might remain mostly as univalents due to the lack of homoeologous recombination. ...
... The knowledge about univalent behavior in meiosis is necessary for the directed development of wheat lines carrying alien introgressions since univalent are subjected of incorrect division and segregation. Thus, abnormities in meiosis result in various modifications and/or in the loss of a transferred chromosome (Silkova et al., 2014). Univalents in meiosis have a tendency to misdivide (break) across their centromeres producing telocentric. ...
Understanding the system of a basic eukaryotic cellular mechanism like meiosis is of fundamental importance in plant biology. Moreover, it is also of great strategic interest in plant breeding since unzipping the mechanism of chromosome specificity/pairing during meiosis will allow its manipulation to introduce genetic variability from related species into a crop. The success of meiosis in a polyploid like wheat strongly depends on regular pairing of homologous (identical) chromosomes and recombination, processes mainly controlled by the Ph1 locus. This means that pairing and recombination of related chromosomes rarely occur in the presence of this locus, making difficult wheat breeding trough the incorporation of genetic variability from related species. In this work, we show that wild and cultivated barley chromosomes associate in the wheat background even in the presence of the Ph1 locus. We have developed double monosomic wheat lines carrying two chromosomes from two barley species for the same and different homoeology chromosome group, respectively. Genetic in situ hybridization revealed that homoeologous Hordeum chromosomes recognize each other and pair during early meiosis in wheat. However, crossing over does not occur at any time and they remained always as univalents during meiosis metaphase I. Our results suggest that the Ph1 locus does not prevent chromosome recognition and pairing but crossing over between homoeologous. The role of subtelomeres in chromosome recognition is also discussed.
... 2R chromosome (the largest in rye genome) was found to be eliminated frequently in crosses between hexaploid triticale and bread wheat (Gupta & Priyadarshan, 1982). The study of meiotic behavior of 2D and 2R in dimonosomic lines of wheat showed no pairing between them (Silkova et al., 2014). The only T2R.2DL translocation found by now, resulted from ruptures in the centromeric region followed by centric fusion and thus did not involve small chromosome segments (Krasilova et al., 2012). ...
The association between genomic constitution and agronomic traits was studied in F2 plants and F3:4 families of two crosses between a winter hexaploid triticale line with a 2D(2R) chromosome substitution and two hexaploid triticale cultivars carrying the complete rye genome (BBAARR). The analyses revealed that 2D(2R) substitution reduces plant height and spikelet number per spike, increases the 1,000-kernel weight, does not reduce grain shrivelling, and promotes early heading and anthesis. 2D(2R) substitution lines exhibit deeper postharvest seed dormancy, which provides resistance to preharvest sprouting. However, 2D(2R) substitution lines are not recommended for winter hexaploid triticale cultivar development purposes due to their reduced grain productivity.
... They found a distinct difference in the univalent transmission rate between the three cultivars, but did not find any clear association between meiotic behavior and the number of univalents transmitted. Recently, Silkova et al. (2014) analyzed the effect of six cases of the substitution of one or two wheat chromosomes by their rye homoeologues on the meiotic behavior of univalents, and found that the 2R/2D substitution suppressed the equational univalent division, whereas 6R/6A substitution resulted in a high frequency of univalent elimination. ...
In the course of reconstructing Aegilops caudata from its own genome (CC) and its plasmon, which had passed half a century in common wheat (genome AABBDD), we produced alloplasmic Ae. cylindrica (genome CCDD) with the plasmon of Ae. caudata. This line, designated (caudata)-CCDD, was found to express male sterility in its second substitution backcross generation (SB2) of (caudata)-AABBCCDD pollinated three times with the Ae. cylindrica pollen. We repeatedly backcrossed these SB2 plants with the Ae. cylindrica pollen until the SB5 generation, and SB5F2 progeny were produced by self-pollination of the SB5 plants. Thirteen morphological and physiological characters, including pollen and seed fertilities, of the (caudata)-CCDD SB5F2 were compared with those of the euplasmic Ae. cylindrica. The results indicated that the male sterility expressed by (caudata)-CCDD was due to genetic incompatibility between the Ae. cylindrica genome and Ae. caudata plasmon that did not affect any other characters of Ae. cylindrica. Also, we report that the genome integrity functions in keeping the univalent transmission rate high.
The development of bread wheat introgressions with alien genetic material from cultural and wild Triticeae species is an effective method for expanding the wheat gene pool necessary for breeding. To date, numerous collections of introgressions as substitutions and chromosome modifications have been obtained; however, the creation and study of wheat with new valuable traits still remain an important line of research. Rye Secale cereale L., whose chromosomes carry genes that control valuable economic and biological characteristics and properties, is widely used to produce new wheat forms. In this study, a wheat-rye translocation obtained by backcrossing the wheat-rye disomic-substitution line 2R(2D)1 with the variety Novosibirskaya 67 was characterized. The chromosomal composition of karyotypes was studied using fluorescent in situ hybridization and C-banding. Two centric translocations, derived from two long arms of chromosomes 2D and 2R, T2DL.2RL, were identified, the remaining 40 wheat chromosomes did not undergo modifications. Meiosis in the lines was stable. Chromosomes T2DL.2RL formed bivalents in all meiocytes, which confirmed their homology. The morphological characteristics of the spike in the T2DL.2RL line and Novosibirskaya 67 did not differ. A comparative analysis of productivity between the T2DL.2RL translocation line and the parental forms, Novosibirskaya 67 and the 2R(2D)1 line, was carried out. The T2DL.2RL line is inferior to Novosibirskaya 67 in all characters with different confidence levels. The productivity characters of the 2R(2D)1 line exceeded or did not differ from those of T2DL.2RL, however, the mass of 1000 grains was significantly lower. The results showed the effect of the T2DL.2RL translocation on the trait “plant height”. This character was significantly lower than that of Novosibirskaya 67 in two vegetation periods. Consequently, the T2DL.2RL translocation reduces plant height and productivity.
On the basis of directed chromosome substitution, ditelosomic (DT) wheat-barley substitution lines (2n = 42 = 40 + 2t) with participation of wild tetraploid barley Hordeum marinum ssp. gussoneanum Hudson (2n = 28) were first obtained and analyzed. GISH analysis of the substitution lines showed that they carried a pair of telocentric barley chromosomes. With the help of ditelosomic analysis, the lines were identified as DT7HIL mar (7A) and DT7HIL mar (7B). On the basis of the compensation test and the study of meiotic stability of substitution lines, it was demonstrated that 7HIL mar chromosome of H. marinum was homoeologous to the group 7 chromosomes of common wheat. Analysis of the gamete transfer frequency in the progeny of reciprocal hybrids between F1 7A-7HIL mar , 7B-7HIL mar , 7D-7HIL mar and Saratovskaya 29 cultivar showed that the gamete with alien chromosome n = 20 + t successfully competed with euploid gamete n = 21 in both macrosporogenesis and microsporogenesis.
