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  • 1
    Electronic Resource
    Electronic Resource
    Early post-pollination events in hexaploid wheat × maize crosses (1990)
    Springer
    Sexual plant reproduction 3 (1990), S. 70-76 
    Details
    ISSN: 1432-2145
    Keywords: Wheat ; Maize ; Hybridization ; Fertilization ; Karyogamy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cytological events in the first 12 h after pollination were studied in crosses between the hexaploid wheat genotype Chinese Spring and the maize genotype Seneca 60. A pollen tube was first observed in the embryo sac 4 h after pollination, and maize sperm nuclei were first observed in the embryo sac after 5 h. On 29 occasions two, and on 1 occasion three, pollen tubes penetrated the embryo sac. Four categories of aberration limiting the frequency of fertilization were identified: (1) in 20% of florets no pollen tube reached the embryo sac; (2) in at least 1.9% the pollen tube severely damaged the wheat egg cell and polar nuclei; (3) in 33% the maize sperm nuclei were not released from the pollen tube; and (4) in 16% the sperm nuclei were released into the embryo sac but failed to move to either of the wheat gametes. In the remaining 29% sperm nuclei were more often found in the egg cell than at the polar nuclei. The results suggest that karyogamy occurs with very high efficiency when a sperm nucleus reaches the egg cell, but with only about 50% efficiency when a sperm nucleus reaches the polar nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00189954
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  • 2
    Electronic Resource
    Electronic Resource
    Comparative responses of tetraploid wheats pollinated with Zea mays L. and Hordeum bulbosum L. (1994)
    Springer
    Theoretical and applied genetics 87 (1994), S. 673-680 
    Details
    ISSN: 1432-2242
    Keywords: Triticum turgidum ssp. durum ; Durum wheat x maize ; Durum wheat x H. bulbosum ; Pollen tubes ; Haploids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ten different tetraploid wheat (Triticum turgidum) genotypes were pollinated with maize (Zea mays). Fertilization was achieved in all ten genotypes and no significant difference in fertilization frequency between the tetraploid wheat genotypes was detected. A mean of 41.1% of pollinated ovaries contained an embryo. All these crosses were characterized by the elimination of the maize chromosomes, and the resulting embryos were haploids. Six of the tetraploid wheat genotypes were also pollinated with Hordeum bulbosum. Fertilization frequencies with H. bulbosum were much lower (mean=13.4%), and significant differences between the tetraploid wheat genotypes were detected. Observation of pollen tube growth revealed that part of the incompatibility reaction between tetraploid wheats and H. bulbosum was due to an effect similar to that of the Kr genes, namely pollen tube growth inhibition. These results indicate that pollinations with maize may have potential as a broad spectrum haploid production system for tetraploid wheats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222892
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  • 3
    Electronic Resource
    Electronic Resource
    Parental genomes are separated throughout the cell cycle in a plant hybrid (1991)
    Springer
    Chromosoma 101 (1991), S. 206-213 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The positions of the genomes originating from each parent were analysed in root-tip nuclei of the mature, sexual F1 hybrid plant Hordeum vulgare (barley) x Secale africanum (a wild rye). The two genomes of the hybrid were identified in both spread and sectioned material by non-radioactive DNA:DNA in situ hybridization using labelled total genomic DNA from one parent as a proble and unlabelled total genomic DNA from the other parent to block non-specific hybridization. Complete three-dimensional reconstructions of sets of labelled sections enabled detailed analysis of the position of the genomes at interphase. The parental genomes lay in various non-intermixed configurations, including lateral and concentric arrangements. On spread preparations, the two parental genomes were found to be spatially separated throughout the cell cycle; the genome originating from H. vulgare tended to be located more centrally than that from S. africanum. This results show that the nucleus is spatially organized above the level of the DNA and chromosome at the genome level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365152
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  • 4
    Electronic Resource
    Electronic Resource
    Nucleolar organizers and fibrillar centres in Triticum aestivum L., cv. Chinese spring (1982)
    Springer
    Chromosoma 87 (1982), S. 447-459 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Serial sectioning of wheat roots prepared for electron microscopy was used to count the number of fibrillar centres per nucleus and nucleolus and to calculate their sizes. After growth at 35 ° C for two days the nucleoli became segregated and a one to one relationship was evident between chromosomal nucleolar organizers and fibrillar centres. This was confirmed using an aneuploid line carrying an additional pair of organizers. Quantitative studies showed that the fibrillar centres occupied a volume 0.24% of the total chromatin reticulum. From this it was calculated that only about 1/3 of the fibrillar centre material was likely to be nucleolar organizer chromatin. The other material was considered to be the protein revealed in silver staining studies. The importance of this was shown by its constant ratio to the size of all nucleoli in a given nucleus. — Evidence was found for the movement and fusion of organizer flanking regions during growth at 35 ° C. The number of junctions between chromatin and nucleolar organizers drops by about half giving one per organizer after segregation, and serial sectioning demonstrated such junctions in close proximity, an arrangement suggestive of incipient fusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333466
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  • 5
    Electronic Resource
    Electronic Resource
    Somatic deletion and redistribution of telomeric heterochromatin in the genus Secale and in Triticale (1983)
    Springer
    Chromosoma 88 (1983), S. 293-298 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract C-banding analysis of populations of Secale kuprijanovii L., S. cereale L., and x Triticosecale Wittmack established that Secale chromosomes that were modified by the loss of a telomeric C-band arose spontaneously by breakage in somatic tissue and could be stabilized and maintained over at least two generations. In S. cereale approximately double-sized C-bands were seen on every arm that originally contained a C-band except 1RS, 2RS, 3RS, and 7RS. One plant was homomorphic for an amplified band on 3RL which was stable over two generations. In the tetraploid triticale analyzed, an amplified telomeric C-band was found on 5RS and was stable in the homomorphic condition for two generations. Even though Secale chromosomes with deleted or amplified telomeric C-bands can arise spontaneously in the somatic and germ tissue of Secale species and triticale, they are not common. The conditions required for their formation and stabilization within a population are not known.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292906
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  • 6
    Electronic Resource
    Electronic Resource
    Replicon size and mean rate of DNA synthesis in rye (Secale cereale L. cv. Petkus Spring) (1982)
    Springer
    Chromosoma 86 (1982), S. 115-122 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Chromosomal DNA replication was investigated in root meristem cells of Secale cereale L. cv. Petkus Spring using DNA fibre auto-radiography. At 23 ° the mean rate of replication, per single replicon fork, was 12.1 μm/h. Replicon size was between 20–25 μm. These results are compared with corresponding measurements for other angiosperm species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330733
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  • 7
    Electronic Resource
    Electronic Resource
    “Cuckoo” Aegilops addition chromosome in wheat ensures its transmission by causing chromosome breaks in meiospores lacking it (1984)
    Springer
    Chromosoma 90 (1984), S. 84-88 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In monosomic additions of Aegilops sharonensis to Chinese Spring wheat (2n=42 wheat chromosomes + 1 homoeologous group 4 Aegilops chromosome known as 4S1), probably all functional gametes carried one Aegilops chromosome. Such preferential transmission is unusual in monosomic alien additions. Male and female meiosis seemed usually normal, but about 75% of embryo sacs and 28% of pollen grains were visibly abnormal near anthesis. Before the first gametophyte mitosis, up to about 13% of megaspores and pollen grains showed abnormalities usual in wheat aneuploids. However, in first mitosis, 50% of megaspores at metaphase and anaphase and 41% of pollen grains at anaphase and telophase contained acentric chromosome (or chromatid) segments of various sizes, up to about 32 in a cell, which were separated from the rest of the chromosome (or chromatid) by a gap or a thin Feulgen-positive thread. Such separated segments (SSs) are not normally seen in wheat and its aneuploids. The data indicat that alien and wheat chromosomes interact in meiocytes so that meiospores with the alien chromosome develop into normal gametophytes, but meiospores lacking the alien chromosome have SSs at first mitosis by whose loss or unequal distribution between daughter nuclei sterilizing deficiencies arise. Thus only gametophytes with the alien chromosome are competent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00352282
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  • 8
    Electronic Resource
    Electronic Resource
    The karyotype of tuleen 346 barley (1982)
    Springer
    Theoretical and applied genetics 62 (1982), S. 53-58 
    Details
    ISSN: 1432-2242
    Keywords: Barley ; Interchange ; C-banding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tuleen 346 barley is a triple homozygote for 3 unequal interchanges, T1-5v, T2-6y and T3-7d, which were induced independently in the variety, ‘Bonus’. It has great potential value in studying differences in behaviour and position among chromosomes within the same cell in barley and its hybrids since at least 5 and usually all 7 chromosome types can be identified in Feulgen preparations, compared with only 3 types in normal barley. Measurement of chromosome arm and satellite lengths in 10 haploid root-tip metaphases showed that in all comparisons except of the longest with the next longest, the 7 chromosome types were distinct in total length (P〈0.001–0.05) and in 8 of the 10 cells, the longest chromosome had a smaller arm ratio than the next longest. In these preparations, each of the 5 shortest chromosomes was easily identifiable by size and morphology. The longest chromosome was about 2.2 times as long as the shortest. C-banding showed that each of the 7 chromosome types had a clearly unique band pattern. The C-band patterns of interchange chromosomes confirmed and increased the precision of previously published breakpoint locations, viz. the short arms of chromosomes 1, 2, 3 and 7 and the long arms of chromosomes 5 and 6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276283
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  • 9
    Electronic Resource
    Electronic Resource
    Preferential C-banding of wheat or rye chromosomes (1982)
    Springer
    Theoretical and applied genetics 63 (1982), S. 227-233 
    Details
    ISSN: 1432-2242
    Keywords: C-banding ; Wheat ; Rye ; Triticale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using different stains, wheat chromosomes could be distinguished from rye chromosomes by preferential staining. C-bands of rye chromosomes were preferentially stained with Giemsa while those of wheat chromosomes were preferentially stained with either Leishman or Wright stain. Preferential staining aids the identification of wheat and rye chromosomes and chromosome segments and in particular the recognition of wheat/rye chromosome substitutions and translocations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304000
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  • 10
    Electronic Resource
    Electronic Resource
    Development and characterisation of a line of bread wheat, Triticum aestivum, which lacks the short-arm satellite of chromosome 1B and the Gli-B1 locus (1984)
    Springer
    Theoretical and applied genetics 68 (1984), S. 327-334 
    Details
    ISSN: 1432-2242
    Keywords: Gliadin ; Triticum ; Polyacrylamide gel-electrophoresis ; Light and electron microscopy ; Chromosome deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary About 360 offspring of a tri-parental cross were screened by gel electrophoresis and unexpectedly one of them did not contain chromosome 1B ω-gliadins derived from either of the primary parents. A line disomic for the ω-gliadin null was developed from the surviving embryo half of the unique grain. Two dimensional electrophoresis revealed that all the storage protein genes at Gli-B1, coding for γ-gliadins, β-gliadins and low-molecular-weight subunits of glutenin as well as the ω-gliadin, were not expressed. The nuclei of dividing root-tip cells were shown by light microscopy to lack the normal short-arm satellites of chromosome 1B, indicating that the genes for the missing storage proteins had been lost through a terminal deletion. Using a radioactive ribosomal RNA probe, the deficient 1B chromosomes were shown to contain ribosomal RNA genes demonstrating that at least two-thirds of the short arm was still present. Examination of serial sections of chromosome 1B at metaphase by low-power electron microscopy showed that the point of scission of this chromosome was within the secondary constriction where the ribosomal RNA genes are located. The Gli-B1 locus must therefore be carried on the short-arm satellite. Transmission of the deficient chromosome from female gametes to progeny was normal (i.e., about 50%) but from pollen it was poor (8.8%). Recombination mapping indicated that the distance from the ribosomal RNA genes (Nor1) to Glu-B1 was 22 cM, equivalent to 13 cM from Nor1 to the centromere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00267886
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