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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 22 (1973), S. 8-18 
    ISSN: 1573-5060
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Meiosis in triploid Solanum tuberosum was studied in plants that originated from crosses between tetraploids and diploids, the latter being mainly dihaploids. Association of chromosomes in first metaphase was regular, being as expected for autotriploid material. In first anaphase lagging chromosomes occurred that mostly divided precociously into their chromatids, the amount of lagging chromosomes being more or less proportional to the average number of univalents at M I. The A I distribution of chromosomes over the poles fitted a normal distribution. In the second meiotic division also lagging chromosomes were observed. During this division disturbances occurred resulting in cells with more or less the somatic chromosome number. The origin of this aberration is discussed, together with the relation between meiotic behaviour and pollen stainability.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 28 (1979), S. 633-642 
    ISSN: 1573-5060
    Keywords: Solanum tuberosum Group Tuberosum ; trisomic series ; chromosome identification ; trivalent configurations ; pachytene analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary By means of pachytene analysis 11 of the 12 possible types of primary trisomics of diploid S. tuberosum have been identified. The typical trivalent configurations for each chromosome are illustrated. Triplo-4,5,7 and 9 occurred more frequently whereas triplo-1 is still lacking in the series. Some of the features of trivalent associations at pachytene are discussed, as also the fact that in the present study only primary trisomics have been found.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 39 (1988), S. 159-167 
    ISSN: 1573-5060
    Keywords: Solanum tuberosum ssp. phureja ; interchange ; inversion loop ; chromosome identification ; trisomics ; pachytene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Meiosis was studied from pachytene and onwards in two clones of S.t. ssp. phureja. At pachytene the bivalents of S.t. ssp. phureja appeared to be morphologically very similar to those of S.t. ssp. tuberosum cv. Gineke. Cross-shaped quadrivalent configurations at pachytene confirmed the presence of a heterozygous interchange. From the configurations at pachytene it was identified that the short arm of chromosome 3 and possibly one of the arms of chromosome 12 was involved in the interchange. In addition, several abnormalities were observed: these included the occurrence of loops in eu- and heterochromatic parts, non-homologous pairing and centromere associations between different bivalents.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 24 (1975), S. 731-741 
    ISSN: 1573-5060
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Trisomic cytotypes were produced in dihaploid (diploid) plants of Solanum tuberosum L. Group Tuberosum, the common potato, according to two methods. Firstly, the aberrant types were selected, through chromosome counting, from parthenogenic dihaploid offspring of tetraploid-diploid crosses. In dihaploid populations from twelve tetraploid potato varieties the frequencies of aneuploids ranged from 3.5 to 11.0%. About 95% of these aneuploids had only one, and the others not more than two extra chromosomes. Secondly, the aneuploids were produced from triploid-diploid crosses. Seedset strongly depended on the crossability of the parental plant material, and the best results were obtained when the motherplants were grafted onto tomato. On avarage the three most successful cross combinations resulted in approximately 0.7 berries per pollination and 6 seeds per berry. With regard to seedsize the seed could be divided in two groups, viz, normal and small seeds. Half of the seed did not germinate or produced inviable seedlings, especially among the small seed group. About 93% of the plants was neuploid, with 25, 26 and 27 being the predominant chromosome number. It was concluded that the production of trisomics was the most successful through triploid-diploid crosses. The results were discussed with reference to the chromosomal behaviour in the meiosis in triploid plants (Lange & Wagenvoort, 1973a). It thus was possible to relate the low seedset to the distribution of chromosomes in the meiotic anaphases. On the one side this distribution resulted in a limitation of the avalability of gametes with monohaploid and near-monohaploid chromosome numbers, while on the other side the macrospores with higher chromosome numbers seemed to be inviable. Finally a crossing scheme was presented for transmitting the trisomic condition into a genetic background with better homogeneity and more homozygosity.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 25 (1976), S. 233-240 
    ISSN: 1573-5060
    Keywords: Solanum tuberosum group tuberosum ; dihaploid ; trisomic series ; chromosome identification, pachytene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The morphology of 12 pachytene bivalents of the dihaploid Solanum tuberosum cv. Gineke is described, and the morphological features which are helpful for a critical chromosome identification are illustrated. The difficulties of identifying the individual chromosomes and the extra chromosomes in trisomics are discussed.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 29 (1980), S. 281-293 
    ISSN: 1573-5060
    Keywords: Solanum tuberosum Group Tuberosum ; potato ; trisomics ; fertility ; plant morphology ; transmission rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Initial single and double trisomics of S. tuberosum Group Tuberosum cv. Gineke were successfully crossed with and backcrossed to clones obtained through inbreeding of self-compatible dihaploids of the same variety. Some trisomics showed reduced flowering or flower abnormalities and contributed therefore only to a small extent. Berry-set and seed-set varied considerably. There was no relation between these phenomena, nor was there any relation between either berry-or seed-set and the identity of the extra chromosome in the female parent. Seed-set seemed to be influenced by the male parent. When a more inbred male parent was used in the crosses with trisomics this often resulted in less seed per cross. There was no clear relation between seed-set and stainability of the pollen grains, but both the strong selection for good pollen and the high level of self-compatibility, have apparently contributed to the success of the crosses. The double trisomic plants yielded less seed than most single trisomics. Only three of the single trisomics produced stainable pollen and two of them yielded progeny when used as male parent in crosses or selfings. In the progenies several of the trisomic types could be distinguished on the basis of plant morphology in the young seedling stage. For ten different trisomics the morphotype is being described. The average rate of female transmission of the extra chromosome was about twenty per cent, but there was a wide variation, both between and within the various trisomic types. The results indicated that for chromosomes 3 and 8 the rate of transmission was higher than the average value. In one out of two trisomic types male transmission of the extra chromosome occurred, with a rate of 4.7%. The possible causes for the observed differences in female transmission of the extra chromosome are being discussed.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 75 (1988), S. 712-716 
    ISSN: 1432-2242
    Keywords: Solanum tuberosum ; Potato ; Trisomics ; Gene location ; Topiary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seven out of twelve possible types of primary trisomies of dihaploid S. tuberosum were crossed as females with a disomic recessive mutant for topiary (tp tp) identified in S. infundibuliforme. All primary trisomics used proved to be homozygous dominant. Trisomic plants from the seven F1's were crossed with a disomic heterozygous F1 plant (supposed genotype Tp tp). In the half sib progeny of each trisomic type the mutant plants could be easily identified by the presence of typical lateral shoots, particularly at the cotyledonary nodes. The observed segregation ratios for normal to mutant were tested against the expected non-critical ratio 3 ∶ 1 and against various critical ratios. It is concluded that the gene tp is located on chromosome 3 of the potato.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 12 (1999), S. 43-52 
    ISSN: 1432-2145
    Keywords: Key words Apomixis ; Sexuality ; Day length ; Embryology ; Brachiaria ; Agamic complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Meiotic and aposporous embryo sacs and the initial steps of parthenogenetic embryogenesis and endosperm formation were investigated in diploid and tetraploid accessions of Brachiaria decumbens in two environments, differing mainly in day length: early summer and late autumn. Both diploid and tetraploid accessions were facultative apomicts. Di(ha)ploids showed a much lower level of apomixis (10% to15%) than tetraploids (80% to 95%). No obligate sexual diploids were found; thus, their occurrence in natural populations is obscure. It is suggested that reproduction in B. decumbens, as in other agamic complexes of the Paniceae tribe, in general, approximates a diploid-tetraploid-(di)haploid reproductive cycle which does not involve triploids. The dihaploids were fertile and survived in nature. Development of the reproductive structures depended on the environment. In autumn, in contrast to early summer, many meiotic and aposporous embryo sacs degenerated during development, leading to a significant reduction in the proportion of parthenogenetic embryos. Whether this effect can be attributed to day length or simply to age remains to be investigated. The ratio of aposporous to sexual embryo sacs was relatively stable over the two seasons.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 61 (1982), S. 239-243 
    ISSN: 1432-2242
    Keywords: Solanum tuberosum ; Trisomics ; Gene location ; Yellow margin ; Lethality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ten out of twelve primary trisomics of dip-loid S. tuberosum were crossed as females with a recessive mutant for yellow margin (ym ym) obtained from S. phureja. All primary trisomics used proved to be homozygous dominant. Trisomic plants from all ten F1's were backcrossed with the mutant and trisomics from eight F1's were crossed also with a disomic heterozygous f1 plant from triple 10 X mutant. In both BC1 and half sib progeny of each trisomic type the mutant plants were easily identified because of their typical small roundish leaflets with yellow or reddish margins. The observed segregation ratios for normal to mutant were tested against the expected non-critical ratios and against various expected critical ratios. From the results of these tests it is concluded that the gene ym is located on chromosome 12 of the potato. A hypothesis of linkage between ym and a gene l x for lethality is put forward. It is concluded that l x is not identical with a previously detected recessive gene l 2 which is responsible for yellow cotyledons and lethality.
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