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  • 1
    Electronic Resource
    Electronic Resource
    Effect of transient oxic conditions on the composition of the nitrate-reducing community from the rhizosphere of Typha angustifolia (1992)
    Springer
    Microbial ecology 24 (1992), S. 51-61 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Within a nitrate-reducing bacterial community, a niche differentiation between denitrifying and nitrate ammonifying bacteria may be determinated by a complex of environmental parameters, such as the availability of carbon, nitrate, and oxygen. Hence, oxygen- and carbon-releasing aerenchymatous plants may affect the composition of the nitrate-reducing community in waterlogged sediment. The composition of the nitrate-reducing community in the rhizosphere of the aerenchymatous plant species Typha angustifolia was compared with the community in nonrhizospheric sediment. All three functional groups (NO2 − accumulators, N2O producers, and presumed NH4 + producers) were present at both sites with an ratio of 36:45:12 and 43:22:18 for nonrhizospheric and rhizospheric sediments, respectively. Most of the isolated were gram-negative, and approximately 50% of these strains demonstrated an obligatory oxidative metabolism. In the absence of nitrate, Enterobacteriaceae (belonging to the NO2 − accumulating group) became dominant during enrichment of bacteria from the rhizosphere of T. angustifolia in a chemostat with glycerol (20 mM) as substrate, both under strictly anoxic and transient oxic conditions. Addition of nitrate to the chemostats led to the predominance of denitrifying pseudomonads, irrespective of the presence or absence of oxygen. However, in the presence of nitrate under anoxic conditions, enterobacteria persisted in the medium together with pseudomonads. It was concluded that oxidative bacteria such as pseudomonads are the better competitors for limiting amounts of glycerol, provided oxygen or nitrate is present. In the absence of these electron acceptors, fermentative bacteria become dominant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171970
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  • 2
    Electronic Resource
    Electronic Resource
    Possibilities of avoidance and control of bacterial plant diseases when using pathogen-tested (certified) or -treated planting material (2002)
    Oxford, UK : Blackwell Science Ltd
    Plant pathology 51 (2002), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Testing of planting material for freedom from phytopathogenic bacteria is an important, although not exclusive, method for control of bacterial diseases of plants. Ideally, pathogen-free or pathogen-/disease-resistant planting material is desirable, but this situation is not always possible on a practical basis. For most bacterial pathogens, resistance is not available in cultivated hosts, and production of pathogen-free planting material requires strict certification schemes via several routes. These include (i) indexing, with subsequent removal of infected/contaminated material from the production chain; (ii) meristem and other tissue culture production systems; (iii) thermo- or chemotherapy; (iv) plant or seed surface disinfection for epiphytic bacterial pathogens; (v) avoidance or decontamination of contaminated production factors such as substrate, soil or irrigation water. These methods cannot guarantee 100% freedom from the pathogen or disease during crop multiplication from certified planting material, because of factors such as sampling error, experimental error, test sensitivities, limitations of therapies (e.g. phytotoxicity or insufficient penetration), re-introduction of the pathogen, insufficient hygiene or decontamination during planting and multiplication of clean propagating material, and manipulations during trade and production. These factors are discussed with reference to several bacterial plant diseases, in particular control of bacterial brown rot and ring rot of potato in Europe and North America. The most efficient control of bacterial diseases can be expected through a combination of the use of healthy/tested planting material and good cultivation practice, including strict crop and storage hygiene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0032-0862.2002.00756.x
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  • 3
    Electronic Resource
    Electronic Resource
    Bacterial leaf blight of strawberry (Fragaria (x) ananassa) caused by a pathovar of Xanthomonas arboricola, not similar to Xanthomonas fragariae Kennedy & King. Description of the causal organism as Xanthomonas arboricola pv. fragariae (pv. nov., comb. nov.) (2001)
    Oxford, UK : Blackwell Science Ltd
    Plant pathology 50 (2001), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A new bacterial disease of strawberry is described. This disease, called bacterial leaf blight of strawberry, is characterized by dry, brown necrotic leaf spots and large brown V-shaped lesions along the leaf margin, midrib and major veins. Symptoms are different from angular leaf spot of strawberry caused by the bacterium Xanthomonas fragariae. Strains of the bacterial leaf blight pathogen were characterized in a polyphasic approach by biochemical tests, fatty acid analysis, protein electrophoresis, serology, PCR, pigment analysis, ice-nucleation activity, AFLP analysis, DNA:DNA hybridization, pathogenicity and host range tests, and compared with a number of reference strains of X. fragariae and other Xanthomonas species. Bacterial leaf blight strains formed a homogeneous group in all tests, completely different from X. fragariae. They were the only strains causing leaf blight of strawberry upon artificial inoculation into strawberry. Fatty acid and protein electrophoretic analysis showed that the strains belong to the phenon X. campestris (sensu latu, including pathovars now classified as belonging to X. arboricola). AFLP analysis and DNA:DNA hybridization further clarified their taxonomic position as belonging to X. arboricola. The name X. arboricola pv. fragariae is proposed for the bacterium causing leaf blight of strawberry with strain PD2780 (LMG 19145) as pathovar type strain. Criteria for routine identification are given and the taxonomic status is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3059.2001.00644.x
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  • 4
    Electronic Resource
    Electronic Resource
    A Streptomyces species identified as the cause of carrot scab (1988)
    Springer
    European journal of plant pathology 94 (1988), S. 303-306 
    Details
    ISSN: 1573-8469
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Samenvatting In 1986 werd een ernstige schurft-aantasting bij peen (Daucus carota) gevonden met name in NO-Nederland. Vanuit schurftlesies werd steeds weer eenzelfde type streptomyceet geïsoleerd. In proeven met zeven isolaten van peen en één van aardappel bleek dat deze morfologisch en biochemisch sterk overeen kwamen, terwijl alle isolaten, ook dat van aardappel, pathogeen waren voor peen ‘Amsterdamse bak’. De hier onderzochte isolaten komen sterk overeen met een soort die in de literatuur bekend is alsStreptomyces scabies, de veroorzaker van aardappelschurft.S. scabies is echter een ongeldige naam door het ontbreken van een typestam. Zolang er niet een geldig neotype is gepubliceerd kan geen speciesnaam aan deze isolaten worden gegeven. Taxonomisch en nomenclatorisch onderzoek is dus gewenst, evenals onderzoek naar schade, invloed van vruchtwisseling met aardappel en/of andere gewassen en effectieve bestrijding (wellicht door beregening?) van schurft bij peen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01998056
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  • 5
    Electronic Resource
    Electronic Resource
    Male transmission of the translocated chromosome in a tertiary trisomic of rye: genetic variation and relation to the rate of development of aneuploid pollen grains (1987)
    Springer
    Theoretical and applied genetics 74 (1987), S. 317-327 
    Details
    ISSN: 1432-2242
    Keywords: Secale cereale L. ; Tertiary trisomic ; Male transmission ; Genetic variation ; Aneuploid microspores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Variation in male and female transmission of the translocated extra chromosome (5R3R) was studied in a tertiary trisomic of rye (Secale cereale L.). In two F5 lines derived from a single F4 line, female transmission was lower than in five others derived from another F4 line. This could be caused by genetic factors or by the strong inbreeding depression in these lines, leading to low viability of trisomic progeny. After selfing, male transmission was estimated as very low, but this was primarily based on the occurrence of tetrasomics that probably have a very poor viability. In testcrosses with disomic female parents, male transmission was much higher (up to 27%), without variation within F5 lines. One F5 line showed significantly higher male transmission than any of the seven tested, including a sister line from the same F4. This was consistent in the F6. Apparently high male transmission is genetically determined. There was a positive correlation with recombination of the marker ti (tigrina) on the extra chromosome and the normal 5R chromosomes. At the first meiotic metaphase, trivalents and quinquivalents were frequent in the trisomics. Assuming loss of univalents, 40% of the microspores should carry the translocated extra chromosome. In most lines, more than 40% were found at pollen mitosis. Observations on timing of pollen mitosis showed a delayed development in aneuploid spores, with clear differences between plants, but no correlation with male transmission. The cause of reduced male transmission and the expression of genetic variation therein can, therefore, not be found in meiotic behaviour or delayed microspore development. Pollen germination and tube growth may be more important.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00274713
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  • 6
    Electronic Resource
    Electronic Resource
    Generative transmission of the extra chromosome in a rye tertiary trisomic and its relation with inbreeding depression and pollen quality (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 487-493 
    Details
    ISSN: 1432-2242
    Keywords: Rye ; Tertiary trisomic ; Transmission ; Inbreeding ; Pollen quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transmission of the extra (translocated) chromosome of tertiary trisomic T282W of rye (Secale cereale L.) upon seifing, through the male and/or the female, ranged from 0% to 36% in different inbred lines. Tetrasomics arising from simultaneous male and female transmission were not recovered and thus apparently not viable. Low seed weight, poor seed germination and a low transmission rate were correlated with low seed weight and reduced plant vigour. Inbreeding depression was concluded to affect transmission rate through its effect on the relative viability of trisomic seeds or seedlings. Male transmission in testcrosses with disomics averaged 7%, but varied between lines. Genetic factors were involved, but their expression remains uncertain. Pollen quality, as determined by a fluorescence reaction, was somewhat lower in trisomics than in disomics of the same genetic background and was not correlated with male transmission rate, which appears to be determined mainly by relative pollen-tube growth of euploid and aneuploid gametophytes. The results are discussed in relation to the use of tertiary trisomics in balanced chromosomal systems for hybrid breeding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229511
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  • 7
    Electronic Resource
    Electronic Resource
    Aligning male and female linkage maps of apple (Malus pumila Mill.) using multi-allelic markers (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 60-73 
    Details
    ISSN: 1432-2242
    Keywords: Key wordsMalus pumila Mill ; Molecular linkagemap ; Marker-assisted selection ; Fruit tree breeding ; Outbred progeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Linkage maps for the apple cultivars ‘Prima’ and ‘Fiesta’ were constructed using RFLP, RAPD, isozyme, AFLP, SCAR and microsatellite markers in a ‘Prima’בFiesta’ progeny of 152 individuals. Seventeen linkage groups, putatively corresponding to the seventeen haploid apple chromosomes, were obtained for each parent. These maps were aligned using 67 multi-allelic markers that were heterozygous in both parents. A large number of duplicate RFLP loci was observed and, in several instances, linked RFLP markers in one linkage group showed corresponding linkage in another linkage group. Distorted segregation was observed mainly in two regions of the genome, especially in the male parent alleles. Map positions were provided for resistance genes to scab and rosy leaf curling aphid (Vf and Sd 1, respectively) for the fruit acidity gene Ma and for the self-incompatibility locus S. The high marker density and large number of mapped codominant RFLPs and some microsatellite markers make this map an ideal reference map for use in other progenies also and a valuable tool for the mapping of quantitative trait loci.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050867
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  • 8
    Electronic Resource
    Electronic Resource
    Multiple field and glasshouse assessments increase the reliability of linkage mapping of the Vf source of scab resistance in apple (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 699-708 
    Details
    ISSN: 1432-2242
    Keywords: Key words Malus ; Apple ; Venturia ; Scab resistance ; Linkage mapping ; Cluster analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Apple scab, caused by the fungus Venturia inaequalis (Cke.) Wint., is an important disease in commercial apple production. A mapping population of 155 individuals, derived from a cross between the apple varieties ‘Prima’ (resistant)בFiesta’ (susceptible), was scored for response to the disease in replicated field and glasshouse trials throughout Europe. Twenty data sets were selected and cluster analysis was used to form a consensus score for the population fitting a 1 : 1 segregation ratio of resistance:susceptibility. The progeny were scored with molecular markers. A detailed map covering 54 cM of the ‘Prima’ linkage group containing the Vf gene for scab resistance was constructed using 24 molecular markers linked to the resistance gene. One isoenzyme marker (Pgm-1), six RFLP markers and 17 RAPD markers formed a linkage group with the consensus measure of resistance to scab. Four marker bridges were established with the corresponding ‘Fiesta’ linkage group with additional markers (one isozyme, one RFLP, three RAPD and one AFLP). A low chi-square value indicated a good fit of the marker ordering, which was in close agreement with previously reported linkage positions for some of the markers and Vf. Differences were observed in the ability of different scoring methods to resolve susceptible and resistant classes. The results obtained for the consensus classification of resistance to scab for the population may suggest the presence of virulent inocula at some sites, which could overcome the Vf gene for resistance. The consequences of relying on individual scoring occasions for studying Vf scab resistance are discussed in the context of linkage analysis, conventional breeding selection, and marker-assisted selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050791
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of varying pollen load on fruit set, seed set and seedling performance in apple and pear (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 122-126 
    Details
    ISSN: 1432-2145
    Keywords: Apple ; Pear ; Pollen ; Gametophytic competition ; Seedling vigor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two apple crosses and one pear cross were carried out using three different pollen densities. In one of the apple crosses, both fruit and seed set decreased when a mixture of pollen and powder (diluted pollen treatment) was used for pollination. Also, seedlings from the undiluted treatment were more vigorous than those originating from pollination with diluted pollen. In the other apple cross, however, no effect on fruit set, seed set or growth in the first year was found. Mean diameter after the second year differed among treatments, but did not seem to be related to pollen density. For pear, the number of good seeds decreased and the number of deaf, probably unfertilized, seeds increased with decreasing pollen density. However, there was no apparent significant effect of pollen density on seedling growth. With respect to scab resistance and mildew attack in both apple crosses, no differences among treatments were found. The results indicate that gametophytic competition may occur in apple crosses, but that it is probably weaker in pear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227656
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  • 10
    Electronic Resource
    Electronic Resource
    The ‘European Apple Genome Mapping Project’-developing a strategy for mapping genes coding for agronomic characters in tree species (1991)
    Springer
    Euphytica 56 (1991), S. 89-94 
    Details
    ISSN: 1573-5060
    Keywords: Malus ; apple ; genetic mapping ; isozymes ; DNA techniques ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A recently initiated collaborative project involving apple breeders in seven European countries is described. The objective is to improve the European apple crop by molecular-aided breeding to increase efficency and reduce the time-scale in breeding for resistance, tree habit and fruit quality. The strategy adopted provides a model for similar studies in fruit, forest and other woody species. The project is based on progenies from a small number of crosses involving many important agronomic genes. Replication of these reference progenies by vegetative propagation will enable studies to be carried out simultaneously in each country. By developing a range of molecular markers, including isozymes, RFLPs and sequence-tagged DNA probes, an integrated molecular map is being constructed for use in a wide range of breeding and genetic studies. Construction of a database recording many mapped molecular markers will enable efficient exploitation of data in future genetic, breeding and physiological studies of apple. Aspects of the adopted strategy, techniques and management are discussed in the context of mapping genes in perennial crop genomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041748
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