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  • 1
    Electronic Resource
    Electronic Resource
    Genetic variation among asexual progeny of Phytophthora infestans detected with RAPD and AFLP markers (2003)
    Oxford, UK : Blackwell Science Ltd
    Plant pathology 52 (2003), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Genotypic variation among 32 single-zoospore isolates (SZI) of Phytophthora infestans, derived asexually from two hyphal-tip parental isolates (PI-105 and PI-1) of the US-8 genotype, was assessed with 80 random amplified polymorphic DNA (RAPD) primers and 18 amplified fragment length polymorphic DNA (AFLP) primer pairs. In previous investigations, the SZIs from parental isolate PI-105 showed high levels of virulence variability and were differentiated into 14 races, whereas the SZIs from PI-1 showed identical virulence to the parent. The purpose of this investigation was to determine if phenotypic variation observed among SZIs of P. infestans could be detected at the DNA level in these isolates. Polymorphism was detected with 51 RAPD primers and with all 18 AFLP primer pairs in PI-105 SZIs. In SZIs from PI-1, polymorphism was also detected with 25 RAPD primers and 17 AFLP primer pairs. Cluster analysis using the unweighted pair-group method with arithmetic averages (UPGMA) separated the SZIs from parent PI-105 into six virulence groups, 11 RAPD groups and three AFLP groups. Cluster analysis of PI-1 SZIs, which all belong to the same virulence group, differentiated them into four RAPD groups and six AFLP groups. No close correlation among RAPD, AFLP and virulence groups could be established within the two progenies of SZIs. Results of this study suggest that there is a considerable level of inherent genetic variability among SZIs derived asexually from the same parental isolate. The possible mechanisms and implications of this genetic variation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3059.2003.00858.x
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of resistance to verticillium wilt in diploid, wild potato interspecific hybrids (1994)
    Springer
    Euphytica 76 (1994), S. 145-152 
    Details
    ISSN: 1573-5060
    Keywords: disease resistance ; genetic introgression ; germplasm enhancement ; potato ; Solanum sp. ; Verticillium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Verticillium wilt (V. albo-atrum Reinke & Berthold or V. dahliae Kleb) threatens potato (Solanum tuberosum L.) production in most growing areas of the world. Genetic resistance offers the most cost-effective and environmentally-sound control measure. However, there is a dearth of genetic and breeding information on resistance to verticillium wilt in potato, because of obscure parentage of some standard cultivars and the complex segregation at the tetraploid level. The wide range of genetic variability in wild relatives of potatoes can be potentially useful as a source of disease resistance, such as verticillium wilt resistance. Six diploid, wild, interspecific Solanum hybrids involving resistant x resistant and susceptible x resistant crosses, were assayed for verticillium wilt resistance under greenhouse conditions to evaluate their potential as sources of verticillium wilt resistance. The cross between S. gourlayi Oka. and S. chacoense Bitt. and its reciprocal had the most resistant progenies based on mean colony counts. No simple mode of inheritance can be proposed based on the observed segregation ratios. However, the continuous distributions observed on verticillium wilt disease response among hybrid families indicate that inheritance of resistance may be polygenic and complex. In addition, skewness of colony count distributions toward the resistance parents were characteristic of all resistant x susceptible crosses suggesting that resistance may be dominant. By contrast, the susceptible x susceptible cross showed a more normal distribution. Overall, the cross between S. gourlayi and S. chacoense showed the most potential as a source of verticillium wilt resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024033
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  • 3
    Electronic Resource
    Electronic Resource
    A shoot induction procedure altered for increased shooting efficiency of potato protoplast-derived calli (cvs. crystal and norgold russet) (1988)
    Springer
    Potato research 31 (1988), S. 651-658 
    Details
    ISSN: 1871-4528
    Keywords: callus culture ; regeneration ; Solanum tuberosum L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The responses of two potato cultivars, Crystal and Norgold Russet, to a standard protoplast regeneration procedure were examined. Both cultivars yielded protoplasts that survived and grew in the initial plating medium. Protoplast-derived callus tissue also grew on the callus proliferation medium. The cultivars differed most in their ability to survive on the shoot induction medium; changes in its growth regulator content and the quantity of agar increased shoot production of Crystal from 1% to 30% and that of Norgold Russet from 7% to 24% on modified medium under low light intensity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02361858
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  • 4
    Electronic Resource
    Electronic Resource
    Convergence of consistently derived Timoshenko beam finite elements (1972)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 5 (1972), S. 243-252 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The accuracy and convergence properties of two new Timoshenko beam finite elements are compared to those now widely used. Both of the new elements are consistently derived from a variational principle written in terms of the transverse beam deflection and normal rotation. The deflection is expanded as a cubic and the rotation as a quadratic in the axial co-ordinate of the beam, giving rise to a seven degrees of freedom element. The first element, called TIM7, includes all the degrees of freedom while the second, called TIM4, reduces this number to four through a constraint introduced by Egle. Both elements display monotonic covergence for beam natural frequencies as a function of the number of degrees of freedom and both will give the analyst some measure of confidence in response calculations for beams excited at high frequencies.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620050210
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