64 research outputs found

    Heterosiszüchtung bei Vitis vinifera L.

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    Die S1-Nachkommen des Roten Traminers (RT) und des Rotweißen Veltliners (RWV) wurden mit Kreuzungen dieser S1 -Familien verglichen und auf Heterosiseffekt geprüft. Die Heterosiskreuzungen wiesen ein erheblich besseres Wachstum als die Selbstungsfamilien auf. Auch die Zahl der fruchtenden Sämlinge dieser Kreuzungen war höher. In bezug auf Traubengröße und in einzelnen Fällen auch auf Beerengröße war die Heterosis in den betreffenden Kreuzungen auffallend, wobei der Durchschnittsertrag pro Stock bei den Heterosiskreuzungen (mit Ausnahme von RWV (S1 ) X RWV (S1 )) auffällig höher lag als bei den Selbstungsfamilien. Auch eine frühere Traubenreife konnte in den Heterosiskreuzungen festgestellt werden. Bei Verwendung dieser Methode in der Züchtungspraxis wird man auch bei der Vitis vinifera ohne die Topcross-Methode nicht auskommen können. Dei Fixation des Heterosiseffektes mittels vegetativer Vermehrung wäre ein großer Vorteil.Heterozygotic breeding at Vitis vinifera L.The S1 -offsprings of the "Roter Traminer" (RT) and the "Rotweißer Veltliner" (RWV) were compared with offsprings of crossings between these S1 -families and investigated for heterosis effects. The latter families showed a much better growth than the former ones. The number of the fruit bearing seedlings also was higher in the hybrid offsprings. With regard to the size of the bunches and also, in some cases, to the size of the berries, heterosis was remarkable in the offsprings concerned. Compared to the S1 -offsprings the average yield per vine was considerably higher in the hybrid offsprings (with the exception of RWV [S1] X RWV [S1]). Moreover, an earlier grape maturity could be ascertained in the hybrid offsprings. Besides using this method in grape breeding, the topcross-method also will be necessary. The fixation of the heterosis effect by means of vegetative propagation would be of great value

    Photosynthesis by six portuguese maize cultivars during drought stress and recovery

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    Photosynthesis, chlorophyll fluorescence and leaf water parameters were measured in six Portuguese maize (Zea mays L.) cultivars during and following a period of drought stress. The leaf relative water content (RWC) responded differently among cultivars but, except for cultivar PB369, recovered close to initial values after watering was restored. Photosynthetic rate and stomatal conductance decreased with drought but more slowly in cultivars PB269 and PB260 than in cultivars AD3R, PB64, PB304 and PB369. Water use efficiency (WUE) decreased during the water stress treatment although with cultivar PB260 the decrease was marked only when the RWC fell below 40%. Recovery of WUE was seen with all cultivars except PB369. The maximum quantum efficiency of photosystem II, the photochemical quenching coefficient, the electron transport rate in PSII and the estimated functional plastoquinone pool tended to decrease with drought, while the non -photochemical quenching coefficient increased. The parameters estimated from chlorophyll fluorescence did not recover in PB369, during re - watering. The results show that PB260 and PB269 were the most tolerant and PB369 was the least tolerant cultivars to water stress. The variation found amongst the cultivars tested suggests the existence of valuable genetic resources for crop improvement in relation to drought tolerance

    Complete Genome Sequence of Treponema paraluiscuniculi, Strain Cuniculi A: The Loss of Infectivity to Humans Is Associated with Genome Decay

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    Treponema paraluiscuniculi is the causative agent of rabbit venereal spirochetosis. It is not infectious to humans, although its genome structure is very closely related to other pathogenic Treponema species including Treponema pallidum subspecies pallidum, the etiological agent of syphilis. In this study, the genome sequence of Treponema paraluiscuniculi, strain Cuniculi A, was determined by a combination of several high-throughput sequencing strategies. Whereas the overall size (1,133,390 bp), arrangement, and gene content of the Cuniculi A genome closely resembled those of the T. pallidum genome, the T. paraluiscuniculi genome contained a markedly higher number of pseudogenes and gene fragments (51). In addition to pseudogenes, 33 divergent genes were also found in the T. paraluiscuniculi genome. A set of 32 (out of 84) affected genes encoded proteins of known or predicted function in the Nichols genome. These proteins included virulence factors, gene regulators and components of DNA repair and recombination. The majority (52 or 61.9%) of the Cuniculi A pseudogenes and divergent genes were of unknown function. Our results indicate that T. paraluiscuniculi has evolved from a T. pallidum-like ancestor and adapted to a specialized host-associated niche (rabbits) during loss of infectivity to humans. The genes that are inactivated or altered in T. paraluiscuniculi are candidates for virulence factors important in the infectivity and pathogenesis of T. pallidum subspecies

    Whole Genome Sequences of Three Treponema pallidum ssp. pertenue Strains: Yaws and Syphilis Treponemes Differ in Less than 0.2% of the Genome Sequence

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    Spirochete Treponema pallidum ssp. pertenue (TPE) is the causative agent of yaws while strains of Treponema pallidum ssp. pallidum (TPA) cause syphilis. Both yaws and syphilis are distinguished on the basis of epidemiological characteristics and clinical symptoms. Neither treponeme can reproduce outside the host organism, which precludes the use of standard molecular biology techniques used to study cultivable pathogens. In this study, we determined high quality whole genome sequences of TPE strains and compared them to known genetic information for T. pallidum ssp. pallidum strains. The genome structure was identical in all three TPE strains and also between TPA and TPE strains. The TPE genome length ranged between 1,139,330 bp and 1,139,744 bp. The overall sequence identity between TPA and TPE genomes was 99.8%, indicating that the two pathogens are extremely closely related. A set of 34 TPE genes (3.5%) encoded proteins containing six or more amino acid replacements or other major sequence changes. These genes more often belonged to the group of genes with predicted virulence and unknown functions suggesting their involvement in infection differences between yaws and syphilis

    On proteins. C. Disulfide bonds of basic trypsin inhibitor from beef pancreas

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