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1.
Gitta Oettler 《Euphytica》1983,32(2):593-600
2.
Shapiro BJ Friedman J Cordero OX Preheim SP Timberlake SC Szabó G Polz MF Alm EJ 《Science (New York, N.Y.)》2012,336(6077):48-51
Genetic exchange is common among bacteria, but its effect on population diversity during ecological differentiation remains controversial. A fundamental question is whether advantageous mutations lead to selection of clonal genomes or, as in sexual eukaryotes, sweep through populations on their own. Here, we show that in two recently diverged populations of ocean bacteria, ecological differentiation has occurred akin to a sexual mechanism: A few genome regions have swept through subpopulations in a habitat-specific manner, accompanied by gradual separation of gene pools as evidenced by increased habitat specificity of the most recent recombinations. These findings reconcile previous, seemingly contradictory empirical observations of the genetic structure of bacterial populations and point to a more unified process of differentiation in bacteria and sexual eukaryotes than previously thought. 相似文献
3.
European ash (Fraxinus excelsior) trees currently face the major threat of ash dieback caused by an invasive fungus, Hymenoscyphus fraxineus. Collar rots in F. excelsior have been increasingly associated with infections by this pathogen. However, the aetiology of the collar rots is still unclear and remains heavily debated. In contrast to most studies of this kind, entire rootstocks of four diseased ash trees were dug out to examine necrotic tissues in these rootstocks and stem bases in detail and to sample necrotic wood for fungal isolation. With the aid of morphological and molecular identification techniques, five to twelve fungal taxa were detected per tree. Members of the Nectriaceae family and Botryosphaeria stevensii, the causal agent of stem and branch cankers on many tree species, were frequently isolated from outer xylem. In contrast, H. fraxineus was the dominating species in interior wood layers. Microsatellite genotyping of 77 H. fraxineus isolates helped to identify up to six different genotypes per tree. The role of H. fraxineus and other isolated fungi in the aetiology of ash collar rots are discussed. 相似文献
4.
Parental effects on crossability,embryo differentiation and plantlet recovery in wheat x rye hybrids
Gitta Oettler 《Euphytica》1984,33(1):233-239
Summary One hexaploid wheat cultivar (Triticum aestivem) and two tetraploid wheat lines (T. durum) were crossed with seventeen inbred lines of rye (Secale cereale). Seed set, degree of hybrid embryo differentiation at the time of excision for in vitro culture and recovery of amphihaploid plantlets from various embryo categories were studied. Degree of embryo differentiation was predominantly determined by maternal wheats, paternal rye genotypes appearing to be of minor importance. T. aestivum x rye hybrid embryos were superior to those produced from T. durum for degree of differentiation. The proportion of plantlets developing from differentiated embryos was high for all wheat parents, whereas undifferentiated embryos were mostly unsuitable for plantlet production. The results revealed that cross-incompatibility in hexaploid wheat x rye crosses was due to failure of fertilization, while in tetraploid wheat x rye crosses it was caused by lack of embryo differentiation. Correlation analyses showed that seed set provided a criterion to predict the amphihaploid plantlets to be expected from a particular wheat x rye combination. 相似文献
5.
Langer Gitta Jutta Fuchs Sebastian Osewold Johannes Peters Sandra Schrewe Falk Ridley Maia Kätzel Ralf Bubner Ben Grüner Jörg 《植物病害和植物保护杂志》2022,129(6):1285-1295
Journal of Plant Diseases and Protection - European ash dieback caused by the alien, invasive ascomycete species Hymenoscyphus fraxineus currently represents, along with its side effects, the... 相似文献
6.
Summary
Fusarium head blight infection causes severe yield losses and contamination of the grain with mycotoxins in triticale (× Triticosecale Wittmack) grown in temperate and semihumid areas. In a two-year experiment thirty-six genotypes were inoculated separately with two isolates of Fusarium graminearum differing fivefold in their in vitro deoxynivalenol (DON) production and the effect on various traits was studied. All traits were significantly affected by head blight. The two isolates differed considerably in their aggressiveness resulting in a mean reduction of grain weight per spike of almost 25% and 50%, respectively. Inter-annual correlation was high for average disease rating (r=0.63, P<-0.01) and low for the other traits. Therefore, disease rating, averaged from two to three records, was regarded a suitable criterion for screening purposes. The effect of isolates on genotypes was not stable over years. The mean DON content of five genotypes with diverse resistance levels was 68 mg kg-1. In vitro DON production of the two isolates used for inoculation did not correspond to their aggressiveness and DON contamination of the grain. 相似文献
7.
Andrea Balázs Magdolna Tóth Balázs Blazics Éva Héthelyi Szabolcs Szarka Emese Ficsor Gitta Ficzek Éva Lemberkovics Anna Blázovics 《Fitoterapia》2012
Three red-fleshed apple cultivars (Malus ‘Geneva’: GFV-03, Hungarian hybrid: GFV-04, Malus pumila Niedwetzkyana: GFV-05) were investigated for their chemical composition by sHS–SPME–GC–MS and HPLC–DAD–MS/MS analytical techniques. 相似文献
8.
The horse chestnut leafminer is an introduced invasive pest that every year causes extensive damage to the leaves of the white flowering horse chestnut tree. An environmentally friendly method to control insect pests involves the use of sex pheromones for mating disruption. A large quantity of artificial pheromone is released into the insect plant system confusing males to the extend that they are unable to locate receptive females. In order to test the potential efficacy of the mating disruption technique on the horse chestnut leafminer we set up semi-field trials with closed experimental units and varying leafminer densities. We counted the number of leaf mines on pheromone treated horse chestnut trees and compared them with an untreated control. Mating disruption lead to a significant reduction in damage by more than 90% in the first and second generation of the leafminer, irrespective of the initial leafminer density. Although these results are very encouraging, high population densities of the horse chestnut leafminer in nature and the patchy distribution of horse chestnut trees in the cities will challenge the efficacy of mating disruption in the field. Further experiments are planned with open experimental units and typical horse chestnut trees in various parks and gardens. 相似文献
9.
Since the beginning of the invasion of the horse chestnut leafminer, Cameraria ohridella Deschka and Dimic 1986 (Lepidoptera: Gracillariidae), into Europe over 20 years ago the damage to white flowering horse chestnut trees, Aesculus hippocastanum L (Sapindales: Hippocastanaceae) has remained extensive. This study evaluates the possible use of pheromone mating disruption
as a control option against the horse chestnut leafminer. The heterogeneous distribution of ornamental trees in parks and
gardens requires a different approach to evaluate pest control than in homogeneous crop fields, orchards or plantations where
mating disruption is usually applied. For this reason we set up field experiments with host trees of the same age and size
in field tents with a defined number of leafminers in two different densities. In the first experiment the effective quantity
of newly developed C. ohridella pheromone dispensers was tested by recapturing males using traps baited with virgin females. Ninety-five percent less males
were captured if three or more dispensers were positioned at a 4 m radius around the outside of an experimental tent. This
set up was then used in the second experiment where male and female leafminers were released into field tents in order to
assess the effect of pheromone on the reduction of leaf mining damage. Surprisingly, the pheromone dispensers were found to
have no effect on the number of leaf mines at either low or high leafminer densities. Mating sites of the horse chestnut leafminer,
multiple matings and distribution of pheromone dispenser are discussed as possible factors influencing the outcome in this
study. 相似文献
10.
Nancy Schellhorn Gitta Siekmann Catherine Paull Geoff Furness Greg Baker 《国际虫害防治杂志》2013,59(3):153-159
Dyes and dusts have been used to mark insects internally and externally for decades, the majority of examples coming from laboratory-reared pest species used in mark-release-recapture studies. Using dyes or dusts to mark populations of pests and beneficial insects simultaneously in the field has received less attention. We evaluated a water-soluble fluorescent dye and a resin-based fluorescent pigment sprayed on crops to mark beneficial and pest insects, and monitored the dispersal of marked insects. Our results show that resin-based dyes provide an effective mark on several species of insects among several orders. The resin-based dye is also relatively inexpensive, non-toxic, UV-stable and water resistant, unlike a water-soluble dye. Using the resin-based dye in a broccoli production system, we were able to monitor simultaneously the movement of field populations of the parasitoids, Diadegma semiclausum (Hellén) (Hymenoptera: Ichneumonidae), and Apanteles ippeus (Nixon) (Hymenoptera: Braconidae) and the adult stage of the host, diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). Resin-based dye applied on a crop is an effective way to mark and monitor the dispersal of populations of beneficial and pest insects in relation to agricultural practices, integrated pest management and conservation biological control. 相似文献