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The activities of chitinase, β-1,3-glucanase, peroxidase and phenylalanine ammonia lyase, constitutive and induced by Stagonospora nodorum were examined in the 10 – 14 day old seedlings of three triticale and two wheat cultivars under controlled environmental conditions and in flag leaves of two triticale cultivars in the field. Two S. nodorum isolates of different virulence were used. Both the constitutive and induced activities in triticale and wheat depended on genotype and in triticale the effect of growth conditions was also evidenced. The constitutive activities of chitinase, β-1,3-glucanase and peroxidase were several fold lower in flag triticale leaves in plants from the field than in the seedlings, growing under controlled conditions, but induction in the infected flag leaves was significantly more pronounced. In triticale genotypic differences in the response to infection were revealed only upon inoculation by S. nodorum isolate of higher virulence. The enzymatic activities increased several fold during successive days after the infection except for phenylalanine ammonia lyase. Induction of this enzyme was only transient and the activity decreased 48 or 96 h after infection when the activities of other enzymes were rising. In flag leaves in the field this activity was differentiated only after infection with more a virulent strain. A tendency appeared in triticale seedlings for association of the resistance to the pathogen with lower enzymatic constitutive activities. This relationship became more evident in triticale infected by S. nodorum and may imply that although the investigated enzymes are certainly involved in general, non-specific defense mechanism, they do not decide on the resistance to pathogen at least in the early stages of infection and cooperate with other factors in the complex pathogen-plant interaction. One can also assume that the enzymatic activities are associated with severity of infection rather than resistance to pathogen.
Long-term research work was performed in the years 1996-2002 on the occurrence and significance of winter wheat glume blotch (Stagonospora nodorum) in the region of middle-southern Poland. It was stated that the disease occurred every year at different intensity and this was dependent on the amount of rainfall during the vegetative period, especially in June. Winter wheat was strongly infected in the years 1999 and 2002 when rainfall in June was the highest. The lowest level of infection was recorded in the year 2000 characterized by the lowest rainfall in this month. Full chemical protection with broad spectrum fungicides performed once at GS 49-55 and always significantly increased grain yield, but the increase was the highest in the years of the highest ear infection by S. nodorum. It was concluded that in experimental period glume blotch of winter wheat could be considered as a disease of the greatest importance in the region of middle - Southern Poland, and thus creation a serious threat to winter wheat cultivated in this area.
1879-2720 leaf samples from 8-13 stations of Hungary were collected in March, April, May and June 2000-2002. Drechslern tritici-repentis, Septoria Iritici, Stagonospora nodorum and Bipolaris sorokiniana were found in the leaf samples. The occurrence of necrotrophic pathogens was highest (10,79%) in 2001 and lowest (2,63%) in 2002. The occurrence and rate of the necrotrophic pathogens changed significantly among years and locations. The resistance of cultivars based on natural infection could not be properly evaluated, as the level of the epidemic was mostly low and contradictory among locations. Additionally forty four cultivars were tested in Szeged after winter wheat in protected and unprotected environment. Among the necrotrophic pathogens, the dominant pathogens were D. tritici-repentis (2001 and 2002) and S. nodorum (2001). The differences in variety resistance were significant. The biotrophic (leaf rust, yellow rust and powdery mildew) as well as the mentioned necrotrophic pathogens caused significant yield decrease in both years. According to values of correlation coefficients, the influence of biotrophic pathogens was greater on the yield.
The genetic similarity of three species: Septoria tritici, Stagonospora nodorum and Stagonospora avenae f. sp. triticea - important pathogens in many cereal production areas worldwide was assessed by random amplified polymorphic DNA (RAPD) assay. In preliminary research DNA of 14, 9, and 7 monopyenidios- pore isolates of S. nodorum, S. tritici, and S. a. tritícea, respectively, were amplified by PCR with four primers. Afterwards the research was focused on three mono- pyenidiospore isolates from each species studied. The isolates of each species selected for the study varied in pathogenicity and were diverse geographically. PCR with the set of 14 selected primers resulted in 99 different bands, ranged from 180 to 2500 base pairs in length. Most primers in PCR (especially RAD11, RAD31, RAD32, RAD33) revealed uniform bands for isolates of S. a. tritícea, that allow to identify this species among the others. The cluster analysis using Unweighed Pair-Group Method with Averaging (UPGMA) revealed interspecies disagreement among the isolates ranging from 32 to 53%. The intraspecies disagreement ranges were 17-20%, 38-43%, 42-44% for S. avenae f. sp. triticea, S. nodorum and S. tritici, respectively. Cluster analysis classified isolates into three homogeneous clusters. Each cluster grouped isolates of one species according to their current taxonomie ranks based on spore size, colony morphology and host ranges. In addition, two of the clusters represented by isolates of S. nodorum and S. a. tritícea were distinctly separated at a lower linkage distance from the third one comprising isolates of S. tritici. A slight inconsistency found in grouping some isolates indicates that such groupings should be done with caution. The present study indicates that the PCR- RAPD assay is of a potential use in taxonomy of Stagonospora spp. and Septoria tritici as well as in molecular identification of casual disease agents.
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