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Mycosporine-like amino acids (MAAs) and scytonemin are UV-screening compounds that have presumably appeared early in the history of life and are widespread in cyanobacteria. Natural colonies of the UV-insensitive Nostoc flagelliforme were found to be especially rich in MAAs (32.1 mg g DW−1), concentrated in the glycan sheath together with scytonemin. MAAs are present in the form of oligosaccharide-linked molecules. Photosystem II activity, measured using PAM fluorescence and oxygen evolution, was used as a most sensitive physiological parameter to analyse the effectiveness of UV-protection. Laboratory experiments were performed under controlled conditions with a simulated solar radiation specifically deprived of UV-wavebands with cut-off filters (295, 305, 320, 345 and 395 nm). The UV-insensitivity of N. flagelliforme was found to cover the whole UV-A (315–400 nm) and UV-B (280–320 nm) range and is almost certainly due to the complementary UV-absorption of MAAs and scytonemin. The experimental approach used is proposed to be suitable for the comparison of the UV-protection ability in organisms that differ in their complement of UV-sunscreen compounds. Furthermore, this study performed with a genuinely terrestrial organism points to the relevance of marine photoprotective compounds for life on Earth, especially for the colonization of terrestrial environments. 相似文献
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Effect of Fungicides on Fusarium Head Blight and Deoxynivalenol Content in Durum Wheat Grain 总被引：1，自引：0，他引：1
Anna Maria Menniti Davide Pancaldi Massimo Maccaferri Lucia Casalini 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(2):109-115
In 1998–99 and 1999–2000 six trials were conducted to evaluate the effect of fungicides on Fusarium head blight in the field, on infected kernels and deoxynivalenol (DON) concentration in grain. A single application of prochloraz, tebuconazole, epoxiconazole or bromuconazole, applied to durum wheat varieties at the manufacturer's recommended dose at the beginning of anthesis stage, provided good control of the disease when infective pressure in the field was low to medium, and when the main pathogens were F. graminearum and F. culmorum. Kresoxim-methyl showed a low efficacy at controlling the disease. Tebuconazole, prochloraz and bromuconazole were effective at controlling F. graminearum and F. culmorum, while kresoxim-methyl was not effective in reducing Fusarium infected kernels. DON concentration in grain of cultivars inoculated with F. graminearum and F. culmorum was high, averaging 4.2mgkg–1 (untreated control). Tebuconazole, prochloraz and bromuconazole reduced DON concentration by 43%, while epoxiconazole was ineffective. DON concentration in kernels of naturally infected cultivars was 1.95mgkg–1, a concentration which exceeds the 1mgkg–1 maximum level of contamination allowed in the United States. Furthermore prochloraz, bromuconazole and tebuconazole applications, in the naturally inoculated trials, reduced DON concentration from 73% to 96%, while epoxiconazole showed the lowest effectiveness. Moreover, a positive linear correlation between Fusarium infected grains and the DON concentration was observed. 相似文献
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Giulia?Alberoni Marina?CollinaEmail author Davide?Pancaldi Agostino?Brunelli 《European journal of plant pathology / European Foundation for Plant Pathology》2005,113(2):211-219
Brown spot, caused by Stemphylium vesicarium, is the main fungal disease of pear in northern Italy where it may cause severe crop losses and it requires numerous fungicide
applications. Monitoring work was performed by collecting fungal populations in Po valley between 1995 and 2003 in order to
study the dicarboximides resistance already detected in the 1990s for procymidone as a result of control failures in field.
Sensitivity tests showed that the resistant strains occur all over the monitored areas. Where present the efficacy of procymidone
in field is completely lost in spite of what is observed often in other fungi. In most of the isolates (phenotype R1), S. vesicarium resistance level to procymidone (Sialex) was shown to be very high (RF≅3000) whereas it was lower towards the other dicarboximides
iprodione (Rovral), vinclozolin (Ronilan) and chlozolinate (Serinal) (RF≅10). Therefore the resistance is partially crossed
even if a high level of resistance was rarely observed for all dicarboximides (phenotype R2). At least two different mechanisms of resistance seem to be involved: one that may provide a moderate resistance and the
other that may give a high resistance level. Monospore isolate sensitivity tests confirmed the qualitative response suggested
by such high resistance factors. 相似文献
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Rossi V. Racca P. Giosue&#; S. Pancaldi D. Alberti I. 《European journal of plant pathology / European Foundation for Plant Pathology》1997,103(5):453-465
A model simulating the progress of Puccinia recondita severity, expressed as a percentage of rusted leaf area (both as average and its 95% confidence interval) on individual wheat leaves over the course of a growing season, with a time step of one day, was elaborated using laboratory and field data from literature. Data on the stages of each infection cycle (uredospore germination, penetration, latency, uredium eruption and infectiousness) were transformed into model parameters by curve fitting, Montecarlo stochastic procedures, corrections and empirical assumptions. Data on host growth, like the timing of all phenological stages, the dynamic of the green area of each leaf from appearance to complete senescence, and tillering were obtained from a specific sub-model. Model validation was performed on actual data not used in model building and representing a wide range of conditions (several winter wheat cultivars grown at eight locations in northern Italy between 1990 and 1994) by using subjective, non-parametric and parametric tests: it revealed a satisfactory agreement between the data simulated by the model and actual data. 相似文献
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