仓储烟叶表面真菌群落组成分析

利用高通量测序平台,对贮存于贵阳库（GY）、坛厂库（TC）和紫云库（ZY）的云南保山C3F（2013）烟叶样品进行宏基因组水平的ITS1基因测序分析,以期揭示陈化烟叶表面真菌群落组成、分布格局及功能分组,探讨化学因子对其结构的影响。结果显示,从15个样品中共检测到了1 173 560条有效序列,包括4个门、140个属;贵阳库优势属为耐干霉菌属Xeromyces,坛厂库优势属为红酵母属Rhodotorula,紫云库优势属为耐干霉菌属Xeromyces;坛厂库优势菌群及变化趋势与贵阳库和紫云库存在差异;真菌群落以腐生营养型和病理营养型为主,分布有潜在人体病原真菌;有机碳、总磷、总钾对真菌群落变化影响显著（P<0.05）。真菌群落组成和格局分布受存储环境、陈化时间及烟叶化学元素的共同影响。     

Climate change triggers effects of fungal pathogens and insect herbivores on litter decomposition

Increasing infestation by insect herbivores and pathogenic fungi in response to climate change will inevitably impact the amount and quality of leaf litter inputs into the soil. However, little is known on the interactive effect of infestation severity and climate change on litter decomposition, and no such study has been published for deciduous forests in Central Europe. We assessed changes in initial chemical quality of beech (Fagus sylvatica L.) and maple litter (Acer platanoides L.) in response to infestation by the gall midge Mikiola fagi Hart. and the pathogenic fungus Sawadaea tulasnei Fuckel, respectively, and investigated interactive effects of infestation severity, changes in temperature and soil moisture on carbon mineralization in a short-term laboratory study. We found that infestation by the gall midge M. fagi and the pathogenic fungus S. tulasnei significantly changed the chemical quality of beech and maple litter. Changes in element concentrations were generally positive and more pronounced, and if negative less pronounced for maple than beech litter most likely due to high quality fungal tissue remaining on litter after abscission. More importantly, alterations in litter chemical quality did not translate to distinct patterns of carbon mineralization at ambient conditions, but even low amounts of infested litter accelerated carbon mineralization at moderately increased soil moisture and in particular at higher temperature. Our results indicate that insect herbivores and fungal pathogens can markedly alter initial litter chemical quality, but that afterlife effects on carbon mineralization depend on soil moisture and temperature, suggesting that increased infestation severity under projected climate change potentially increases soil carbon release in deciduous forests in Central Europe.     

Bottom‐up effects of fungicides on tadpoles of the European common frog (Rana temporaria)

Biodiversity is under pressure worldwide, with amphibians being particularly threatened. Stressors related to human activity, such as chemicals, are contributing to this decline. It remains, however, unclear whether chemicals exhibiting a fungicidal activity could indirectly affect tadpoles that depend on microbially conditioned leaf litter as food source. The indirect effect of fungicides (sum concentration of a fungicide mixture composed of azoxystrobin, carbendazim, cyprodinil, quinoxyfen, and tebuconazole: 100 µg/L) on tadpoles was assessed relative to leaf litter colonized by microbes in absence of fungicides (control) and a worst‐case scenario, that is leached leaf litter without microbial colonization. The quality of leaf litter as food for tadpoles of the European common frog (Rana temporaria) was characterized through neutral lipid fatty acid profiles and microbial sum parameters and verified by sublethal responses in tadpoles (i.e., feeding rate, feces production, growth, and fatty acid composition). Fungicides changed the nutritious quality of leaf litter likely through alterations in leaves’ neutral lipid fatty acid profiles (i.e., changes in some physiologically important highly unsaturated fatty acids reached more than 200%) in combination with a potential adsorption onto leaves during conditioning. These changes were reflected by differences in the development of tadpoles ultimately resulting in an earlier start of metamorphosis. Our data provide a first indication that fungicides potentially affect tadpole development indirectly through bottom‐up effects. This pathway is so far not addressed in fungicide environmental risk assessment and merits further attention.     

Predators mediate the effects of a fungal pathogen on prey: an experiment with grasshoppers,wolf spiders,and fungal pathogens

1. Prey interact with multiple kinds of enemies such as predators, parasites, and pathogens. Interactions among enemies can alter prey dynamics but they are often studied separately. 2. During the summers of 2005–2006, we conducted a field experiment to examine interactions among grasshoppers, spider predators, and a lethal fungal pathogen of grasshoppers. Grasshopper nymphs were stocked into field enclosures. Predation was manipulated by adding spiders to enclosures on day 1, day 5, or day 10 of the experiment, or no spiders were added. We monitored grasshopper survival and grasshopper mortality from fungal pathogens for 4 weeks. 3. Fungal pathogens were abundant in 2005 but not in 2006, probably because of favourable weather conditions in 2005. When fungal pathogens were abundant, spider presence reduced grasshopper mortality from fungal pathogens, but only when spiders were present early in the experiment (added on day 1 or day 5). 4. The outcome of predator–prey interactions varied between years, probably as a result of differences in pathogen prevalence. In 2005, spider presence reduced the number of deaths from the pathogen, leading to a slight trend of increased grasshopper density. However, in 2006, when pathogens were not an important source of mortality, spider predation was compensatory.     

Interactive effects of selected pesticides on the two-spotted spider mite and its fungal pathogen Neozygites floridana

Benomyl affected populations of Tetranychus urticae by interfering with the pathogenic fungus, Neozygites floridana. Benomyl delayed but prolonged spider mite outbreaks. Few mites were infected with the pathogen when benomyl was used. Reductions in mite populations treated with fentin hydroxide were associated with a high incidence of N. floridana infection. Benomyl did not affect sporulation of N. floridana but appeared to inhibit conidial germination or growth of the fungus.

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Résumé Le bénomyl a modifié les populations de Tetranychus urticae Koch en interférant avec son champignon pathogène, Neozygites floridana (Weiser & Muma). Le bénomyl retardait mais prolongeait les pullulations de l'acarien. Peu d'acariens étaient infectés par le champignon quand on utilisait du bénomyl. Les réductions des populations d'acariens traitées avec l'hydroxyde de fentine étaient associées à un haut niveau d'infection par N. floridana. Le bénomyl ne modifiait pas la sporulation de N. floridana mais semblait inhiber la germination des conidies ou la croissance du champignon.

     

The effects of meteorological factors on airborne fungal spore concentration in two areas differing in urbanisation level

Although fungal spores are an ever-present component of the atmosphere throughout the year, their concentration oscillates widely. This work aims to establish correlations between fungal spore concentrations in Porto and Amares and meteorological data. The seasonal distribution of fungal spores was studied continuously (2005–2007) using volumetric spore traps. To determine the effect of meteorological factors (temperature, relative humidity and rainfall) on spore concentration, the Spearman rank correlation test was used. In both locations, the most abundant fungal spores were Cladosporium, Agaricus, Agrocybe, Alternaria and Aspergillus/Penicillium, the highest concentrations being found during summer and autumn. In the present study, with the exception of Coprinus and Pleospora, spore concentrations were higher in the rural area than in the urban location. Among the selected spore types, spring-autumn spores (Coprinus, Didymella, Leptosphaeria and Pleospora) exhibited negative correlations with temperature and positive correlations both with relative humidity and rainfall level. On the contrary, late spring-early summer (Smuts) and summer spores (Alternaria, Cladosporium, Epicoccum, Ganoderma, Stemphylium and Ustilago) exhibited positive correlations with temperature and negative correlations both with relative humidity and rainfall level. Rust, a frequent spore type during summer, had a positive correlation with temperature. Aspergillus/Penicillium, showed no correlation with the meteorological factors analysed. This knowledge can be useful for agriculture, allowing more efficient and reliable application of pesticides, and for human health, by improving the diagnosis and treatment of respiratory allergic disease.     

The effects of pheromone concentration on the flight behaviour of the oriental fruit moth, Grapholitha molesta

ABSTRACT. Male oriental fruit moths, Grapholitha molesta (Busck) (Tortricidae), flew at lower overall and net ground velocities when they flew toward higher concentration pheromone sources. Turning frequency was greater with increased pheromone concentration, while the distance of turns from the plume axis back towards the axis decreased. Turning magnitude and inter-reversal track angles remained constant at all concentrations tested. Concomitant with the changes in ground velocity but constant inter-reversal angles, were decreases in airspeed, decreases in the moths' course angles and increases in their drift angles. The significance of these changes is discussed in relation to their possible role in a longitudinal chemoklinotactic programme of turning operating in conjunction with anemotaxis to allow location of a pheromone source in wind.     

大气二氧化碳浓度变化对禾谷缢管蚜种群动态的影响

利用开顶式熏气室研究了大气CO₂浓度和土壤水分对禾谷缢管蚜Rhopalosiphum padi (L.)种群动态的影响,并分析了禾谷缢管蚜密度与被处理小麦叶片化学成分的关系。结果表明：（1）禾谷缢管蚜种群密度随CO₂浓度升高而持续增大并与土壤水分密切相关,各CO₂浓度下均以60%田间持水量时的密度最大;（2）CO₂和土壤水分对小麦叶片化学成分有明显的影响,麦叶水分、可溶性蛋白质、可溶性糖、淀粉含量随CO₂浓度和土壤水分含量上升而增加,纤维素含量随CO₂浓度上升而增加、随土壤水分含量上升而降低,单宁、丁布（DIMBOA）含量在CO₂浓度为550 μl/L时最高,但单宁含量随土壤水分上升而增加,丁布含量在60%田间持水量时最低;（3）禾谷缢管蚜密度与叶片水分、可溶性蛋白质、可溶性糖、淀粉含量呈正相关,与丁布、单宁含量呈负相关。结论：在未来的气候条件下,随着CO₂浓度升高禾谷缢管蚜种群可能会持续增长,这种增长在半干旱区更加突出。禾谷缢管蚜种群增长的原因之一是大气CO₂和土壤水分条件改变了植物的化学成分构成。     

大气二氧化碳浓度变化对禾谷缢管蚜种群动态的影响

利用开顶式熏气室研究了大气CO₂浓度和土壤水分对禾谷缢管蚜Rhopalosiphum padi (L.)种群动态的影响,并分析了禾谷缢管蚜密度与被处理小麦叶片化学成分的关系。结果表明：（1）禾谷缢管蚜种群密度随CO₂浓度升高而持续增大并与土壤水分密切相关,各CO₂浓度下均以60%田间持水量时的密度最大;（2）CO₂和土壤水分对小麦叶片化学成分有明显的影响,麦叶水分、可溶性蛋白质、可溶性糖、淀粉含量随CO₂浓度和土壤水分含量上升而增加,纤维素含量随CO₂浓度上升而增加、随土壤水分含量上升而降低,单宁、丁布（DIMBOA）含量在CO₂浓度为550 μl/L时最高,但单宁含量随土壤水分上升而增加,丁布含量在60%田间持水量时最低;（3）禾谷缢管蚜密度与叶片水分、可溶性蛋白质、可溶性糖、淀粉含量呈正相关,与丁布、单宁含量呈负相关。结论：在未来的气候条件下,随着CO₂浓度升高禾谷缢管蚜种群可能会持续增长,这种增长在半干旱区更加突出。禾谷缢管蚜种群增长的原因之一是大气CO₂和土壤水分条件改变了植物的化学成分构成。     

The effects of elevated atmospheric CO2 on lipid metabolism in leaves from mature wheat (Triticum aestivum cv. Hereward) plants

Winter wheat (Triticum aestivum L. cv. Hereward) plants were grown for 35 d either at 350 μ mol mol^–1 CO₂ or at 650 μ mol mol^–1 CO₂. Lipid synthesis was studied in these plants by incubating the 5th leaf on the main stem with [1–¹⁴C]acetate. Increased CO₂ concentrations did not significantly affect the total incorporation of radiolabel into lipids of whole leaf tissue, but altered the distribution for individual lipid classes. Most noticeable amongst acyl lipids was the reduction in labelling of diacylglycerol and a corresponding increase in the proportion of phosphatidylcholine labelling. In the basal regions, there were similar changes and, in addition, phosphatidylglycerol labelling was particularly increased following growth in an enriched CO₂ atmosphere. The stimulation of labelling of the mitochondrial-specific lipid, diphosphatidylglycerol, prompted an examination of the mitochondrial population in wheat plants. Mitochondria were localized in intact wheat sections by immunolabelling for the mitochondrial-specific chaperonin probe. Growth in elevated CO₂ doubled the number of mitochondria compared to growth in ambient CO₂. Fatty acid labelling was also significantly influenced following growth at elevated CO₂ concentrations. Most noticeable were the changes in 16C:18C ratios for the membrane lipids, phosphatidylcholine, phosphatidylglycerol and monogalactosyldiacylglycerol. These data imply a change in the apportioning of newly synthesized fatty acids between the 'eukaryotic' and 'prokaryotic' pathways of metabolism under elevated CO₂.     

Effect of surplus glucose on physiological and biochemical characteristics of sugar beet leaves in relation to the age of the leaf and the whole plant

Effect of surplus glucose on physiological and biochemical parameters of leaves of different age was investigated in sugar beet (Beta vulgaris L., subsp. saccharifera) plants in the stages of vegetative growth (SVG). Early and late SVG were differentiated by the ratio between the weights of roots and aboveground organs (0.10 and 0.35, respectively). The excess of Glu was produced by incubation of the disks excised from detached leaves in water or 0.1 M Glu at radiant flux density of 250 μmol/(m² s) with the light regime pattern described as night/day/night/light (8/16/8/3 h). In all the leaf disks incubated in water and glucose solution, the content of Glu and other soluble carbohydrates considerably increased as compared with their content in the leaves they were taken from. After disk incubation in water and glucose solution, the content of chlorophyll (a + b) rose as compared with its level in respective leaves in early SVG; in late SVG, it declined. In early SVG, the rate of the O₂ photosynthetic evolution (Ph) in the ageing leaves under saturating concentration of NaHCO₃ after incubation in water and Glu solution declined more considerably than in young leaves. In late SVG, incubation of leaf disks in water and Glu solution weakly affected P _n. The rate of O₂ dark consumption in the leaf disks of all the types of treatment increased after incubation in water and especially in Glu solution. Activity of soluble carbonic anhydrase (sCA) in the extracts from young leaves in early SVG after their incubation in water and Glu solution was essentially the same, but after the incubation of ageing leaves in Glu solution, it reliably decreased. In late SVG, sCA activity sharply decreased after incubation in water and Glu solution irrespective of the leaf age. In late SVG, activity of Rubisco in the young leaves did not change after their incubation in water but decreased after incubation of the leaves of the three ages in Glu solution. In early SVG, nonphotochemical fluorescence quenching (NPQ) in the young intact leaf was lower than in the ageing leaf, and after leaf incubation in water and Glu solution, it rose. In late SVG, the value of NPQ was greater than in early SVG and, in contrast to the leaves of early SVG, it declined after leaf incubation; in water, this decline was more pronounced than in the Glu solution. In early SVG, efficient quantum yield of photosystem II (PSII) was much greater than in late SVG and it declined in the leaves incubated with Glu. It was concluded that surplus Glu can maintain biosynthetic processes in the young leaves of young sugar beet plants (trophic function). A decline in the level of chlorophyll and the activities of sCA and Rubisco in the course of leaf development and senescence is considered as a symptom of the suppression of biosynthesis of proteins of chlorophyll-protein complexes and the enzymes (Rubisco and sCA).