Wolbachia对土耳其斯坦叶螨生殖影响的转录组测序分析     

张燕娜  赵倩  赵伊英 《植物保护》2020,46(4):81-90

为进一步探索内共生菌Wolbachia对土耳其斯坦叶螨生殖调控的影响,本试验筛选出完全感染Wolbachia和完全不感染的土耳其斯坦叶螨品系进行转录组测序。结果表明:感染Wolbachia后,叶螨体内一些与生殖相关的基因发生明显变化,其中3 810个基因在雌成螨中受到影响,2 885个基因在雄成螨中受到影响;其中一些参与脂质转运、氧化还原反应、消化及解毒作用的基因具有明显的性别特异性。这为内共生菌Wolbachia引起宿主生殖调控提供了新的理论依据。  相似文献   

Predicting the seasonal flight activity of Myzus persicae,the main aphid vector of Virus Yellows in sugar beet     

Martin Luquet  Sylvain Poggi  Christelle Buchard  Manuel Plantegenest  Yann Tricault 《Pest management science》2023,79(11):4508-4520

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Nutrient cycling in a clonal stand of Eucalyptus and an adjacent savanna ecosystem in Congo: 3. Input–output budgets and consequences for the sustainability of the plantations     

Jean-Paul Laclau  Jacques Ranger  Philippe Deleporte  Yann Nouvellon  Laurent Saint-Andr  Serge Marlet  Jean-Pierre Bouillet 《Forest Ecology and Management》2005,210(1-3):375-391

Clonal plantations of Eucalyptus have been introduced since 1978 on savanna soils of the coastal plains of Congo. Atmospheric deposition, canopy exchange and transfer through the soil were estimated on the whole rooting depth (6 m) over 3 years, in an experimental design installed in a native savanna and an adjacent 6-year-old Eucalyptus plantation. Complementary measurements after planting the experimental savanna made it possible to establish input–output budgets of nutrients for the whole Eucalyptus rotation and to compare them with the native savanna ecosystem.

In this highly-weathered soil, atmospheric deposits and symbiotic N fixation by a legume species balanced the nutrient budgets in savanna, despite large losses during annual burnings. After afforestation, weeding in the Eucalyptus stands eliminated the leguminous species responsible for a N input by symbiotic fixation of about 20 kg ha⁻¹ year⁻¹. Whereas the budgets of P, K, Ca and Mg were roughly balanced, the current silviculture led to a deficit of about 140 kg N ha⁻¹ in the soil, throughout a 7-year rotation. This deficit was large relative to the pool of total N in the upper soil layer (0–50 cm), which was about 2 t ha⁻¹. Therefore, the sustainability of Congolese plantations will require an increase in N fertilizer inputs over successive rotations to balance the N budget. These results were consistent with field trials of fertilization. Practical consequences of these budgets were identified, in order to: (i) direct field trials of fertilization, (ii) select appropriate methods of soil preparation, weed control and harvest, (iii) highlight the importance of fire prevention in this area, and (iv) support the implementation of field trials aiming at introducing a biological nitrogen fixing understorey in Eucalyptus stands.  相似文献   

Assessing the effects of climate change on the phenology of European temperate trees   总被引：4，自引：0，他引：4  

Yann Vitasse  Christophe François  Nicolas DelpierreEric Dufrêne  Antoine KremerIsabelle Chuine  Sylvain Delzon 《Agricultural and Forest Meteorology》2011,151(7):969-980

Modelling phenology is crucial to assess the impact of climate change on the length of the canopy duration and the productivity of terrestrial ecosystems. Focusing on six dominant European tree species, the aims of this study were (i) to examine the accuracy of different leaf phenology models to simulate the onset and ending of the leafy season, with particular emphasis on the putative role of chilling to release winter bud dormancy and (ii) to predict seasonal shifts for the 21st century in response to climate warming.Models testing and validation were done for each species considering 2 or 3 years of phenological observations acquired over a large elevational gradient (1500 m range, 57 populations). Flushing models were either based solely on forcing temperatures (1-phase models) or both on chilling and forcing temperatures (2-phases models). Leaf senescence models were based on both temperature and photoperiod.We show that most flushing models are able to predict accurately the observed flushing dates. The 1-phase models are as efficient as 2-phases models for most species suggesting that chilling temperatures are currently sufficient to fully release bud dormancy. However, our predictions for the 21st century highlight that chilling temperature could be insufficient for some species at low elevation. Overall, flushing is expected to advance in the next decades but this trend substantially differed between species (from 0 to 2.4 days per decade). The prediction of leaf senescence appears more challenging, as the proposed models work properly for only two out of four deciduous species, for which senescence is expected to be delayed in the future (from 1.4 to 2.3 days per decade). These trends to earlier spring leafing and later autumn senescence are likely to affect the competitive balance between species. For instance, simulations over the 21st century predict a stronger lengthening of the canopy duration for Quercus petraea than for Fagus sylvatica, suggesting that shifts in the elevational distributions of these species might occur.  相似文献   

Cytotoxicity,Fractionation and Dereplication of Extracts of the Dinoflagellate Vulcanodinium rugosum,a Producer of Pinnatoxin G     

Marie Geiger  Gwena?lle Desanglois  Kevin Hogeveen  Valérie Fessard  Thomas Leprêtre  Florence Mondeguer  Yann Guitton  Fabienne Hervé  Véronique Séchet  Olivier Grovel  Yves-Fran?ois Pouchus  Philipp Hess 《Marine drugs》2013,11(9):3350-3371

Pinnatoxin G (PnTX-G) is a marine toxin belonging to the class of cyclic imines and produced by the dinoflagellate Vulcanodinium rugosum. In spite of its strong toxicity to mice, leading to the classification of pinnatoxins into the class of “fast-acting toxins”, its hazard for human health has never been demonstrated. In this study, crude extracts of V. rugosum exhibited significant cytotoxicity against Neuro2A and KB cells. IC₅₀ values of 0.38 µg mL⁻¹ and 0.19 µg mL⁻¹ were estimated on Neuro2A cells after only 24 h of incubation and on KB cells after 72 h of incubation, respectively. In the case of Caco-2 cells 48 h after exposure, the crude extract of V. rugosum induced cell cycle arrest accompanied by a dramatic increase in double strand DNA breaks, although only 40% cytotoxicity was observed at the highest concentration tested (5 µg mL⁻¹). However, PnTX-G was not a potent cytotoxic compound as no reduction of the cell viability was observed on the different cell lines. Moreover, no effects on the cell cycle or DNA damage were observed following treatment of undifferentiated Caco-2 cells with PnTX-G. The crude extract of V. rugosum was thus partially purified using liquid-liquid partitioning and SPE clean-up. In vitro assays revealed strong activity of some fractions containing no PnTX-G. The crude extract and the most potent fraction were evaluated using full scan and tandem high resolution mass spectrometry. The dereplication revealed the presence of a major compound that could be putatively annotated as nakijiquinone A, N-carboxy-methyl-smenospongine or stachybotrin A, using the MarinLit™ database. Further investigations will be necessary to confirm the identity of the compounds responsible for the cytotoxicity and genotoxicity of the extracts of V. rugosum.  相似文献   

Within-stand and seasonal variations of specific leaf area in a clonal Eucalyptus plantation in the Republic of Congo     

Yann Nouvellon  Jean-Paul Laclau  Daniel Epron  Antoine Kinana  André Mabiala  Olivier Roupsard  Jean-Marc Bonnefond  Guerric le Maire  Claire Marsden  Jean-Daniel Bontemps  Laurent Saint-André 《Forest Ecology and Management》2010,259(9):1796-1807

Specific leaf area (SLA; m²_leaf kg^?1_leaf) is a key ecophysiological parameter influencing leaf physiology, photosynthesis, and whole plant carbon gain. Both individual tree-based models and other forest process-based models are generally highly sensitive to this parameter, but information on its temporal or within-stand variability is still scarce. In a 2–4-year-old Eucalyptus plantation in Congo, prone to seasonal drought, the within-stand and seasonal variability in SLA were investigated by means of destructive sampling carried out at 2-month intervals, over a 2-year period. Within-crown vertical gradients of SLA were small. Highly significant relationships were found between tree-average SLA (SLA_t) and tree size (tree height, H_t, or diameter at breast height, DBH): SLA_t ranged from about 9 m² kg^?1 for dominant trees to about 14–15 m² kg^?1 for the smallest trees. The decrease in SLA_t with increasing tree size was accurately predicted from DBH using power functions. Stand-average SLA varied by about 20% during the year, with lowest values at the end of the 5-month dry season, and highest values about 2–3 months after the onset of the wet season. Variability in leaf water status according to tree size and season is discussed as a possible determinant of both the within-stand and seasonal variations in SLA.  相似文献   

Responses of terrestrial herb assemblages to weeding and fertilization in cacao agroforests in Indonesia     

Daniele Cicuzza  Yann Clough  Sri Sudarmiyati Tjitrosoedirdjo  Michael Kessler 《Agroforestry Systems》2012,85(1):75-83

Terrestrial herbs are important ecological components in tropical agroforests, but little is known about how they are affected by agricultural management. In cacao agroforests of Central Sulawesi, Indonesia, we studied the change in herb species richness, cover, and biomass over 3?years in 86 subplots subjected to high and low weeding frequency as well as fertilized and non-fertilized treatments. We recorded 111 species with rapid changes in species composition between the 3?years. Species richness increased sharply in the 2nd year, presumably as a result of changes in the management with the experimental regimes, and decreased in the 3rd, probably due to competitive exclusion. Species richness, cover, and biomass were all significantly higher in the infrequently weeded plots than in the frequently weeded ones, but there were only slight responses to the fertilization treatment. An indicator species analysis recovered 45 species that were typical for a given year and a further eight that were typical for certain treatments, but these species showed no clear patterns relative to their ecology or biogeography. We conclude that the herb assemblages in cacao agroforests are quite resilient against weeding, but that the cover of species shifts rapidly in response to management.  相似文献   

Introduction to the invited issue on carbon allocation of trees and forests     

Epron D  Nouvellon Y  Ryan MG 《Tree physiology》2012,32(6):639-643

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Does the effect of forest roads extend a few meters or more into the adjacent forest? A study on understory plant diversity in managed oak stands     

Catherine Avon  Laurent Bergès  Yann Dumas  Jean-Luc Dupouey 《Forest Ecology and Management》2010

Roads are recognised as having different ecological roles such as barrier, corridor or habitat, but the spatial extent of road effects on plant communities in forests remains unclear. We studied the effect of forest road distance on plant understory diversity at 20 sites in young and adult oak stands in a French lowland forest with a long history of management and road construction. All vascular and bryophyte species were collected at five distances ranging from the road verge to 100 m into the adjacent forest stand. We analysed species composition, individual species response, a priori life-history traits response – life form, habitat preference and dispersal mode – and environmental indicator values in relation to road distance and stand age. Plant composition strongly differed between road verge and forest interior habitats. The main road effect extended less than 5 m into the forest stand. A third habitat was detected at the forest-road edge resulting from the road effect on light and soil conditions, and from edge-specific topography. Non-forest species were almost absent from the forest interior. In contrast, many bryophytes and several vascular plants kept away from the road. We identified a posteriori six species groups that better explained the variability of plant response profiles than a priori life-history traits. Plant response to road distance was also dependent on stand age: some species colonised from the road into the forest interior in young stands following regeneration cutting, while other species displayed the reverse pattern in adult stands once canopy closed above the forest road. Even if the depth of forest road effect measured in lowland managed stands was narrow, building of a new forest road has non-negligible effects on plant population dynamics. Forest managers should take into account the impacts of roads on biodiversity, since the expected intensification of silviculture in response to global changes is set to accentuate the effect of forest roads. We recommend further study on the role of dispersal by vehicles (i.e. agestochory) in road effects.  相似文献   

Relating coarse root respiration to root diameter in clonal Eucalyptus stands in the Republic of the Congo     

Marsden C  Nouvellon Y  Epron D 《Tree physiology》2008,28(8):1245-1254

Root respiration is an important component of the carbon balance of a forest ecosystem. We measured CO2 efflux of excised fine roots and intact coarse roots in 3-, 4- and 13-year-old Eucalyptus stands in the region of Pointe-Noire, Republic of the Congo. A transportable and adaptable closed chamber gas exchange system directly measured CO2 efflux of roots from 0.5 to 32 mm in diameter. Fluxes were corrected for measurement system leaks and normalized to a reference temperature of 30 degrees C. Mean fine root respiration rates at the reference temperature varied between 8.5 and 10.8 micromol CO2 kg(-1) s(-1) depending on the stand. Coarse root respiration was strongly negatively correlated to root diameter. We propose a model based on a radial gradient of respiratory activity within the root to simulate the exponential decrease in respiration with diameter. Although many sources of uncertainty in the measurements remain, as discussed in this paper, these results provide a basis for scaling up organ-level root respiration measurements to the tree and stand levels.  相似文献