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1.
Ammar Madania Merfat Altawil Walid Naffaa Paul H Volker Mohammad Hawat 《Journal of Phytopathology》2013,161(7-8):452-458
Maize is the third most important cereal after wheat and barley in Syria. Maize plants are attacked by several Fusarium species causing mainly stalk and ear rot of maize which poses a major impact worldwide. Identification of Fusarium species is important for disease control and for assessment of exposure risk to mycotoxines. To identify Fusarium species attacking maize in Syria, a total of 32 Fusarium isolates were recovered from maize ears collected from four different geographical regions, mainly from Ghouta surrounding Damascus. Fusarium isolates were identified based on morphology and on partial DNA sequencing of the TEF1‐α and rDNA/ITS genes. The majority (26 of 32) of these isolates was identified as F. verticillioides (subdivided into four groups), whereas three isolates turned out to be F. thapsinum, F. equiseti and F. andiyazi. The remaining three isolates were close to F. andiyazi, although further investigation is needed to confirm whether they represent a yet undescribed species. Furthermore, our results showed that sequencing the TEF1‐α gene is much more informative than sequencing of the rDNA/ITS region for Fusarium identification at the species level. PCR analysis showed that only F. verticillioides isolates were potentially fumonisin producers and that only the F. equiseti isolate was potentially trichotecene producer. This is the first report on Fusarium thapsinum, F. equiseti and F. andiyazi attacking maize in Syria. 相似文献
2.
Diversity of Cercomonad Species in the Phyllosphere and Rhizosphere of Different Plant Species with a Description of Neocercomonas epiphylla (Cercozoa,Rhizaria) a Leaf‐Associated Protist 下载免费PDF全文
Sebastian Flues Malte Blokker Kenneth Dumack Michael Bonkowski 《The Journal of eukaryotic microbiology》2018,65(5):587-599
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Estelle Kilias Christian Wolf Eva‐Maria Nöthig Ilka Peeken Katja Metfies 《Journal of phycology》2013,49(5):996-1010
In this study, we present the first comprehensive analyses of the diversity and distribution of marine protist (micro‐, nano‐, and picoeukaryotes) in the Western Fram Strait, using 454‐pyrosequencing and high‐pressure liquid chromatography (HPLC) at five stations in summer 2010. Three stations (T1; T5; T7) were influenced by Polar Water, characterized by cold water with lower salinity (<33) and different extents of ice concentrations. Atlantic Water influenced the other two stations (T6; T9). While T6 was located in the mixed water zone characterized by cold water with intermediate salinity (~33) and high ice concentrations, T9 was located in warm water with high salinity (~35) and no ice‐coverage at all. General trends in community structure according to prevailing environmental settings, observed with both methods, coincided well. At two stations, T1 and T7, characterized by lower ice concentrations, diatoms (Fragilariopsis sp., Porosira sp., Thalassiosira spp.) dominated the protist community. The third station (T5) was ice‐covered, but has been ice‐free for ~4 weeks prior to sampling. At this station, dinoflagellates (Dinophyceae 1, Woloszynskia sp. and Gyrodinium sp.) were dominant, reflecting a post‐bloom situation. At station T6 and T9, the protist communities consisted mainly of picoeukaryotes, e.g., Micromonas spp. Based on our results, 454‐pyrosequencing has proven to be an adequate tool to provide comprehensive information on the composition of protist communities. Furthermore, this study suggests that a snap‐shot of a few, but well‐chosen samples can provide an overview of community structure patterns and succession in a dynamic marine environment. 相似文献
4.
Laury Dijoux Heroen Verbruggen Lydiane Mattio Nathalie Duong Claude Payri 《Journal of phycology》2012,48(6):1465-1481
Halimeda is a genus of calcified and segmented green macroalgae in the order Bryopsidales. In New Caledonia, the genus is abundant and represents an important part of the reef flora. Previous studies recorded 19 species that were identified using morphological criteria. The aim of this work was to reassess the diversity of the genus in New Caledonia using morpho‐anatomical examinations and molecular analyses of the plastid tufA and rbcL genes. Our results suggest the occurrence of 22 species. Three of these are reported for the first time from New Caledonia: Halimeda kanaloana, H. xishaensis, and an entity resembling H. stuposa. DNA analyses revealed that the species H. fragilis exhibits cryptic or pseudocryptic diversity in New Caledonia. We also show less conclusive evidence for cryptic species within H. taenicola 相似文献
5.
Clarholm M 《Antonie van Leeuwenhoek》2002,81(1-4):309-318
The paper explores interactions between the two first organism groups to appear on earth, the bacteria and protozoa, and their
interplay with the rest of the ecosystem focusing upon northern boreal forests. The microbial loop is suggested as a mechanism
for local inputs of new N to the ecosystem. The possibility to couple short-term microbial processes with their long-term
effects, — as registered in plants, soil and the atmosphere, via the abiotic variables — is explored. The latter are investigated
in relation to the environments they create for the micro-organisms, and how this results in varying soil fertility. A chain
of events is presented that relate high Ca concentration in the mineral soil and high water availability to increased nitrogen
availability for plants via the micro-organisms. An example is given of the influence of these parameters directly upon protozoa
along an extreme fertility gradient, and also indirect evidence from a Finnish field study of 30 sites with four fertility
levels. Finally, there is a discussion about ways to convert knowledge gained in detailed studies of microbial interactions
into forms useful when evaluating the present status of and effects of ameliorative management on ecosystems strongly affected
by humans.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
Ma Alicia de la Colina Mark E. Hauber Bill M. Strausberger Juan Carlos Reboreda Bettina Mahler 《Ecology and evolution》2016,6(14):4684-4696
Generalist parasites exploit multiple host species at the population level, but the individual parasite's strategy may be either itself a generalist or a specialist pattern of host species use. Here, we studied the relationship between host availability and host use in the individual parasitism patterns of the Shiny Cowbird Molothrus bonariensis, a generalist avian obligate brood parasite that parasitizes an extreme range of hosts. Using five microsatellite markers and an 1120‐bp fragment of the mtDNA control region, we reconstructed full‐sibling groups from 359 cowbird eggs and chicks found in nests of the two most frequent hosts in our study area, the Chalk‐browed Mockingbird Mimus saturninus and the House Wren Troglodytes aedon. We were able to infer the laying behavior of 17 different females a posteriori and found that they were mostly faithful to a particular laying area and host species along the entire reproductive season and did not avoid using previously parasitized nests (multiple parasitism) even when other nests were available for parasitism. Moreover, we found females using the same host nest more than once (repeated parasitism), which had not been previously reported for this species. We also found few females parasitizing more than one host species. The use of an alternative host was not related to the main hosts' nest availability. Overall, female shiny cowbirds use a spatially structured and host species specific approach for parasitism, but they do so nonexclusively, resulting in both detectable levels of multiple parasitism and generalism at the level of individual parasites. 相似文献
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Yubo Hou Nanjing Ji Huan Zhang Xinguo Shi Hansen Han Senjie Lin 《Journal of phycology》2019,55(1):37-46
Proliferating cell nuclear antigen (PCNA) plays critical roles in eukaryotic DNA replication and replication‐associated processes. It is typically encoded by one or two gene copies (pcna) in eukaryotic genomes. Recently reported higher copy numbers of pcna in some dinoflagellates raised a question of how this gene has uniquely evolved in this phylum. Through real‐time PCR quantification, we found a wide range of pcna copy number (2–287 copies) in 11 dinoflagellate species (n = 38), and a strong positive correlation between pcna copy number and genome size (log10–log10 transformed). Intraspecific pcna diverged up to 21% and are dominated by nonsynonymous substitutions, indicating strong purifying selection pressure on and hence functional necessity of this gene. By surveying pcna copy numbers in eukaryotes, we observed a genome size threshold at 4 pg DNA, above which more than two pcna copies are found. To examine whether retrotransposition is a mechanism of pcna duplication, we measured the copy number of retroposed pcna, taking advantage of the 22‐nt dinoflagellate‐specific spliced leader (DinoSL) capping the 5′ end of dinoflagellate nuclear‐encoded mRNAs, which would exist in the upstream region of a retroposed gene copy. We found that retroposed pcna copy number increased with total pcna copy number and genome size. These results indicate co‐evolution of dinoflagellate pcna copy number with genome size, and retroposition as a major mechanism of pcna duplication in dinoflagellates. Furthermore, we posit that the demand of faithful replication and maintenance of the large dinoflagellate genomes might have favored the preservation of the retroposed pcna as functional genes. 相似文献
9.
I. Finiti M. O. Leyva J. López‐Cruz B. Calderan Rodrigues B. Vicedo C. Angulo A. B. Bennett M. Grant P. García‐Agustín C. González‐Bosch 《Plant biology (Stuttgart, Germany)》2013,15(5):819-831
Plant cell wall modification is a critical component in stress responses. Endo‐1,4‐β‐glucanases (EGs) take part in cell wall editing processes, e.g. elongation, ripening and abscission. Here we studied the infection response of Solanum lycopersicum and Arabidopsis thaliana with impaired EGs. Transgenic TomCel1 and TomCel2 tomato antisense plants challenged with Pseudomonas syringae showed higher susceptibility, callose priming and increased jasmonic acid pathway marker gene expression. These two EGs could be resistance factors and may act as negative regulators of callose deposition, probably by interfering with the defence‐signalling network. A study of a set of Arabidopsis EG T‐DNA insertion mutants challenged with P. syringae and Botrytis cinerea revealed that the lack of other EGs interferes with infection phenotype, callose deposition, expression of signalling pathway marker genes and hormonal balance. We conclude that a lack of EGs could alter plant response to pathogens by modifying the properties of the cell wall and/or interfering with signalling pathways, contributing to generate the appropriate signalling outcomes. Analysis of microarray data demonstrates that EGs are differentially expressed upon many different plant–pathogen challenges, hormone treatments and many abiotic stresses. We found some Arabidopsis EG mutants with increased tolerance to osmotic and salt stress. Our results show that impairing EGs can alter plant–pathogen interactions and may contribute to appropriate signalling outcomes in many different biotic and abiotic plant stress responses. 相似文献
10.
Effects of nutrients and warming on Planktothrix dynamics and diversity: a palaeolimnological view based on sedimentary DNA and RNA 下载免费PDF全文
Olga Savichtcheva Didier Debroas Marie Elodie Perga Fabien Arnaud Clément Villar Emilie Lyautey Amy Kirkham Cécile Chardon Benjamin Alric Isabelle Domaizon 《Freshwater Biology》2015,60(1):31-49
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Diversity and abundance of human‐pathogenic fungi associated with pigeon faeces in urban environments 下载免费PDF全文
Pathogenic fungi are a growing health concern worldwide, particularly in large, densely populated cities. The dramatic upsurge of pigeon populations in cities has been implicated in the increased incidence of invasive fungal infections. In this study, we used a culture‐independent, high‐throughput sequencing approach to describe the diversity of clinically relevant fungi (CRF) associated with pigeon faeces and map the relative abundance of CRF across Seoul, Korea. In addition, we tested whether certain geographical, sociological and meteorological factors were significantly associated with the diversity and relative abundance of CRF. Finally, we compared the CRF diversity of fresh and old pigeon faeces to identify the source of the fungi and the role of pigeons in dispersal. Our results demonstrated that both the composition and relative abundance of CRF are unevenly distributed across Seoul. The green area ratio and the number of multiplex houses were positively correlated with species diversity, whereas wind speed and number of households were negatively correlated. The number of workers and green area ratio were positively correlated with the relative abundance of CRF, whereas wind speed was negatively correlated. Because many CRF were absent in fresh faeces, we inferred that most species cannot survive the gastrointestinal tract of pigeons and instead are likely transmitted through soil or air and use pigeon faeces as a substrate for proliferation. 相似文献
12.
The outcome of species interactions may manifest differently at different spatial scales; therefore, our interpretation of observed interactions will depend on the scale at which observations are made. For example, in ladybeetle–aphid systems, the results from small‐scale cage experiments usually cannot be extrapolated to landscape‐scale field observations. To understand how ladybeetle–aphid interactions change across spatial scales, we evaluated predator–prey interactions in an experimental system. The experimental habitat consisted of 81 potted plants and was manipulated to facilitate analysis across four spatial scales. We also simulated a spatially explicit metacommunity model parallel to the experiment. In the experiment, we found that the negative effect of ladybeetles on aphids decreased with increasing spatial scales. This pattern can be explained by ladybeetles strongly suppressing aphids at small scales, but not colonizing distant patches fast enough to suppress aphids at larger scales. In the experiment, the positive effects of aphids on ladybeetles were strongest at three‐plant scale. In a model scenario where predators did not have demographic dynamics, we found, consistent with the experiment, that both the effects of ladybeetles on aphids and the effects of aphids on ladybeetles decreased with increasing spatial scales. These patterns suggest that dispersal was the primary cause of ladybeetle population dynamics in our experiment: aphids increased ladybeetle numbers at smaller scales because ladybeetles stayed in a patch longer and performed area‐restricted searches after encountering aphids; these behaviors did not affect ladybeetle numbers at larger spatial scales. The parallel experimental and model results illustrate how predator–prey interactions can change across spatial scales, suggesting that our interpretation of observed predator–prey dynamics would differ if observations were made at different scales. This study demonstrates how studying ecological interactions at a range of scales can help link the results of small‐scale ecological experiments to landscape‐scale ecological problems. 相似文献
13.
Sebastian Ploch Laura E. Rose David Bass Michael Bonkowski 《The Journal of eukaryotic microbiology》2016,63(5):635-641
The largest biological surface on earth is formed by plant leaves. These leaf surfaces are colonized by a specialized suite of leaf‐inhabiting microorganisms, recently termed “phyllosphere microbiome”. Microbial prey, however, attract microbial predators. Protists in particular have been shown to structure bacterial communities on plant surfaces, but virtually nothing is known about the community composition of protists on leaves. Using newly designed specific primers targeting the 18S rDNA gene of Cercozoa, we investigated the species richness of this common protist group on leaves of four Brassicaceae species from two different locations in a cloning‐based approach. The generated sequences revealed a broad diversity of leaf‐associated Cercozoa, mostly bacterial feeders, but also including known plant pathogens and a taxon of potential endophytes that were recently described as algal predators in freshwater systems. This initial study shows that protists must be regarded as an integral part of the microbial diversity in the phyllosphere of plants. 相似文献
14.
Gabriele Rondoni Isabel Borges Jana Collatz Eric Conti Alejandro C. Costamagna Franois Dumont Edward W. Evans Audrey A. Grez Andy G. Howe Eric Lucas Julie‐lonore Maisonhaute Antnio Onofre Soares Tania Zaviezo Matthew J.W. Cock 《Entomologia Experimentalis et Applicata》2021,169(1):6-27
Since the late 19th century, exotic ladybirds (Coleoptera: Coccinellidae) have been used extensively for suppressing herbivorous insects of economic importance. In recent decades, the introduction of non‐native biological control (BC) agents has been greatly limited due to the awareness of the potential non‐target effects of introductions. Nonetheless, recent episodes of biological invasions of economically important pests have raised the need to carefully consider whether the expected benefits of pest control go beyond the possible environmental risks of introduction. To better understand the factors that contributed to successful BC programs, here we review the literature behind classical and augmentative BC using exotic ladybirds. Additionally, by means of case studies, we discuss the BC efficacy of selected exotic species, e.g., Coccinella septempunctata L., Harmonia axyridis (Pallas), and Hippodamia variegata (Goeze), and their position within the communities of predators in the introduced areas of USA, Canada, and Chile. In Europe, much of the research on exotic ladybirds has been conducted on the undesired impact of H. axyridis. Therefore, we summarize the risk assessment data for this species and review the field research investigating the ecological impact on European aphidophagous predators. According to the BIOCAT database of classical BC programs, 212 ladybird species belonging to 68 genera have been released in about 130 years of BC activity, with 14.6% of introductions having resulted in partial, substantial, or complete control of the target pest. However, because post‐release evaluation of establishment and BC success has not always been conducted, this rate could underestimate the successful cases. Among other factors, ladybird establishment and pest suppression mostly depend on (1) intrinsic factors, i.e., high voracity, synchronized predator‐prey life cycle, and high dispersal ability, and (2) extrinsic factors, i.e., adaptability to the new environment and landscape composition. This review contributes to improved understanding of ladybirds as exotic BC agents. 相似文献
15.
Rapid detection of viable Legionella pneumophila in tap water by a qPCR and RT‐PCR‐based method 下载免费PDF全文
R. Boss A. Baumgartner S. Kroos M. Blattner R. Fretz D. Moor 《Journal of applied microbiology》2018,125(4):1216-1225
Aims
A molecular method for a rapid detection of viable Legionella pneumophila of all serogroups in tap water samples was developed as an alternative to the reference method (ISO). Legionellae are responsible for Legionnaires’ disease, a severe pneumonia in humans with high lethality.Methods and Results
The developed method is based on a nutritional stimulation and detection of an increase in precursor 16S rRNA as an indicator for viability. For quantification, DNA was detected by qPCR. This method was compared to the ISO method using water samples obtained from public sports facilities in Switzerland. The sensitivity and specificity were 91 and 97%, respectively, when testing samples for compliance with a microbiological criterion of 1000 cell equivalents per l.Conclusion
The new method is sensitive and specific for Leg. pneumophila and allows results to be obtained within 8 h upon arrival, compared to one week or more by the ISO method.Significance and Impact of the Study
The method represents a useful tool for a rapid detection of viable Leg. pneumophila of all serogroups in water by molecular biology. It can be used as an alternative to the ISO method for official water analysis for legionellae and particularly when a short test time is required. 相似文献16.
‘Last In–First Out’: seasonal variations of non‐structural carbohydrates,glucose‐6‐phosphate and ATP in tubers of two Arum species 下载免费PDF全文
E. Petrussa F. Boscutti A. Vianello V. Casolo 《Plant biology (Stuttgart, Germany)》2018,20(2):346-356
- Knowledge on the metabolism of polysaccharide reserves in wild species is still scarce. In natural sites we collected tubers of Arum italicum Mill. and A. maculatum L. – two geophytes with different apparent phenological timing, ecology and chorology – during five stages of the annual cycle in order to understand patterns of reserve accumulation and degradation.
- Both the entire tuber and its proximal and distal to shoot portion were utilised. Pools of non‐structural carbohydrates (glucose, sucrose and starch), glucose‐6‐phosphate and ATP were analysed as important markers of carbohydrate metabolism.
- In both species, starch and glucose content of the whole tuber significantly increased from sprouting to the maturation/senescence stages, whereas sucrose showed an opposite trend; ATP and glucose‐6‐phosphate were almost stable and dropped only at the end of the annual cycle. Considering the two different portions of the tuber, both ATP and glucose‐6‐phosphate concentrations were higher in proximity to the shoot in all seasonal stages, except the flowering stage.
- Our findings suggest that seasonal carbon partitioning in the underground organ is driven by phenology and occurs independently of seasonal climate conditions. Moreover, our results show that starch degradation, sustained by elevated ATP and glucose‐6‐phosphate pools, starts in the peripheral, proximal‐to‐shoot portion of the tuber, consuming starch accumulated in the previous season, as a ‘Last In–First Out’ mechanism of carbohydrate storage.
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Anna Barbanti Hector Torrado Enrique Macpherson Luca Bargelloni Rafaella Franch Carlos Carreras Marta Pascual 《Molecular ecology resources》2020,20(3):795-806
High‐throughput sequencing has revolutionized population and conservation genetics. RAD sequencing methods, such as 2b‐RAD, can be used on species lacking a reference genome. However, transferring protocols across taxa can potentially lead to poor results. We tested two different IIB enzymes (AlfI and CspCI) on two species with different genome sizes (the loggerhead turtle Caretta caretta and the sharpsnout seabream Diplodus puntazzo) to build a set of guidelines to improve 2b‐RAD protocols on non‐model organisms while optimising costs. Good results were obtained even with degraded samples, showing the value of 2b‐RAD in studies with poor DNA quality. However, library quality was found to be a critical parameter on the number of reads and loci obtained for genotyping. Resampling analyses with different number of reads per individual showed a trade‐off between number of loci and number of reads per sample. The resulting accumulation curves can be used as a tool to calculate the number of sequences per individual needed to reach a mean depth ≥20 reads to acquire good genotyping results. Finally, we demonstrated that selective‐base ligation does not affect genomic differentiation between individuals, indicating that this technique can be used in species with large genome sizes to adjust the number of loci to the study scope, to reduce sequencing costs and to maintain suitable sequencing depth for a reliable genotyping without compromising the results. Here, we provide a set of guidelines to improve 2b‐RAD protocols on non‐model organisms with different genome sizes, helping decision‐making for a reliable and cost‐effective genotyping. 相似文献
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Alternation of generations – unravelling the underlying molecular mechanism of a 165‐year‐old botanical observation 下载免费PDF全文
Characteristically, land plants exhibit a life cycle with an ‘alternation of generations’ and thus alternate between a haploid gametophyte and a diploid sporophyte. At meiosis and fertilisation the transitions between these two ontogenies take place in distinct single stem cells. The evolutionary invention of an embryo, and thus an upright multicellular sporophyte, in the ancestor of land plants formed the basis for the evolution of increasingly complex plant morphologies shaping Earth's ecosystems. Recent research employing the moss Physcomitrella patens revealed the homeotic gene BELL1 as a master regulator of the gametophyte‐to‐sporophyte transition. Here, we discuss these findings in the context of classical botanical observations. 相似文献