Evidence for selection pressure from resistant potato genotypes but not from fungicide application within a clonal Phytophthora infestans population          下载免费PDF全文

J. S. Stellingwerf  S. Phelan  F. M. Doohan  V. Ortiz  D. Griffin  A. Bourke  R. C. B. Hutten  D. E. L. Cooke  S. Kildea  E. Mullins 《Plant pathology》2018,67(7):1528-1538

Insight into pathogen population dynamics provides a key input for effective disease management of the potato late blight pathogen Phytophthora infestans. Phytophthora infestans populations vary from genetically complex to more simple with a few clonal lineages. The presence or absence of certain strains of P. infestans may impact the efficacy of fungicides or host resistance. Current evidence indicates that genetically, the Irish populations of P. infestans are relatively simple with a few clonal lineages. In this study, P. infestans populations were genetically characterized based on samples collected at the national centre for potato breeding during the period 2012–16. The dominance of clonal lineages within this P. infestans population was confirmed and the potential selection pressure of fungicide treatment (2013–15) and host resistance (2016) on this clonal P. infestans population was then investigated. It was found that fungicide products did not notably affect the genetic structure of sampled populations relative to samples from untreated control plants. In contrast, samples taken from several resistant potato genotypes were found to be more often of the EU_13_A2 lineage than those taken from control King Edward plants or potato genotypes with low resistance ratings. Resistant potato varieties Sarpo Mira and Bionica, containing characterized R genes, were found to strongly select for EU_13_A2 strains.  相似文献   

播期和密氮组合对镇麦10号干物质积累及产量的调控效应   总被引：4，自引：0，他引：4  

李东升  温明星  蔡金华  曲朝喜  陈爱大 《麦类作物学报》2015,35(10):1226-1432

为确定江苏淮南麦区红皮强筋小麦高产栽培的适宜播期、种植密度和氮肥施用量,选用红皮强筋小麦新品种镇麦10号作为试验材料,在基施45%复合肥375 kg·hm^-2和尿素150 kg·hm^-2条件下,分析了播期和密氮组合对小麦群体干物质积累和产量的影响。结果表明,播期和密氮组合对镇麦10号产量及干物质积累量有极显著的影响。随着播期的延迟,镇麦10号产量先升后降,穗数和千粒重下降,穗粒数略有增加。11月5日播种较10月20日和11月20日播种分别增产2.26%和10.59%;种植密度对籽粒产量的影响因播期不同而有所差异;种植密度增加有利于提高有效穗数,但降低穗粒数和千粒重。10月20日播种时,提高种植密度不利于产量的增加,在基本苗225×10⁴ 株·hm^-2下平均产量最高,较基本苗300×10⁴ 和375×10⁴ 株·hm^-2分别增产3.52%和9.21%;11月5日和11月20日播种时,籽粒产量随着密度的提高而增加,以基本苗375×10⁴ 株·hm^-2的产量最高,较基本苗225×10⁴ 和300×104株·hm^-2分别增产6.32%、4.89%和4.58%、3.25%。增加追氮量有利于穗数、穗粒数和千粒重的增加,但过量追氮时,穗数、穗粒数和千粒重降低;追施纯氮120 kg·hm^-2可显著提高籽粒产量,追氮量过多过少均不利于产量的增加。早播、增加种植密度、增施氮肥均能促进镇麦10号干物质积累,但不利于产量的提高。在本试验条件下,镇麦10号高产最适播期为11月5日,最优密度为375×10⁴ 株·hm^-2,适宜追氮量为120 kg·hm^-2。  相似文献   

追施氮肥对‘镇麦168’产量和品质性状的影响     

温明星陈爱大  曲朝喜李东升 《中国农学通报》2014,30(12):193-197

为给‘镇麦168’及其同类型小麦品种的大面积推广种植提供施肥依据,选用‘镇麦168’为试验材料,采用二因素随机区组设计,探讨追施氮肥对产量和主要品质性状的影响。结果表明,在底肥相同的情况下,在一定范围内追施氮肥,产量、籽粒蛋白质含量、湿面筋含量和稳定时间均呈抛物线变化。施氮总量相同时,拔节期追施氮肥对‘镇麦168’有极显著的增产效应,追施氮肥处理的平均单产比对照增产19.4%,其中以施氮肥A2(112.5 kg/hm²)处理的增产效果最为显著,较对照增1853.7 kg/hm²,增幅达34.3%,同时能显著提高‘镇麦168’籽粒蛋白质、湿面筋含量、面团稳定时间、沉降值以及容重。综上,在江苏淮南麦区生态条件下,以拔节期追施氮肥112.5 kg/hm²为‘镇麦168’较为合理的氮肥运筹模式。  相似文献   

Airborne remote sensing assessment of the damage to cotton caused by spray drift from aerially applied glyphosate through spray deposition measurements     

Y. Huang  S.J. Thomson  B.V. Ortiz  K.N. Reddy  W. Ding  R.M. Zablotowicz  J.R. Bright 《Biosystems Engineering》2010,107(3):212-220

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Naegleria fowleri-associated encephalitis in a cow from Costa Rica     

Morales JA  Chaves AJ  Visvesvara GS  Dubey JP 《Veterinary parasitology》2006,139(1-3):221-223

Species of Naegleria, Acanthamoeba, and Balamuthia are soil amoebae that can cause encephalitis in animals and humans. Of these, Naegleria fowleri is the cause of often fatal primary meningoencephalitis in humans. N. fowleri-associated encephalitis was diagnosed in a cow that was suspected to have rabies. Only formalin-fixed brain was available for diagnosis. There was severe meningoencephalitis involving all parts of the brain and numerous amoebic trophozoites were present in lesions. The amoebae reacted with N. fowleri-specific polyclonal antibodies in an indirect immunofluorescent antibody test. This is the first report of amoebic encephalitis in any host from Costa Rica.  相似文献   

Genetic diversity of the myrtle rust pathogen (Austropuccinia psidii) in the Americas and Hawaii: Global implications for invasive threat assessments          下载免费PDF全文

J. E. Stewart  A. L. Ross‐Davis  R. N. Graҫa  A. C. Alfenas  T. L. Peever  J. W. Hanna  J. Y. Uchida  R. D. Hauff  C. Y. Kadooka  M.‐S. Kim  P. G. Cannon  S. Namba  S. Simeto  C. A. Pérez  M. B. Rayamajhi  D. J. Lodge  M. Arguedas  R. Medel‐Ortiz  M. A. López‐Ramirez  P. Tennant  M. Glen  P. S. Machado  A. R. McTaggart  A. J. Carnegie  N. B. Klopfenstein 《Forest Pathology》2018,48(1)

Since the myrtle rust pathogen (Austropuccinia psidii) was first reported (as Puccinia psidii) in Brazil on guava (Psidium guajava) in 1884, it has been found infecting diverse myrtaceous species. Because A. psidii has recently spread rapidly worldwide with an extensive host range, genetic and genotypic diversities were evaluated within and among A. psidii populations in its putative native range and other areas of myrtle rust emergence in the Americas and Hawaii. Microsatellite markers revealed several unique multilocus genotypes (MLGs), which grouped isolates into nine distinct genetic clusters [C1–C9 comprising C1: from diverse hosts from Costa Rica, Jamaica, Mexico, Puerto Rico, and USA‐Hawaii, and USA‐California; C2: from eucalypts (Eucalyptus spp.) in Brazil/Uruguay and rose apple (Syzygium jambos) in Brazil; C3: from eucalypts in Brazil; C4: from diverse hosts in USA‐Florida; C5: from Java plum (Syzygium cumini) in Brazil; C6: from guava and Brazilian guava (Psidium guineense) in Brazil; C7: from pitanga (Eugenia uniflora) in Brazil; C8: from allspice (Pimenta dioica) in Jamaica and sweet flower (Myrrhinium atropurpureum) in Uruguay; C9: from jabuticaba (Myrciaria cauliflora) in Brazil]. The C1 cluster, which included a single MLG infecting diverse host in many geographic regions, and the closely related C4 cluster are considered as a “Pandemic biotype,” associated with myrtle rust emergence in Central America, the Caribbean, USA‐Florida, USA‐Hawaii, Australia, China‐Hainan, New Caledonia, Indonesia and Colombia. Based on 19 bioclimatic variables and documented occurrences of A. psidii contrasted with reduced sets of specific genetic clusters (subnetworks, considered as biotypes), maximum entropy bioclimatic modelling was used to predict geographic locations with suitable climate for A. psidii which are at risk from invasion. The genetic diversity of A. psidii throughout the Americas and Hawaii demonstrates the importance of recognizing biotypes when assessing the invasive threats posed by A. psidii around the globe.  相似文献   

The influence of Ringer's lactate or HES 130/0.4 administration on the integrity of the small intestinal mucosa in a pig hemorrhagic shock model under general anesthesia          下载免费PDF全文

Ana Liza Ortiz DVM  PhD  Helena Vala DVM  PhD  Carlos Venâncio DVM  PhD  João Mesquita DVM  PhD  Aura Silva DVM  PhD  Jose Manuel Gonzalo‐Orden DVM  PhD  David Ferreira DVM  PhD 《Journal of Veterinary Emergency and Critical Care》2017,27(1):96-107

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Melanin granules melanophages and a fully‐melanized epidermis are common traits of odontocete and mysticete cetaceans          下载免费PDF全文

Blanca Morales‐Guerrero  Cecilia Barragán‐Vargas  German R. Silva‐Rosales  Christian D. Ortega‐Ortiz  Diane Gendron  Laura M. Martinez‐Levasseur  Karina Acevedo‐Whitehouse 《Veterinary dermatology》2017,28(2):213-e50

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Genetic analysis and molecular mapping of quantitative trait loci in common bean against Pythium ultimum     

Campa A  Pérez-Vega E  Pascual A  Ferreira JJ 《Phytopathology》2010,100(12):1315-1320

Pythium ultimum is a soil pathogen that can cause seed decay and damage to roots in common bean. In this study, the response of a set of 40 common bean genotypes to P. ultimum and inheritance of the resistance in the 92 F? recombinant inbred lines (RIL) developed from a cross between Xana and Cornell 49242 was investigated by using emergence rate and seedling vigor. Emergence of the 40 genotypes showed a significant association between white seed coat and response to this pathogen. Among these, 11 common bean genotypes, all with colored seeds, exhibited a high percentage of emergence and seedling vigor not significantly different (P > 0.05) to noninoculated plants. Response of the RIL population revealed both qualitative and quantitative modes of inheritance. A major gene (Py-1) controlling the emergence rate was mapped in the region of the gene P, a basic color gene involved in control of seed coat color, located on LG 7. Using the RIL subpopulation with colored seeds, a significant quantitative trait loci (QTL) associated with the emergence rate (ER3(XC)) and another with seedling vigor (SV6(XC)) were identified on the LG 3 and 6, respectively. QTL SV6(XC) was mapped in the region of the gene V, another gene involved the genetic control of color. QTLs associated with seed traits were mapped in the same relative position as regions involved in responses to P. ultimum suggesting the possible implication of avoidance mechanisms in the response to this pathogen.  相似文献   

Forest monitoring with TerraSAR-X: first results     

Johannes Breidenbach  Sonia M. Ortiz  Manfred Reich 《European Journal of Forest Research》2010,129(5):813-823

Several TerraSAR-X satellite images acquired in high resolution spotlight mode with different polarisations for two study sites in southern Germany were used to distinguish forest from other land cover classes (agriculture, built-up, water bodies) using logistic regression models. In general, we observed that the mean and particularly the standard deviation of the backscatter were viable measures to discriminate land cover classes. Both measures were lowest for water bodies and highest for built-up areas, with agricultural areas and forest in intermediate positions. Trees outside forest were not differentiable from forest with the applied method. The HH-polarised image was better suited for a classification of built-up areas, whereas the VV-polarised image was more appropriate when classifying agricultural areas. Consequently, the combination of the two differently polarised images leads to a significantly better model. Since forests in one study area were generally found on steeper slopes in comparison to other land cover classes, the inclusion of terrain slope further improved the classification, which resulted in an overall accuracy of 92–95%. Systematic differences in the parameter values of the explanatory variables for one class between the study areas may be caused by differing class probabilities. Thus, transferring the model of one study area to the image of another resulted in a 7–9% loss of accuracy.  相似文献