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排序方式： 共有1698条查询结果，搜索用时 15 毫秒
31.
To determine the potential of sexual reproduction among host-adapted populations of Phytophthora infestans sensu lato in Ecuador, 13 A1 isolates belonging to clonal lineages US-1, EC-1 and EC-3, and 11 A2 isolates belonging to the clonal lineage EC-2, were paired on agar plates to induce crossing. In the first experiment, six A1 isolates (three US-1, two EC-1 and one EC-3) were each crossed with three A2 isolates (total = 18 crosses). Matings involving isolates of the EC-1 lineage produced more oospores of healthy appearance than did matings with isolates of US-1 or EC-3. In the second experiment, the oospores of 35 crosses (21 EC-1 × EC-2; 10 US-1 × EC-2; four EC-3 × EC-2) were dispersed on water agar to assess oospore germination. Overall, germination percentages were low. Only one cross produced enough progeny for evaluation. Twenty-three single-oospore offspring were isolated and evaluated for mating type; electrophoretic patterns of glucose-6-phosphate isomerase ( Gpi ) and peptidase ( Pep ) alloenzyme loci; mitochondrial DNA haplotype; and genomic DNA fingerprint. Multilocus genotype data indicated that all 23 isolates resulted from meiotic recombination. Four progeny with homothallic phenotype appeared to be unstable heterokaryons. Markers at several loci segregated according to simple Mendelian expectations for a diploid organism, but the ratios of three RFLP loci and the Pep locus were not consistent with Mendelian expectations. All progeny were nonpathogenic on hosts of the parental genotypes. Reduced mating success and reduced pathogenic fitness of progeny appear to be postmating mechanisms of reproductive isolation in populations of P. infestans sensu lato in Ecuador. 相似文献
32.
A. Sisto M. G. Cipriani S. Tegli M. Cerboneschi G. Stea E. Santilli 《Plant pathology》2007,56(3):366-372
The genetic diversity of 71 Pseudomonas savastanoi pv. savastanoi strains isolated from different host species and from diverse geographical regions was determined by fluorescent amplified fragment length polymorphism (f-AFLP) analysis. The study was carried out using three different selective primer combinations. Strains of P. syringae pv. syringae , P. syringae pv. phaseolicola , P. syringae pv. glycinea , P. syringae pv. tagetis and P. amygdali were also included as outgroups. Based on cluster analysis of f-AFLP data, all P. savastanoi pv. savastanoi strains showed a high degree of similarity, grouping in a cluster and forming a taxon clearly separate from outgroup strains. AFLP analyses failed to support placing strains of P. savastanoi pv. savastanoi , P. syringae pv. phaseolicola and P. syringae pv. glycinea in the same species. Strains of P. savastanoi pv. savastanoi formed subclusters that correlated with the host species. Strains identified within these subclusters were related to the geographical region where the strains were isolated. Strains of P. savastanoi pv. savastanoi from olive were divided into two subclusters. Strains from oleander were differentiated from those from ash and were divided into two additional subclusters, distinct from olive strains. Three strains isolated from jasmine showed a high level of similarity among them but, at a lower Dice similarity coefficient, were linked to a subcluster including olive strains. Finally, two strains isolated from privet were similar to strains from olive and were included in the same subcluster. 相似文献
33.
Aboagye Kwarteng Dofuor;Joshua Obeng;Frederick Leo Sossah;Angelina Fathia Osabutey;Hanif Lutuf;Jonathan Osei-Owusu;Fred Kormla Ablormeti;Rahmat Quaigrane Duker;Seyram Kofi Loh;Joseph Okani Honger;Maxwell Jnr Opoku;Owusu Fordjour Aidoo; 《Plant pathology》2024,73(7):1708-1718
Pseudocercospora fruit and leaf spot (PFLS), also known as angular leaf spot of citrus, is a devastating fungal disease that poses a significant threat to citrus production, profitability and food security in sub-Saharan Africa and the Arabian Peninsula. In the present review, we explore current knowledge regarding PFLS management initiatives, including cultural practices, chemical control strategies and biological interventions. Furthermore, this review highlights the challenges faced in controlling PFLS and emphasizes the urgent need for sustainable and cost-effective solutions to combat the disease. We discuss recent advancements and emerging prospects in understanding PFLS, including novel approaches for disease management and the potential for developing resistant citrus cultivars through breeding programmes or genetic modification. By synthesizing existing research findings and identifying gaps in knowledge, this review aims to provide a comprehensive understanding of PFLS and its impact on food security. We emphasize the importance of collaborative efforts, knowledge exchange and developing integrated disease management strategies to control PFLS and mitigate its detrimental effects on citrus production and farmers' livelihoods in affected regions. 相似文献
34.
Since weeds serve as hosts for nematode pests, the host status of 20 weed species (commonly occurring in fields of developing farmers) to Meloidogyne incognita and M. javanica, respectively, were investigated. Greenhouse studies showed that seven weed species had Rf values >1 for both nematode species indicating susceptibility, while 13 had Rf values ≤ 1 indicating resistance. Greenhouse results showed that Hibiscus trionum and Amaranthus tricolor were identified as the most susceptible and Chenopodium carinatum and Datura ferox the poorest hosts for M. incognita and M. javanica. For field experiments at Kuruman, Solanum retroflexum was the most susceptible weed to a M. javanica population, while the same was evident for H. trionum at Nelspruit, where a mixed population of M. incognita and M. javanica occurred and at Potchefstroom, where a population of M. incognita was present. Results from this study indicated that certain weed species are highly susceptible to root-knot nematodes and should be removed timely and effectively to prevent population level increases of root-knot nematode pests in the fields of farmers. 相似文献
35.
《Veterinary Medicine and Science》2017,3(2):71-81
The expanding international wildlife trade, combined with a lack of surveillance for key animal diseases in most countries, represents a potential pathway for transboundary disease movement. While the international wildlife trade represents over US $300 billion per year industry involving exchange of billions of individual animals, animal products, and plants as traditional medicines, meat from wild animals, trophies, live exotic pets, commercial products and food, surveillance and reporting of OIE ‐Listed diseases in wildlife are often opportunistic. We reviewed peer‐reviewed literature for reports of 73 OIE ‐Listed terrestrial animal diseases in wild animals and found 528 possible wild animal hosts using our methodology. Not all host–pathogen relationships indicate that a particular species serves an epidemiologically significant role in the transmission of disease, but improved reporting of infections in wild animals along with clinical and pathological findings would contribute to improved One Health risk assessments. 相似文献
36.
以檀香种子为材料,研究了不同浓度赤霉素、播种基质以及伴生树种对幼苗生长的影响,结果表明:采用1 000 mg/L赤霉素处理种子24h可促进种子发芽,发芽率达85%以上;以砂壤土+竹炭粉为播种基质出苗率最高;利用抛荒龙眼地并以龙眼树作为檀香成林期伴生植物对檀香生长具有促进作用,栽培12个月时测定,檀香树高、地径分别达172.3cm和2.48cm,为抛荒龙眼地重新利用提供新的思路。 相似文献
37.
38.
猪圆环病毒2型（Porcine circovirus virus type 2,PCV2）是引起断奶仔猪多系统衰竭综合征（Postweaning multisystemic wasting syndrome,PMWS）以及其他猪相关疾病的主要病原体。复制酶（Replicase,Rep）蛋白是由PCV2 ORF1基因编码的功能性复制启动蛋白,通过与ORF1编码的另一复制相关蛋白Rep′共同作用参与PCV2的DNA滚环复制。Rep蛋白作为PCV2的一种必需功能性蛋白,是研究PCV2抗病毒治疗的一个新突破口。然而,目前有关PCV2致病机理及疫苗的研究大多集中在Cap蛋白,对于Rep蛋白的作用机制研究较少。因此,本文结合国内外近年研究进展,对PCV2 Rep蛋白的胞内互作蛋白进行了系统分析,尤其对现今已发现的8种胞内互作蛋白在PCV2复制过程中可能发挥的重要作用及机制进行了阐释,并对其他可能与PCV2 Rep蛋白存在相互作用的胞内蛋白进行预测,以期为进一步阐明Rep蛋白在PCV2致病中的作用提供理论依据。 相似文献
39.
张洪喜 《沈阳农业大学学报》1986,(4)
沙潜Opatrums Subaratum Fald.是我国北方干旱区重要的苗期害虫,危害严重。一年完成一个世代,成虫在土中或缝隙处越冬。早春出蛰,4月上旬至5月中旬为活动盛期。成虫取食的寄主植物有34科110余种,主要为种子和幼苗,经多年观察,成虫对豆饼、花生饼和棉子饼有趋性。成虫耐饥能力很强,寿命长,且能进行产雌雄孤雌生殖。在适宜温度下卵期随温度升高而缩短,卵期4～28天。幼虫在表土层活动,经6龄或7龄,幼虫期48～53天,地势高排水良好的土壤有利于幼虫的生长发育,幼虫在5～8厘米土层中化蛹,蛹期7～11天.沙潜主要天敌是步行(虫甲)、地蝼(虫甲),食量很大。 相似文献
40.
A. P. Sclavounos A. E. Voloudakis Ch. Arabatzis P. E. Kyriakopoulou 《European journal of plant pathology / European Foundation for Plant Pathology》2006,115(2):163-172
A severe strain of Cucumber mosaic virus (CMV) originating from an infected tomato plant (Gastouni-Olympia, Greece) was isolated in tobacco (Nicotiana tabacum cv. Xanthi nc), after three serial local lesion passages in Chenopodium quinoa and designated CMV-G. CMV-G induces yellow mosaic (YM) symptoms in tobacco. When CMV-G was passed mechanically through C. quinoa, phenotypic variants inducing YM or green mild mosaic (MM) in tobacco were isolated. Aphid transmission, from different hosts, appears to be an effective approach for separating MM variants of CMV-G from YM variants. In particular, aphid transmission from zucchini proved to be very efficient in selecting for MM variants. In contrast, aphids transmitted only YM variants from tomato plants. Molecular characterization of CMV-G and its progeny resulted in their classification in the CMV subgroup IB, free of satellite RNA, being the first discovery of the subgroup IB in Greece. In the Solanaceae family (tobacco, tomato, pepper) YM variants induced more severe symptoms than the MM variants. YM and MM phenotype was stable in tobacco for all seven passages tried using the obtained YM and MM variants. Cross-protection experiments showed that an isolated MM variant was able to protect tobacco plants against a challenge infection by a YM variant. 相似文献