Current situation of Tomato yellow leaf curl virus in Portugal     

D. Louro  J. E. Fernandes  A. Quinot 《EPPO Bulletin》2002,32(1):47-47

The name Tomato yellow leaf curl virus (TYLCV) has been applied to a group of virus species of the genus Begomovirus in the family Geminiviridae that cause a similar tomato disease worldwide. In 1995, TYLCV was first reported in Algarve (southern Portugal) as responsible for an epidemic outbreak of a severe tomato disease. Molecular data have shown that this Portuguese TYLCV isolate was distinct from those previously reported in Europe, as it belonged to the TYLCV-Israel species ¹ . Since then, TYLCV epidemics have occurred annually, being a limiting factor mainly for autumn/winter glasshouse tomato crops. In 1998, TYLCV was also found associated with the emergence of a novel disease of Phaseolus vulgaris in Algarve. The affected bean plants were severely stunted and gave no marketable yield. However, the disease occurs only sporadically, even in conditions of high TYLCV infection pressure. Recently, Tomato chlorosis virus (ToCV), a whitefly-transmitted bipartite closterovirus (genus Crinivirus , family Closteroviridae ), was found associated with an unusual tomato yellow leaf syndrome, in single or mixed infection with TYLCV. The impact of this new pathosystem on tomato production has yet to be determined. Surveys are in progress in mixed cropping systems infested with whiteflies. So far, TYLCV and ToCV diseases are limited to the Algarve region.  相似文献   

Genetic analyses of resistance of the wheat differential cultivars Carstens V and Spaldings Prolific to two races of Puccinia striiformis     

A. Calonnec †‡  R. Johnson §  C. de Vallavieille-Pope 《Plant pathology》2002,51(6):777-786

Genetic analysis of resistance of wheat seedlings to two races of Puccinia striiformis was conducted on F₁, F₂ and F₃ generations from crosses Carstens V (CV) × Lee, Spaldings Prolific (SPA) × Lee and CV × SPA. F₂ generations from crosses of CV and SPA with Strubes Dickkopf (SD) were also studied. The plants were classified into six resistance classes and analysed by factorial correspondence analysis and nonhierarchical classification. The two P. striiformis isolates tested were a French isolate of race 43E138 and a Lebanese isolate of race 2E16, selected for the differences in their virulence spectra for the common differential cultivars Strubes Dickkopf and Nord Desprez. Resistance of CV and SPA was recessive and dominant to races 43E138 and 2E16, respectively. CV possessed three or four resistance genes, one of them being expressed with both races. Two genes of CV had a cumulative effect for resistance to 43E138 and two or three gave dominant resistance to 2E16. SPA had three resistance genes, all of which gave resistance to 2E16 and two of which also gave resistance to 43E138. SPA had one gene in common with CV for resistance to both races. Furthermore, the gene for resistance to race 2E16 in CV and SPA was allelic with a gene in SD, and was probably Yr25 .  相似文献   

Comparison of Crinipellis perniciosa isolates from Brazil by ERIC repetitive element sequence-based PCR genomic fingerprinting     

M. C. C. de Arruda †  R. N. G. Miller  M. A. S. V. Ferreira  M. S. S. Felipe 《Plant pathology》2003,52(2):236-244

Fifty isolates of Crinipellis perniciosa originating from Theobroma cacao , Heteropterys acutifolia and Solanum lycocarpum , from six states within Brazil, were characterized through ERIC-PCR, representing the first application of this method for molecular characterization within C. perniciosa . Phenetic analysis of banding patterns revealed a separation of isolates on the basis of host of origin, with T. cacao -derived isolates showing only a 0·2 similarity level to a cluster comprising the isolates from H. acutifolia and S. lycocarpum . Considerable intraspecific variability was observed within C. perniciosa isolates from T. cacao , with distinct groups observed correlating with geographical origin. Given that a number of isolates from T. cacao from the Amazon region grouped with isolates from Bahia state, this work discusses the possibility that current C. perniciosa populations pathogenic on T. cacao in Bahia originated from the Amazon region, rather than from alternative host plants.  相似文献   

Purification and some properties of Papaya meleira virus, a novel virus infecting papayas in Brazil     

E. Maciel-Zambolim †  S. Kunieda-Alonso  K. Matsuoka  M. G. de Carvalho  F. M. Zerbini 《Plant pathology》2003,52(3):389-394

'Meleira', or 'sticky disease', is currently the most damaging papaya disease in the mid-eastern Brazilian growing regions. Consistent disease transmission via latex injection, presence of similar isometric particles in the laticiferous vessels of diseased plants, and detection of double-stranded DNA in naturally and experimentally infected papaya trees suggest that a virus is the causal agent. Conclusive evidence for viral aetiology was previously lacking, mostly because every attempt to purify the putative virus from infected papayas had failed. Following the successful purification and partial characterization of the meleira virus, healthy papaya seedlings injected with purified virus particles later developed typical symptoms of the disease. Negatively stained, isometric, full and 'empty' purified virus particles measured 42 and 38 nm, respectively. The viral genome was a single dsRNA molecule of about 12 kbp. Several capsid proteins, ranging in size from 14·4 to 45 kDa, were consistently revealed by PAGE. Papaya meleira virus (PMeV) appears to represent a novel group of viruses, with no known similar counterpart among known plant-, vertebrate-, invertebrate- or prokaryote-infecting viruses.  相似文献   

Functional Analysis of ABC Transporter Genes From Botrytis cinerea Identifies BcatrB as a Transporter of Eugenol     

Henk-jan Schoonbeek  Johannes G.M. van Nistelrooy  Maarten A. de Waard 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(9):1003-1011

The role of multiple ATP-binding cassette (ABC) and major facilitator superfamily (MFS) transporter genes from the plant pathogenic fungus Botrytis cinerea in protection against natural fungitoxic compounds was studied by expression analysis and phenotyping of gene-replacement mutants. The expression of 11 ABC (BcatrA–BcatrK) and three MFS genes (Bcmfs1, Bcmfs2 and Bcmfs4) was studied. All genes showed a low basal level of expression, but were differentially induced by treatment with cycloheximide and the plant defence compounds camptothecin, eugenol, psoralen, resveratrol and rishitin. The latter compounds induced expression of BcatrB at a high level. Eugenol was more toxic to BcatrB gene-replacement mutants than to the control isolates. Eugenol also caused an instantaneous increase in mycelial accumulation of the fungicide fludioxonil, a known substrate of BcatrB. However, there was no difference in virulence between the wild-type and BcatrB gene-replacement mutants on Ocimum basilicum, a plant known to contain eugenol. The results indicate that BcatrB is a transporter of lipophilic compounds, such as eugenol, but its role in virulence remains uncertain.  相似文献   

Resistance to Leveillula taurica in the genus Capsicum   总被引：1，自引：0，他引：1  

V. L. de Souza  A. C. Café-Filho† 《Plant pathology》2003,52(5):613-619

One hundred and sixty-two Capsicum genotypes were evaluated for powdery mildew (Leveillula taurica) resistance, following inoculations with a suspension of 5 × 10⁴ conidia mL⁻¹ on 10-leaved to 12-leaved plants. Genotypes were graded into five resistance classes, based on the areas under the disease progress curves calculated from disease incidence (percentage infected leaves per plant) and severity (total number of colonies per plant). Results revealed a continuum from resistance to susceptibility, with the majority (70%) of C. annuum materials being classified as moderately to highly susceptible to L. taurica. Conversely, C. baccatum, C. chinense and C. frutescens were most often resistant, indicating that resistance to L. taurica among Capsicum species is found mainly outside the C. annuum taxon. Nevertheless, some resistant C. annuum material was identified that may be useful for resistance breeding. Eight genotypes were identified as immune to the pathogen: H-V-12 and 4638 (previously reported), and CNPH 36, 38, 50, 52, 279 and 288. Only H-V-12 and 4638 are C. annuum, while all others belong to the C. baccatum taxon. Latent period of disease on a set of commercial sweet pepper genotypes varied, indicating diverse levels of polygenic resistance. The latent period progressively reduced with plant maturity, from 14·3 days in plants at the mid-vegetative stage to 8·6 days in plants at the fruiting stage. Young plants of all commercial genotypes tested at the early vegetative stage were immune, irrespective of the reaction of the genotype at later stages, demonstrating widespread juvenile resistance to L. taurica in the Capsicum germplasm. Inoculation of plants of different botanical taxa with a local isolate indicated a wide host range. Some hosts, including tomato (Lycopersicon esculentum), artichoke (Cynara scolymus) and poinsettia (Euphorbia pulcherrima), produced large amounts of secondary inoculum. Other hosts included okra (Abelmoschus esculentus), eggplant (Solanum melongena), cucumber (Cucumis sativus), Solanum gilo, Chenopodium ambrosioides and Nicandra physaloides.  相似文献   

Genetic analysis of resistance to Puccinia striiformis in the wheat differential cultivars Heines VII, Heines Peko and Strubes Dickkopf     

A. CALONNEC  R. JOHNSON  & C. de VALLAVIEILLE-POPE 《Plant pathology》1997,46(3):373-386

One major gene for resistance to isolate WYR 85-22 of race 6E0 of Puccinia striiformis was identified by genetic analysis of the differential cultivars Heines Peko, Strubes Dickkopf and Heines VII. This gene was different from Yr2 Yr6 already identified in Heines Peko ( Yr2 Yr6 ) and Heines VII ( Yr2 ), was allelic in the three cultivars and also to a gene expressed in the other differentials Reichersberg 42 ( Yr7 ) and Clement ( Yr9 ). In Heines Peko, Strubes Dickkopf and Heines VII, a minor gene was also postulated, which, it is proposed, gave only a low level of resistance by itself but strengthened the expression of the major gene when the latter was homozygous or heterozygous. The genetics of the resistance was analysed using six resistance classes and applying multidimensional analyses. The number of resistance genes was hypothesized using data from F3 families from crosses between the three differentials and the cultivar Heines Kolben, which is susceptible to this race.  相似文献   

淡紫拟青霉菌料防治大豆胞囊线虫的后效研究   总被引：6，自引：2，他引：6  

王昌家  张新德 《中国生物防治》1997,13(1):26-28

淡紫拟青霉不同菌株的培养菌料，施２２５ｋｇ／ｈｍ２，对大豆胞囊线虫不但当年有４５％～６９％的较好防效，而且第２年和第３年仍然有２２．５％～３７．７％和７．３％～２２．９％的后效，即空胞囊和被寄生的胞囊数量增加。  相似文献   

桃树根癌病防治技术探讨   总被引：8，自引：0，他引：8  

罗维德  杨金兰  杨永启 《中国植保导刊》2004,24(3):13-17

桃树根癌病是公认最难防治的土传细菌病害之一。在对该病进行较系统研究的基础上,采用多种抗菌药剂、多种方法进行了室内、外药敏测定与防治试验,显示出异菌氰、次氯酸钠、乙蒜素、妥布霉素、环丙沙星、庆大霉素及其混用对防治桃树根癌病菌有明显防效。  相似文献   

Renal ultrasonographic evaluation in the oncilla (Leopardus tigrinus).     

Georgea Bignardi Jarretta  Pedro Primo Bombonato  Marcelo Alcindo de Barros Vaz Guimar?es 《Journal of zoo and wildlife medicine》2004,35(3):356-360

Ultrasonography is currently used in veterinary medicine to examine the anatomy and physiology of internal organs and to establish normal standards for exotic animal species. Specifically, the kidneys may be evaluated and measured in length, width, and height. The kidneys in 33 oncilla (Leopardus tigrinus), including 20 males and 13 females, were opportunistically located, characterized, and measured by ultrasound using a 7.5-MHz linear transducer at two different zoologic facilities in S?o Paulo, Brazil. Renal volume was calculated from these linear measurements. The mean linear measurements and volume of the right and left kidneys were not significantly different.  相似文献