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The haustorial fine structure of the bean rust fungus, Uromyces appendiculatus var. appendiculatus, was studied within the cells of its host, Phaseolus vulgaris. Results were obtained after high-pressure freezing and subsequent freeze-substitution or freeze-fracturing. Good preservation of leaf tissue after freeze-substitution needed cryoprotection with 8% methanol. For freeze-fracturing, no chemical treatment was applied. In addition to the organelles which are generally found in fungi after cryo-fixation, tubular-vesicular complexes were found in the cytoplasm. Both techniques revealed an extrahaustorial matrix of even width, surrounding the haustorial body. The extrahaustorial membrane was not undulated, and the side facing the plant cytoplasm was lined with a delicate fringe of well-stained material. The extrahaustorial membrane was nearly devoid of intramembrane particles. The host plasma membrane in infected tissue, especially the protoplasmic face, had fewer intramembrane particles than those in uninfected tissue. The haustorial plasma membrane contained many intramembrane particles. 相似文献
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Cryptosporidium parvum is a protozoan parasite that causes intestinal infection in a variety of mammals. We have previously described a factor in adult rat or adult bovine intestinal mucosa that protects against C. parvum infection when fed to susceptible infant rats. This factor is absent in intestinal mucosa from bovine calves. In the present study we describe the further characterization of the active component of bovine intestinal mucosa. The ability to protect infant rats against C. parvum infection was found to be associated with the extrinsic membrane protein fraction of the intestinal mucosa. Extrinsic membrane preparations from adult cows, adult rats, and calves were separated by SDS-PAGE. A band with apparent molecular mass of 54 kDa was seen in preparations from adult rat and cow, but not calf. Protein was transferred to PVDF membrane and from this the band was excised and subjected to N-terminal sequence analysis using a gas-phase protein sequenator. A 15-amino acid consensus sequence was generated with homology to leucine aminopeptidase (LAP). Purified LAP was purchased from a commercial source and tested for ability to protect infant rats against C. parvum infection. Rats fed LAP from 7 to 11 days of age and challenged with C. parvum at 9 days were significantly less infected than controls upon necropsy at 15 days of age. These data suggest that a protein with N-terminal sequence homology to LAP may reduce susceptibility of infant rats to C. parvum infection. 相似文献
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Modesto Lenon Romano de Almeida Anna Flávia Neri Steiner Daniel Ricardo Maass Ribeiro César Freitas Nodari Rubens Onofre Welter Leocir José da Silva Aparecido Lima 《European journal of plant pathology / European Foundation for Plant Pathology》2022,163(3):695-706
European Journal of Plant Pathology - Anthracnose (Elsinöe ampelina) is a major fungal disease in humid regions, causing damage to grapevine berries and decreasing fruit quality. Studies... 相似文献
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Camila Bitencourt Patricia M. O. Pierre Felipe A. M. F. Pinto Paulo C. P. Fermino-Junior Beatriz R. Gomes Andriele C. de Morais Jhennifer M. Dias Leocir J. Welter 《Plant pathology》2021,70(8):1897-1907
This work evaluates the formation of oospores of Plasmopara viticola, the causal agent of grape downy mildew (DM), in highland regions in southern Brazil. Leaves of susceptible and resistant grape genotypes naturally infected with the pathogen were collected in the autumn of 2017, 2018, and 2019 from vineyards located in the highlands of Santa Catarina state. Leaf tissues were evaluated by light microscopy and scanning electron microscopy. Oospores of P. viticola were identified in both susceptible and resistant host genotypes. They were concentrated in the central regions of the DM lesions, close to the leaf veins, and exhibited a rounded shape, yellowish colour, thick wall, and a diameter ranging from 16.28 to 49.15 µm. The formation of oospores is strong evidence that sexual reproduction is occurring in P. viticola in the climatic conditions of the highlands of southern Brazil. Sexual reproduction contributes to the maximization of genetic diversity via meiosis. Populations with high genetic variability are more likely to break resistance mechanisms conferred by resistance genes and to develop resistance to fungicides applied for disease control. To our knowledge, this is the first scientific study to prove the formation of P. viticola oospores in Brazil. The results presented provide a solid basis for further studies on sexual recombination in P. viticola. Genetic improvement programmes for grapevines, disease management methods, and disease prediction models need to consider the sexual reproduction of this pathogen, otherwise their effectiveness may be compromised. 相似文献
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S Welter A Bracho-Nuñez C Mir I Zimmer J Kesselmeier R Lumaret JP Schnitzler M Staudt 《Tree physiology》2012,32(9):1082-1091
Interspecific gene flow is common in oaks. In the Mediterranean, this process produced geographical differentiations and new species, which may have contributed to the diversification of the production of volatile terpenes in the oak species of this region. The endemic North African deciduous oak Quercus afares (Pomel) is considered to be a stabilized hybrid between the evergreen Quercus suber (L.) and the deciduous Quercus canariensis (Willd.), presumably being monoterpene and isoprene emitters, respectively. In a common garden experiment, we examined the terpene emission capacities, terpene synthase (TPS) activities and nuclear genetic markers in 52 trees of these three oak species. All but one of the Q. suber and Q. canariensis trees were found to be genetically pure, whereas most Q. afares trees possessed a mixed genotype with a predominance of Q. suber alleles. Analysis of the foliar terpene emissions and TPS activities revealed that all the Q. canariensis trees strongly produced isoprene while all the Q. suber trees were strong monoterpene producers. Quercus afares trees produced monoterpenes as well but at more variable and significantly lower rates, and with a monoterpene pattern different than that observed in Q. suber. Among 17 individuals tested, one Q. afares tree emitted only an insignificant amount of terpenes. No mixed isoprene/monoterpene emitter was detected. Our results suggest that the capacity and pattern of volatile terpene production in Algerian Q. afares populations have strongly diverged from those of its parental species and became quantitatively and qualitatively reduced, including the complete suppression of isoprene production. 相似文献
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Guginski-Piva Claudia Aparecida Bogo Amauri Gomes Beatriz Ribeiro Menon Jessica Karine Nodari Rubens Onofre Welter Leocir José 《植物病害和植物保护杂志》2018,125(4):405-413
Journal of Plant Diseases and Protection - Recent review described that grape anthracnose in Brazil is caused by Elsinoe ampelina. However, in many countries, anthracnose can be associated with... 相似文献
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de Souza Jonas Batistel Fernanda Welter Katieli Caroline Silva Mateus Mendes Costa Diogo Fleury Portela Santos Flávio Augusto 《Tropical animal health and production》2015,47(1):265-268
Tropical Animal Health and Production - The objective of this study was to compare the use of an external marker titanium dioxide (TiO2) as an alternative to chromic oxide (Cr2O3) in dairy cows.... 相似文献
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Viruses of the Poty-, Potex- and Tobamo-virus groups, and presumably Nepoviruses could be isolated from degenerating beech trees (Fagus sylvatica L.) in West-Germany. They are discussed as predisposing factors of tree decline. 相似文献
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