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Le biotecnologie per la difesa sostenibile delle colture e delle produzioni agroindustriali: i virus
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Properties of grapevine fanleaf virus
No full textPurified preparations of grapevine fanleaf virus consist of three serologically indistinguishable centrifugal components, T, M and B, with sedimentation coefficients of 50, 86 and 120 S respectively, and containing 0, 30 and 42% RNA. At equilibrium in CsCl gradients, T, M and B components precipitate. Their buoyant densities are 1.31, 1.41 and 1.49 g/ml, respectively. Infectivity is associated mostly with B component. RNA is single stranded and occurs as two species with mol. wt. of 1.4x106 (RNA 2) and 2.4x106 (RNA I). M particles contain only RNA 2 whereas B particles contain both species. RNA 2 is non infective, some infectivity is associated with preparations of RNA I, and infectivity can increase tenfold when RNA I and RNA 2 are mixed. The capsid contains a single protein species with mol. wt. of about 54000. Comparable data for arabis mosaic and raspberry mosaic viruses are similar. The present cryptogram of grapevine fanleaf virus is R/I:2.4/42+1.4/30:S/S:S/Ne
Identification of DNA sequences related to Xylella fastidiosa in oleander, almond and olive trees exhibiting leaf scorch symptoms in Apulia (Southern Italy).
No full text5th International Symposium on Fig
No full textDifferent syndromes of a putative viral origin are comprised under the name of Fig mosaic disease (FMD), an aetiologically ill-defined infectious disease of fig trees, reported from all fig-growing countries in the world. In fact, at least 10 different viruses and three viroids have been detected to date in FMD-affected trees: five closterovirids (Fig leaf mottle-associated virus 1 and 2, Fig mild mottle-associated virus, Arkansas closterovirus 1 and 2); a Trichovirus (Fig latent virus 1) and several isometric, bacilliform or enveloped viruses (Fig criptic virus, Fig fleck-associated virus, Fig badnavirus 1, Fig mosaic virus). Of these, Fig mosaic virus (genus Emaravirus) is the one with the highest association with FMD. Fig badnavirus 1, whose DNA is integrated in the fig genome, may not induce a disease even when virus particles are expressed in fig seedlings. The development of typical FMD symptoms in seedlings in which FMV was transmitted by its vector (the eriophyid mite Aceria ficus) support the conclusion that FMV is indeed one, if not the major, agent of FMD. Virtually nothing is known on the pathogenicity and epidemiology of the other fig-infecting viruses. FMD has an extremely high incidence in nature and symptomless trees are often only apparently healthy. Thus, any campaign for the improvement of the fig industry should utilize sanitation techniques for the production of certified healthy stocks for propagation and trade
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