Effects of three esca-associated fungi on Vitis vinifera L.: I. Characterization of secondary metabolites in culture media and host responses to the pathogens in calli

Phaeomoniella chlamydospora (Pch) and Togninia minima (Tmi) produced scytalone, isosclerone and pullulans in liquid cultures, as well as in calli. Secondary metabolites and host defense compounds were shown to occur in calli of Vitis vinifera cv. Italia and cv. Matilde infected by the esca-associated fungi Pch, Tmi and Fomitiporia mediterranea (Fme). Calli of both cvs. were grown as dual cultures with Pch, Tmi and Fme. The fungi grew well in the presence of calli of both cvs., but callus growth was reduced. Accumulation and changes of total phenolics and recurring phenolics, and of two phytotoxic pentaketides and pullulans were analyzed by HPLC. On comparing results for cv. Italia and cv. Matilde, it can be seen that concentrations of phenolics are strongly related to the cv. The paper discusses the possible relationship between melanin biosynthesis in Pch and Tmi, which utilize pentaketide metabolites as intermediates and their pathogenicity related to phytotoxity of scytalone and isosclerone.     

Full season efficacy of moxidectin microsphere sustained release formulation for the prevention of heartworm (Dirofilaria immitis) infection in dogs

The authors report the efficacy of an injectable, moxidectin sustained release (SR) formulation for the prevention of canine heartworm infection in endemic areas in northern and central Italy. Three field trials were carried out on a total of 324 dogs. Two hundred forty-three dogs were treated with moxidectin SR 6 months apart and 81 dogs (positive controls) with moxidectin tablets given monthly for 5 consecutive months during the risk season each year throughout the study. Results of testing for microfilariae and circulating adult female antigens were negative for all the experimentally treated dogs at the 6, 7, 11 and 19 months after the last injection. No adverse reactions to moxidectin SR were observed but a moderate pain at palpation and swelling (5-6 cm) at the injection site after the first treatment. In the study areas, prevalence of Dirofilaria immitis infection calculated by testing dogs which had no preventive treatment in the previous transmission season ranged from 33 to 63%. This study confirms the efficacy and safety of injectable, moxidectin SR formulation in the prevention of heartworm infection in dogs and demonstrates that the prophylactic efficacy lasts for the full season and strongly suggests that the product gives 1-year protection.     

Pepper resistance-breaking tobamoviruses: Can they co-exist in single pepper plants?

We previously reported a procedure for identifying pathotypes of the tobamoviruses infecting the L-resistant genotypes of pepper based on the polymerase chain reaction (PCR) (Tenllado et al., 1994). We have now used this method to assess pathotype incidence in virus isolates from field pepper samples representing three successive epidemic episodes in southeastern Spain, and to analyse the interaction of pathotypes during experimental infections in pepper plants. The majority of virus isolates corresponded to the P_1,2 pathotype, and only three out of twenty behaved as P_1,2,3 pathotypes. Interestingly, restriction enzyme analysis of the PCR-amplified products distinguished two restriction subgroups on each P_1,2 and P_1,2,3 pathotype, referred to as restrictopatterns I₁ and I₂ or II₁ and II₂, respectively. Experimental coinoculations of pepper plants with mixtures of two different pathotypes showed coexistence between them when inoculations proceeded simultaneously. However, reciprocal cross-protection was observed between P_1,2 and P_1,2,3 pathotypes when they were successively inoculated, while no cross-protection was observed between P₁ and either P_1,2 or P_1,2,3 pathotypes. The potential of the PCR-based method for detecting heterogeneity within P_1,2 and P_1,2,3 pathotypes, and the possibility of genetically engineered resistance to those viruses by genetic transformation with viral coat protein genes are briefly discussed.     

Vaccines against bluetongue in Europe

After the incursion of bluetongue virus (BTV) into European Mediterranean countries in 1998, vaccination was used in an effort to minimize direct economic losses to animal production, reduce virus circulation and allow safe movements of animals from endemic areas. Vaccination strategies in different countries were developed according to their individual policies, the geographic distribution of the incurring serotypes of BTV and the availability of appropriate vaccines. Four monovalent modified live virus (MLV) vaccines were imported from South Africa and subsequently used extensively in both cattle and sheep. MLVs were found to be immunogenic and capable of generating strong protective immunity in vaccinated ruminants. Adverse side effects were principally evident in sheep. Specifically, some vaccinated sheep developed signs of clinical bluetongue with fever, facial oedema and lameness. Lactating sheep that developed fever also had reduced milk production. More severe clinical signs occurred in large numbers of sheep that were vaccinated with vaccine combinations containing the BTV-16 MLV, and the use of the monovalent BTV-16 MLV was discontinued as a consequence. Abortion occurred in <0.5% of vaccinated animals. The length of viraemia in sheep and cattle that received MLVs did not exceed 35 days, with the single notable exception of a cow vaccinated with a multivalent BTV-2, -4, -9 and -16 vaccine in which viraemia persisted at least 78 days. Viraemia of sufficient titre to infect Culicoides insects was observed transiently in MLV-vaccinated ruminants, and natural transmission of MLV strains has been confirmed. An inactivated vaccine was first developed against BTV-2 and used in the field. An inactivated vaccine against BTV-4 as well as a bivalent vaccine against serotypes 2 and 4 were subsequently developed and used in Corsica, Spain, Portugal and Italy. These inactivated vaccines were generally safe although on few occasions reactions occurred at the site of inoculation. Two doses of these BTV inactivated vaccines provided complete, long-lasting immunity against both clinical signs and viraemia, whereas a single immunization with the BTV-4 inactivated vaccine gave only partial reduction of viraemia in vaccinated cattle when challenged with the homologous BTV serotype. Additional BTV inactivated vaccines are currently under development, as well as new generation vaccines including recombinant vaccines.     

Good new(t)s: Rapid recolonization of a restored fish-invaded habitat by two newt species in southern Italy

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Different efficiencies in organic P exploitation of two Italian alfalfa (Medicago sativa) landraces involving a possible adaptation pattern of the phytase encoding MsPHY1 gene

The agricultural practice of manure cropping can result in the accumulation of surplus phosphorus (P) in soils with consequent losses by leaching. Two Italian alfalfa landraces originating from intensive (“Cremonese”) versus extensive (“Senese”) cattle farming regions were studied in order to investigate their variation for (a) efficiency in exploiting different P sources–farm dairy effluents (FDE), phytic acid (Phy), and inorganic P (IP)–in a lysimeter trial, and (b) the sequence of the MsPHY1 gene, which encodes a root extracellular phytase, releasing inorganic P for plant growth. The Cremonese landrace showed higher P uptake efficiency than Senese in the FDE and Phy treatments and lower inorganic P losses in leachates, particularly in the FDE treatment. The MsPHY1 gene was highly variable and the variation was not neutral but maintained by selection. Two non-synonymous SNPs, in particular SNP970, located in a motif containing conserved metal-ligating residues, produced alternative alleles with frequency differences between landraces. A pattern of adaptive response for the ability to use organic P forms is discussed at both the physiological and genetic levels.