Objective The main objectives are as follows:* To develop quick and specific procedures to discriminate between mild and severe strains of citrus tristeza virus (CTV) and set up a simple protocol for detection of severe CTV strains in field trees or nursery plants.* To use this technology for a)early screening of mild CTV isolates with protective capacity against severe isolates and b) monitoring cross protection in the field.* To develop quick and reliable methods to diagnose and characterize psorosis-ringspot isolates from the Mediterranean area and South America.* To search for the natural vector of psorosis-ringspot in the South American areas where this disease naturally spreads.Expected OutcomeThe results obtained in this project should provide technology to better control severe CTV isolates through eradication of new foci, sanitary control of nursery plants or cross protection. Measures a) and b) would be helpful in Mediterranean countries where severe isolates are uncommon, and measures b) and c) in South American areas where those isolates are widespread. Nucleic acid sequences from psorosis ringspot virus will give new insight on this new type of virus. Specific probes for quick detection of this virus and the possibility to control psorosis-ringspot vectors in South America will allow to control this disease.The key activities envisaged are:* Comparison of a panel of isolates of different biotype by SSCP analysis and sequencing those gene variants that might be associated to pathogenic characteristics. The diverging sequences will be used as targets for diagnosis of specific isolates by hybridisation or PCR. A simple protocol using tissue prints and nonisotopic probes will be assayed for field sampling.* Mild isolates checked for the absence of minor pathogenic components will be assayed for cross protection in the greenhouse. The presence of the severe strain in co-inoculated plants will be monitored by SSCP, hybridisation and PCR and correlated with symptom expression. This technology will be validated with preimmunized field trees naturally exposed to severe CTV isolates in areas where these isolates are widespread.* We will search for nucleic acid sequences associated with psorosis-ringspot virus and will use them to develop a hybridization or PCR protocol for diagnosis and to obtain additional virus sequences. New antibodies to the virus will be obtained. Biological characterisation, EM, serology and molecular probes will be used to compare psorosis-ringspot isolates from the Mediterranean region and South America.* The most frequent insects (mainly aphids) found in citrus in South America will be tested for ability to transmit psorosisringspot. Fields of science natural sciencesbiological sciencesbiochemistrybiomoleculesnucleic acidsnatural sciencesbiological sciencesmicrobiologyvirologynatural sciencesbiological scienceszoologyentomology Programme(s) FP4-INCO - Specific research, technological development and demonstration programme in the field of cooperation with third countries and international organizations, 1994-1998 Topic(s) 03010204 - Crop production Call for proposal Data not available Funding Scheme CSC - Cost-sharing contracts Coordinator INSTITUTO VALENCIANO DE INVESTIGACIONES AGRARIAS EU contribution No data Address KM 4.5,Ctra. Moncada-Naquera KM 4.5 46113 MONCADA (VALENCIA) Spain See on map Total cost No data Participants (6) Sort alphabetically Sort by EU Contribution Expand all Collapse all CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS Spain EU contribution No data Address 14,Camino de Vera 14 46022 VALENCIA See on map Total cost No data Consiglio Nazionale delle Ricerche Italy EU contribution No data Address Strada delle Cacce 73 10135 Torino See on map Total cost No data Instituto Agronómico de Campinas Brazil EU contribution No data Address KM 158,Rod. Anhanguera KM 158 13490 970 Cordeiropolis See on map Total cost No data Instituto Nacional de Tecnologia Agropecuaria Argentina EU contribution No data Address 3200 Concordia See on map Total cost No data Ministry de Ganaderia, Agricultura y Pesca Uruguay EU contribution No data Address 4703,Av. Millan 4703 12900 Montevideo See on map Total cost No data Universidad Nacional de La Plata Argentina EU contribution No data Address 49 Y 50,Calles 115 1900 La Plata See on map Total cost No data