Project Number: 1920-22000-034-00
Project Type: Appropriated

Start Date: Apr 16, 2007
End Date: Apr 15, 2012

Objective:
Develop pathogen detection arrays in support of certification programs for Prunus and Citrus crops and provide innovative diagnostic systems for new and emerging plant pathogens; investigate molecular and biological factors in pathogen/host/vector systems that affect host adaptation, vector adaptation, and evolution of new pathogenic forms; and, investigate critical factors that influence developmental and circulative processes of vector transmission in new or emerging plant pathogenic diseases (pathogen ingestion and fate in persistent and non-persistent transmission systems) i.e., Huanglongbing and citrus psyllids, Soybean dwarf virus and soybean aphid, Plum pox virus and aphid vectors, Citrus tristeza virus and brown citrus aphid, and other foreign and emerging plant pathogens. Contribute to curation of microbial collections for all CRIS projects at the unit, perform physical audits of pathogens, monitor APHIS permit status, oversee and track regulations regarding transport and storage of APHIS Select Agents, and liaison with APHIS for containment inspections and certifications. PER PDRAM NAA2 FY07 Program Redirection for Plum Pox Research Adding this objective: Investigate virus adaptation to changing hosts using plum pox as a working model and develop a fluorescent viral labeling system for tracking viruses in aphids.

Approach:
Establish and maintain foreign (exotic) and emerging insect-transmitted plant pathogens under quarantine containment and determine factors involved in pathogen change and adaptation, mechanisms of transmission, and novel detection strategies. Specific approaches will include using microarray format to select optimal probes for multiple Prunus pathogen detection macroarrays and adaptation of TIGER diagnostics for the detection of potyviruses. Viral adaptation to host and vector will be studied experimentally using repeated passages of Plum pox virus and Soybean dwarf virus as model systems. Virus/vector interactions will be studied using fluorescently tagged virions of PPV and SbDV to study viral movement in aphids. The presence or absence of transovarial transmission of HLB by the citrus psyllid will be determined by following the developmental stages of hundreds of progeny of infective psyllids from egg to adult on non-HLB hosts using Real-time PCR and specific primers for HLB. The presence, pathway, and location of HLB in citrus psyllids will be monitored by real-time PCR on whole psyllids, dissected psyllid organs, and use of fluorescently tagged HLB bacteria.