Project Number: 5302-22000-010-00
Project Type: Appropriated

Start Date: Apr 12, 2012
End Date: Apr 11, 2017

Objective:
The overall goal of this project is to mitigate losses due to Xylella fastidiosa-caused diseases during crop production and to develop effective, sustainable disease and insect-vector management strategies by characterizing host-pathogen-vector-environment interactions of these complex pathosystems. Specific objectives for the project are outlined below: Objective 1: Characterize genomic and biological diversity of Xylella fastidiosa strains. Objective 2: Elucidate molecular interactions of Xylella fastidiosa with horticultural and model plant hosts that result in disease susceptibility or resistance. Objective 3: Determine biological/ecological/transmission properties of Xylella fastidiosa vectors. Objective 4: Develop and assess strategies to manage diseases caused by Xylella fastidiosa.

Approach:
Pierce’s disease (PD) is an economically important disease affecting US grape production. PD is caused by the xylem-limited bacterium Xylella fastidiosa (Xf), a generalist pathogen also causing disease in numerous horticultural crops and landscape ornamentals. In California, prevalence and incidence of PD increased following introduction and establishment of the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis. Presently, PD is managed in California via an area-wide surveillance and insecticide application program aimed at suppressing GWSS populations in citrus (the most common feeding/oviposition host) and urban landscape plants. Development of an integrated management program for PD requires detailed knowledge of host-pathogen-vector-environment interactions. Such knowledge is limited for this complex pathosystem involving multiple hosts and vectors, a genetically diverse pathogen, and a non-uniform agro-ecosystem. The project objectives are designed to address knowledge gaps in the biology, ecology, and genetics of Xf, sharpshooter vectors, and host plants. Genomic diversity, as well as the evolutionary, biological and epidemiological relationships among Xf strains will be characterized. The genetic and molecular basis of host-pathogen-vector interactions will be determined to better understand PD development and epidemiology. Biotic and abiotic factors that affect sharpshooter ecology and pathogen transmission mechanisms/efficiency will be identified. The nature, basis, and mechanism(s) of host resistance to Xf will be identified, characterized, and incorporated into advanced grape selections. New information and products will facilitate mitigation of PD losses, with the ultimate goal of developing an environmentally friendly, integrated management strategy that may augment or replace the area-wide surveillance and insecticide application program.