Location: Crop Diseases, Pests and Genetics Research
Project Number: 2034-22000-012-000-D
Project Type: In-House Appropriated
Start Date: Apr 12, 2017
End Date: Apr 11, 2022
Objective:
The goal of this Project is to identify tools to reduce losses caused by pathogens and insect pests of grapevine. The Project Plan includes basic and applied research with flexibility for research on new pathogens and insect pests of grape, should the need arise. The overall concept is based on the multi-trophic structure of the Pierce’s disease pathosystem, which includes many host species and pathogen strains, other microorganisms, insect vectors, natural enemies, and a diverse agricultural landscape.
Objective 1: Identify and characterize genes involved with pathogenicity of X. fastidiosa.
• Subobjective 1A: Examine Xf genomic and phenotypic diversity.
• Subobjective 1B: Determine functional activity of Xf toxin-antitoxin (TA) systems.
• Subobjective 1C: Elucidate the genetic basis of Xf physiological responses to cold and elimination of Xf from grapevines exposed to cold.
• Subobjective 1D: Develop plasmid vector for protein expression/localization and gene complementation.
• Subobjective 1E: Develop antivirulence molecules to disrupt functionality of Xf virulence genes.
Objective 2: Identify novel plant resistance mechanisms to infection by microorganisms (including X. fastidiosa) and/or feeding by insect vectors.
• Subobjective 2A: Identify novel PD resistance genes.
• Subobjective 2B: Identify molecular markers of PD resistance in a plant breeding population.
• Subobjective 2C: Elucidate plant defense responses to fungal canker, viral, nematode, bacterial infections, and physiological interactions among these pathogens in planta.
• Subobjective 2D: Elucidate plant physiological defenses to Xf infection and interaction of Xf with the environment.
• Subobjective 2E: Evaluate grapevine germplasm with respect to deterrence of vector probing behaviors, and determine transmission efficiency of Xf by the vector from and to PD-resistant and -susceptible grapevines.
Objective 3: Describe the arthropod community in California vineyards and provide new information on the phytobiome of grapevines.
• Subobjective 3A: Describe the arthropod community found in and near vineyards.
• Subobjective 3B: Determine seasonal changes in the proportion of Xf-inoculative vectors in vineyards.
• Subobjective 3C: Assess microbiome variations associated with Xf-infected grapevines and glassy-winged sharpshooter (GWSS).
Objective 4: Elucidate reproductive, developmental, and feeding parameters of hemipteran pests of grapevines.
• Subobjective 4A: Determine the role of nutrition on GWSS fecundity.
• Subobjective 4B: Describe and characterize tremulatory signals used in mating communication of insect pests of grapevine.
• Subobjective 4C: Identify vibrational signals that affect GWSS behaviors, and evaluate natural and synthetic signals to disrupt mating communication of GWSS.
• Subobjective 4D: Describe and characterize BMSB feeding behaviors on grapevines, and determine the mechanism of damage to the crop.
Approach:
The approach is to synergistically exploit weak links between main components of the Pierce’s disease (PD) pathosystem (pathogen, vector, plant) and insect pests to induce an unstable or neutral interaction that can lead to disruption of destructive processes affecting grape production. Xylella fastidiosa (Xf) diversity will be examined to provide insights on environmental adaptation and host-specific pathogenicity. Xf gene function will be examined to identify genes affecting pathogenicity and virulence. Plasmids will be developed as tools to characterize Xf gene function and expression. Protocols for delivery of antivirulence molecules into grapevines will be evaluated. Grapevine response to infection will be examined to identify molecular and metabolic networks affecting disease severity and resistance. Effects on PD epidemiology due to deployment of grapevines bearing partial resistance to PD will be determined empirically and modeled by computer simulations. Assemblages of arthropods and microorganisms associated with vineyards will be surveyed. Insect vector fecundity will be quantified to identify novel means to suppress vector populations responsible for pathogen spread. Interaction of Xf with diverse pathogens (fungal, viral, nematode) affecting grapevines will be examined. An additional component of the research will focus on new threats to grape production, including but not limited to, invasive insects such as the brown marmorated stink bug.
