Location: Crop Diseases, Pests and Genetics Research
Project Number: 2034-21220-008-012-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Oct 1, 2024
End Date: Sep 30, 2026
Objective:
The overall goal of this project is to test wide range of grape germplasm to discover potential unique sources that have resistance and/or non-preference for Vine Mealybug Resistance (VMB); verify and validate the resistance to VMB from previously reported germplasm under similar testing conditions; use population genetics to determine diversity of resistant sources; develop better understanding of mechanisms of resistance; and develop tools that better assist to breed resistant plants to VMB.
The specific objectives of this project are:
1) Test germplasm from 19 different grape species, hybrids, rootstocks with lab-based assay to identify germplasm with resistance/or non-preference to mealybugs.
2) Develop genotypic data to conduct genetic diversity, population structure and genome wide association analysis for tested germplasm.
Results from this project will be multifold. First, it would provide necessary information about potential resistance to P. ficus in grape germplasm; second, we would test germplasm that had shown to resist P. ficus and P. citri in earlier reports under similar experimental conditions and validate those results; third, a multi-disciplinary approach could be developed to understand the mechanisms of host plant resistance and host pathogen interaction; and lastly, results could pave the way to develop insect-resistant varieties through conventional breeding.
Approach:
Objective 1. We have acquired hardwood cuttings of germplasm presented in coordination with the National Clonal Germplasm Repository, USDA-ARS, Davis (NCGR-Davis), and Foundation Plant services, University of California, Davis (FPS-Davis). Plants will be propagated in Spring 2024 and 2025. Bench grafts (5-10 buds) to a commercial rootstock will be made for germplasm that does not yield plants from hardwood cuttings. Green cuttings will be taken May-June 2024 from original vines if neither course is successful to create mother vines. Mealybugs for experiments will be established according to the methods described in Sisterson & Uchima 2023.
Objective 2. DNA will be extracted from all accessions, and DArTag markers will be used that can identify allelic variations. DArTag marker allow to assess genetic diversity and relationships among cultivars as well as genome wide association analysis when phenotypic data is available.
