Location: Crop Improvement and Protection Research
Project Number: 2038-21530-003-022-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Apr 1, 2024
End Date: Mar 31, 2025
Objective:
Lettuce production in California faces significant losses from diseases including impatiens necrotic spot virus (INSV), Pythium wilt, Verticillium wilt, and Fusarium wilt. Three of these have a broad host range including cultivated and weed species found throughout the area, which makes control by rotation nearly impossible. Fumigation for soil-borne diseases is increasingly unavailable due to chemical restrictions and high associated costs. Therefore, genetic resistance is the ideal, and often only, solution to control spread and reduce losses. The overall goal of this continuing project is to release lettuce with improved resistance to diseases impacting production. Associated with this are annual objectives to develop germplasm, information, and tools that move us closer to this goal. For 2024-2025, our objectives are to: 1) develop lettuce germplasm resistant to INSV, 2) develop tools to evaluate germplasm resistance to Pythium wilt, 3) characterize resistance to Verticillium wilt races 1 and 2 and develop improved lettuce germplasm, and 4) characterize the variant isolate and develop germplasm with resistance to Fusarium wilt.
Approach:
• Objective 1- We will develop lettuce germplasm resistant to Impatiens necrotic spot virus in replicated field experiments and greenhouse experiments using manual inoculation and viruliferous thrips transmission.
• Objective 2- We will develop a controlled-environment assay and evaluate germplasm resistance to Pythium wilt.
• Objective 3- To characterize resistance to Verticillium wilt Races 1 and 2 and develop improved lettuce germplasm, we will evaluate germplasm in Race 1-infested and disease-free field experiments, screen with the Vr1-linked molecular marker, and evaluate resistance to Race 2 in growth room and greenhouse experiments.
• Objective 4- Characterize the variant isolate and develop germplasm with resistance to Fusarium wilt evaluate germplasm in Verticillium Race 1-infested field experiments and Fusarium-infected greenhouse tests.
