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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Research Project #442153

Research Project: Lettuce Breeding for Improved Resistance to INSV, Pythium, Verticillium, and Fusarium

Location: Crop Improvement and Protection Research

Project Number: 2038-21530-003-009-T
Project Type: Trust Fund Cooperative Agreement

Start Date: Apr 1, 2022
End Date: Mar 31, 2024

California’s Monterey County harvests 100,000 acres of lettuce (Lactuca sativa L.) annually at a value of $1.2 billion. Incidence of diseases including Impatiens Necrotic Spot Virus (INSV), Verticillium wilt, and Fusarium wilt has increased significantly causing devastating losses to lettuce production. Genetic resistance is the most economical and environmentally sound control method, but completely resistant varieties are not available. Therefore, identification and characterization of resistance and development of improved lettuce germplasm is imperative. Our objectives are to: 1) characterize resistance to Verticillium dahliae Races 1 and 2, 2) release germplasm with combined resistance to Verticillium and Fusarium wilts, and 3) develop germplasm with improved resistance to INSV. Success will be indicated by releasing new lettuce germplasm, publications, citations, and requests for seeds and information.

Objective 1- 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 2- To develop Fusarium wilt-resistant lines and combine with Verticillium wilt resistance, we will evaluate germplasm in Verticillium Race 1-infested field experiments and Fusarium-infected greenhouse tests. Objective 3- 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.