Vegetables and Pulses
Lettuce NPGS Germplasm – Verticillium Wilt Resistance
VERTICILLIUM WILT RACE 1 RESISTANCE FOUND IN NPGS LETTUCE PLANT INTRODUCTIONS
Barbara C. Hellier; Alex M. Cornwall; and Marilyn L. Warburton
USDA-ARS Plant Germplasm Introduction and Testing Research Unit, 201 Clark Hall, Washington State University, Pullman, Washington 99164.
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- Summary
- Problems addressed
- Solutions developed
- Impact
- Germplasm
- Additional resources
- Chapter information
1. SUMMARY
Resistance to Verticillium Wilt Race 1 was found in 7 accessions of heirloom lettuce varieties in the U.S. National Plant Germplasm System (NPGS). These accessions gave breeders the tools needed to develop new lettuce cultivars resistant to this disease. Iceberg lettuce breeding lines with resistance were developed and both the resistant cultivars and breeding lines have been distributed to breeders and researchers in the U.S. and worldwide.
The goal was to screen and breed for resistance to Verticillium Wilt Race 1.
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2. PROBLEMS ADDRESSED
Verticillium Wilt, caused by Verticillium dahlia Kleb. is a severe disease in lettuce (Lactuca sativa L.) and has caused crop loss of entire fields in the Salinas and Pajaro Valleys, California, which are part of the prime lettuce growing region in the U.S. The farm gate value of lettuce in this area (Santa Cruz and Monterey counties, CA) was $1.4 billion in 2022 with half of the production in head lettuce (iceberg type). All lettuce types are susceptible to Verticillium Wilt but iceberg lettuce is the most affected. Finding sources of resistance was essential, because cultural and chemical control are not economically or environmentally friendly options.
3. SOLUTIONS DEVELOPED
In 2004 and 2005, researchers at the USDA-ARS Crop Improvement and Protection Research Station in Salinas, California conducted resistance screening trials of a wide range of lettuce lines including accessions from the USDA-ARS Western Regional Plant Introduction Station (the NPGS genebank unit in Pullman, Washington). The researchers found 7 accessions—older cultivars now maintained by the genebank unit—with resistance to Verticillium Wilt Race 1. Subsequently, the resistance discovered in the trials was incorporated into iceberg lettuce breeding lines.
Collaborators involved in developing solution:
- Ryan Hayes, Ivan Simko, and Steven Klosterman, USDA-Agricultural Research Service, Salinas, California, USA
- Gary Vallad, Qing-Ming Qin, Krishna Subbarao, and Karunakaran Maruthachalam, University of California, Davis, Davis, California, USA
- Rebecca Grube Sideman, University of New Hampshire, Durham, New Hampshire, USA
- Yaguang Luo, USDA-Agricultural Research Service, Beltsville, Maryland, USA
- Germán Sandoya, University of Florida, Belle Glade, Florida, USA
4. IMPACT
From 2011 to present (February 2024), the NPGS has filled 148 orders from lettuce breeders a