January 18, 2011
New Romaine Lettuce Lines Launched
Breeding lines prove dieback resistant, show improved shelf life
California and Arizona, the two largest lettuce-producing states, account for more than 95% of the lettuce grown in the United States. Since the early 1990s, the states' lettuce crops have been subject to "dieback", a disease indicated by symptoms including mottling, yellowing, and death of older leaves, and stunting and eventual death of lettuce plants. Dieback disease, caused by two soil-borne viruses, affects romaine and leaf-type lettuce, often leading to crop loss of 60% or more. Most disturbing is the news that the virus is not effectively reduced using either chemical treatment or rotation with nonhost crops, and the virus can live on in infested soil.
SM09A and SM09B are F8 romaine breeding lines of lettuce (Lactuca sativa L.) resistant to the dieback disease and with good shelf life. SM09B was selected from a cross between 'Darkland' and PI 491224. SM09A was developed from 'Green Towers' ('Darkland' x PI 491224). "In replicated field trials, the two breeding lines showed complete resistance to dieback. Testing of salad-cut lettuce in modified atmosphere packaging indicated slower decay in the two breeding lines compared with other dieback-resistant romaine varieties", noted Simko.
Image Caption: SM09A, one of two new romaine lettuce breeding lines found to be resistant to dieback disease, also showed good shelf life. Credit: Photo by Ivan Simko
On the Net:
- American Society for Horticultural Science
- Limited samples of seeds are available for distribution for research purposes, including the development and commercialization of new cultivars. Samples are deposited in the National Plant Germplasm System under numbers PI 658678 and PI 658679. Address written requests to Simko at [email protected].
- The complete study and abstract are available on the ASHS HortScience electronic journal web site: http://hortsci.ashspublications.org/cgi/content/full/45/4/670