New romaine lettuce lines launched

In an effort to control looming economic losses to the region's vital lettuce industry, scientists are being challenged to develop new breeding lines that provide genetic resistance to the virus. Add in another challenge for researchers: some recently developed romaine cultivars that are resistant to dieback have limited shelf life, decaying quickly when processed for salad.Three romaine-type breeding lines with resistance to the disease were previously released by the U.S. Department of Agriculture-Agricultural Research Service in Salinas, California. Now, the Salinas breeding program has introduced new romaine breeding lines that prove praiseworthy in terms of both disease resistance and shelf life. Ivan Simko and Ryan J. Hayes from the USDA-ARS in Salinas, Krishna V. Subbarao of the Department of Plant Pathology at the University of California, and Rebecca Grube from the University of New Hampshire introduced the new romaine lines in a recent issue of HortScience.

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.

More information: The complete study and abstract are available on the ASHS HortScience electronic journal web site: http://hortsci.ash … ull/45/4/670

Provided by American Society for Horticultural Science