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United States Department of Agriculture

Agricultural Research Service

Research Project: Evaluation, Enhancement, Genetics and Breeding of Lettuce, Spinach, and Melon

Location: Crop Improvement and Protection Research

Title: Sm09a and Sm09b: Romaine Lettuce Breeding Lines Resistant to Dieback and with Improved Shelf-Life.

Authors
item Simko, Ivan
item Hayes, Ryan
item Subbarao, Krishna -
item Sideman, Rebecca -

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2010
Publication Date: April 20, 2010
Citation: Simko, I., Hayes, R.J., Subbarao, K.V., Sideman, R.G. 2010. SM09A and SM09B: Romaine Lettuce Breeding Lines Resistant to Dieback and with Improved Shelf-life.. HortScience,Year 2010, volume 45, pages 670-672.

Interpretive Summary: We have developed two F8 romaine breeding lines of lettuce (Lactuca sativa L.) that are resistant to dieback and have good shelf-life. SM09B was selected from a cross between ‘Darkland’ and PI491224, while SM09A was developed from ‘Green Towers’ ' (‘Darkland’ × PI491224). Resistance to the disease in both breeding lines is derived from PI491224, a primitive romaine-type lettuce that is highly perishable when processed for salad. In replicated field trials, the two breeding lines showed complete resistance to dieback. Field observations were confirmed through the analysis of molecular markers closely linked to the dieback resistance gene Tvr1. Testing of salad-cut lettuce in modified atmosphere packaging indicated slower decay in the two breeding lines compared to other dieback-resistant romaines. Both SM09A and SM09B produce closed heads of acceptable size, with a core length about 20% longer and with 10% more leaves than cvs. Darkland and Green Towers (Table 2). SM09A is light-green, while SM09B has a medium-green color. Limited testing for yield indicates that the proportion of harvestable heads (0.92 for SM09A and 0.70 for SM09B) is similar to other romaine cultivars (with the exception of ‘Bandit’).

Technical Abstract: SM09A and SM09B are F8 romaine breeding lines of lettuce (Lactuca sativa L.) resistant to dieback and with good shelf-life. SM09B was selected from a cross between ‘Darkland’ and PI491224, while SM09A was developed from ‘Green Towers’ × (‘Darkland’ × PI491224). Resistance to the disease in both breeding lines is derived from PI491224, a primitive romaine-type lettuce that is highly perishable when processed for salad. In replicated field trials, the two breeding lines showed complete resistance to dieback. Field observations were confirmed through the analysis of molecular markers closely linked to the dieback resistance gene Tvr1. Testing of salad-cut lettuce in modified atmosphere packaging indicated slower decay in the two breeding lines compared to other dieback-resistant romaines.

Last Modified: 7/28/2014
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