Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: March 20, 2005
Publication Date: July 20, 2005
Citation: Hayes, R.J., Bull, C.T., Goldman, P.H., Ryder, E.J. 2005. Development of lettuce breeding lines resistant to baterial leaf spot. Hortscience. v. 40. p. 1098. Technical Abstract: Bacterial leaf spot of lettuce caused by Xanthomonas campestris pv. vitians (Xcv) is an important lettuce disease in California. No adequate control measures have been found, although resistance exists in several heirloom cultivars. Deployment of resistant cultivars to bacterial leaf spot will reduce these periodic and costly disease events. The objectives of this research were to 1) identify new sources of resistance within modern crisphead cultivars and 2) select for resistance in 'Salad Crisp' x 'Iceberg' progeny. Field plots were established and grown with overhead irrigation, and a 3 strain mixture of Xcv was applied until run-off one week after thinning at 1 x 109 CFU/ml. Twenty-six crisphead cultivars were tested in unreplicated field trials and rated on a 1 (susceptible) ' 4 (resistant) scale. Selection was carried out between and within families from the F2 to F4 generation. Sixteen F3 families were evaluated in unreplicated plots, and 12 F5 families were tested in replicated plots for disease incidence and severity. No useable levels of resistance were identified in the modern crisphead cultivars tested to date. All F3 families had resistance greater than 'Iceberg', and 19 plants from 8 families were selected for further breeding. Subsequently 12 plants from 2 F4 families were selected. Replicated trials of 12 F5 families indicated that all lines have disease severity comparable to both parents. Breeding lines from crosses to Salinas 88 are currently being developed.