Genetic analysis of resistance to bacterial leaf spot in the heirloom lettuce cultivar Reine des Glaces

Authors: SANDOYA, G - University Of California; MAISONNEUVE, B - Institut National De La Recherche Agronomique (INRA); TRUCO, M - University Of California; BULL, C - Pennsylvania State University; Simko, Ivan; TRENT, M - Former ARS Employee; Hayes, Ryan; MICHELMORE, R - University Of California

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2019
Publication Date: 11/16/2019
Citation: Sandoya, G.V., Maisonneuve, B., Truco, M.J., Bull, C.T., Simko, I., Trent, M., Hayes, R.J., Michelmore, R.W. 2019. Genetic analysis of resistance to bacterial leaf spot in the heirloom lettuce cultivar Reine des Glaces. Molecular Breeding. 39:160. https://doi.org/10.1007/s11032-019-1072-6.
DOI: https://doi.org/10.1007/s11032-019-1072-6

Interpretive Summary: The production of lettuce in the US and abroad is impacted by the bacterium Xanthomonas campestris pathovar (pv.) vitians (Xcv), a pathogen that causes bacterial leaf spot (BLS) of lettuce. BLS initially presents as water-soaked leaf spots on the outer leaves of the plants. Lesions then turn into black spots that may coalesce, resulting in larger spots that diminish yield and the quality of lettuce, particularly in climates with high humidity and precipitation during the cultivation period. Reine des Glaces (RG), an old Batavia-type cultivar, exhibited an uninvestigated partial resistance to Xcv. Genes for disease resistance were analyzed using two mapping populations derived from RG × Eruption and RG × Delsay using isolates collected in California, Canada, and France, each representing a different race. A major resistance gene was identified chromosome 2 in both populations; additional, minor effect genes were also detected on other chromosome. The major gene collocates with the Xar1 and Xcvr genes that had previously been identified using populations derived from Salinas 88 × La Brillante and PI 358001-1 × Tall Guzmaine. RG provides another resistance resource for combating BLS using data provided by this study for marker-assisted selection.

Technical Abstract: Bacterial leaf spot (BLS) is a disease that affects lettuce (Lactuca sativa L.) worldwide. The disease is caused by the bacterium Xanthomonas campestris pathovar vitians (Xcv), which exclusively infects lettuce and is particularly devastating in warm humid climates. Reine des Glaces (RG), an old Batavia-type cultivar, exhibited an uninvestigated partial resistance to Xcv. Quantitative trait loci (QTLs) were analyzed using two recombinant inbred line (RIL) populations derived from RG × Eruption and RG × Delsay using three isolates collected in California and Canada, each representing a different race, and an isolate collected in France. A major QTL was identified in linkage group 2 in both populations; additional, minor QTLs were also detected in other linkage groups. The major QTL collocates with the Xar1 and Xcvr genes that had previously been identified using RIL populations derived from Salinas 88 × La Brillante and PI 358001-1 × Tall Guzmaine. RG provides another resistance resource for combating BLS using data provided by this study for marker-assisted selection.