The LsVe1L allele provides a molecular marker for resistance to Verticillium dahliae race 1 in lettuce

Authors: INDERBITZIN, P - University Of California; CHRISTOPOULOU, M - University Of California; LAVELLE, D - University Of California; REYES-CHIN-WO, S - University Of California; MICHELMORE, R - University Of California; SUBBARAO, K - University Of California; Simko, Ivan

Submitted to: BMC Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2019
Publication Date: 7/10/2019
Citation: Inderbitzin, P., Christopoulou, M., Lavelle, D., Reyes-Chin-Wo, S., Michelmore, R.W., Subbarao, K.V., Simko, I. 2019. The LsVe1L allele provides a molecular marker for resistance to Verticillium dahliae race 1 in lettuce. Biomed Central (BMC) Plant Biology. 19:305. https://doi.org/10.1186/s12870-019-1905-9.
DOI: https://doi.org/10.1186/s12870-019-1905-9

Interpretive Summary: The Salinas and Pajaro Valleys of coastal central California are among the most important lettuce-producing regions in the United States. One of the top disease concerns for lettuce in the area is Verticillium wilt caused by the fungus Verticillium dahliae, which is a soilborne pathogen with a wide host range that also includes artichoke, cotton, eggplant, hops, potato, sunflower, tobacco, and tomato. Resistance of lettuce against V. dahliae race 1 was previously mapped to the single dominant Verticillium resistance 1 (Vr1) locus. We used genome sequencing and/or PCR screening along with pathogenicity assays of 151 accessions of lettuce to investigate allelic diversity and its relationship to race 1 resistance in lettuce. This approach identified a total of four Ve genes; LsVe1, LsVe2, LsVe3, and LsVe4. The majority of accessions, however, contained a combination of only three of these LsVe genes clustered on chromosomal linkage group 9. A single allele, LsVe1L, was present in all resistant accessions and absent in all susceptible accessions. This allele can be used as a molecular marker for V. dahliae race 1 resistance in lettuce. A PCR assay for rapid detection of race 1 resistance in lettuce was designed based on nucleotide polymorphisms. Application of this assay allows identification of resistant genotypes in early stages of plant development or at a seed-level without time- and labor-intensive testing in the field.

Technical Abstract: Verticillium wilt caused by the fungus Verticillium dahliae race 1 is among the top disease concerns for lettuce in the Salinas and Pajaro Valleys of coastal central California. Resistance of lettuce against V. dahliae race 1 was previously mapped to the single dominant Verticillium resistance 1 (Vr1) locus. Lines of tomato resistant to race 1 are known to contain the closely linked Ve1 and Ve2 genes that encode receptor-like proteins with extracellular leucine-rich repeats; the Ve1 and Ve2 proteins act antagonistically to provide resistance against V. dahliae race 1. The Vr1 locus in lettuce contains a cluster of several genes with sequence similarity to the tomato Ve genes. We used genome sequencing and/or PCR screening along with pathogenicity assays of 151 accessions of lettuce to investigate allelic diversity and its relationship to race 1 resistance in lettuce. This approach identified a total of four Ve genes; LsVe1, LsVe2, LsVe3, and LsVe4. The majority of accessions, however, contained a combination of only three of these LsVe genes clustered on chromosomal linkage group 9 (within e.g. ~ 25 Kb in the resistant cultivar La Brillante and within ~ 127 Kb in the susceptible cultivar Salinas). A single allele, LsVe1L, was present in all resistant accessions and absent in all susceptible accessions. This allele can be used as a molecular marker for V. dahliae race 1 resistance in lettuce. A PCR assay for rapid detection of race 1 resistance in lettuce was designed based on nucleotide polymorphisms. Application of this assay allows identification of resistant genotypes in early stages of plant development or at a seed-level without time- and labor-intensive testing in the field.