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ARS Home » Pacific West Area » Pullman, Washington » Plant Germplasm Introduction and Testing Research » Research » Publications at this Location » Publication #311004
Title: Association analysis of bacterial leaf spot resistance and SNP markers derived from expressed sequence tags (ESTs) in lettuce (Lactuca sativa L.)

Author
item LU, HUANGJUN - University Of Florida
item Hu, Jinguo
item Kwon, Soon

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2014
Publication Date: 4/18/2014
Citation: Lu, H., Hu, J., Kwon, S.J. 2014. Association analysis of bacterial leaf spot resistance and SNP markers derived from expressed sequence tags (ESTs) in lettuce (Lactuca sativa L.). Molecular Breeding. 34:997–1006.

Interpretive Summary: Bacterial leaf spot (BLS) of lettuce, caused by Xanthomonas campestris pv. vitians, is an economically important disease of lettuce throughout North America. Since there are no chemicals available for effective control of the disease, host-plant resistance is highly desirable to protect lettuce production. This paper reports the results of screening 179 lettuce germplasm lines for their response to BLS in Belle Glade, FL and associating the resistance with single nucleotide polymorphism (SNP) markers that had been used to genotype these lines. We identified one line of high resistance and five lines of moderate resistance, one SNP marker associated with disease severity and two SNP markers associated with the resistance in the leaf lettuce PI 358001-1 which had no disease symptoms. The identified resistant lines and the associated SNPs should be useful to develop resistant cultivars to battle against the devastating disease in lettuce.

Technical Abstract: Bacterial leaf spot of lettuce, caused by Xanthomonas campestris pv. vitians, is a devastating disease of lettuce worldwide. Since there are no chemicals available for effective control of the disease, host-plant resistance is highly desirable to protect lettuce production. A total of 179 lettuce genotypes consisting of 29 leaf, 15 crisphead, one stem, 21 romaine, and 113 butterhead types were evaluated for response to X. c. vitians. One source of high resistance and five sources of moderate resistance were identified with four being butterhead lettuce and two leaf lettuce. The population genetic structure based on 350 expressed-sequence-tag-derived single nucleotide polymorphism generated two clades: Clade I and Clade II. The butterhead type was genetically distinct from romaine and crisphead types, while the leaf type was found to frequently exchange genes with other types through the history of breeding. Association mapping identified one single nucleotide polymorphism (QGB19C20.yg-1-OP5) associated with disease severity in Q general linear model and Q + K mixed linear model. Two SNP markers (Contig15389-1-OP1 and Contig6039-19-OP1) were associated with the resistance in the leaf lettuce PI 358001-1 which had no disease symptoms. The marker QGB19C20.yg-1-OP5 is in linkage group 2, while both of Contig15389-1-OP1 and Contig6039- 19-OP1 are in linkage group 4. The resistant lines and the associated SNPs should be useful to develop resistant cultivars to battle against the devastating disease in lettuce.