title: Molecular Mapping of High Resistance to Bacterial Leaf Spot in Lettuce PI 358001-1.
abstract: Lettuce (Lactuca sativa L.) is a diploid (2n = 18) with a genome size of 2,600 Mbp, and belongs to the family Compositae. Bacterial leaf spot (BLS), caused by Xanthomonas campestris pv. vitians, is a major disease of lettuce worldwide. Leaf lettuce PI 358001-1 has been characterized as an accession highly resistant to BLS and has white seed. In order to understand inheritance of the high resistance in this germplasm line, an F3population consisting of 163 families was developed from the cross PI 358001-1 × 'Tall Guzmaine' (a susceptible Romaine lettuce variety with black seed). The segregation ratio of reaction to disease by seedling inoculation with X. campestris pv. vitians L7 strain in the F3families was shown to be 32:82:48 homozygous resistant/heterozygous/homozygous susceptible, fitting to 1:2:1 (n = 162, χ2= 3.19, P = 0.20). The segregation ratio of seed color by checking F2plants was 122:41 black/white, fitting to 3:1 (n = 163, χ2= 0.002, P = 0.96). The results indicated that both BLS resistance and seed color were inherited as a dominant gene mode. A genetic linkage map based on 124 randomly selected F2plants was developed to enable molecular mapping of the BLS resistance and the seed color trait. In total, 199 markers, comprising 176 amplified fragment length polymorphisms, 16 simple-sequence repeats, 5 resistant gene candidate markers, and 2 cleaved amplified polymorphic sequences (CAPS) markers were assigned to six linkage groups. The dominant resistance gene to BLS (Xcvr) was mapped on linkage group 2 and the gene locus y for seed color was identified on linkage group 5. Due to the nature of a single gene inheritance, the high-resistance gene should be readily transferred to adapted lettuce cultivars to battle against the devastating disease of lettuce.
authors.affiliation: First and second authors: Everglades Research and Education Center, University of Florida/Institute of Food and Agricultural Sciences, Belle Glade 33430; and third author: United States Department of Agriculture-Agricultural Research Service, Western Regional Plant Introduction Station, Washington State University, Pullman 99164.
authors.forename: Yunwen
authors.initials: Y
authors.lastname: Wang
authors.affiliation: First and second authors: Everglades Research and Education Center, University of Florida/Institute of Food and Agricultural Sciences, Belle Glade 33430; and third author: United States Department of Agriculture-Agricultural Research Service, Western Regional Plant Introduction Station, Washington State University, Pullman 99164.
authors.forename: Huangjun
authors.initials: H
authors.lastname: Lu
authors.affiliation: First and second authors: Everglades Research and Education Center, University of Florida/Institute of Food and Agricultural Sciences, Belle Glade 33430; and third author: United States Department of Agriculture-Agricultural Research Service, Western Regional Plant Introduction Station, Washington State University, Pullman 99164.
authors.forename: Jinguo
authors.initials: J
authors.lastname: Hu
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D002874:Chromosome Mapping; D060467:Disease Resistance / Q000235:genetics*; D008040:Genetic Linkage; D018545:Lactuca / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D018895:Microsatellite Repeats / Q000235:genetics; D010641:Phenotype; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D012639:Seeds / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D016959:Xanthomonas campestris / Q000502:physiology*