Yang, W., Sacks, E. J., Lewis Ivey, M. L., Miller, S. A., and Francis, D. M. 2005. Resistance in Lycopersicon esculentum intraspecific crosses to race T1 strains of Xanthomonas campestris pv. vesicatoria causing bacterial spot of tomato. Phytopathology 95: 519-527. We used molecular markers to identify quantitative trait loci (QTL) that confer resistance in the field to Xanthomonas campestris pv. vesica-toria race T1, a causal agent of bacterial spot of tomato. An F2 population derived from a cross between Hawaii 7998 (H 7998) and an elite breeding line, Ohio 88119, was used for the initial identification of an association between molecular markers and resistance as measured by bacterial populations in individual plants in the greenhouse. Polymorphism in this cross between a Lycopersicon esculentum donor of resistance and an elite L. esculentum parent was limited. The targeted use of a core set of 148 polymerase chain reaction-based markers that were identified as polymor-phic in L. esculentum × L. esculentum crosses resulted in the identifica-tion of 37 markers that were polymorphic for the cross of interest. Previous studies using an H 7998 × L. pennellii wide cross implicated three loci, Rx1, Rx2, and Rx3, in the hypersensitive response to T1 strains. Markers that we identified were linked to the Rx1 and Rx3 loci, but no markers were identified in the region of chromosome 1 where Rx2 is located. Single marker-trait analysis suggested that chromosome 5, near the Rx3 locus, contributed to reduced bacterial populations in lines carry-ing the locus from H 7998. The locus on chromosome 5 explained 25% of the phenotypic variation in bacterial populations developing in infected plants. An advanced backcross population and subsequent inbred back-cross lines developed using Ohio 88119 as a recurrent parent were used to confirm QTL associations detected in the F2 population. Markers on chromosome 5 explained 41% of the phenotypic variation for resistance in replicated field trials. In contrast, the Rx1 locus on chromosome 1 did not play a role in resistance to X. campestris pv. vesicatoria race T1 strains as measured by bacterial populations in the greenhouse or symp-toms in the field. A locus from H 7998 on chromosome 4 was associated with susceptibility to disease and explained 11% of the total phenotypic variation. Additional variation in resistance was explained by plant matur-ity (6%), with early maturing families expressing lower levels of resis-tance, and plant habit (6%), with indeterminate plants displaying more resistance. The markers linked to Rx3 will be useful in selection for resistance in elite × elite crosses.

试验采用聚乙二醇（PEG）6000溶液模拟水分胁迫条件（0、-0.2、-0.4、-0.6、-0.8 MPa）对包括3份醋栗番茄、4份栽培番茄的变种和2份对照的种子进行萌发试验，结果显示，在-0.4、-0.6、-1.8 MPa水势下，所有材料都不能发芽。在-0.2 MPa水势下，供试材料的发芽能力都比正常水分（0 MPa）下有所下降，且材料间差异显著，NC 84173和LA 4133发芽最差，而PI114490表现最好，可作为耐旱材料用于育种。