Screening Cultivated and Wild Tomato Germplasm for Resistance to Xanthomonas gardneri

摘要

Bacterial spot of tomato is caused by four species of Xanthomonas. The disease causes lesions on tomato leaves and black spots on fruits, leading to yield and quality loss. The bacterial species X. gardneri has been implicated in outbreaks of bacterial spot in processing tomato fields in Brazil, Canada, and the mid-west United States. As pesticides are currently not reliable for control of bacterial spot, the development of cultivars resistant to X. gardneri and to bacterial spot in general is of primary interest. 140 lines of Solanum lycopersicum from the SolCAP elite processing collection and 51 lines of S. pimpinellifolium from the Tomato Genetic Resource Center core collection were tested against two strains of X. gardneri for hypersensitive response (HR) under greenhouse conditions. The most interesting accessions and controls were then tested under field conditions. Three accessions of the wild tomato species S. pimpinellifolium appear to be resistant to X. gardneri in both greenhouse and field trials. S. lycopersicum lines developed using some of the wild parents also appear to be partially resistant. Four segregating populations were developed for two of the sources of resistance, and disease response appears to be conditioned by as few as1 to 4 loci with moderate heritability.