Mapping a wild tomato introgression associated with tomato yellow leaf curl virus resistance in a cultivated tomato line

Tomato yellow leaf curl virus (TYLCV), a heterogeneous complex of whitefly- vectored geminiviruses, is a serious production constraint of tomato (Lycop ersicon esculentum Mill,) in Asia, the Middle East, and the Americas. In th is study we report on mapping of a DNA fragment introgressed into cultivate d tomato presumably from the wild species L, hirsutum Humb. and Bonpl and f ound to be associated with TYLCV resistance. To locate introgressions of wi ld tomato alleles in TYLCV-resistant tomato line H24, its DNA was digested with sh restriction enzymes and probed with 90 RFLP markers evenly spaced t hroughout the genome. This polymorphism survey revealed the presence of one wild tomato introgression each on chromosomes 8 and 11. Plants of a F-2 cr oss between H24 and a susceptible tomato line were probed with randomly amp lified polymorphic DNA (RFLP) markers linked to the targeted regions and F- 3 families were developed by self-pollination of F-2 plants that carried no ne, one, or both introgressions in either homozygous or heterozygous states . Plants of F-3 families, parents, and control tomato line Ty52 (homozygous for the Ty-1 allele for TYLCV tolerance) were exposed to viruliferous whit eflies (Bemisia tabaci Gennadius) in greenhouses at the Asian Vegetable Res earch and Development Center, Taiwan, and the University of Agricultural Sc iences, Bangalore, India. Results indicated that F-3 families homozygous fo r the introgression on chromosome 11 were resistant to TYLCV at both locati ons. Additional probing showed that the chromosome 11 introgression spanned markers TG36 to TG393, covering a distance of at least 14.6 centimorgans. This is the first report of TYLCV resistance in tomato mapped to chromosome 11.