Fine Mapping Ty-3, a Major Begomovirus Resistance Gene In Tomato

Fla. 8680, a Tomato Yellow Leaf Curl Virus (TYLCV) resistant breeding line, was used to develop an F₂ population for fine mapping Ty-3. Fla. 8680 has a Solanum chilense introgression of approximately 27cM on chromosome 6, spanning markers C2_At2g39690 (5.3cM) to T0834 (32cM). Seven-hundred-nineteen F₂ plants were screened with molecular markers to identify 30 recombinants within this region. F₄ and F₅ recombinant inbred lines (RILs) were tested for resistance to TYLCV in fall 2007 and spring 2008, respectively. Results indicate that Ty-3 maps to the 7 cM interval between markers T0774 (18cM) and P6-25 (25cM). Two recombinants, each containing this region within a shortened introgression, were used to develop a large segregating population to further fine map Ty-3. In spring 2009, over 9000 seedlings were screened with molecular markers at the distal ends of the introgressions, and over 200 recombinants were selected and transplanted to the field. Multiple cuttings taken from each recombinant were inoculated with whiteflies viruliferous for TYLCV and tested for resistance in a replicated field experiment. These results will be presented.