The 2011 ASHS Annual Conference

The Tomato Yellow Leaf Curl Virus (TYLCV) and Tomato Mottle Virus (ToMoV) resistant breeding lines, Fla. 8753 and 994344-SBK, were each crossed to susceptible breeding lines to develop F₂ populations for mapping resistance loci. Resistant and susceptible progeny from two Fla. 8753 populations were selectively genotyped, and a test for transmission disequilibrium at the SlNAC1 locus was highly significant (P < 0.0001). Progeny of these selections were evaluated the following season, and approximately two-thirds of susceptible selections showed clear segregation for resistance. The SlNAC1 marker again co-segregated with resistance, and a recessive allele at this locus was indicated. Segregation among 120 progeny in the 994344-SBK population also indicated a recessive allele at the Ty-5 locus as a major contributor to resistance. ‘Tyking’ was determined to be the donor of the chromosome 4 introgression at the Ty-5 locus in each of these lines. This locus alone did not confer parental levels of resistance, and segregation for an additional locus was observed.