Initial development of a set of introgression lines from Solanum peruvianum PI 126944 into tomato: exploitation of resistance to viruses

Resistance to Tomato yellow leaf curl virus (TYLCV) and Tomato spotted wilt virus (TSWV), among other diseases, has been reported in Solanum peruvianum PI 126944. Introgression lines (ILs) from S. peruvianum PI 126944 into the genetic background of cultivated tomato (S. lycopersicum) are being developed. Several generations were derived from three interspecific hybrids previously obtained. A lot of crosses and embryo rescue were required until the third backcross, due to the high degree of incompatibility existing between tomato and PI 126944. Crosses between F1 plants were made to obtain a pseudo-F2 generation. The same procedure was followed up to the pseudo-F6 generation. Additional crosses between plants of different generations were made in order to increase progeny. Of 263 molecular markers tested, 105 were polymorphic between tomato and PI 126944. This set of polymorphic markers consisted of 90 simple sequence repeats (SSR) and 15 cleaved amplified polymorphic sequences (CAPS). The amount of the S. peruvianum genome was reduced in advancing generations and this was coupled in some cases with a reduction of incompatibility. However, the S. peruvianum genome was almost completely represented among the different plants of the most advanced generations. ILs will be basically developed from them. Some of the generations developed were resistant to TYLCV and TSWV.