QTL Analysis in Recombinant Inbred Lines Derived From a Four-Way Cross of Two F1 Hybrids of Tomato

Most tomato cultivars are F₁ hybrids. Tomato breeding for the fresh produce market in Japan has focused on high quality (e.g., high sugar content), but the yields of Japanese F₁ cultivars are generally lower than those of high-yield hybrids developed for mass-production hydroponic culture systems in Europe. To analyze the genetic factors that contribute to the yield and quality of tomato, we selected two F₁ cultivars as parents and crossed them to establish the experimental populations. One parent was the Japanese F₁ cultivar ‘Momotaro 8’ (Takii & Company, Ltd., Japan), which is characterized by high sugar content, and the other was the high-yield Dutch F₁ cultivar ‘Geronimo’ (De Ruiter Seeds, the Netherlands). This cross corresponded to a four-way cross, as the four parental lines of the two F₁ cultivars were considered to be the founders. We generated an F₁ population consisting of 240 plants by crossing the two cultivars and each F₁ plant was subjected to additional cycles of selfing with single-seed descent to generate recombinant inbred lines (RILs). Genotyping data of F₆ RILs using more than 200 genome-wide simple sequence repeat (SSR) markers were subjected to the construction of linkage map. Results of QTL analysis in RILs at F₆, F₇ and F₈ generations are reported. Acknowledgements. This work was supported by grants from the Ministry of Agriculture, Forestry and Fisheries of Japan (Genomics for Agricultural Innovation, SGE1002).