Pyramiding disease resistance in tomato by duplex PCR targeting resistance genes and exploiting gene linkage

Tomato is the second most important vegetable crop in the world after potato. Its production is hindered by fungal and viral diseases. Control of these diseases requires a significant investment that represents up to 40% of the production costs. Marker-assisted gene pyramiding is a powerful breeding tool which allow the rapid constitution of breeding lines with broad spectrum of resistance against diseases. Nevertheless, the accuracy and rapidity of introgression of genes of interest are some of the most critical barriers to successful application. In this paper, we use a simple and rapid method that combines duplex PCR for two important virus resistance genes (i.e., Sw-5 and Tm-2) and uses the linkage between genes Tm-2 and Forl to speed the introgression of these resistance genes into a "Pomodoro di Sorrento" tomato line. The method was used through six generations of backcrossing followed by three generations of selfing and resulted in a homozygous resistant line.