Molecular Markers for Selecting Diverse Disease Resistances in Tomato Breeding Programs

Tomato (Solanum lycopersicum L.) is an economically important crop worldwide. In addition, tomato serves as an excellent model system for plant genetics and biology, including fruit biology, abiotic stress tolerance, and plant-microbe interactions. Development and practical use of molecular markers have been actively pursued in molecular breeding programs for tomato, especially for disease resistance to allow selection of a single resistance gene and combination of multiple resistance genes. Due to insufficient genetic variation in cultivated tomatoes, various wild relatives of tomato have been investigated and utilized as disease resistance sources. In order to pursue the resistance provided by these wild relatives in developing new tomato varieties, molecular markers have been developed and intensively utilized in tomato breeding programs. In this review, we summarize the currently available molecular markers that confer resistance against major tomato diseases, including Tomato yellow leaf curl virus (TYLCV), Tomato spotted wilt virus (TSWV), Tomato mosaic virus (ToMV), verticillium wilt, fusarium wilt, late blight caused by Phytophthora infestans, leaf mold caused by Cladosporium fulvum, root-knot caused by Meloidogyne spp., bacterial spot caused by Xanthomonas spp., and bacterial speck caused by Pseudomonas syringae. The provided marker information is expected to contribute to development of marker-assisted selection for disease resistance and to exploration of novel genetic sources for a tomato breeding program.