Development of Functional Molecular Marker System to Differentiate Multiple Disease Resistances in Tomatoes

Marker assisted selection (MAS) for disease resistance is widely applied in practical tomato breeding program both in public and private sectors. Due to the commercial value and the importance as a model crop system, tomato has taken the lead in MAS among the other horticultural crops. Tomato yellow leaf curl virus (TYLCV), which is transmitted by whitefly (Bemisia tabaci), is one of the major threats for tomato production worldwide. Ty1 and Ty3 resistances originated from Solanum chilense accession LA1969 and LA1932/LA2779, respectively. Recently, a gene responsible for Ty1 has been identified as a DFDGD-class RNA dependent RNA polymerase (RDR) and it is demonstrated to be allelic with Ty3 resistance. Resistance against vascular wilt diseases in tomato caused by Verticillium, is conferred by Ve locus containing two closely linked inversely oriented genes, Ve1 and Ve2. Ve resistance was shown to provide resistance against a V. alboatrum race 1 and found to encode the extracellular Leu-rich repeat (eLRR) receptor-like protein (RLP) class of disease resistance proteins. Late blight in tomato is caused by Phythophthora infestans, and several resistances have been identified in wild tomato species applied in the practical breeding program. Ph3 resistance from S. pimpinellifolium (L3708) conferring incomplete resistance against wide-range of P. infestans isolates is considered the most effective resistance source against tomato late blight. Very recently, a CC-NBS-LRR gene on chromosome 9 has been identified to be responsible for the Ph3 resistance. In this study, we developed reliable and comprehensive molecular markers designed based on the single nucleotide polymorphisms (SNPs) or insertion/deletion (InDel) directly responsible for the resistance phenotype. These functional molecular markers are expected to enhance the effectivity and accuracy of MAS for disease resistance in tomato breeding programs.