Novel molecular marker associated with Tm2a gene conferring resistance to tomato mosaic virus in tomato. Plant Breeding. May 2013 Dilip R. Panthee, Allan F. Brown, Gad G. Yousef, Ragy Ibrahem, Candice Anderson.
NC State University Plants for Human Health Institute, NC Research Campus.
Tomato mosaic virus (ToMV) is an important Tobamovirus that causes significant crop losses. Resistance to the ToMV is conferred by the genes Tm1, Tm2 and Tm2a. Among these three genes, Tm2a confers resistance to most strains of the ToMV. Screening of genetic lines under field conditions based on phenotype is time-consuming and challenging due to concerns associated with stability of the virus and its potential transmission to other plants. Tightly linked molecular markers associated with resistance genes can improve selection efficiency and avoid these problems. This study developed a PCR-based marker based on restriction site differences from Tm2a locus-specific sequences, which was found to be useful in identifying the resistant and susceptible genotypes and was consistent with phenotypic data. The marker is a codominant cleaved amplified polymorphic sequence (CAPS) marker producing 270- and 600-bp DNA fragments from resistant genotypes and an 870-bp fragment from susceptible genotypes when digested with HaeIII restriction enzyme. This novel marker can be useful for tomato breeders to screen progeny from segregating populations for ToMV resistance.