SCAR Marker Linked to RIPENING-INHIBITOR (Rin) in Tomato

Various tomato varieties were grown worldwide and consumed in many dishes, sauces, and drinks. In addition, it provides to mankind beneficial antioxidants for human health such as lycopene. For its fresh market usage, shelf-life is important especially for exporting varieties in tropical climate. Delaying maturity is one of powerful method to increasing shelf-life. Ripening gene related delaying fruit maturity was previously known through mutation. Recessive mutation, RIPENING-INHIBITOR (rin) is a noteworthy gene, because it effectively blocks the ripening process and hybrids (Rin/rin) represents slow-ripening, long shelf-life and freshness. Restriction fragment length polymorphism (RFLP) analysis has permitted the rin regions of chromosome 5 on high-density genetic maps. Also, positional cloning of the rin locus revealed that the locus was related to two tandem MADS-box genes (LeMADS-RIN and LeMADS-MC), whose expression patterns are associated with fruit ripening and sepal development, respectively. Additionally, tomatoes carrying rin displayed enlarged sepals, although it does depend on the lines. Since breeders need the long shelf-life character in the tomato breeding program, we had set to develop a rin related DNA marker. We searched for the proper primer sequences in the deletion region between Rin and rin mRNA sequences, and also in the intron region of rin. Primers that simultaneously amplified two bands with a co-dominant pattern were selected and converted to the SCAR (Sequence Characterized Amplified Region) marker. As a preliminary data, these markers work well to distinguish heterozygous (Rin/rin) and homozygous (Rin/Rin, rin/rin) genotypes, and are able to select the character of long shelf-life.