Cloning and mapping of genes involved in tomato ascorbic acid biosynthesis and metabolism

Ascorbic acid is a key component of plant antioxidant system and it has a multitude of functions in organisms. The cDNA clones encoding homologues of dehydroascorbate reductase (DHAR) and ascorbate oxidase (AO) genes, which are involved in ascorbic acid metabolism, were isolated from tomato plants. Deduced amino acid sequences exhibited 50–88% identities with the corresponding sequences from other plant species. In order to screen for candidate genes linked to tomato ascorbic acid biosynthesis and metabolism, the ascorbic acid-associated genes were mapped. These genes were located on the tomato map using a population of introgression lines (ILs) having one segment of Lycopersicon pennellii (LA716) in a L. esculentum (M82) background. The 75 ILs allowed the genome to be segmented into 107 bins. Fourteen genes involved in ascorbic acid biosynthesis and metabolism were mapped to 15 loci and most of the probes revealed a single copy signal. Furthermore, the digital expression profiles of the genes associated with ascorbic acid biosynthesis and metabolism were described.