Mutations in Phytoene Synthase 1 Gene Alters Carotenoid Production

Studies have revealed the role of tomatoes in preventing cancers, cardio-vascular diseases, and blindness. These healthful characteristics are contributed by different compounds which include flavonoids, phenylpropanoids, some vitamins, and carotenoids. Carotenoids are formed by the action of the enzyme phytoene synthase. Antoine Gady and colleagues at the Wageningen-UR used TILLING (Targeting Induced Local Lesions in Genomes) to identify point mutations in the Psy1 gene that could cause vital changes in the production of carotenoids in tomatoes.

The researchers found two point mutations in the candidate gene. The first mutation led to a replacement of the gene with a mutant allele (W180*) and another one that caused amino acid substitution (P192L). The first mutation produced yellow fruits which did not turn red even during ripening. The second mutation produced fruits that remained yellow until post-breaker and eventually turned red. Metabolite profiling confirmed the absence of carotenoids in W180* line, which further implied that PSY1 is the only enzyme that regulates carotenoid production. The P192L line exhibited slow synthesis of PSY1 leading to delay in lycopene and beta-carotene accumulation. Further analysis revealed that P192L mutation affects the activity of PSY1 through misfolding, leading to low accumulation of the enzyme.

Read the abstract at http://www.springerlink.com/content/n2288102267x8644/.