Horticulture and Crop Science Exit Seminar
Title: The effects of lycopene β-yclase (CYC-B) allele introgression on cherry tomato fruit quality
β-carotene is a carotenoid pigment from plants that supplies the most reliable source of pro-vitamin A in the diet. Tomato (Solanum lycopersicum), as one of the most frequently consumed vegetables, provides a model for improving dietary β-carotene. High β-carotene is imparted by alleles of the fruit specific β-cyclase gene, Beta (B). Alleles of B from three different sources were introgressed into a grape-cherry tomato, Tainan (PI 647556). These sources are Jaune Flamme and Purdue 89-28-1, both derived from green-fruited species. The variety 97L97, a USDA release with B from S. galapagense was also used. Alleles were sequenced to develop molecular markers for seedling selection. BC1 and BC2 populations were genotyped for the B allele from each of the exotic sources. Background selection was applied on the BC1 plants using polymorphic insertion-deletion markers located on chromosome two and eleven. BC2 populations were screened with 24 single nucleotide polymorphisms (SNPs) distributed across the genome. The application of background genotyping facilitated the identification and selection of BC2 individuals with the equivalent recurrent parent genome expected in BC3 to BC5 plants. Evaluation of fruit quality was conducted in two growing seasons involving BC1S1 and BC2S1 generations, with quantitative data collected for carotenoids, soluble solids, titratable acidity, fruit shape and size, and sensory attributes as measured by trained panelists. Differences were identified between progeny with the Tainan, 97L97, Purdue 89-28-1, and Jaune Flammee CYC-B promoter sources on the instrumentally measured traits. The sensory attributes measured were for fruit aroma, flavor, and texture. Panelists detected differences in flavor and texture attributes that depended on the source of the B allele. These analyses helped us determine which source of high β-carotene is most useful in developing a quality grape-cherry tomato.