Presenter: Eka Sari
Advisors: Dr. David Francis, Dr. Leah McHale, and Dr. Joseph Scheerens
Proposal Type: MS Proposal
Title of Presentation: Improving pro-vitamin A level by introgression of lycopene β-cyclase alleles into cherry tomato selected for consumer preference
Abstract: A deficiency in the micronutrient Vitamin A is common among women and children in low- and middle-income countries. According to data collected by the United Nations International Children’s Emergency Fund (UNICEF) between 1995 and 2005, one in every three pre-school aged children are deficient in vitamin A due to inadequate dietary intake. Beta-carotene is one of the carotenoid compounds from plants that supplies the most reliable source of pro-vitamin A in the diet. Tomato, as one of the highest consumed vegetables, provides an excellent source of dietary beta-carotene. Significant natural variation for beta-carotene levels exist in tomato, making it a promising target for genetic improvement through introgression. Breeders have invested considerable effort creating inbred lines and cultivars containing high beta-carotene. Previous studies suggested that the chromoplast-specific cyc-B gene is responsible for enhancing beta-carotene content in tomato. The gene is located on chromosome 6 and the high beta-carotene phenotype is conferred by mutations in the promoter. Previous studies showed that the high beta-carotene trait could be transferred to a processing tomato genetic background. In the course of my MS research I aim to create genetic resources in a cherry tomato background, Tainan (PI 647556), by introgressing the B allele from three promoter sources including Jaune Flammee, Purdue 89-28-1, and OH97L97. The promoter of Tainan was sequenced using three overlapping primer sets. Analysis of this sequence with previously characterized promoter sources revealed novel polymorphisms. My principal objective is to create genetic resources in a high-sugar cherry tomato that will be attractive to consumers as a source of fresh and/or dried fruit. Analysis of the selections will focus on consumer acceptance. The specific objectives of this project are: 1) Compare the sequence of the Tainan cyc-B promoter to other known sequences; 2) develop a marker assisted backcross strategy to select for high beta-carotene cherry tomatoes; 3) evaluate BC2S1 (selected with the genetic equivalent of BC3S1 to BC4S1) progeny for consumer quality. Quality assessment will include fruit size, fruit weight, fruit shape, carotenoid content, fruit soluble solid content, sugar content (glucose/fructose ratio), titratable acidity, and organoleptic characteristics.