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Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/3/1999 Publication Date: N/A Citation: N/A Interpretive Summary: A number of mutants have been described in tomato which influence fruit pigmentation. The Beta (B) mutant increases levels of the orange pigment beta-carotene at the expense of the red pigment lycopene. Two approaches were used to identify molecular markers linked to B and Mo-B. These included: 1) analysis of near isogenic lines (NILs) unique for B and 2) bulked segregant analysis (BSA) of a population comprised of individuals segregating for B. For BSA, DNA from high beta-carotene individuals and DNA from low beta-carotene individuals was combined to create two bulked DNA samples. Red- and orange-fruited NILs and bulks of red- and orange fruited individuals from a segregating population were evaluated using randomly amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) analyses. Two RAPD markers linked to B were identified using BSA and one AFLP marker linked to Mo-B was identified using the NILs. The results are beneficial to scientists conducting basic and applied research with tomato, as well as other crop commodities, wherein pigment composition influences product quality. Technical Abstract: The Beta (B) locus in tomato increases fruit B-carotene content at the expense of lycopene, resulting in orange pigmented fruit. Expression of B is influenced by the beta modifier (Mo-B) gene which segregates independently of B. RAPD and AFLP analyses were performed using near isogenic lines (NILs) unique for B, and bulked segregant analysis (BSA) of a L. esculentum x L. cheesmanii derived F2 population segregating for B. Using 1018 random primers and 64 primer pairs, polymorphic RAPD and AFLP products were identified which distinguished the NILs and the two bulked DNA samples constructed for BSA. A single 100 bp AFLP amplification product (E-ACA/M-CTG-100) which distinguished the NILs cosegregated with Mo-B and was demonstrated to be tightly linked to the locus. E-ACA/M-CTG 100 exhibited a recombination frequency of 1.7% in the F-2 progeny derived from an initial cross between the isolines. Two RAPD products (OPAR18-1100, UBC792-830) of 1100 bp and 830 bp were polymorphic between orange- and red-fruited bulks constructed from F-2 individuals in the L. esculentum and L. cheesmanii mating series. OPAR18-1100 and UBC792-830 displayed recombination frequencies of 4.2% and 7.6% in F-2 progeny. |
