INHERITANCE OF CAROTENOID DIFFERENCES IN THE TOMATO HYBRID YELLOW x TANGERINE

Abstract

ELLOW varieties of tomatoes have been known since the crop was first Y i n t r o d u c e d into Europe shortly after the discovery of America, and were probably to be found in Mexico before the conquest (JENKINS 1949). HALSTED et al. (1905) reported on the red x yellow hybrid, establishing the fact that the color difference was due to segregation at a single locus, a conclusion that has been confirmed repeatedly by subsequent workers.Presumably, the yellow arose as a mutant from the red, and probably the mutation occurred on several occasions.RICK (private communication) has recently found a yellow mutant in the variety Pearson.The tangerine or orange tomato has a more obscure history.MACARTHUR ( 1934) lists, red fruit flesh ( T ) 'U. tangerine ( t ) in his table to tomato character contrasts (p.124).H e also states, (' The monofactorial inheritance of the characters [listed in the table] has been definitely proven with adequate numbers and suitable tests."H e refers to an earlier paper (1931) which contains data on the segregation of most characters listed in his 1934 paper.However, we found no reference to the tangerine tomato in his 1931 paper.Apparently, MACARTHUR (1934) was the first to study segregation in the yellow x tangerine hybrid, but his report on this hybrid is incidental to a presentation of the linkage relations between various loci, and consists of three brief references.First, " The factor interactions of the two types of dwarfness lead to 12 : 3 : 1 ratios in F2 ; those between the two forms of green stem and the two flesh colors produce 9 : 3 : 4 ratios" (p.125).Secondly, in table I11 (p.128) the crossover value between the yellow and tangerine loci is given as 52.1 t-2.5, which indicates that he made the yellow-tangerine hybrid.Finally, in tables IX and X (p.130) he gives additional crossover data from which he concludes that the tangerine locus is in linkage group VI1 with the two loci, uniform fruit and hairy stem, both of which show independent assortment with yellow in linkage group 11.FLEMING and MYERS ( 1938) through correspondence with MACARTHUR, were able to establish the latter's F2 ratio as 9 red : 3 yellow : 4 orange ( 3 orange and 1 light orange).However, in their own data on the yellow-tangerine hybrid they obtained results which they interpreted in a somewhat more complicated manner.I n backcrosses between the F1 and the parents of the yellow x tangerine hybrid, they obtained the expected 1 : 1 ratios.In Fz, on the other hand, they report 459 red : 134 yellow : 179 orange.The significant excess of reds and deficiencies of yellows and oranges are not in accord with MACARTI-IUR'S hy-