THE INHERITANCE OF CAROTENOID PIGMENT SYSTEMS IN THE TOMATO

Abstract

N the tomato three types of fruit flesh color have long been known. The I red flesh (RRTT) of normal canning tomatoes is due to the presence of major quantities of the pigment lycopene. A minor quantity of beta-carotene is also present, as are traces of certain other carotenoid pigments. Yellowfleshed tomatoes (rrTT) are characterized by the lack of pigment in major quantities. Orange tomatoes (RRtt) of the Jubilee or Tangerine varieties, on the other hand, contain a mixture of carotenoids of which prolycopene and zeta-carotene are the principal components. Recently a new pigment type, orange in color, has been isolated (LINCOLN and PORTER 1950). Unlike the orange Tangerine type, this tomato contains largely beta-carotene with minor quantities of lycopene. LINCOLN and PORTER postulate that in beta-orange tomatoes the shift from red (lycopene) to orange (beta-carotene) depends primarily upon a single gene B which lacks dominance. When the present study was initiated the monohybrid segregations of R/r and of T/t were well established on a visual basis ( MACARTIIUR 1931, 1934). Moreover, considerable analytical information was available concerning the parent pigment types (LEROSEN, WENT and ZECIIMEISTER 1941 ; ZECHMEISTER, LEROSEN, WENT and PAULING 1941 ; LEROSEN and ZECHMEISTER 1942; NASH and ZSCHEILE 1945; PORTER and ZSCHEILE 1946a, 1946b). Crosses between r and t, however, had not been thoroughly analyzed, and crosses involving B and either Y or t had not been reported. The possibility existed that B might be an allele of either Y or t. FLEMING and ~!IYERS (1937) cite correspondence with MACARTHUR in which the latter suggested that crosses involving Tangerine orange (RRtt) and yellow (YYTT) produce a 9 red : 3 yellow : 4 orange (3 orange and 1 light orange) F2 ratio. From their own data, however, these authors suggested that the inheritance was considerably more complicated. Recently JENKINS and MACKINNEY (1951) have confirmed MACARTHUR’S prediction. Moreover, MACKINNEY and JENKINS ( 1949, 1952) have extended the analytical information with regard to parent types and have included an analysis of the segregants involving these two genes. The present work supports the data reported by MACKINNEY and JENKINS with respect to R and T, and in addition extends the analysis to include the gene B.