MATERIAL AND GENIC CYTOPLASMIC DIFFERENCES IN RECIPROCALLY CROSSED TOMATOES

Abstract

A series of generations was synthesized to study reciprocal differences for three developmental periods, early yield and fruit size in tomatoes. A small fruited early cultivar, Johnny Jumpup, and a large fruited later cultivar, Bounty, were used as parents. From individual cloned parent plants and their reciprocal F1's, all possible first backcross and F2lines were derived. Maternal effects were demonstrated in BC1lines for each of three periods and for early yield. Increased earliness was expressed rather uniformly by BC1lines derived from F1females over those derived from either of the parental females.Genic-cytoplasmic differences were demonstrated in BC1lines for each of three development periods and for early yield. Earliness for each of these characters was associated with lines having common cytoplasmic-recurrent parentage, over those not having common such parentage. Magnitudinally, the differences were more closely associated with the Johnny Jumpup cytoplasmic-Bounty recurrent parent line than with the converse.Similarity in direction and magnitude of differences in F1and F2lines indicated that matroclinous reciprocal F1differences for the development periods and early yield were persistent through the F2. Therefore, the association of cytoplasm with an F1genotype, rather than maternal effects, appears to be the primary cause of differences for earliness in F1's resulting from reciprocal crosses. The larger fruited, earlier parent should be used as the female in F1hybrid seed production, if other considerations do not predominate.