The tomato ge locus: linkage relations and geographic distribution of alleles.

RASTICALLY distorted segregation of certain marker genes on chromosome D4 of the tomato (Lycopersicon esculentzrm Mill.) prompted an earlier investigation (RICK 1966) of a series of alleles that effect gamete elimination. Three alleles-Ge", GeC, and GeP-are known at this locus, but gametes are eliminated only in Gec/Gep heterozygotes; both male and female Gee gametes are aborted; the interaction is approximately 95% penetrant. Segregation of linked genes is modified in such heterozygotes, the degree of distrxbance depending on the tightness of the linkage. Preliminary data placed the locus of Ge in the vicinity of fuZ and w-4, possibly within the proximal heterochromatin of chromosome 4 . Studies of the Ge locus were continued in order to (1 ) position its locus more precisely and (2) determine which alleles are present in samples o€ wild and cultivated tomatoes from various geographic areas. The first objective was pursued with hope of learning more precisely what relationship, if any, the locus of Ge might have with heterochromatin and the second to ascertain what light might be shed on the relationships amongst tomato cultivars and between them and related wild species.