HOMOLOGOUS SUCROSE SYNTHASE GENES IN BARLEY (HORDEUM-VULGARE) ARE LOCATED IN CHROMOSOMES 7H (SYN-1) AND 2H - EVIDENCE FOR A GENE TRANSLOCATION

The chromosomal location of the two types of sucrose synthase genes, Ss1 and Ss2, has been investigated in barley by Southern blot analysis of wheat- barley addition lines using non-cross-hybridizing-specific probes corresponding to the C-terminal regions of their respective cDNA clones (congruent-to 250 bp). The Ss1 gene. whose cDNA of 2,667 bp has been entirely sequenced, is located in the beta-arm of chromosome 7H (syn. 1), while that corresponding to the homologous Ss2 is in the short arm of 2H, suggesting the existence of a translocation event between these two chromosomes in cultivated barley after an initial gene duplication and divergent evolution.