MAPPING THE GA(3)-INSENSITIVE DWARFING GENE CT1 ON CHROMOSOME-7 IN RYE

A gibberellic acid-insensitive dwarfing gene in rye (ct1) was mapped i n an F-2 population on chromosome 7R close to the centromere. Two RFLP markers were found, which flank the gene at distances of 1 and 3 cM, respectively. A total of 11 markers were mapped on 7R of which six clu ster around the centromere and show segregation distortion in the case of the codominant markers. The ctl gene is closely linked to copies o f both alpha-amylase and EmBP, as is the ct2 gene on chromosome 5R. Be cause of the different chromosomal locations of the GA(3)-insensitive dwarfing genes in rye and wheat it is concluded that these genes are n ot homoeologous. This is supported by further differences in their phe notypic and genotypic expressions.