Brief communication. Assignment of the Fr3 locus to soybean linkage group 9

A study was conducted to determine the linkage relationship between the loci Fr3 (root fluorescence) and Ap (acid phosphatase) in the soybean [Glycine max (L.) Merr.], as well as to ascertain the linkage relationship of Fr3 with two other loci in the soybean classical linkage group 9. Exact plant-to-plant reciprocal crosses were made between near-isogenic line Hark-Fr3 and near-isogenic line Clark-ti(Kunitz trypsin inhibitor null) and Hark-Fr3 with cultivar Norredo. F2 segregation data, for the Fr3-Ap gene pair from reciprocal crosses of Hark-Fr3 X Clark-ti, gave a recombination value of 4.51 +/- 0.55 with 1464 F2 plants. However, reciprocal crosses of Hark-Fr3 X Norredo gave a recombination value of 10.25 +/- 0.83 with 1344 F2 plants. Finally, the gene order of Fr3-Ap-Ti-Lap1 (leucine aminopeptidase) was established for classical linkage group 9 in soybean.