Molecular markers linked to the fin gene controlling determinate growth habit in common bean.

Abstract

Bulked segregant analysis (BSA) was used to identify molecular markers linked to determinate growth habit (Wn gene) in a F2 population derived from the cross Andecha (FinFin) £ BRB130 (WnWn). Fourteen RAPD markers and one microsatellite (BMd45-AIA) were linked to the Wn gene when tested on the entire population. The SCAR, SI19b, designed from the RAPD marker OI19385 (linked to the Wn gene at a recombination fraction, RF = 0.14; LOD = 5.29), showed a codominant segregation in the F2 population Andecha £ BRB130 consistent with that of the corresponding RAPD. The microsatellite BMd45-AIA showed a codominant segregation in this population and was also linked to the Wn gene (RF = 0.11; LOD = 10.73). The DNA sequences of markers SI19b and BMd45-AIA present in Andecha and BRB130 were analyzed. The two alleles of marker SI19b diVer in 4 single base pairs and in a deletion of 30 bp, whereas the two alleles of marker BMd45-AIA diVer in a single base pair and in a deletion of 38 bp. In both cases, speciWc short sequences (CTGAAGA for SI19b and ACAGAGAGA for BMd45-AIA) were repeated at the beginning and the end of the deleted segments, suggesting that “looping” structures during replication could have caused these deletions. Linkage between the Wn gene and the molecular markers SI19b and BMd45-AIA was investigated in two other segregating populations: a F2 population derived from the cross MDRK (WnWn) £ V225 (FinFin), and a RIL population derived from the cross Xana (WnWn) £ Cornell 49242 (FinFin). SI19b was polymorphic (codominant segregation) only in the RIL population Xana £ Cornell 49242, and showed a weak linkage with the Wn gene (26.9 cM; LOD = 2.34). BMd45-AIA showed codominant segregation in both populations, and was tightly linked to the Wn gene, at 4.1 cM (LOD = 9.2) in the F2 population MDRK £ V225, and at 3.3 cM (LOD = 16.2) in the RIL population Xana £ Cornell 49242.