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

摘要

Bulked segregant analysis (BSA) was used to identify molecular markers linked to determinate growth habit (fin gene) in a F₂ population derived from the cross Andecha (FinFin) × BRB130 (finfin). Fourteen RAPD markers and one microsatellite (BMd45-AIA) were linked to the fin gene when tested on the entire population. The SCAR, SI19b, designed from the RAPD marker OI19₃₈₅ (linked to the fin 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 fin 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 differ in 4 single base pairs and in a deletion of 30 bp, whereas the two alleles of marker BMd45-AIA differ in a single base pair and in a deletion of 38 bp. In both cases, specific 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 fin gene and the molecular markers SI19b and BMd45-AIA was investigated in two other segregating populations: a F₂ population derived from the cross MDRK (finfin) × V225 (FinFin), and a RIL population derived from the cross Xana (finfin) × Cornell 49242 (FinFin). SI19b was polymorphic (codominant segregation) only in the RIL population Xana × Cornell 49242, and showed a weak linkage with the fin gene (26.9 cM; LOD = 2.34). BMd45-AIA showed codominant segregation in both populations, and was tightly linked to the fin 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.