Quantitative trait loci mapping of resistance to aluminum toxicity in common bean

Aluminum toxicity in acidic soils is a major constraint to common bean (Phaseolus vulgaris L.) production. The objective of this study was to identify quantitative trait loci (QTL) for Al resistance in a population of 150 F4:8 recombinant inbred lines (RILs) derived from parents Solwezi and AO-1012-29-3-3A, which contrasted in resistance to Al. The RILs and their parents were evaluated for Al resistance in a hydroponic system that had two nutrient solutions with either 0 μM (control solution) or 15 μM Al concentration (Al stress solution). Primary traits including root length (RL), root dry weight (RDW), and shoot dry weight (SDW) were measured. Percentage reductions in RL, RDW, and SDW were calculated from their respective primary traits. The RILs were genotyped with 5,398 single nucleotide polymorphisms and QTL identified using composite interval mapping. A total of eight QTL for Al resistance were identified on chromosomes Pv02, Pv04, Pv06, Pv07, Pv09, and Pv10. Variation in Al resistance explained by individual QTL ranged from 7.6 to 14.7%. Aluminum resistance QTL RL10.1 on Pv10 explained 10% of the genetic variation in RL. The QTL RL10.1 overlapped with QTL RDW10.1 identified for RDW in Al stress solution. Another Al resistance QTL RL6.1, which explained 10% of Al resistance variation, was identified on Pv06. The QTL on Pv02 and Pv07 appear to overlap with previously reported QTL for Al resistance. A candidate gene Phvul.007G025900 encoding an Al-activated malate transporter was identified within the QTL RL7.1 The genetic architecture of Al resistance in the Solwezi and AO-1012-29-3-3A population is polygenic with additive action.