Genetic variation and quantitative trait loci mapping of resistance to aluminum toxicity in common bean (phaseolus vulgaris l.)

Abstract

Aluminum (Al) toxicity in acidic soils is a major constraint to common bean (Phaseolus vulgaris) production. The genetic architecture of Al toxicity resistance in common bean is not well understood. The objective of this study was to identify the quantitative trait loci (QTL) for resistance to aluminum toxicity in a mapping population of 150 F4:8 recombinant inbred lines (RILs) derived from parents Solwezi and AO-1012-29-3-3A. The parent, Solwezi is resistant to Al toxicity compared to AO-1012-29-3-3A. The RILs and their parents were evaluated for resistance to Al toxicity in a hydroponic system that had two nutrient solutions with 0 M Al (control solution) or 15 M Al concentration (Al stress solution). Primary traits including root length (RL), root dry weight (RDW), and shoot dry weight (SDW) were measured. Also, secondary traits including percentage reductions in RL, RDW and SDW were calculated from their respective primary traits. The RILs were genotyped using 5393 SNP markers and QTLs identified using Composite Interval Mapping. A total of Eight QTLs for Al toxicity resistance were identified on chromosomes Pv02, Pv04, Pv05, Pv06, Pv07, Pv09 and Pv10. The R2 values for these nine QTL ranged from 7.6% to 14.7%. The Al-toxicity resistance QTL RL10.1 on Pv10 explained 10% of the genetic variation in RL and the Al-resistant parent Solwezi contributed the positive allele. The QTL RL10.1 overlapped with the QTL RDW10.1 identified using RDW. Another Al-resistance QTL RL.6.1 with R2 of 10% was identified on Pv06 using percentage reduction in RL. The genetic architecture of Al resistance in Solwezi and AO-1012-29-3-3A population is polygenic with additive action.