Genetic variation and quantitative trait loci mapping of resistance to aluminum toxicity in common bean (phaseolus vulgaris l.)
Date
2020
Authors
Njobvu, Justin
Journal Title
Journal ISSN
Volume Title
Publisher
The University of Zambia
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.
Description
Thesis
Keywords
Genetic variation--Bean production