Genome-wide association study elucidates the genetic architecture of manganese tolerance inBrassica napus

Abstract

AbstractBrassica napus(canola) is a significant contributor to the world’s oil production and is cultivated across continents, yet acidic soils with Al3+and Mn2+toxicities limit its production. The genetic determinants underlying acidic soil tolerance in canola are unknown and require to be uncovered for canola breeding and production. Here, through comprehensive phenotyping, whole genome resequencing, and genome-wide association analysis, we identified three QTLs for tolerance to Mn2+toxicity on chromosomes A09, C03, and C09. Allelism tests between four tolerance sources confirmed that at least one locus on A09 controls Mn2+tolerance inB. napus. Integrated analysis of genomic and expression QTL and Mn2+tolerance data reveals thatBnMTP8.A09,in conjunction withBnMATE.C03,BnMTP8.C04andBnMTP8.C08, play a central role in conferring Mn2+tolerance inB. napus. Gene expression analysis revealed a high correlation (R2= 0.74) between Mn2+tolerance and theBnMTP8.A09expression. Yeast complementation assays show thatBnMTP8.A09can complement manganese-hypersensitive yeast mutant strainPMR1Δ and restore Mn2+tolerance to wild-type levels. Inductively coupled plasma mass spectrometry revealed that Mn2+tolerant accessions accumulate less Mn in the shoots compared to Mn2+sensitives, suggesting that theBnMTP8.A09transporter likely sequesters Mn2+into the tonoplast. Taken together, our research unveils the genetic architecture of Mn2+tolerance and identifiesBnMTP8.A09as a major gene imparting tolerance to Mn2+toxicity inB. napus.