A Quantitative Trait Loci Analysis of Zinc Hyperaccumulation in Arabidopsis Halleri

• The mechanisms of metal hyperaccumulation are still not understood, so we conducted a quantitative trait locus (QTL) analysis of zinc (Zn) hyperaccumulation in
Arabidopsis halleri, in a cross between this and its sister species, A. petraea, in order to determine the number and approximate location of the genomic regions significantly contributing to this adaptation.
• An F2 cross between the two species was made, and the leaf Zn concentration of 92 individuals was measured at both low (10 μM) and high (100 μM) Zn concentrations.
Twenty-five markers were established that were distributed on all of the eight chromosomes.
• Mapping of the markers established that they were essentially collinear with previous studies. QTLs exceeding a logarithm to the base 10 of the odds (LOD) value of 3
were found on chromosomes 4 (low Zn), 6 (high Zn) and 7 both high and low Zn). Evidence for a QTL on chromosome 3 (low Zn) was also found.
• This analysis validates a previously used method of QTL analysis, based on microarray analysis of segregating families. Genes that have altered during the evolution of this character should also be QTL: this analysis calls into question a number of candidate genes from consideration as such primary genes because they do not appear to be
associated with QTLs.