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As a drastic environmental change, metal pollution may promote the rapid evolution of genetic adaptations contributing to metal tolerance. In Arabidopsis halleri, genetic bases of zinc (Zn) and cadmium (Cd) tolerance have been uncovered only in a metallicolous accession, although tolerance is species-wide. The genetic determinants of Zn and Cd tolerance in a nonmetallicolous accession were thus investigated for the first time., The genetic architecture of tolerance was investigated in a nonmetallicolous population ( SK2) by using first backcross progeny obtained from crosses between SK2 and Arabidopsis lyrata petraea, a nonmetallophyte species., Only one significant and common quantitative trait locus ( QTL) region was identified explaining 22.6% and 31.2% of the phenotypic variation for Zn and Cd tolerance, respectively. This QTL co-localized with HEAVY METAL ATPASE 4 (Ah HMA4) , which was previously validated as a determinant of Zn and Cd tolerance in a metallicolous accession. Triplication and high expression of HMA4 were confirmed in SK2. In contrast, gene duplication and high expression of METAL TOLERANT PROTEIN 1A ( MTP1A), which was previously associated with Zn tolerance in a metallicolous accession, were not observed in SK2., Overall, the results support the role of HMA4 in tolerance capacities of A. halleri that may have pre-existed in nonmetallicolous populations before colonization of metal-polluted habitats. Preadaptation to metal-contaminated sites is thus discussed. [ABSTRACT FROM AUTHOR]

Pollution by heavy metals is one of the strongest environmental constraints in human-altered environments that only a handful of species can cope with. Identifying the genes conferring to those species the ability to grow in polluted areas is a first step towards a global understanding of the evolutionary processes involved and will eventually improve phytoremediation practices. We used a genome-scan approach to detect loci under divergent selection among four populations of Arabidopsis halleri growing on either polluted or nonpolluted habitats. Based on a high density of amplified fragment length polymorphism (AFLP) markers (820 AFLP markers, i.e. ~1 marker per 0.3 Mb), evidence for selection was found for some markers in every sampled population. Four loci departed from neutrality in both metallicolous populations and thus constitute high-quality candidates for general adaptation to pollution. Interestingly, some candidates differed between the two metallicolous populations, suggesting the possibility that different loci may be involved in adaptation in the different metallicolous populations. [ABSTRACT FROM AUTHOR]

The article discusses about analysis of cadmium tolerance trait in Arabidopsis halleri.

The article discusses the cadmium tolerance and accumulation in the hyperacccumulators including Noccaea caerulescens and Arabidopsis halleri, the later seemed to show more tolerance towards Cd and a cross between A. halleri and a non tolerant relative was found with additional genes.

Genome scans based on anonymous Amplified Fragment Length Polymorphism (AFLP) markers scattered throughout the genome are becoming an increasingly popular approach to study the genetic basis of adaptation and speciation in natural populations. A shortcoming of this approach is that despite its efficiency to detect signatures of selection, it can hardly help pinpoint the specific genomic region(s), gene(s), or mutation(s) targeted by selection. Here, we present two methods to be undertaken after performing an AFLP-based genome scan to easily obtain the sequences of AFLP loci detected as outliers by population genomics approaches. The first one is based on the gel excision of the target AFLP fragment, after simplification of the AFLP fingerprint and separation of the fragments by migration. The second one is a combination of classical AFLP protocol and 454 pyrosequencing.