The genetic basis of zinc tolerance in the metallophyte Arabidopsis halleri ssp. halleri (Brassicaceae): an analysis of quantitative trait loci
Glenda Willems 1, Dörthe Dräger 2, Mikael Courbot 3, Cécile Godé 1, Nathalie Verbruggen 3 and Pierre Saumitou-Laprade 1*
1 Laboratoire de Génétique et Evolution des Populations Végétales
2 Max Planck Institute of Molecular Plant Physiology
3 Laboratoire de Physiologie et de Génétique Moléculaire des Plantes, ULB
* To whom correspondence should be addressed. E-mail: pierre.saumitou{at}univ-lille1.fr.
Submitted on August 8, 2006
Revised on October 12, 2006
Accepted on 22 February 2007
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Abstract |
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The species Arabidopsis halleri, an emerging model for the study of heavy metal tolerance and accumulation in plants, has evolved a high level of constitutive zinc tolerance. Mapping of quantitative trait loci (QTL) was used to investigate the genetic architecture of zinc tolerance in this species. A first generation backcross progeny of A. halleri ssp. halleri from a highly contaminated industrial site and its non-tolerant relative A. lyrata ssp. petraea was produced and used for QTL mapping of zinc tolerance. A genetic map covering most of the A. halleri genome was constructed using 85 markers. Among these markers, 65 were anchored in A. thaliana and revealed high synteny with other Arabidopsis genomes. Three QTLs of comparable magnitude on three different linkage groups were identified. At all QTL positions zinc tolerance was enhanced by A. halleri alleles, indicating directional selection for higher zinc tolerance in this species. The two-LOD support intervals associated with these QTLs cover 24 cM, 4 cM, and 13 cM. The importance of each of these three regions is emphasized by their co-localisation with HMA4, MTP1-A and MTP1-B respectively, three genes well known to be involved in metal homeostasis and tolerance in plants.
Key Words:
A. thaliana wild relatives, adaptive walk, heavy metal, interspecific cross, sequence-based markers anchored in A. thaliana
