Construction of a genetic linkage map of Thlaspi caerulescens and quantitative trait loci analysis of zinc accumulation

Abstract

Summary• Zinc (Zn) hyperaccumulation seems to be a constitutive species-level trait in Thlaspi caerulescens . When compared under conditions of equal Zn availability, considerable variation in the degree of hyperaccumulation is observed among accessions originating from different soil types. This variation offers an excellent opportunity for further dissection of the genetics of this trait.• A T. caerulescens intraspecific cross was made between a plant from a nonmetallicolous accession [Lellingen (LE)], characterized by relatively high Zn accumulation, and a plant from a calamine accession [La Calamine (LC)], characterized by relatively low Zn accumulation.• Zinc accumulation in roots and shoots segregated in the F3 population. This population was used to construct an LE/LC amplified fragment length polymorphism (AFLP)-based genetic linkage map and to map quantitative trait loci (QTL) for Zn accumulation. Two QTL were identified for root Zn accumulation, with the trait-enhancing alleles being derived from each of the parents, and explaining 21.7 and 16.6% of the phenotypic variation observed in the mapping population.• Future development of more markers, based on Arabidopsis orthologous genes localized in the QTL regions, will allow fine-mapping and map-based cloning of the genes underlying the QTL.

QTL analysis of cadmium and zinc accumulation in the heavy metal hyperaccumulator Thlaspi caerulescens

“…The current map T. caerulescens compares very well to the genetic map made for another population using a common parent [e.g., Lellingen (LE) £ LC in Assunção et al 2006], for which a similar total map length and comparable size of the corresponding LGs was observed. A comparison based on AFLP markers with LC speciWc bands showed the same map position in both maps.…”

“…Overdominance is unlikely both for Cd and Zn QTLs. In all cases of interecotypic Thlaspi crosses reported so far, F 1 plants showed accumulation rates that were intermediate between the parents, or dominance was directed toward low accumulation (Frérot et al 2003(Frérot et al , 2005Assunção et al 2006). Epistasis cannot be tested for because we were not able to distinguish between homozygote and heterozygote genotypes for the QTLs in a number of individuals suYcient for statistical anal- ysis.…”

Mapping QTLs for mineral accumulation and shoot dry biomass under different Zn nutritional conditions in Chinese cabbage (Brassica rapa L. ssp. pekinensis)

“…However, genetic studies on mineral content in crops have been limited mainly to seeds, such as for common bean (Beebe et al 2000;Islam et al 2002), rice (Gregorio et al 2000), wheat (Monasterio and Graham 2000), maize (Banziger and Long 2000) and also the model species Arabidopsis thaliana (Vreugdenhil et al 2004). QTLs were also identified for mineral concentrations in leaves for P (Bentsink et al 2003), Cs (Payne et al 2004) and K (Harada and Leigh 2006) in A. thaliana and for Zn in Thlaspi caerulescens (Assunção et al 2006;Deniau et al 2006). These studies have demonstrated the presence of allelic variation affecting mineral accumulation, although the identity of the underlying genes remains unknown.…”

Isolation of Zn-responsive genes from two accessions of the hyperaccumulator plant Thlaspi caerulescens

“…Comparison of T. caerulescens accessions suggests that Zn tolerance, transport and accumulation are subject to independent variation (Assunção et al 2003a, b). Moreover, the Zn accumulation capacity is governed by more than one gene (Assunção et al 2006). Zinc tolerance is dependent on internal Zn sequestration capacity and, to a lesser extent, on reduced Zn accumulation (Assunção et al 2003b).…”