Arabidopsis halleri shows hyperbioindicator behaviour for Pb and leaf Pb accumulation spatially separated from Zn

Abstract

Summary Lead (Pb) ranks among the most problematic environmental pollutants. Background contamination of soils is nearly ubiquitous, yet plant Pb accumulation is barely understood. In a survey covering 165 European populations of the metallophyte Arabidopsis halleri, several field samples had indicated Pb hyperaccumulation, offering a chance to dissect plant Pb accumulation. Accumulation of Pb was analysed in A. halleri individuals from contrasting habitats under controlled conditions to rule out aerial deposition as a source of apparent Pb accumulation. Several elemental imaging techniques were employed to study the spatial distribution and ligand environment of Pb. Regardless of genetic background, A. halleri individuals showed higher shoot Pb accumulation than A. thaliana. However, dose–response curves revealed indicator rather than hyperaccumulator behaviour. Xylem sap data and elemental imaging unequivocally demonstrated the in planta mobility of Pb. Highest Pb concentrations were found in epidermal and vascular tissues. Distribution of Pb was distinct from that of the hyperaccumulated metal zinc. Most Pb was bound by oxygen ligands in bidentate coordination. A. halleri accumulates Pb whenever soil conditions render Pb phytoavailable. Considerable Pb accumulation under such circumstances, even in leaves of A. thaliana, strongly suggests that Pb can enter food webs and may pose a food safety risk.

The two copies of the zinc and cadmiumZIP6transporter ofArabidopsis hallerihave distinct effects on cadmium tolerance

“…Next, the two AhZIP6 ‐suppressed lines and the two controls were grown in native A. halleri soil from the metalliferous site in Bestwig (for GPS and soil data, see Höreth et al, 2020) and in the phenotyping soil used for the characterization of field‐collected individuals of European A. halleri populations (Stein et al, 2017). Growth as determined by shoot biomass was comparable between the metalliferous site soil and the phenotyping soil, indicating that the metal‐contaminated soil did not exert toxic effects on the plants.…”

Different strategies of Cd tolerance and accumulation in Arabidopsis halleri and Arabidopsis arenosa

“…As a result, relatively low concentrations of Pb were found in plants on the metalliferous site, particularly in the leaves, because of the low TF for Pb (Figure 1h). Zn, which suggests the evolution of different accumulation pathways and strategies (Höreth et al, 2020). Therefore, we cannot exclude the fact that Pb affects plant growth and development on the metalliferous site in Piekary Śląskie and further research is necessary.…”

Translocation of Foliar Absorbed Zn in Sunflower (Helianthus annuus) Leaves

“…Although the foliar application of Zn caused a toxic response, this stress was only temporary—the stress-relevant GO terms which were upregulated rapidly after Zn application (L1) were subsequently downregulated after 24 h (L2), while those that were downregulated in L1 were upregulated in L2 ( Supplementary Additional File 3 ). Accordingly, Zn was found mainly in the epidermal layers (including the NGTs) in the first 3 h ( Figure 3 ), with this likely being a detoxification strategy ( Frey et al, 2000 ; Tappero et al, 2007 ; Horeth et al, 2020 ; Li et al, 2021 ). In contrast, after 24 h, much of the Zn had moved to the horizontal BSEs and the veins.…”