Uncovering the physiology and distribution of thallium in Tl-hyperaccumulating and Tl-sensitive populations of Biscutella laevigata L

2024

Article référencé dans le Web of Science WOS:001336670100001

Salinitro M., Isnard Sandrine, Brueckner D., Spiers K. M., Aarts M. G. M., Remigio A. C., van der Ent A.

Annals of Botany, 2024, 134, p. 803-814 ISSN 0305-7364

Thallium (Tl) is extremely toxic to all life forms and is an emerging pollutant. Plants in the Brassicaceae family, including edible crops, have an enhanced capacity for Tl accumulation, even from soils with low thallium concentration. The most extreme Tl hyperaccumulator is Biscutella laevigata, capable of attaining >32 000 mu g Tl g(-1) dry weight (DW) in its leaves. center dot Methods Biscutella laevigata from a non-metallicolous accession (Feltre, Italy) and a metallicolous accession (Les Malines, France) were subjected to a dosing experiment in hydroponics (0, 5 and 30 mu m Tl), followed by synchrotron-based micro-X-ray fluorescence analysis to elucidate tissue- and cellular-level Tl distribution. center dot Key Results Flow cytometric data on the two accessions showed that the Feltre accession has a genome size twice of that of the Les Malines accession (256 and 125 pg per 2C, respectively), suggesting that they are phylogenetically distant populations. The Feltre accession did not accumulate Tl (125 mu g Tl g(-1) DW on average in leaves) at the 5 mu m Tl dose level, whereas the Les Malines accession had a mean of 1750 mu g Tl g(-1) DW, with peaks of 24 130 mu g Tl g(-1) DW, at the 30 mu m Tl dose level. At 30 mu m Tl, the non-metallicolous accession did not grow, and at 5 mu m Tl it showed reduced biomass compared with the metallicolous one. In the Les Malines accession, the synchrotron-based micro-X-ray fluorescence analysis revealed that Tl was localized in the vacuoles of epidermal cells, especially underneath trichomes and in trichome basal cells. Thallium also occurred in solid crystalline deposits (3-5 mu m in size, similar to 40 wt% Tl) that were found mainly in foliar margins and under trichome bases. center dot Conclusions Biscutella laevigata is an attractive model for studying Tl hypertolerance and hyperaccumulation on account of the extreme expression of this trait and its marked intraspecific variability.

Sciences fondamentales / Techniques d'analyse et de recherche [020] ; Pollution [038] ; Sciences du monde végétal [076]

FRANCE

Fonds IRD [F B010092006]

fdi:010092006