Cerium negatively impacts the nutritional status in rapeseed

Cerium (Ce) has been reported to be both beneficial and harmful to plants. This contradiction deserves explanation in the light of increased anthropogenic release of Ce in the environment. Ce tolerance and accumulation were evaluated in hydroponically cultivated Brassica napus L. (rapeseed). Ce and other nutrient concentrations were measured with increasing Ce concentration in the nutrient solution. Moreover, Ce and calcium(Ca) accumulationwere evaluated at different Ca and Ce concentrations in nutrient solution and a Michaelis-Menten type inhibition model considering Ce and Ca competition was tested. Plants were also sprayed with Ce solution in Ca-deficient media. Ce decreased the growth and root function,which affected shoot nutritional status. Calciumwas the most severely inhibited nutrient in both roots and shoots. High Ca concentrations in the nutrient solution inhibited Ce accumulation in a non-competitive way. Moreover, phosphorus (P) precipitated Ce inside root cells. Ce spraying did not alleviate Ca deficiency symptoms and the results were critically compared to the available literature

Variation in heavy metal accumulation and genetic diversity at a regional scale among metallicolous and non-metallicolous populations of the facultative metallophyte Biscutella laevigata subsp. laevigata.

Biscutella laevigata is a facultative metallophyte, with populations on non-metalliferous and metalliferous soils. Some of its metallicolous populations have been shown to hyperaccumulate thallium or lead in nature. Only Tl hyperaccumulation has been experimentally confirmed. We aimed to compare the patterns of metal (hyper)accumulation and genetic diversity among populations of B. laevigata subsp. laevigata in NE Italy. None of the populations exhibited foliar hyperaccumulation of Cu, Zn, or Pb. The root-to-shoot accumulation rates for these metals were unchanged or decreased rather than enhanced in the metallicolous populations, in comparison with the non-metallicolous ones. Hyperaccumulation of Tl was confined to the population of the Cave del Predil mine. This population was genetically very distinct from the others, as demonstrated by AFLP-based cluster analysis. The two other mine populations did not surpass the threshold for Tl hyperaccumulation, but showed enhanced foliar Tl concentrations and root-to-shoot translocation rates, in comparison with the non-metallicolous populations. Genetic analysis suggested that adaptation to metalliferous soil must have been independently evolved in the metallicolous populations. \ua9 2015, Taylor & Francis Group, LLC