Intra-specific differences in mineral element composition in the Ni-hyperaccumulator Alyssum bertolonii: A survey of populations in nature

The patterns of variability in shoot metal concentrations within and among different populations of the serpentine endemic nickelhyperaccumulator Alyssum bertolonii were evaluated and the relationship between plant element concentrations and both soil metal concentrations and genetic diversity was investigated. Metal concentration was determined in 180 plants and in the relative soils from nine populations of A. bertolonii sampled on nine serpentine outcrops of Tuscany covering the whole distribution area of the species. The results indicated a high heterogeneity of metal concentration among soils and populations and a positive correlation for nickel in plants and soils. Moreover, an evident relationship between Ni concentration heterogeneity and genetic differentiation was found. Genetic diversity also correlated with the Ni variability of soils. In conclusion this field survey highlighted the large extent of polymorphism associated with Ni concentration of A. bertolonii probably due to both soil properties and genetic basis. These data should be taken into consideration for careful management of plant germplasm with a view to conserving and exploiting the hyperaccumulating capacity.