Can adaptation to metalliferous environments affect plant response tobiotic stress? Insight from Silene paradoxa L. and phytoalexins.

This work was performed to evaluate if metal adaptation can affect the response to biotic stress in higherplants. Three populations of Silene paradoxa, from a noncontaminated soil, a serpentine soil and a cop-per mine soil respectively, were cultivated in the presence/absence of nickel or copper and then wereexposed to pathogen-associated molecular patterns (PAMP). In particular, the non-catalytic fungal pro-tein cerato-platanin, secreted by the parasitic Ascomycete Ceratocystis platani, was used, because of itswell documented ability to act as a PAMP, and the production of phytoalexins was assayed. Cerato-platanin exposition determined phytoalexin production in a population- and treatment-dependent way.Particularly, an over-production of phytoalexins was recorded for the copper mine population grown inthe presence of copper, suggesting that, in particular cases, the adaptation to metalliferous environmentscan effectively affect plant response to biotic stress. Nevertheless, this supposition cannot be general-ized to all the types of metalliferous environments and of metals studied; however, this work can beconsidered one of the first example of positive interaction between abiotic and biotic stimuli.