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

• Metallicolous and nonmetallicolous populations of Silene paradoxa were compared.
• Phytoalexin production after PAMP exposition was investigated.
• Copper tolerant population grown in presence of copper over-produced phytoalexins.
• A differential involvement of MAPKs was proposed.

This work was performed to evaluate if metal adaptation can affect the response to biotic stress in higher plants. Three populations of Silene paradoxa, from a noncontaminated soil, a serpentine soil and a copper mine soil respectively, were cultivated in the presence/absence of nickel or copper and then were exposed to pathogen-associated molecular patterns (PAMP). In particular, the non-catalytic fungal protein cerato-platanin, secreted by the parasitic Ascomycete Ceratocystis platani, was used, because of its well 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 in the presence of copper, suggesting that, in particular cases, the adaptation to metalliferous environments can effectively affect plant response to biotic stress. Nevertheless, this supposition cannot be generalized to all the types of metalliferous environments and of metals studied; however, this work can be considered one of the first example of positive interaction between abiotic and biotic stimuli.