Arabidopsis uses Zinc-toxicity as a defence mechanism against the necrotrophic fungus Plectosphaerella cucumerina

Using the X-ray fluorescence technology at the Swiss Light Source synchrotron (SLS of the Paul Scherrer Institute, Switzerland), this study shows that Arabidopsis plants are capable of locally accumulating high concentrations of zinc and manganese in the area in which the entry of the pathogenic fungus Plectosphaerella cucumerina (PcBMM) occurs. In addition, it is evidenced that HMA2 and HMA4 are the transporter proteins involved in the zinc efflux to infected tissues, since mutant plants in these two transporters are not capable of accumulating zinc in response to the pathogen, making those plants more susceptible to the PcBMM fungus. The data obtained show a relevant role of zinc in the resistance of Arabidopsis against the necrotrophic fungus PcBMM. This new defense route would act in parallel to the previously described immunity routes regulated by phytohormones, such as salicylic acid, ethylene or jasmonic acid and its elimination has a direct effect on resistance to pathogens.