PR‐10 protein is induced by copper stress in roots and leaves of a Cu/Zn tolerant clone of birch, <i>Betula pendula</i>

Abstract

The response of a Cu‐ and Zn‐tolerant birch ( Betula pendula ) clone to copper stress was investigated. The plants were exposed to control and EC50 concentrations of Cu (0·3 and 30 μ M CuSO 4 , respectively) for 7 d in hydroponic culture. Total proteins were extracted from the roots and leaves and separated by two‐dimensional polyacrylamide gel electrophoresis. The differences in protein patterns on silver‐ or Coomassie‐stained gels were analysed. The most apparent quantitative difference was the increase in the amount of a 17 kDa polypeptide caused by Cu stress in both roots and leaves. The protein was identified as Bet v 1‐Sc3 (according to the current nomenclature PR‐10c) using N‐terminal amino acid sequencing and on‐line high‐performance liquid chromatography/electrospray ionization/ion trap mass spectrometry. The present results indicate that PR‐10 is not only activated by pathogens but also by excessive amounts of copper ions. PR‐10 proteins in birch have been reported earlier not to be induced by Ag, Li or Cd in birch suspension culture, but Cu has not been previously tested.