Dehydration-related changes of peroxidase and polyphenol oxidase activity in fronds of the resurrection fern Asplenium ceterach L.

Abstract

Asplenium ceterach belongs to a group of poikilohydric ferns and it can recover uninjured from an almost completely dehydrated state. In our study, short term dehydration (24h) at four different water potentials, resulted in moderate water loss (partial desiccation) in fern tissue. The main phenolic acids represented in A. ceterach were chlorogenic (CGA) and caffeic acid (CA) and their content decreased during the dehydration process. For the first time, peroxidase (POD) and polyphenol oxidase (PPO) isoforms were determined in the rustyback fern. The results exhibit the presence of numerous anionic POD isoforms, with pI ranging from 4.4 to 5.8, but none of the cationic isoforms was detected. Two PPO isoforms were identified, one anionic with pI 6.3 and one cationic with pI of about 9.0. Short-term dehydration brought about a remarkable increase in POD and PPO activity using CGA as a substrate. Changes in enzyme activity and content of substrates during dehydration may play an important role in the adaptation of the rustyback fern to water deficit, and increase the overall plant resistance to stress conditions.