Authors: PoYu Chen KuoTing Lee WenChang Chi Heribert Hirt ChingChun Chang HaoJen Huang
Publish Date: 2008/05/28
Volume: 228, Issue: 3, Pages: 499-
Abstract
Cross tolerance is a phenomenon that occurs when a plant in resisting one form of stress develops a tolerance to another form Pretreatment with nonlethal heat shock has been known to protect cells from metal stress In this study we found that the treatment of rice roots with more than 25 μM of Cu2+ caused cell death However heat shock pretreatment attenuated Cu2+induced cell death The mechanisms of the cross tolerance phenomenon between heat shock and Cu2+ stress were investigated by pretreated rice roots with the protein synthesis inhibitor cycloheximide CHX CHX effectively block heat shock protection suggesting that protection of Cu2+induced cell death by heat shock was dependent on de novo protein synthesis In addition heat pretreatment downregulated ROS production and mitogenactivated protein kinase MAPK activities both of which can be greatly elicited by Cu2+ stress in rice roots Moreover the addition of purified recombinant GST–OsHSP70 fusion proteins inhibited Cu2+enhanced MAPK activities in an in vitro kinase assay Furthermore loss of heat shock protection was observed in Arabidopsis mkk2 and mpk6 but not in mpk3 mutants under Cu2+ stress Taken together these results suggest that the interaction of OsHSP70 with MAPKs may contribute to the cellular protection in rice roots from excessive Cu2+ toxicity
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