Expression of a truncated tobacco NtCBP4 channel in transgenic plants and disruption of the homologous Arabidopsis CNGC1 gene confer Pb2+ tolerance

• Main Authors: Sunkar , Ramanjulu (Weizmann Institute of Science, Rehovot(Israël). Department of Plant Sciences), Kaplan , Boaz (Weizmann Institute of Science, Rehovot (Israël). Department of Plant Sciences), Bouche , Nicolas (INRA , Versailles (France). UMR 1318 Institut Jean-Pierre BOURGIN), Arazi , Tzahi (Weizmann Institute of Science, Rehovot(Israël). Department of Plant Sciences), Dolev , Dvora (Weizmann Institute of Science, Rehovot(Israël). Department of Plant Sciences), Talke , Ina N. (University of York, York(Royaume Uni). The Plant Laboratory, Department of Biology), Maathuis , Frans J.M. (University of York, York(Royaume Uni). The Plant Laboratory, Department of Biology), Sanders , Dale (University of York, York(Royaume Uni). The Plant Laboratory, Department of Biology), Bouchez , David (INRA , Versailles (France). UMR 1318 Institut Jean-Pierre BOURGIN), Fromm , Hillel (auteur de correspondance) (Weizmann Institute of ScienceUniversity of Leeds, Rehovot Leeds(Royaume Uni). Department of Plant Sciences Centre for Plant Sciences, Leeds Institute for Biotechnology and Agriculture (LIBA), School of Biology)
• Format: Publication
• Language: English
• Published: 2000
• Subjects: calcium; cyclic nucleotides; heavy metals; ion channel; knockout mutant; T-DNA

Recently we reported on a plasma membrane tobacco protein (designated NtCBP4) that binds calmodulin. When overexpressed in transgenic plants, NtCBP4 confers Pb2+ hypersensitivity associated with enhanced accumulation of this toxic metal. To further investigate possible modulation of Pb2+ tolerance in plants, we prepared transgenic plants that express a truncated version of this protein (designated NtCBP4 DeltaC) from which its C-terminal, with the calmodulin-binding domain and part of the putative cyclic nucleotide-binding domain, was removed. In contrast to the phenotype of transgenic plants expressing the full-length gene, transgenic plants expressing the truncated gene showed improved tolerance to Pb2+, in addition to attenuated accumulation of this metal. Furthermore, disruption by T-DNA insertion mutagenesis of the Arabidopsis CNGC1 gene, which encodes a homologous protein, also conferred Pb2+ tolerance. We suggest that NtCBP4 and AtCNGC1 are components of a transport pathway responsible for Pb2+ entry into plant cells.