Production of reactive oxygen species (ROS) and
hypersensitive cell death are characteristic features of the induced pathogen resistance in plants.
Ca2+-signals preceding the pathogen-induced cell death have been shown to involve Ca2+
entry via the plasma membrane. We therefore analyzed Ca2+-signals and Ca2+-channels
involved in the responses to pathogen attack and ROS. For this purpose, we used the Ca2+-reporter
protein aequorin as well as the combined single-cell fluorescence imaging and patch clamp technique. Moreover,
we compared Ca2+-channel activities in Arabidopsis wild type and the pathogen-resistant
mutant, dnd1 (Yu et al., 1998) . Cellular responses to ROS were significantly reduced in
dnd1. Since DND1 was shown to encode the Ca2+-permeable and cyclic
nucleotide-gated ion channel CNGC2 (Clough et al., 2000) , this channel represents a
possible candidate for H2O2-dependent Ca2+ entry via the plasma membrane. We
thoroughly examined this hypothesis and will present recent results on how CNGC2 transmits cellular responses
to reactive oxygen species, a step essential for the control of hypersensitive cell death.
- Clough SJ, Fengler KA, Yu IC, Lippok B, Smith RK, Jr., Bent AF (2000) The Arabidopsis
dnd1 "defense, no death" gene encodes a mutated cyclic nucleotide-gated ion channel. Proc. Natl.
Acad. Sci. USA 97: 9323-9328
- Yu IC, Parker J, Bent AF (1998) Gene-for-gene disease
resistance without the hypersensitive response in Arabidopsis dnd1 mutant. Proc. Natl. Acad. Sci. USA 23: 7824