Roles of a Putative Voltage-Gated Ca²⁺ Channel, OsTPC1, in Fungal Elicitor-Induced Defense Responses in Rice Cultured Cells.

Abstract

Spatiotemporal patterns of cytosolic [Ca²⁺] play a pivotal role as a second messenger in various signaling pathways. However the molecular bases of Ca²⁺ influx and its regulation remain largely unknown. We identified a putative voltage-gated Ca²⁺-permeable channel, OsTPC1, in rice and established its overexpressors as well as its retrotransposon-insertional functional knockout mutants (Ostpc1). OsTPC1 has been suggested to play a role in the regulation of defense responses including activation of a MAP kinase and hypersensitive cell death induced by a xylanase elicitor, TvX in rice cells (Kurusu et al. Plant J. 2005). We here established transgenic cell lines stably expressing apoaequorin and analyzed TvX elicitor-induced cytosolic [Ca²⁺] changes in the wild type and Ostpc1 cells. Moreover, TvX-induced gene expression pattern was compared between the wild type and Ostpc1 cells by oligomicroarray transcriptome analyses. Possible physiological roles of OsTPC1 in elicitor-induced defense responses will be discussed.