Negative feedback regulation of microbe-associated molecular pattern-induced cytosolic Ca2+ transients by protein phosphorylation.

Microbe/pathogen-associated molecular patterns (MAMPs/PAMPs) often induce rises in cytosolic free Ca(2+) concentration ([Ca(2+)](cyt)) and protein phosphorylation. Though they are postulated to play pivotal roles in plant innate immunity, their molecular links and the regulatory mechanisms remain largely unknown. To investigate the regulatory mechanisms for MAMP-induced Ca(2+) mobilization, we have established a transgenic rice (Oryza sativa) cell line stably expressing apoaequorin, and characterized the interrelationship among MAMP-induced changes in [Ca(2+)](cyt), production of reactive oxygen species (ROS) and protein phosphorylation.

Identification of a putative voltage-gated Ca2+ channel as a key regulator of elicitor-induced hypersensitive cell death and mitogen-activated protein kinase activation in rice.

Elicitor-triggered transient membrane potential changes and Ca2+ influx through the plasma membrane are thought to be important during defense signaling in plants. However, the molecular bases for the Ca2+ influx and its regulation remain largely unknown. Here we tested effects of overexpression as well as retrotransposon (Tos17)-insertional mutagenesis of the rice two-pore channel 1 (OsTPC1), a putative voltage-gated Ca(2+)-permeable channel, on a proteinaceous fungal elicitor-induced defense responses in rice cells.