Functional characterization of a calcium-permeable cation channel in plants

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To counter abiotic and biotic stress, intricate signalling networks that govern the initation of defense and resistance responses have evolved in plants. The understanding of the central elements of stimulus-response coupling is vital for a targeted improvement of crops. A very early response of plants to most abiotic and biotic stress factors is an elevation of cytosolic free calcium ([Ca2+]cyt), which is mediated by the activation of Ca2+-permeable ion channels. Our knowledge on the molecular identity of those channel proteins is still very rudimentary, which presents a major obstacle in our understanding of signalling und stress responses in plants. The Ca2+-permeable Two Pore Channel 1 has previously been identified in the vacuolar membrane and initial analyses suggested its involvement in Ca2+-dependent processes. This project aims to elucidate the role of this channel in stimulus responses and to analyse the circumstances under which this channel is required in the generation of [Ca2+]cyt signals. Furthermore, the mode of negative feedback regulation of the channel and its activation by second messenger molecules will be analysed by a combination of electrophysiological and cell biological approaches, including [Ca2+]cyt imaging using aequorin and Yellow Cameleon techniques. The knowledge gained from those experiments will aid in our understanding of Ca2+ homeostasis and signalling, which may eventually be used in the design of crops with more efficient stress responses.