Cyclic nucleotide-gated ion channel (CNGC)-mediated signal transduction in plant stress responses

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The long-term goal of our research is to understand cyclic nucleotide-gated channel (CNGC)-mediated signal transduction in plant stress responses, with an emphasis on immunity. CNGCs are one of the largest cation channel families in plants and accumulating evidence suggests their involvement in a wide variety of biological phenomena, such as immunity, gravitropism, thermo-tolerance, and pollen growth, through their calcium (Ca2+) channel function. CNGCs have been suggested to form heterotetramers and interact with signal decoder proteins, such as calmodulin. Ca2+ is a universal second messenger in the eukaryotic signaling pathways that control many phenomena, such as muscle contraction and neuronal transmission in animals. Similarly, Ca2+ plays a central role in signal transduction in plants. Transient changes in cytosolic Ca2+ levels ([Ca2+]cyt) in plants are rapidly induced by diverse stimuli such as abiotic stress (drought, heat, etc.), biotic stresses (pathogen infection, etc.), as well as developmental cues (reproduction, root hair growth, circadian clock). To generate stimulus-specific signals that elicit the appropriate responses, Ca2+ signals must contain unique information. However, despite the importance of Ca2+ signals, our understanding of the generation of stimulus-specific Ca2+ signals remains limited. Even the identity of stress-related Ca2+ channels in plants is still enigmatic due to redundancies and technical challenges in capturing transient Ca2+ signals. In our laboratory, with the support of the previous NSERC DG, we identified CNGCs as key players in plant immunity and have reported that some of them are tightly connected to Ca2+ signals. In the next five years, we will focus on these three aspects: 1. The interplay of CNGCs, Ca2+ and the plant hormone auxin, 2. CNGC interactors and possible signaling complexes and 3. CNGC-mediated intra- and inter-cellular Ca2+ signals in abiotic and biotic stress responses by utilizing genetically encoded Ca2+ sensors. Our overreaching hypothesis is that CNGCs form a signaling complex with ion pumps, receptors, and decoder proteins upon signal perception to generate stimulus-specific temporal signals in response to a wide variety of biological stimuli. Ca2+ signaling is paramount in plant stress responses, yet even fundamental information such as the types of channels, stimuli-specific Ca2+ signatures, and the identity of many downstream signaling components are not clear. The proposed project will aim to provide essential information on plant Ca2+ signaling upon stress perception. In addition, an understanding of plant stress responses is crucial for sustainable food production, especially with current unpredictable climate fluctuations. Our research program will reveal fundamental information to assist in the development of novel methods to protect plants from various stresses.