The regulation of heterotirmeric G protein signaling by interacting proteins in plants

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Our work is directed toward understanding the basis of plant tolerance to environmental stresses including drought, salt and low temperature stress. We are investigating the fundamental genetic and molecular responses to environmental stress in order to understand the basis of tolerance to stress and develop strategies to improve tolerance to drought and salt toxicity. Unpredictable changes in climatic conditions, including drought and extreme temperatures pose challenging and costly risks to agriculture. Plants have a wide genetic variation for stress tolerance and throughout the history of agriculture there has been genetic selection for improved yield under stress conditions. The need to improve tolerance in plants is increased by changing climatic conditions and the success in achieving improvements will be dependent on understanding the biological mechanisms underpinning stress tolerance. My laboratory has identified a large number of regulatory genes in wheat whose change in expression correlates with the level of tolerance of wheat different genotypes.***Presently we are investigating some of these candidate tolerance genes at the molecular level in the model species Arabidopsis. We are asking how caleosin genes RD20/CLO3, and CLO7 interact with molecular signaling pathways that control root growth and the density of stomata on the leaf surface. High root density and deep root penetration in the soil contributes to the plants ability to take up water from the soil, when water availability is limited. Stomata are small valves on the surface of the leaf that can open and close and control the water loss and gas exchange, most importantly CO2 uptake from the atmosphere during photosynthesis. Our work focuses on the function of the caleosin genes in their interaction with a class of proteins referred to as heterotrimeric G proteins, or G-proteins, that function as signaling molecules, that is, on/off switches that can control the degree of root growth, and stomatal development. ***The regulation of the density of stomata is known to be complex and controlled by genes that act in a signal transduction circuit. We have discovered that stress-induced caleosins interact with G-proteins and that they control stomatal density in response to stress signals. It is unknown how the caleosins and G-proteins interconnect with the stomatal development signaling pathway. One of our major objectives is to discover how these two signalling pathways are interconnected at the molecular level. The development of detailed knowledge of the regulation of root development, stomatal development and the control of stomatal opening can be used as the basis of plant improvement in order to develop crops that are more tolerant to drought, salt and extreme weather conditions. **