Ca2+ Waves in Systemic Signaling Networks in Plants

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Intellectual MeritThe immobile nature of the plant lifestyle requires an ability to continuously monitor local conditions and trigger responses to help cope as these conditions change. Stimuli are often highly localized, yet responses must occur throughout the plant body. Thus, the signaling networks within plants must broadcast information not only within the cells directly receiving the stimulus but also over much longer distances. This project seeks to define how the calcium ion plays a role in this long-distance signaling system. Preliminary work has revealed that in response to local stress, such as wounding of the leaf or increasing levels of salt around the root, waves of Ca2+ propagate from the site of stress perception to distant regions of the plant within seconds. This preliminary analysis has also highlighted a potential role for reactive oxygen species (ROS) and an ion channel named TPC1 in this rapidly propagating Ca2+ wave system. The major research goals to be undertaken in this project are therefore to use plants engineered to produce protein-based Ca2+ reporters to monitor and characterize the Ca2+ changes both at the site of stress perception and in the tissues transmitting this signal. Molecular changes dependent on the Ca2+ wave will then be monitored to define the relationship between the Ca2+ wave and other well-defined plant stress response pathways such as those triggered by ROS and the defense hormones jasmonic- and salicylic-acid. The third goal will be to engineer the TPC1 gene to alter the regulation of this ion channel such that it should no longer respond to ROS or Ca2+. The ability of these mutated versions of the channel to support the movement of the Ca2+ wave will then be assessed. Through pursuing these three goals, this research program will help define how this newly discovered Ca2+ wave signaling system plays a role in helping plants adapt to a constantly changing environment.Broader ImpactsThis project will integrate research and education. Research opportunities for undergraduates will be offered through programs such as the Undergraduate Research Scholars Program and recruitment from members of the Posse Foundation that promote the representation of underrepresented groups in science. Opportunities for high school researchers will also be made available. Along with their research training these scholars will be encouraged to present their work at local, national and international meetings. In addition, efforts at outreach to the general public will be made at the local level through events such as the Wisconsin Institutes of Discovery Science Festival, Wisconsin Science Expeditions and Saturday Science at The Wisconsin Institutes of Discovery. A plant biology movie resource, disseminated through outlets such as YouTube, will also be developed. This resource will be directed towards engaging the general public through movies and explanations of plant responses, whilst also providing them with access to the science behind the images.