The following seminar will take place at 3.30pm on Monday 12th February in the Plant Research Centre Auditorium.
Barley stomata and the evolution of guard cell signalling
Professor Rainer Hedrich, Institute for Molecular Plant Physiology and Biophysics, University of Wuerzburg, Germany
The latest major group of plants to evolve were the grasses. These became important in the mid-Paleogene about 40 million years ago. During evolution leaf CO2 uptake and transpirational water loss were optimized by the acquisition of grass specific stomatal complexes. In contrast to the kidney-shaped guard cells (GCs) typical of the dicots such as Arabidopsis, in the grasses and agronomically important cereals, the guard cells are dumbbell-shaped and are associated with morphologically distinct subsidiary cells (SCs). We studied the molecular basis of guard cell action in the major cereal crop barley. Upon feeding ABA to xylem sap of an intact barley leaf, stomata closed in a nitrate dependent manner. This process was initiated by activation of guard cell SLAC-type anion channel currents. HvSLAC1 expressed in Xenopus oocytes gave rise to S-type anion currents that increased several fold upon stimulation with >3 mM nitrate. We identified a tandem polymorphic site that within the SLAC1 channels differs fundamentally between monocots and dicots. When the motif of nitrate-insensitive dicot Arabidopsis SLAC1 was replaced by the monocot signature, AtSLAC1 converted into a grass-type like nitrate-sensitive channel. Our work reveals a fundamental difference between monocot and dicot guard cells and prompts questions into the selective pressures during evolution that resulted in fundamental changes in the regulation of SLAC1 function.
Professor Hedrich is visiting the Waite, from 12-15th February, to collaborate as a partner investigator on an ARC Discovery Award with Professor Matthew Gilliham and to initiate new collaborations with other researchers at the Waite campus. If you would like to meet with Professor Hedrich please contact Matt Gilliham who is co-ordinating his schedule.
ABOUT THE SPEAKER
Professor Rainer Hedrich, Chair of Molecular Plant Physiology and Biophysics at the Julius-von-Sachs-Institute of Julius-Maximilians-Universität Würzburg, Germany, our inaugural Waite Fellow (2017), returns to the School of Agriculture, Food and Wine to continue his collaborative projects with School members.
Professor Hedrich is a global leader in plant ion channel biology, stomatal biology and plant nutrition. The molecular mechanisms controlling stomatal guard cells of green plants and the evolutionary success of the carnivorous Venus flytrap (Dionaea muscipula) are two focal areas of interest. In recognition of his contributions Rainer Hedrich received numerous awards including the Körber-Award for the European Research, ISI Web of Knowledge highly cited researcher among 250 in animal and plant sciences, and a European Research Council (ERC) Advanced Grant Award. His studies of plant ion channels have provided important insights into the molecular basis of pH regulation and water balance in plants, and an understanding of the molecular basis and function of stomata guard cells. He is particularly interested in the strengths of the Waite in cereal genomics and the potential for applying his insights on gas exchange for agriculture with partners here.