Seminar by Dr Jost on TUE Aug 27th at blg300 room 219 at 4pm.
Please join us to host the speaker after her talk. Drinks and nibbles will be provided.
Molecular characterization of phosphite action in plants – improving plant protection against hemibiotrophs.
Ricarda Jost1, Oliver Berkowitz1,2, Hazel Gaza1, Marina Borges Osorio1, Daniel Kollehn2, Patrick M. Finnegan1, Giles E.St.J. Hardy 2 & Hans Lambers1
1School of Plant Biology and Institute of Agriculture, The University of Western Australia, Crawley WA 6009, Australia; 2Centre for Phytophthora Science and Management, School of Biological Sciences & Biotechnology, Murdoch University, Murdoch WA 6150, Australia.
Abstract:
Phosphite (Phi, H2PO3–) is the active component in phosphonate-based fungicides that are widely used to combat plant hemibiotrophic pathogens, e.g. oomycetes such as the foliar potato late blight pathogen (Phytophthora infestans) and the root rot pathogen (Phytophthora cinnamomi) that threatens many natural ecosystems. While Phi directly impacts on spore germination and inhibits mycelial growth in vitro, it also evokes long-lasting protection of the treated plants themselves. However, the molecular basis for this boosting of plant defense responses is largely unknown.
The structural similarity of Phi to the plant macronutrient phosphate (Pi, H2PO4–) suggests its interference with plant Pi homeostasis. In this study, we introduce a number of strategies that will further our mechanistic understanding of Phi-induced resistance. First results suggest that Phi is not a generic mimetic of Pi: It attenuates anthocyanin accumulation in Pi-limited leaves and reduces both root hair length and density to a similar extent as Pi, but leads to an overall suppression of plant growth. Despite these dramatic effects on plant physiology, Phi does not suppress the expression of most Pi-starvation induced genes to the same extent as Pi itself. Instead, metabolite profiling reveals distinct changes in other primary and secondary metabolic pathways with corresponding changes in gene expression. Therefore, we conclude that the effects of Phi only partially overlap with plant responses to changes in phosphorus status and have much wider implications for reprogramming plant metabolism that can ultimately lead to an increased alertness to the presence of pathogens.
CV summary:
My first passion as an emerging plant biologist was the molecular characterization of plant sulfur metabolism in the pre-genomic era. In 1996, I completed my M.Sc. on this topic in the department of Plant Physiology with Prof Elmar W. Weiler at the Ruhr-University of Bochum in Germany. I then started my PhD in the same group, but moved to the Institute of Plant Genetics and Crop Plant Research (IPK) in Gatersleben with my supervisor, Prof Rüdiger Hell in 1998 to establish the ‘Molecular Mineral Assimilation’ group in the department of Prof Uwe Sonnewald. In 2001, I obtained my PhD from the Martin-Luther University Halle-Wittenberg, successfully defending my thesis entitled ‘Structure and regulation of genes for cysteine biosynthesis in Arabidopsis thaliana’. In 2001, I obtained my first postdoctoral fellowship within the DFG Collaborative German Plant Sulfur Group consortium working on ‘The role of sulfur metabolism and sulfur rich peptides for pathogen resistance in Brassicacean species’. Two years later, I left the IPK for The Australian National University in Canberra to work on a GRDC-funded project on ‘Gene expression induced by root mechanical impedance in wheat’ with Dr Josette Masle in the group of Prof Graham Farquhar. In 2009, I left this very successful, ongoing project to join the School of Plant Biology and work with A/Prof Patrick Finnegan and W/Prof Hans Lambers on an ARC linkage project entitled ‘Susceptibility to Phytophthora cinnamomi and sensitivity to phosphate in native Australian plants: why are they linked?’. In 2011, we successfully applied for an ARC discovery project attempting to answer the question ‘Is the extreme phosphate sensitivity found among Australian plants a consequence of their adaptation to a severely phosphate-limited environment?’ In 2011, I won a 4-months’ UWA Fay Gale Fellowship to work in the department of Prof Mark Stitt at the Max-Planck Institute of Molecular Plant Physiology in Golm, Germany, to study metabolic aspects of both phosphite action in Arabidopsis and phosphorus metabolism in the Australian native plant harsh hakea.
Seminar coordinator: Judith.Lichtenzveig@curtin.edu.au
