Abstract - We have developed proteomics methods that rapidly quantify absolute amounts of >2000 leaf proteins per sample. We analysed 320 eucalypt leaves across 32 species sampled from Tasmania, New South Wales, and Queensland, spanning large gradients of mean annual precipitation and temperature (200-3200 mm and 5-27 °C).
Most leaf protein by weight is involved in photosynthesis. The top 300 to 500 most abundant proteins account for >90% total leaf protein by weight and most of them are involved in photosynthesis and photorespiration. We quantified relationships between environmental conditions and protein allocation to functional categories such as photosystems, Calvin cycle, electron transport, and photorespiration. For example, we found a general decline in total protein with increasing temperature and a decrease in photosystems proteins with increasing light; Calvin cycle proteins responded only weakly to environmental conditions.
This is the first study that directly measures how leaf protein amounts vary over environmental gradients on a continental scale. Our new proteomics approach is relevant to plant physiology, ecology, and vegetation modeling because it allows fast and accurate measurement of leaf protein amounts that are typically only estimated from gas exchange or total leaf nitrogen measurements.
Steve Van Sluyter is a plant biochemist at Macquarie University with a PhD from the University of Melbourne School of Botany. Prior to Macquarie University he worked and conducted most of his PhD research at the Australian Wine Research Institute developing new enzymatic technologies for winemaking. Since 2013 he has been applying quantitative proteomics methods to native Australian plants to answer fundamental questions about how leaf proteins are differentially allocated to functional categories across environmental gradients and leaf ages. His native leaf proteomics work has been supported by a SIEF John Stocker Postdoctoral Fellowship and an ARC Discovery Project grant. He also currently runs a Wine Australia-funded project that aims to develop vineyard yield prediction models for use in the Australian wine industry.
James Lawson is a postdoctoral fellow at Macquarie University. He earned his PhD from Macquarie in 2015, using a functional trait approach to understand how hydrology and other environmental variables template the ecology of riparian plant communities. He now works with Steve van Sluyter looking at biogeographic patterns in leaf protein expression across the Australian continent. James also has a background in systems and computational biology.