Counting Carbs: Patterns rather than absolute values of non-structural carbohydrates may be compared across labs

The plant ecophysiology field is intrigued and perplexed by products of photosynthesis known as soluble or non-structural carbohydrates (NSCs), compounds that are used for growth, metabolism, and storage. NSC concentrations of different plant tissue (leaves, stem, bark, roots) are of research interest because they can reveal information about plant responses to environmental stress, such as plant survival and mortality during drought. Many different carbohydrates can be classified as NSCs, but most studies quantifying their role in plant performance have focused on starch, sucrose, fructose, and glucose.

NSCs can provide clues to questions about whole-plant carbon balance (e.g. where is carbon allocated to and used?) and regulation of stored carbohydrates. However, NSC analysis methods vary, giving rise to questions about how well NSC data can be compared across labs. If the measurements from one lab using a specific technique differ from those in another lab that uses another method for quantifying NSC concentrations, then our ability to compare results across labs or model carbon balance in plants will be compromised.

To address this, Quentin et al. (2015) sent samples from five woody plant tissues that varied in NSC content and tissue type to 29 labs to be analyzed for NSC concentrations using laboratory-specific protocols. The authors found that laboratory measurements of NSC content varied greatly among the labs and thus cannot be compared among labs. However, there is a silver lining: the relative patterns of NSC dynamics across the samples within a lab may be compared across labs. Cross-lab studies such as Quentin et al. (2015) are crucial for future method development and meaningful comparisons of NSC concentrations and dynamics from different studies and labs. We need reliable estimates of various carbohydrate pools to better understand the role of carbon and NSCs in plant responses to environmental stress or forest management approaches, but Quentin et al. (2015) show that we are not there yet.

Audrey G. Quentin, Elizabeth A. Pinkard, Michael G. Ryan, David T. Tissue, L. Scott Baggett, Henry D. Adams, Pascale Maillard, Jacqueline Marchand, Simon M. Landhäusser, André Lacointe, Yves Gibon, William R.L. Anderegg, Shinichi Asao, Owen K. Atkin, Marc Bonhomme, Caroline Claye, Pak S. Chow, Anne Clément-Vidal, Noel W. Davies, L. Turin Dickman, Rita Dumbur, David S. Ellsworth, Kristen Falk, Lucía Galiano, José M. Grünzweig, Henrik Hartmann, Günter Hoch, Sharon Hood, Joanna E. Jones, Takayoshi Koike, Iris Kuhlmann, Francisco Lloret, Melchor Maestro, Shawn D. Mansfield, Jordi Martínez-Vilalta, Mickael Maucourt, Nathan G. McDowell, Annick Moing, Bertrand Muller, Sergio G. Nebauer, Ülo Niinemets, Sara Palacio, Frida Piper, Eran Raveh, Andreas Richter, Gaëlle Rolland, Teresa Rosas, Brigitte Saint Joanis, Anna Sala, Renee A. Smith, Frank Sterck, Joseph R. Stinziano, Mari Tobias, Faride Unda, Makoto Watanabe, Danielle A. Way, Lasantha K. Weerasinghe, Birgit Wild, Erin Wiley, David R. Woodruff, 2015, ‘Non-structural carbohydrates in woody plants compared among laboratories’, Tree Physiology, http://dx.doi.org/10.1093/treephys/tpv073