Abstract
Alternative energy strategies based on plant biomass-derived bioenergy and biofuels rely on understanding and optimization of plant structure, chemistry, and performance. Starch, a constitutive element of all green plants, is important to food, biofuels, and industrial applications. Models of carbohydrate storage granules are highly heterogeneous in representing morphology and structure, though a deeper understanding of the role of structure in functional behavior is emerging. A better understanding of the in situ nanoscale properties of native granules is needed to help improve the starch quality in food crops as well as optimize lignocellulosic biomass production in perennial nonfood crops. Here, we present a new technique called soft mechanical nano-ablation (sMNA) for accessing the interior of the granules without compromising the inner nanostructure. We then explore the nanomechanics of granules within the ray parenchyma cells of Populus xylem, a desirable woody biofuel feedstock. The employed soft outer layer nanoablation and atomic force microscopy reveal that the inner structure comprises 156 nm blocklets arranged in a semicrystalline organization. The nanomechanical properties of the inner and outer structures of a single starch granule are measured and found to exhibit large variations, changing by a factor of 3 in Young's modulus and a factor of 2 in viscoplastic index. These findings demonstrate how the introduced approach facilitates studies of structure-function relationships among starch granules and more complex secondary cell wall features as they relate to plant performance.
Original language | English |
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Pages (from-to) | 2594-2602 |
Number of pages | 9 |
Journal | ACS Omega |
Volume | 5 |
Issue number | 6 |
DOIs | |
State | Published - Feb 18 2020 |
Funding
We would like to thank Damien Chaudanson at CINaM for the raw SEM images. This work was sponsored by the BioEnergy Science Center (BESC) of the Oak Ridge National Laboratory (ORNL). The BESC is a US Department of Energy (DOE) Bioenergy Research Center supported by the Office of Biological and Environmental Research (BER) in the DOE Office of Science. ORNL is managed by UT-Battelle, LLC, for the US DOE under contract DE-AC05-00OR22725. This work was also sponsored by the A*MIDEX foundation on the Innovation and Emergence AAP2017 (project no: A-M-AAP-EI-17-10-170224-18.04-CHARRIER-E) and the CNRS through the PICS2019 program.