© 2009 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
This paper is available online free of all access charges (see http://jxb.oxfordjournals.org/open_access.html for further details)
RESEARCH PAPER |
Exploring abiotic stress on asynchronous protein metabolism in single kernels of wheat studied by NMR spectroscopy and chemometrics
1University of Copenhagen, Faculty of Life Sciences, Department of Food Science, Quality and Technology, Rolighedsvej 30, 1958 Frederiksberg C, Denmark
2University of Aarhus, Faculty of Agricultural Sciences, Department of Genetics and Biotechnology, Forsøgsvej 1, 4200 Slagelse, Denmark
3Technical University of Denmark, Enzyme and Protein Chemistry, Department. of Systems Biology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
* To whom correspondence should be addressed: E-mail: haw{at}life.ku.dk
Extreme climate events are being recognized as important factors in the effects on crop growth and yield. Increased climatic variability leads to more frequent extreme conditions which may result in crops being exposed to more than one extreme event within a growing season. The aim of this study was to examine the implications of different drought treatments on the protein fractions in grains of winter wheat using 1H nuclear magnetic resonance spectroscopy followed by chemometric analysis. Triticum aestivum L. cv. Vinjett was studied in a semi-field experiment and subjected to drought episodes either at terminal spikelet, during grain-filling or at both stages. Principal component trajectories of the total protein content and the protein fractions of flour as well as the 1H NMR spectra of single wheat kernels, wheat flour, and wheat methanol extracts were analysed to elucidate the metabolic development during grain-filling. The results from both the 1H NMR spectra of methanol extracts and the 1H HR-MAS NMR of single kernels showed that a single drought event during the generative stage had as strong an influence on protein metabolism as two consecutive events of drought. By contrast, a drought event at the vegetative growth stage had little effect on the parameters investigated. For the first time, 1H HR-MAS NMR spectra of grains taken during grain-filling were analysed by an advanced multiway model. In addition to the results from the chemical protein analysis and the 1H HR-MAS NMR spectra of single kernels indicating that protein metabolism is influenced by multiple drought events, the 1H NMR spectra of the methanol extracts of flour from mature grains revealed that the amount of fumaric acid is particularly sensitive to water deficits.
Key words: Chemometrics, drought, fumaric acid, grain-filling, HR-MAS NMR, PARAFAC, PCA trajectory, single kernel, wheat
Received 19 August 2008; Revised 14 October 2008 Accepted 24 October 2008