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Plant function and evolutionary biology
RESEARCH ARTICLE

Osmotic adjustment of young sugar beets (Beta vulgaris) under progressive drought stress and subsequent rewatering assessed by metabolite analysis and infrared thermography

Rita Wedeking A C , Anne-Katrin Mahlein B , Ulrike Steiner B , Erich-Christian Oerke B , Heiner E. Goldbach A and Monika A. Wimmer A D
+ Author Affiliations
- Author Affiliations

A Department of Plant Nutrition, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Bonn, Karlrobert-Kreiten-Str. 13, 53 115 Bonn, Germany.

B Department of Phytomedicine, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Meckenheimer Allee 166a, 53 115 Bonn, Germany.

C Environmental Safety/Metabolism, Bayer CropScience AG, Alfred-Nobel-Str. 50, 40 789 Monheim, Germany.

D Corresponding author. Email: m.wimmer@uni-bonn.de

Functional Plant Biology 44(1) 119-133 https://doi.org/10.1071/FP16112
Submitted: 23 March 2016  Accepted: 17 October 2016   Published: 14 November 2016

Abstract

The main objective of this work was to provide the chronology of physiological and metabolic alterations occurring under drought and demonstrate how these relate to a phenotypic approach (infrared thermal imaging, IRT). This should provide tools to tailor phenotyping approaches for drought tolerance and underlying metabolic alterations. In the present study, destructive analysis of growth and cell morphology, water status, osmotic adjustment, metabolic changes and membrane damage were combined with non-destructive determination of leaf temperature using infrared thermography (IRT) in 6-week-old sugar beets subjected to progressive drought stress and subsequent rewatering. Different methods were suitable for the characterisation of the dynamic development of distinct stress phases: although IRT allowed detection of initial impairment of transpiration within 1 day of drought stress, destructive methods allowed us to distinguish a phase of metabolic adjustment including redirection of carbon flow into protective mechanisms and a subsequent phase of membrane destabilisation and cellular damage. Only the combination of invasive and non-invasive methods allowed for the differentiation of the complete sequence of physiological changes induced by drought stress. This could be especially beneficial for the selection of phenotypes that are adapted to early drought. During rewatering, sugar beet shoots rapidly re-established water relations, but membrane damage and partial stomatal closure persisted longer, which could have an impact on subsequent stress events. During the onset of secondary growth, taproots required more time to recover the water status and to readjust primary metabolites than shoots.

Additional keywords: sugar beet, stress dynamics.


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