Dynamics of metabolic responses to periods of combined heat and drought in Arabidopsis thaliana under ambient and elevated atmospheric CO2.

Gaurav Zinta,Ivan A Janssens,Darin Peshev,Han Asard,Ivan Nijs,Hamada Abdelgawad,Wim Van Den Ende,James T Weedon,Gerrit T S Beemster

doi:10.1093/jxb/ery055

Gaurav Zinta, Ivan A Janssens + Show 7 more

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https://doi.org/10.1093/jxb/ery055

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Abstract

As a consequence of global change processes, plants will increasingly be challenged by extreme climatic events, against a background of elevated atmospheric CO2. We analysed responses of Arabidopsis thaliana to periods of a combination of elevated heat and water deficit at ambient and elevated CO2 in order to gain mechanistic insights regarding changes in primary metabolism. Metabolic changes induced by extremes of climate are dynamic and specific to different classes of molecules. Concentrations of soluble sugars and amino acids increased transiently after short (4-d) exposure to heat and drought, and readjusted to control levels under prolonged (8-d) stress. In contrast, fatty acids showed persistent changes during the stress period. Elevated CO2 reduced the impact of stress on sugar and amino acid metabolism, but not on fatty acids. Integrating metabolite data with transcriptome results revealed that some of the metabolic changes were regulated at the transcriptional level. Multivariate analyses grouped metabolites on the basis of stress exposure time, indicating specificity in metabolic responses to short and prolonged stress. Taken together, the results indicate that dynamic metabolic reprograming plays an important role in plant acclimation to climatic extremes. The extent of such metabolic adjustments is less under high CO2, further pointing towards the role of high CO2 in stress mitigation.

Highlights

Extreme heat and drought often co-occur and dramatically (IPCC, 2012)
Plants were re-watered to 70% relative water content (RWC) and the temperature was reset to 21/18 °C.The four experimental treatments were: (i) ambient CO2; (ii) elevated CO2 (‘CO2’); (iii) heat and drought under ambient CO2 (‘HD’); and (iv) heat and drought under elevated CO2 (‘HD+CO2’).Whole-plant rosettes were harvested between 10:00–12:00, at 32 d after sowing (DAS), at 4 d and 8 d of stress exposure (36 DAS and 40 DAS, respectively), and after recovery (45 DAS)
The sucrose concentration showed a strong decline after 36 DAS under elevated CO2 and stress, but relatively little change in ambient non-stressed conditions (Fig. 2d)

Summary

Introduction

The predicted future atmosphere reduce plant growth.They are predicted to become more fre- will contain higher CO2 levels, impacting plant growth and quent and severe as a consequence of global climate change development. Less is known about combined heat extremes and drought stress effects under elevated CO2, a scenario very relevant to global climate change. Plant responses to heat and drought depend on the intensity and frequency of these events, and on plant-specific factors such as developmental stage and adaptation potential. Inhibition of photosynthesis, changes in cell metabolism, and deterioration of membranes and proteins are frequently observed under severe stress. Metabolic changes may lead to imbalances in redox homeostasis and elevated levels of reactive oxygen species (ROS), causing oxidative stress (Mittler, 2002; Foyer and Noctor, 2005; Krasensky and Jonak, 2012; MunnéBosch et al, 2013). Defences against short-term exposure to extreme heat or drought include regulation of stomatal opening and induction of protective molecules (e.g. osmolytes, heat shock proteins, and antioxidants) (Wang et al, 2003; Vinocur and Altman, 2005;Wahid et al, 2007;Ashraf, 2010)

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