Mitochondrial Uncoupling Protein 1 Overexpression Increases Yield in Nicotiana tabacum under Drought Stress by Improving Source and Sink Metabolism.

Pedro Barreto,Juliana E C T Yassitepe,Paulo Arruda,Zoe A Wilson

doi:10.3389/fpls.2017.01836

Abstract

Mitochondrial uncoupling proteins (UCPs) sustain mitochondrial respiration independent of intracellular ATP concentration. Uncoupled respiration is particularly beneficial under stress conditions, during which both photosynthesis and respiration may be impaired. Sustaining carbon fixation during the reproductive phase is essential for plants to develop viable pollen grains and for seed setting. Here, we examined whether UCP1 overexpression (UCP1-oe) would help tobacco plants cope with drought stress during reproductive development. We observed that WT and UCP1-oe plants lost water at the same rate under moderate drought stress, but that UCP1-oe lines regained water faster upon rewatering. UCP1-oe plants maintained higher levels of respiration and photosynthesis and decreased H2O2 content in the leaves during the drought stress period. We examined whether UCP1-oe impacts reproductive tissues and seed production by monitoring the progress of flower development, focusing on the early stages of pollen formation. UCP1-oe lines induced the expression of mitochondrial genes and increased mtDNA content in reproductive tissues, which increased the consumption of carbohydrates and reduced H2O2 content and pollen disturbances. Finally, the beneficial impact of UCP1-oe on the source and sink organs resulted in an increased seed size and number under both control conditions and drought stress.

Highlights

Plants face a range of adverse conditions that impose metabolic constraints during their lifecycle
After 15 days of irrigation was withdrawn (IW), plants were rewatered; 24 h after irrigation resumption, it was evident that UCP1 overexpression (UCP1-oe) lines rehydrated faster than the WT plants based on the plant turgidity (Figure 1D) and relative water content (RWC) (Figure 1E)
We examined the presence of the heterologous A. thalianaUCP1 mRNA (Figure 1G) and UCP1 protein (Figure 1H) in flower buds

Summary

Introduction

Plants face a range of adverse conditions that impose metabolic constraints during their lifecycle. Among these stresses, water deficit is perhaps the most important because it affects both cell energy supply and demand (Flexas et al, 2005; Atkin and Macherel, 2009). The consequences of drought stress are not limited to a cellular context but extend to whole plant physiology. The effect of water deficit on plant energy status is especially harmful during reproduction, where there is competition for nutrients between newly established sink tissues (flowers) and roots from source tissues (leaves). UCP1 Protects from Stress and Increases Yield (Lemoine et al, 2013). Because of that water deficit is the major abiotic stress factor affecting crop development and yield (Lemoine et al, 2013). In the past few years, the frequency and intensity of drought have increased in many regions around the globe, and there are predictions of further increases as the result of global climate change (IPCC, 2014)

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