Abstract
Exposure of plants to abiotic stresses, such as salinity, cold, heat, or drought, affects their growth and development, and can significantly reduce their productivity. Plants have developed adaptive strategies to deal with situations of abiotic stresses with guarantees of success, which have favoured the expansion and functional diversification of different gene families. The family of mitochondrial transcription termination factors (mTERFs), first identified in animals and more recently in plants, is likely a good example of this. In plants, mTERFs are located in chloroplasts and/or mitochondria, participate in the control of organellar gene expression (OGE), and, compared with animals, the mTERF family is expanded. Furthermore, the mutations in some of the hitherto characterised plant mTERFs result in altered responses to salt, high light, heat, or osmotic stress, which suggests a role for these genes in plant adaptation and tolerance to adverse environmental conditions. In this work, we investigated the effect of impaired mTERF6 function on the tolerance of Arabidopsis to salt, osmotic and moderate heat stresses, and on the response to the abscisic acid (ABA) hormone, required for plants to adapt to abiotic stresses. We found that the strong loss-of-function mterf6-2 and mterf6-5 mutants, mainly the former, were hypersensitive to NaCl, mannitol, and ABA during germination and seedling establishment. Additionally, mterf6-5 exhibited a higher sensitivity to moderate heat stress and a lower response to NaCl and ABA later in development. Our computational analysis revealed considerable changes in the mTERF6 transcript levels in plants exposed to different abiotic stresses. Together, our results pinpoint a function for Arabidopsis mTERF6 in the tolerance to adverse environmental conditions, and highlight the importance of plant mTERFs, and hence of OGE homeostasis, for proper acclimation to abiotic stress.
Highlights
IntroductionThe increased salt content in arable soils severely compromises plant growth and productivity
The increased salt content in arable soils severely compromises plant growth and productivity.This is due to osmotic stress, which promotes water loss and hinders its uptake by plant roots, and to ionic stress (Na+ and Cl− in most cases), which generates toxicity and hinders the recruitment of other ions [1]
Sci. 2018, 19, 2388 altered response of the mterf6 mutants to the stress conditions assayed, which is consistent with the substantial changes in mTERF6 expression we found in silico after exposing the wild-type to different abiotic stresses
Summary
The increased salt content in arable soils severely compromises plant growth and productivity. This is due to osmotic stress, which promotes water loss and hinders its uptake by plant roots, and to ionic stress (Na+ and Cl− in most cases), which generates toxicity and hinders the recruitment of other ions [1]. The development of new varieties of more halotolerant crop plants requires unravelling the genetic and molecular mechanisms that underlie tolerance to salinity. Leister et al [3] have reported that perturbed organellar gene expression (OGE) homeostasis activates the acclimation and tolerance responses of plants, likely through retrograde communication. We initiated a bioinformatics and reverse genetics approach in the plant model system
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