Functional characterization of mitochondrial stress response in Arabidopsis thaliana

Botao Zhang

Research output: ThesisDoctoral Thesis

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Abstract

[Truncated abstract] Plants, because of their immobile nature, are continually exposed to a variety of extreme environmental conditions i.e. stresses. Stresses have adverse effects on plant growth, development and seed production. Nearly all biotic and abiotic stresses disrupt the metabolic balance of cells, resulting in osmotic stress and enhanced production of reactive oxygen species (ROS) (Mittler et al., 2004). Mitochondria are one of the major sources of ROS and a major target of oxidative stress, and are vital for maintaining the viability during biotic and abiotic stress. Previous studies showed that there are a number of mitochondrial proteins that are induced by different treatments directly targeted to mitochondria (Clifton et al., 2006). However, the response of mitochondria to stress and the roles mitochondria play under stress are still not very clear. In this study, the functional characterization of mitochondrial stress response was conducted. By combining a list of 1196 Arabidopsis thaliana genes that putatively encode mitochondrial proteins with 16 publicly available microarray datasets under stress conditions, 45 nuclear encoded proteins were defined as mitochondrial stress-responsive proteins. Furthermore, the mitochondrial localization of these proteins was tested using green fluorescent protein (GFP) fusion assays. In total 26 proteins could be confirmed to be targeted to mitochondria and were thus considered to be mitochondrial stress responsive proteins. Two of the mitochondrial stress responsive genes were selected for functional characterization. One of these proteins, AtLETM1 (leucine zipper-EF-hand-containing transmembrane protein), was investigated using T-DNA insertion lines. Analysis revealed the presence of a paralog in Arabidopsis. Inactivation of either AtLETM1 or AtLETM2 did not result in any severe deleterious growth phenotypes, while inactivation of both genes was lethal.
Original languageEnglish
QualificationDoctor of Philosophy
Publication statusUnpublished - 2012

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