Profiling of mitochondrial transcriptome in germinating wheat embryos and seedlings subjected to cold, salinity and osmotic stresses

Abstract

Mitochondrial functions are potential targets of abiotic stresses that are major environmental factors limiting plant development and productivity. To evaluate mitochondrial responses to abiotic stresses we studied mitochondrial transcriptome profiles at the early stages of wheat development after imbibition under normal and induced stress conditions. Three stresses given were low temperature (4°C), high salinity (0.2 M NaCl) and high osmotic potential (0.3 M mannitol). All these stresses greatly reduced growth but dramatically increased respiration both via the cytochrome and alternative pathways. Macroarray analysis of the mitochondrial transcriptome revealed that most of the changes in transcript levels were stress specific but groups of genes responded commonly to different stresses. Under 3-days continuous stresses, 13 genes showed low temperature specific responses with either up-or down-regulation, while 14 and 23 genes showed responses specific to high salinity and high osmotic potential, respectively. On the other hand, 13 genes showed common responses, among which cob and ccmFn increased their transcript levels while transcripts of the other genes including nad6, atp4 and atp9 decreased. The differential profiles of mitochondrial transcriptome revealed by the macroarray analysis were verified by the quantitative reverse transcriptase PCR analysis. Taken together, three among five nuclearencoded mitochondria-targeted genes included in the array showed decreases under the stresses, while MnSOD and AOX increased their transcript amounts. Our results indicated the existence of common and different regulatory mechanisms that can sense different abiotic stresses and modulate both nuclear and mitochondrial gene expression in germinating wheat embryos and seedlings.

Metabolism of reactive oxygen species and reactive nitrogen species in pepper (Capsicum annuum L.) plants under low temperature stress

“…2010). In embryonic axes of lotus ( Nelumbo nucifera ) exposed to LT (4 °C) for 48 h the MnSOD gene was induced eightfold (Naydenov et al . 2010).…”

Functional analysis of superoxide dismutases (SODs) in sunflower under biotic and abiotic stress conditions. Identification of two new genes of mitochondrial Mn-SOD

“…In Raphanus sativus, the mitochondrial Mn-SOD gene expression was strongly induced by osmotic stress, moderately induced by phytohormones such as ABA and IAA, and not induced by xenobiotics other than cercosporin (Kwon and An, 2003). In wheat seedlings exposed to several types of stress (low temperature, salinity, and osmotic stress), the mitochondrial Mn-SOD transcript was induced (Naydenov et al, 2010), indicating that changes in mitochondrial redox capacity can provoke overexpression at the transcriptional level of nuclear genes encoding mitochondrial antioxidant proteins, as in the case of Mn-SOD. These data contrast with findings in other plant species, e.g.…”

The genome and transcriptome of perennial ryegrass mitochondria

“…An earlier microarray analysis of mitochondrial gene expression at the early stage of wheat shoot tissues reported that the ccm FN gene showed increased transcript level under three different stress conditions, low temperature (4°C), high salinity (0.2 M NaCl) and high osmotic potential (0.3 M mannitol) [48]. …”