Accumulation of dehydrin-like proteins in the mitochondria of cereals in response to cold, freezing, drought and ABA treatment

BACKGROUND: Dehydrins are known as Group II late embryogenesis abundant proteins. Their high hydrophilicity and thermostability suggest that they may be structure stabilizers with detergent and chaperone-like properties. They are localised in the nucleus, cytoplasm, and plasma membrane. We have recently found putative dehydrins in the mitochondria of some cereals in response to cold. It is not known whether dehydrin-like proteins accumulate in plant mitochondria in response to stimuli other than cold stress. RESULTS: We have found five putative dehydrins in the mitochondria of winter wheat, rye and maize seedlings. Two of these polypeptides had the same molecular masses in all three species (63 and 52 kD) and were thermostable. Drought, freezing, cold, and exogenous ABA treatment led to higher accumulation of dehydrin-like protein (dlp) 63 kD in the rye and wheat mitochondria. Protein 52 kD was induced by cold adaptation and ABA. Some accumulation of these proteins in the maize mitochondria was found after cold exposition only. The other three proteins appeared to be heat-sensitive and were either slightly induced or not induced at all by all treatments used. CONCLUSIONS: We have found that, not only cold, but also drought, freezing and exogenous ABA treatment result in accumulation of the thermostable dehydrins in plant mitochondria. Most cryotolerant species such as wheat and rye accumulate more heat-stable dehydrins than cryosensitive species such as maize. It has been supposed that their function is to stabilize proteins in the membrane or in the matrix. Heat-sensitive putative dehydrins probably are not involved in the stress reaction and adaptation of plants

Influence of CSP 310 and CSP 310-like proteins from cereals on mitochondrial energetic activity and lipid peroxidation in vitro and in vivo

BACKGROUND: The development of chilling and freezing injury symptoms in plants is known to frequently coincide with peroxidation of free fatty acids. Mitochondria are one of the major sources of reactive oxygen species during cold stress. Recently it has been suggested that uncoupling of oxidation and phosphorylation in mitochondria during oxidative stress can decrease ROS formation by mitochondrial respiratory chain generation. At the same time, it is known that plant uncoupling mitochondrial protein (PUMP) and other UCP-like proteins are not the only uncoupling system in plant mitochondria. All plants have cyanide-resistant oxidase (AOX) whose activation causes an uncoupling of respiration and oxidative phosphorylation. Recently it has been found that in cereals, cold stress protein CSP 310 exists, and that this causes uncoupling of oxidation and phosphorylation in mitochondria. RESULTS: We studied the effects of CSP 310-like native cytoplasmic proteins from a number of cereal species (winter rye, winter wheat, Elymus and maize) on the energetic activity of winter wheat mitochondria. This showed that only CSP 310 (cold shock protein with molecular weight 310 kD) caused a significant increase of non-phosphorylative respiration. CSP 310-like proteins of other cereals studied did not have any significant influence on mitochondrial energetic activity. It was found that among CSP 310-like proteins only CSP 310 had prooxidant activity. At the same time, Elymus CSP 310-like proteins have antioxidant activity. The study of an influence of infiltration by different plant uncoupling system activators (pyruvate, which activates AOX, and linoleic acid which is a substrate and activator for PUMP and CSP 310) showed that all of these decreased lipid peroxidation during cold stress. CONCLUSIONS: Different influence of CSP 310-like proteins on mitochondrial energetic activity and lipid peroxidation presumably depend on the various subunit combinations in their composition. All the plant cell systems that caused an uncoupling of oxidation and phosphorylation in plant mitochondria can participate in plant defence from oxidative damage during cold stress

The Influence of Carbohydrate Status and Low Temperature on the Respiratory Metabolism of Mitochondria from Etiolated Leaves of Winter Wheat

The separate and combined effect of sucrose (12%, 7 days) and low temperature (2 °С, 7 days) on the growth of plants, the content of carbohydrates in the leaves and oxidative activity of mitochondria isolated from them has been studied on the etiolated plants of winter wheat (Triticum aestivum L.). It has been shown that sucrose and low temperature cause inhibition of the growth and increasing of the carbohydrates content. Using the different oxidation substrates (malate, malate + rotenone, succinate, NADH and NADPH) have been identified changes in the mitochondrial oxidative activity and the functioning of alternative oxidase and rotenone-insensitive NAD(P)H dehydrogenases. It has been determined that activity of the alternative oxidase and “external” rotenone-insensitive NAD(P)H dehydrogenases in the mitochondria of etiolated leaves depends on the carbohydrate status of the plant, regardless of the growth temperature

Change of AOX1a Expression, Encoding Mitochondrial Alternative Oxidase, Influence on the Frost-Resistance of Arabidopsis Plants

The resistance of Arabidopsis thaliana (L.) Heynh (Columbia ecotype) plants: Col-0 line (wild type), AS-12 line (plants transformed with the construct carrying the AOX1a gene under control of the CAMV 35S promoter in the antisense orientation) and line XX-2 (plants transformed with the AOX1a gene construct in the sense orientation) (Umbach et al., 2005), to action of subzero temperature has been studied. It is shown that change of the AOX1a expression is accompanied by change of the AOX contribution in respiration and increase of the base frost-resistance of Arabidopsis plants. In the leaves of plants with overexpression of АОХ1а was reduced activity of total superoxide dismutase (SOD), but was increased activity of guaiacol peroxidase and was less content of hydrogen peroxide. It was found that cold hardening during 7 days at 5°C increases the resistance of plants to the subsequent action of subzero temperature regardless of АОХ1а expression degree. The hardening lead to activation of respiration, increase of the contribution of AOX in the respiration, a significant increase of the water-soluble carbohydrates content and increase of the activity SOD and total guaiacol peroxidases in leaves of all lines the plants. In hardened plants of Arabidopsis wild type and AOX1a transformants were detected differences in the contents of individual types of reactive oxygen species and the activity of antioxidant enzymes. The trend to decrease of hydrogen peroxide content in lines with altered expression of AOX1a was observed, but content of superoxide anion radical (SAR) was significantly lower in the AS-12 line compared with the Col-0 and XX-2 plants after hardening. The low content of SAR in leaves of AS-12 line was partly caused by increase of activity total SOD. Thus, we have identified differences in the basic frost-resistance of Arabidopsis plants with altered AOX1a expression, but significant differences in frost-resistance of hardened plants of wild-type and lines with altered AOX1a expression was not found. It was concluded that the frost-resistance of plants depends on the activity of AOX, but the decrease of its activity can be compensated by the activation of other protective systems including antioxidant enzymes