570 Biowissenschaften; Biologie
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- Arabidopsis thaliana (1)
- Dehydration tolerance (1)
- Protein carbonylation (1)
- Proteomic (1)
- Seedlings (1)
- Triticum aestivum L. (1)
- acid invertase (1)
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Plants are often challenged by an array of unfavorable environmental conditions. During cold exposure, many changes occur that include, for example, the stabilization of cell membranes, alterations in gene expression and enzyme activities, as well as the accumulation of metabolites. In the presented study, the carbohydrate metabolism was analyzed in the very early response of plants to a low temperature (2 degrees C) in the leaves of 5-week-old potato plants of the Russet Burbank cultivar during the first 12 h of cold treatment (2 h dark and 10 h light). First, some plant stress indicators were examined and it was shown that short-term cold exposure did not significantly affect the relative water content and chlorophyll content (only after 12 h), but caused an increase in malondialdehyde concentration and a decrease in the expression of NDA1, a homolog of the NADH dehydrogenase gene. In addition, it was shown that the content of transitory starch increased transiently in the very early phase of the plant response (3-6 h) to cold treatment, and then its decrease was observed after 12 h. In contrast, soluble sugars such as glucose and fructose were significantly increased only at the end of the light period, where a decrease in sucrose content was observed. The availability of the monosaccharides at constitutively high levels, regardless of the temperature, may delay the response to cold, involving amylolytic starch degradation in chloroplasts. The decrease in starch content, observed in leaves after 12 h of cold exposure, was preceded by a dramatic increase in the transcript levels of the key enzymes of starch degradation initiation, the alpha-glucan, water dikinase (GWD-EC 2.7.9.4) and the phosphoglucan, water dikinase (PWD-EC 2.7.9.5). The gene expression of both dikinases peaked at 9 h of cold exposure, as analyzed by real-time PCR. Moreover, enhanced activities of the acid invertase as well as of both glucan phosphorylases during exposure to a chilling temperature were observed. However, it was also noticed that during the light phase, there was a general increase in glucan phosphorylase activities for both control and cold-stressed plants irrespective of the temperature. In conclusion, a short-term cold treatment alters the carbohydrate metabolism in the leaves of potato, which leads to an increase in the content of soluble sugars.
Primary carbohydrate metabolism in plants includes several sugar and sugar-derivative transport processes. Over recent years, evidences have shown that in starch-related transport processes, in addition to glucose 6-phosphate, maltose, glucose and triose-phosphates, glucose 1-phosphate also plays a role and thereby increases the possible fluxes of sugar metabolites in planta. In this study, we report the characterization of two highly similar transporters, At1g34020 and At4g09810, in Arabidopsis thaliana, which allow the import of glucose 1-phosphate through the plasma membrane. Both transporters were expressed in yeast and were biochemically analyzed to reveal an antiport of glucose 1-phosphate/phosphate. Furthermore, we showed that the apoplast of Arabidopsis leaves contained glucose 1-phosphate and that the corresponding mutant of these transporters had higher glucose 1-phosphate amounts in the apoplast and alterations in starch and starch-related metabolism.
The appearance of the first leaf from the coleoptile in wheat seedlings (Triticum aestivum L.) coincides with the development of seedling susceptibility to water deficiency on the fifth day following imbibition. In dehydrated wheat seedlings, an increase in the protein carbonyl group has been observed. The coincidence of higher protein carbonylation levels with development of dehydration intolerance drew our attention. To gain more insight into the molecular basis of wheat drought tolerance, the seedling profiles of carbonylated proteins were analysed and compared. Two-dimensional gel electrophoresis (2D-PAGE) and mass spectrometry (MALDI-TOF and LC-MS/MS) were used to indicate and identify differential carbonylated proteins. Among the protein spots with at least a two-fold change in protein abundance in dehydrated seedlings in relation to control (well-watered) plants during the tolerant phase of growth, 19 carbonylated proteins increased and 18 carbonylated proteins decreased in abundance. Among 26 differentially expressed carbonylated proteins in sensitive seedlings, the abundance of 10 protein spots increased while that of 16 proteins decreased upon dehydration. We have demonstrated a link between protein carbonylation and seedling sensitivity to dehydration. The analysis of carbonylated protein profiles clearly showed that proteins with a potential role in the maintenance of dehydration tolerance in wheat seedlings are mainly linked to energy production, anti-fungal and/or insecticidal activity, or to the regulation of both protein synthesis and degradation.
Starch and Glycogen Analyses
(2020)
For complex carbohydrates, such as glycogen and starch, various analytical methods and techniques exist allowing the detailed characterization of these storage carbohydrates. In this article, we give a brief overview of the most frequently used methods, techniques, and results. Furthermore, we give insights in the isolation, purification, and fragmentation of both starch and glycogen. An overview of the different structural levels of the glucans is given and the corresponding analytical techniques are discussed. Moreover, future perspectives of the analytical needs and the challenges of the currently developing scientific questions are included