http://ktisis.cut.ac.cy/handle/10488/14 Search the Channel search http://ktisis.cut.ac.cy/simple-search http://ktisis.cut.ac.cy/handle/10488/8155 Title: Alternative oxidase 1 (Aox1) gene expression in roots of Medicago truncatula is a genotype-specific component of salt stress tolerance<br/><br/>Authors: Mhadhbi, Haythem; Fotopoulos, Vasileios; Mylona, Photini V.; Jebara, Moez; Mohamed, Elarbi Aouani; Polidoros, Alexios N.<br/><br/>Abstract: Alternative oxidase (AOX) is the central component of the non-phosphorylating alternative respiratory pathway in plants and may be important for mitochondrial function during environmental stresses. Recently it has been proposed that Aox can be used as a functional marker for breeding stress tolerant plant varieties. This requires characterization of Aox alleles in plants with different degree of tolerance in a certain stress, affecting plant phenotype in a recognizable way. In this study we examined Aox1 gene expression levels in Medicago truncatula genotypes differing in salt stress tolerance, in order to uncover any correlation between Aox expression and tolerance to salt stress. Results demonstrated a specific induction of Aox1 gene expression in roots of the tolerant genotype that presented the lowest modulation in phenotypic and biochemical stress indices such as morphologic changes, protein level, lipid peroxidation and ROS generation. Similarly, in a previous study we reported that induction of antioxidant gene expression in the tolerant genotype contributed to the support of the antioxidant cellular machinery and stress tolerance. Correlation between expression patterns of the two groups of genes was revealed mainly in 48 h treated roots. Taken together, results from both experiments suggest that M. truncatula tolerance to salt stress may in part due to an efficient control of oxidative balance thanks to (i) induction of antioxidant systems and (ii) involvement of the AOX pathway. This reinforces the conclusion that differences in antioxidant mechanisms can be essential for salt stress tolerance in M. truncatula and possibly the corresponding genes, especially Aox, could be utilized as functional marker. Mon, 29 Oct 2012 22:58:59 GMT http://ktisis.cut.ac.cy/handle/10488/8152 Title: Priming against environmental challenges and proteomics in plants: update and agricultural perspectives<br/><br/>Authors: Tanou, Georgia; Fotopoulos, Vasileios; Molassiotis, Athanassios<br/><br/>Abstract: Priming is the cellular state in which the harmful effects of abiotic stress factors in plants are hindered by pre-exposure to a stimulus, thus resulting in greater survival. It is becoming increasingly evident that priming techniques (e.g., external application of natural or synthetic compounds in plants) can enhance the tolerance of crops to environmental stresses. Innovative systems biology approaches such as proteomics are currently recognized as essential tools to understand the molecular mechanisms underlying plant responses to environmental stimuli and priming phenomena. The few published proteomic studies on priming in the context of environmental stress identify key protein targets and signaling pathways which are being involved in the alleviation of negative effects of stress factors. Since priming is a very promising strategy in modern crop production management, further research is needed in order to establish the global picture of priming phenomena against environmental challenges as well as to characterize specific priming-related protein indicators in plants Mon, 29 Oct 2012 22:58:59 GMT http://ktisis.cut.ac.cy/handle/10488/8151 Title: The nitric oxide donor sodium nitroprusside regulates polyamine and proline metabolism in leaves of Medicago truncatula plants<br/><br/>Authors: Filippou, Panagiota; Antoniou, Chrystalla; Fotopoulos, Vasileios<br/><br/>Abstract: Nitric oxide (NO), polyamines, and proline have all been suggested to play key roles in a wide spectrum of physiological processes and abiotic stress responses. Although exogenous application of polyamines has been shown to induce NO production, the effect of NO on polyamine biosynthesis has not yet been elucidated. Several reports exist that demonstrate the protective action of sodium nitroprusside (SNP), a widely used NO donor, which acts as a signal molecule in plants responsible for the regulation of the expression of many defense-related enzymes. This study attempted to provide a novel insight into the effects of application of low (100 μΜ) and high (2.5 mM) concentrations of SNP on the biosynthesis of two major abiotic stress response-related metabolites, polyamines and proline, in mature (40 day) and senescing (65 day) Medicago truncatula plants. Physiological data showed that long-term (24 h), higher SNP concentration resulted in decreased photosynthetic rate and stomatal conductance followed by intracellular putrescine and proline accumulation, as a result of an increase in biosynthetic arginine decarboxylase (ADC) and Δ1 -pyrroline-5-carboxylate synthetase (P5CS) enzymatic activity, respectively. Further analysis of polyamine oxidase (PAO)/diamine oxidase (DAO) polyamine catabolic enzymes indicated that DAO enzymatic activity increased significantly in correlation with putrescine accumulation, whereas PAO activity, involved in spermidine/spermine degradation, increased slightly. Moreover, transcriptional analysis of polyamine and proline metabolism genes (P5CS, P5CR, ADC, SPMS, SPDS, SAMDC, PAO, DAO) further supported the obtained data and revealed a complex SNP concentration-, time-, and developmental stage-dependent mechanism controlling endogenous proline and polyamine metabolite production. This is the first report to provide a global analysis leading to a better understanding of the role of the widely used NO donor SNP in the regulation of key stress-related metabolic pathways. Mon, 29 Oct 2012 22:58:59 GMT http://ktisis.cut.ac.cy/handle/10488/8150 Title: Proteomics in the fruit tree science arena: new insights into fruit defense, development and ripening<br/><br/>Authors: Molassiotis, Athanassios; Tanou, Georgia; Fotopoulos, Vasileios<br/><br/>Abstract: Fruit tree crops are agricultural commodities of high economic importance, while fruits also represent one of the most vital components of the human diet. Therefore, a great effort has been made to understand the molecular mechanisms covering fundamental biological processes in fruit tree physiology and fruit biology. Thanks to the development of cutting-edge ‘omics’ technologies such as proteomic analysis, scientists now have powerful tools to support traditional fruit tree research. Such proteomic analyses are establishing high-density 2-DE reference maps and peptide mass fingerprint databases that can lead fruit science into a new post-genomic research era. Here, an overview of the application of proteomics in key aspects of fruit tree physiology as well as in fruit biology, including defense responses to abiotic and biotic stress factors, is presented. Α panoramic view of ripening-related proteins is also discussed, as an example of proteomic application in fruit science. Mon, 29 Oct 2012 22:58:59 GMT