Entity

Time filter

Source Type


Tsaniklidis G.,Agricultural University of Athens | Nikoloudakis N.,Vegetative Propagation Material Control Station | Delis C.,Technological Educational Institute of Kalamata | Aivalakis G.,Agricultural University of Athens
Horticultural Science | Year: 2014

Ascorbate metabolism is an essential procedure for all plant cells that plays important roles in several physiological processes such as plant development and reactive oxygen species detoxification. To shed more light on ascorbate metabolism in certain organs of tomato plants, we performed a detailed compartmentalized analysis of ascorbate concentration, ascorbate peroxidase/dehydroascorbate reductase enzyme activities and transcript accumulation of genes related to ascorbate metabolism. Our results showed higher level of ascorbate concentration and ascorbate peroxidase and dehydroascorbate reductase activities in young leaves and shoot tips, while min. ascorbate concentration was recorded in root tips. The study of the expression of the genes involved in ascorbate metabolism revealed that several genes followed similar patterns. However, APX3 gene expression was considerably higher in reproductive organs, while plastidial APX6 and DHAR2 genes transcripts were barely detectable in root tips. Organ-specific expression of genes involved in ascorbate metabolism suggests that different isoenzymes have a specific role in regulation of the redox status of some of the organs in tomato plants. Source


Maria T.,Agricultural University of Athens | Tsaniklidis G.,Agricultural University of Athens | Delis C.,Technological Educational Institute of Kalamata | Nikolopoulou A.-E.,Agricultural University of Athens | And 3 more authors.
Plant Gene | Year: 2016

The flavor of tomato fruits is mostly influenced by the accumulation of sugars and organic acids. During fruit ripening a conversion of starch to sugars occurs, which modulates significantly the taste and consequently the quality of the ripe tomato fruits. β-Amylases, a group of major starch hydrolytic enzymes involved in starch degradation were examined in developing cherry tomatoes. Our results suggest that the enzyme activity and the gene transcript accumulation of plastidial β-amylase isoenzymes were elevated during the late stages of fruit development indicating a participation of the enzyme in starch depletion and in the increase of total soluble sugar levels in ripe tomatoes. © 2015 The Authors. Published by Elsevier B.V. All rights reserved. Source


Rounis V.,Agricultural University of Athens | Skarmoutsos K.,Agricultural University of Athens | Tsaniklidis G.,Agricultural University of Athens | Nikoloudakis N.,Vegetative Propagation Material Control Station | And 3 more authors.
Journal of Plant Growth Regulation | Year: 2015

Farmers often resort to the production of auxin-induced parthenocarpic tomato fruits to overcome the adverse climatic conditions which are unfavorable for sufficient fertilization and to lengthen the production period. Even though this practice improves the out-of-season yield, it often undermines fruit quality. In the current study, we examined the effect of induced parthenocarpy in cherry tomato cv. Conchita on the concentration of the main sugars, and on the expression, the activity and the localization of UDP-glucose pyrophosphorylase (UGPase) and sucrose phosphate synthase (SPS), enzymes that are actively involved in sucrose metabolism. Minor differences were detected in sugar levels of seeded and parthenocarpic fruits, whereas considerable variances were found in transcript accumulation and enzyme activities of both UGPase and SPS. Moreover, both proteins were present in the developing seeds. Our data indicate that although induced parthenocarpy significantly influences sucrose metabolism, it has a negligible effect on sugar levels. © 2014, Springer Science+Business Media New York. Source


Tsaniklidis G.,Agricultural University of Athens | Delis C.,Technological Educational Institute of Kalamata | Nikoloudakis N.,Vegetative Propagation Material Control Station | Katinakis P.,Agricultural University of Athens | Aivalakis G.,Agricultural University of Athens
Plant Physiology and Biochemistry | Year: 2014

Tomato fruits are an important source of l-Ascorbic acid, which is an essential compound of human diet. The effect of the widespread practice of cold storing (5-10°C) tomato fruits was monitored to determine its impact on the concentration and redox status of l-Ascorbic acid. Total l-Ascorbic acid levels were well maintained in both attached fruits and cold treated fruits, while in other treatments its levels were considerably reduced. However, low temperature storage conditions enhanced the expression of most genes coding for enzymes involved in l-Ascorbic acid biosynthesis and redox reactions. The findings suggest that the transcriptional up-regulation under chilling stress conditions of most genes coding for l-Ascorbic acid biosynthetic genes galactono-1,4-lactone dehydrogenase, GDP-. d-mannose 3,5-epimerase but also for the isoenzymes of ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase enzyme, glutathione reductase that are strongly correlated to the l-Ascorbic redox status. Moreover, fruits stored at 10°C exhibited higher levels of transcript accumulation of MDHAR2, DHAR1, DHAR2, GR1 and GR2 genes, pointing to a better ability to manage chilling stress in comparison to fruits stored at 5°C. © 2014 Elsevier Masson SAS. Source


Tsilikochrisos G.,Agricultural University of Athens | Tsaniklidis G.,Agricultural University of Athens | Delis C.,Technological Educational Institute of Kalamata | Nikoloudakis N.,Vegetative Propagation Material Control Station | Aivalakis G.,Agricultural University of Athens
Scientia Horticulturae | Year: 2015

Cherry tomatoes are more susceptible than larger fruit varieties to producing auxin-induced parthenocarpic fruits indistinguishable from seeded fruits in most organoleptic characteristics. In this study, the effects of auxin-induced parthenocarpy and of the short-term cold storage on the expression of GDH genes, one of the main regulatory enzymes of nitrogen metabolism, were examined. Seeded and parthenocarpic fruits exhibited differences in the pattern of expression of the genes coding for α- and β-subunits of GDH during fruit development. Short-term cold storage at 5. °C significantly increased transcript accumulation of GDH genes, while storage at 10. °C for five days mostly caused a reduction in the expression of the genes in both fruit types. Finally, no significant differences between the two fruit types were detected in the localization of GDH protein and GDH enzyme activity. © 2014 Elsevier B.V. Source

Discover hidden collaborations