Publications (6)20.88 Total impact
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Article: Role of lupeol synthase in Lotus japonicus nodule formation.
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ABSTRACT: • Triterpenes are plant secondary metabolites, derived from the cyclization of 2,3-oxidosqualene by oxidosqualene cyclases (OSCs). Here, we investigated the role of lupeol synthase, encoded by OSC3, and its product, lupeol, in developing roots and nodules of the model legume Lotus japonicus. • The expression patterns of OSC3 in different developmental stages of uninfected roots and in roots infected with Mesorhizobium loti were determined. The tissue specificity of OSC3 expression was analysed by in situ hybridization. Functional analysis, in which transgenic L. japonicus roots silenced for OSC3 were generated, was performed. The absence of lupeol in the silenced plant lines was determined by GC-MS. • The expression of ENOD40, a marker gene for nodule primordia initiation, was increased significantly in the OSC3-silenced plant lines, suggesting that lupeol influences nodule formation. Silenced plants also showed a more rapid nodulation phenotype, consistent with this. Exogenous application of lupeol to M. loti-infected wild-type plants provided further evidence for a negative regulatory effect of lupeol on the expression of ENOD40. • The synthesis of lupeol in L. japonicus roots and nodules can be solely attributed to OSC3. Taken together, our data suggest a role for lupeol biosynthesis in nodule formation through the regulation of ENOD40 gene expression.New Phytologist 01/2011; 189(1):335-46. · 6.64 Impact Factor -
Article: A root- and hypocotyl-specific gene coding for copper-containing amine oxidase is related to cell expansion in soybean seedlings.
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ABSTRACT: Polyamines are considered to participate in various processes of plant development. In this study, the possible implication of putrescine catabolism by the copper-containing amine oxidases (CuAOs, EC 1.4.3.6) in the development of roots and hypocotyls was examined. For this purpose, two cDNA clones of Glycine max (L.) Merr. cv. Williams, designated as GmCuAO1 and GmCuAO2, exhibiting extensive similarity with previously characterized CuAO clones from other plants, have been isolated and characterized. The expression of the GmCuAO1 gene is root- and hypocotyl-specific, while GmCuAO2 seems not to be expressed in a tissue-specific manner. Moreover, the GmCuAO1 gene is predominantly expressed in tissues which are characterized by rapid extension growth, such as the apical segments of etiolated hypocotyls. Using convex and concave segments of the etiolated hypocotyl apical hook it has been demonstrated that GmCuAO1 is strongly expressed in expanding cells of the concave part when exposed to light, while the same pattern is also followed by the activity of enzymes involved in putrescine catabolism. In dark and photoperiodically grown hypocotyls, activity measurements of the enzymes involved in putrescine catabolism have shown that the activity of these enzymes is several-fold higher in rapidly growing tissues. Furthermore, the cellular and tissue distribution of GmCuAO1 gene transcripts in the root axis and in hypocotyls confirmed their abundance in developing tissues and expanding cells. The results provide evidence suggesting that a tissue-specific gene coding for CuAO is correlated with cell expansion in fast-growing tissues of root and hypocotyls.Journal of Experimental Botany 02/2006; 57(1):101-11. · 5.36 Impact Factor -
Article: Co-expression of two sugar transporters in primary and lateral roots of etiolated Glycine max seedlings*
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ABSTRACT: Two Glycine max cDNA clones were characterized and designated as GmSUC2 and GmSTP. The encoded proteins were classified, by prediction of membrane topology and sequence homology, as members of the plant sugar porter family of the Major Facilitator Superfamily. The studies on the temporal and spatial accumulation of the corresponding transcripts, using semi-quantitative RT-PCR and in situ hybridization methods, revealed a differing but overlapping expression pattern at various source and sink organs of soybean plants. These results, in accordance to the structural variations apparent from the deduced protein sequences imply that the corresponding proteins may possess diverse roles in source and sink organs of soybean plants, as well as in various tissues, during primary and lateral root development.Plant Growth Regulation 02/2005; 45(3):259-266. · 1.60 Impact Factor -
Article: Ornithine decarboxylase and arginine decarboxylase gene transcripts are co-localized in developing tissues of Glycine max etiolated seedlings.
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ABSTRACT: Unlike other eukaryotes, which synthesize polyamines (PA) only from ornithine, plants possess an additional pathway utilizing arginine as a precursor. In this study, we have identified cDNA clones coding for a Glycine max ornithine decarboxylase (ODC, EC 4.1.1.7) and an arginine decarboxylase (ADC, EC 4.1.1.19). Expression analysis using semi-quantitative RT-PCR approach revealed that both genes coding for enzymes involved in putrescine biosynthesis (ODC and ADC) were found in most plant organs examined. Significant expression levels of both genes were detected in root tips and hypocotyls. The spatial distribution of GmODC and GmADC transcripts in primary and lateral roots and hypocotyls revealed that these genes are co-expressed in expanding cells of cortex parenchyma, expanding cells of central cylinder in main roots and in developing tissues and expanding cells of soybean hypocotyls. The data point out a correlation of the expression patterns of GmODC and GmADC gene to certain physiological roles such as organ development and cell expansion.Plant Physiology and Biochemistry 02/2005; 43(1):19-25. · 2.84 Impact Factor -
Article: Induction and spatial organization of polyamine biosynthesis during nodule development in Lotus japonicus.
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ABSTRACT: Putrescine and other polyamines are produced by two alternative pathways in plants. One pathway starts with the enzyme arginine decarboxylase (ADC; EC 4.1.1.19), the other with ornithine decarboxylase (ODC; EC 4.1.1.17). Metabolite profiling of nitrogen-fixing Lotus japonicus nodules, using gas chromatography coupled to mass spectrometry, revealed a two- to sixfold increase in putrescine levels in mature nodules compared with other organs. Genes involved in polyamine biosynthesis in L japonicus nodules were identified by isolating cDNA clones encoding ADC (LjADC1) and ODC (LjODC) from a nodule library. Searches of the public expressed sequence tag databases revealed the presence of a second gene encoding ADC (LjADC2). Real-time reverse-transcription-polymerase chain reaction analysis showed that LjADC1 and LjADC2 were expressed throughout the plant, while LjODC transcripts were detected only in nodules and roots. Induction of LjODC and LjADC gene expression during nodule development preceded symbiotic nitrogen fixation. Transcripts accumulation was maximal at 10 days postinfection, when a 6.5-fold increase in the transcript levels of LjODC was observed in comparison with the uninfected roots, while a twofold increase in the transcript levels of LjADC1 and LjADC2 was detected. At later stages of nodule development, transcripts for ADC drastically declined, while in the case of ODC, transcript accumulation was higher than that in roots until after 21 days postinfection. The expression profile of genes involved in putrescine biosynthesis correlated well with the expression patterns of genes involved in cell division and expansion, including a L. japonicus Cyclin D3 and an alpha-expansin gene. Spatial localization of LjODC and LjADC1 gene transcripts in developing nodules revealed that both transcripts were expressed in nodule inner cortical cells and in the central tissue. High levels of LjADC1 transcripts were also observed in both nodule and connecting root vascular tissue, suggesting that putrescine and other polyamines may be subject to long-distance transport. Our results indicate that polyamines are primarily involved in physiological and cellular processes involved in nodule development, rather than in processes that support directly symbiotic nitrogen fixation and assimilation.Molecular Plant-Microbe Interactions 01/2005; 17(12):1283-93. · 4.43 Impact Factor -
Article: Genes coding for a putative cell-wall invertase and two putative monosaccharide/H+ transporters are expressed in roots of etiolated Glycine max seedlings
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ABSTRACT: Sink tissues depend on the supply of sugars produced by source tissues. Cell-wall invertases (EC 3.2.1.26) are considered to have a pivotal role in supplying sink tissues with carbohydrates via an apoplasmic pathway, while associated monosaccharide/H+ transporters take up the produced hexoses. In this study, we characterized genes coding for a putative cell-wall invertase (GmCWINV1) and two putative monosaccharide/H+ transporters (GmMST1 and GmMST2) of Glycine max. Semi-quantitative RT-PCR analysis revealed that GmMST1 and GmMST2 are expressed in various plant organs. In situ hybridization revealed that they are expressed in different root tissues. These results propose that different monosaccharide/H+ transporters may play different roles in source and sink organs. In addition, the temporal and spatial expression of GmCWINV1, as was determined by semi-quantitative RT-PCR and in situ hybridization analyses, was detected in tissues where GmMST1 and GmMST2 were also expressed, indicating that, at least part of the sucrose unloaded from soybean phloem may be hydrolyzed into hexoses before being transported from the apoplasmic space into the respective sink cells.Plant Science.
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Institutions
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2011
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University of Thessaly
- Βιοχημείας και Βιοτεχνολογίας
Lárisa, Thessalia, Greece
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2005–2006
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Agricultural University of Athens
- Laboratory of Molecular Biology
Athens, Attiki, Greece
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