Papers by Andreas I. Theocharis (Ανδρέας Ι. Θεοχάρης)
… Journal of Crop …, 2010
Several grapevine varieties are grown in vineyards worldwide including interspecific (Vitis vinif... more Several grapevine varieties are grown in vineyards worldwide including interspecific (Vitis vinifera Vitis spp), intraspecific (V. viniferaL. V. vinifera L.) and inter-intraspecific (interspecific intraspecific) hybrids with unknown origin, ambiguous naming and genetic ...
Http Www Theses Fr, 2010
Burkholderia phytofirmans strain PsJN is a plant growth-promoting rhizobacterium (PGPR) able to e... more Burkholderia phytofirmans strain PsJN is a plant growth-promoting rhizobacterium (PGPR) able to establish rhizosphere and endophytic populations in grapevine. This bacterium was able to induce resistance against Botrytis cinerea and to low temperatures. To further investigate the interaction between grapevine and strain PsJN, changes in the expression pattern of several defense-related genes were analyzed in Chardonnay grapevine plantlets following root inoculation with bacteria. Results showed significant increase in the expression of defense related genes in leaves, although the bacteria were not present int the upper parts of the grapevine plantlets. The observed pattern of defense related-genes was typical for induced systemic resistance.
Molecular Plant-Microbe Interactions®, 2012
Low temperatures damage many temperate crops, including grapevine, which, when exposed to chillin... more Low temperatures damage many temperate crops, including grapevine, which, when exposed to chilling, can be affected by symptoms ranging from reduced yield up to complete infertility. We have previously demonstrated that Burkholderia phytofirmans PsJN, a plant growth-promoting rhizobacteria (PGPR) that colonizes grapevine, is able to reduce chilling-induced damage. We hypothesized that the induced tolerance may be explained at least partly by the impact of bacteria on grapevine photosynthesis or carbohydrate metabolism during cold acclimation. To investigate this hypothesis, we monitored herein the fluctuations of photosynthesis parameters (net photosynthesis [Pn], intercellular CO2 concentration, stomatal conductances, ΦPSII, and total chlorophyll concentration), starch, soluble sugars (glucose, fructose, saccharose, mannose, raffinose, and maltose), and their precursors during 5 days of chilling exposure (4°C) on grapevine plantlets. Bacterization affects photosynthesis in a non–st...
Molecular Plant-Microbe Interactions, 2012
Several endophytic bacteria reportedly induce resistance to biotic stress and abiotic stress tole... more Several endophytic bacteria reportedly induce resistance to biotic stress and abiotic stress tolerance in several plant species. Burkholderia phytofirmans PsJN is a plant-growth-promoting rhizobacterium (PGPR) that is able to colonize grapevine tissues and induce resistance to gray mold. Further, PsJN induces physiological changes that increase grapevine tolerance to low nonfreezing temperatures. To better understand how bacteria induced the observed phenomena, stress-related gene expression and metabolite accumulation were monitored in 6-week-old Chardonnay grapevine plantlets after exposure to low nonfreezing temperatures. Under normal conditions (26°C), plantlet bacterization had no significant effect on the monitored parameters. By contrast, at 4°C, both stress-related gene transcripts and metabolite levels increased earlier and faster, and reached higher levels in PsJN-bacterized plantlets than in nonbacterized counterparts, in accordance with priming phenomena. The recorded ch...
Interaction of Plant with Beneficial Microbes; Plant Molecular Physiology & Biotechnology; Study ... more Interaction of Plant with Beneficial Microbes; Plant Molecular Physiology & Biotechnology; Study of Genetic Diversity by Molecular Markers; Transcription Analysis by cDNA Technology, Analysis of Biochemical & Physiological Parameters in Plants under Stress
"Apart from water availability, low temperature is the most important environmental factor limiti... more "Apart from water availability, low temperature is the most important environmental factor limiting the productivity and geographical distribution of plants across the world. To cope
with cold stress, plant species have evolved several physiological and molecular adaptations to maximize cold tolerance by adjusting their metabolism. The regulation of some gene products represents an additional mechanism of cold tolerance. A consequence of these mechanisms is that plants are able to survive exposure to low temperature via a process known as cold acclimation. In this review, we briefly summarize recent progress in research and hypotheses on how sensitive plants perceive cold. We also explore how this perception is translated into changes within plants following exposure to low temperatures. Particular emphasis is placed on physiological parameters as well as transcriptional, post-transcriptional and post-translational regulation of cold-induced gene products that occur after exposure to low temperatures, leading to cold acclimation."
Low temperatures damage many temperate crops, including grapevine, which, when exposed to chillin... more Low temperatures damage many temperate crops, including grapevine, which, when exposed to chilling, can be affected by symptoms ranging from reduced yield up to complete infertility. We have previously demonstrated that Burkholderia phytofirmans PsJN, a plant growth-promoting rhizobacteria (PGPR) that colonizes grapevine, is able to reduce chilling-induced damage. We hypothesized that the induced tolerance may be explained at least partly by the impact of bacteria on grapevine photosynthesis or carbohydrate metabolism during cold acclimation. To investigate this hypothesis, we monitored herein the fluctuations of photosynthesis parameters (net photosynthesis [P(n)], intercellular CO(2) concentration, stomatal conductances, ΦPSII, and total chlorophyll concentration), starch, soluble sugars (glucose, fructose, saccharose, mannose, raffinose, and maltose), and their precursors during 5 days of chilling exposure (4°C) on grapevine plantlets. Bacterization affects photosynthesis in a non-stomatal dependent pattern and reduced long-term impact of chilling on P(n). Furthermore, all studied carbohydrates known to be involved in cold stress tolerance accumulate in non-chilled bacterized plantlets, although some of them remained more concentrated in the latter after chilling exposure. Overall, our results suggest that modification of carbohydrate metabolism in bacterized grapevine plantlets may be one of the major effects by which this PGPR reduces chilling-induced damage
Several endophytic bacteria reportedly induce resistance to biotic stress and abiotic stress tole... more Several endophytic bacteria reportedly induce resistance to biotic stress and abiotic stress tolerance in several plant species. Burkholderia phytofirmans strain PsJN (PsJN) is a plant growth-promoting rhizobacterium (PGPR) that is able to colonize grapevine tissues and induce resistance to gray mold. Further, PsJN induces physiological changes that increase grapevine tolerance to low non-freezing temperatures. To better understand how bacteria induced the observed phenomena, stress-related gene expression and metabolite accumulation were monitored in 6-week-old Chardonnay grapevine plantlets after exposure to low non-freezing temperatures. Under normal conditions (26°C), plantlet bacterization had no significant effect on the monitored parameters. By contrast, at 4°C, both stress-related gene transcripts and metabolite levels increased earlier, faster, and reached higher levels in PsJN-bacterized plantlets than in non-bacterized counterparts, in accordance with priming phenomena. The recorded changes may be correlated with the tolerance to cold stress conferred by the presence of PsJN. This is the first time that PGPR-induced priming has been shown to protect plants against low temperature stress. Moreover, one week after cold exposure, levels of stress-related metabolites had declined more in PsJN-bacterized plants, suggesting that the endophyte is involved in the cold acclimation process via scavenging system.
Burkholderia phytofirmans strain PsJN has been well characterized as a Plant Growth Promoting Rhi... more Burkholderia phytofirmans strain PsJN has been well characterized as a Plant Growth Promoting Rhizobacteria (PGPR) that triggers induced resistance in grapevine against fungal pathogens. Recently, it has been demonstrated that B. phytofirmans may also enhance resistance to stress in low non-freezing temperatures. To better understand the interaction between grapevine and B. phytofirmans strain PsJN, changes in the expression pattern of different defence related genes were investigated in Chardonnay grapevine leaves after root inoculation with PsJN strain. B. phytofirmans induced a systemic spread of a signal from roots to leaves after root inoculation with bacteria, a phenomenon referred to as Induced Systemic Resistance (ISR). The expression pattern of well-characterized grapevine defence genes was also monitored in grapevine plantlets bacterized four weeks earlier, and subjected to low non-freezing temperature. Results report that PsJN induces earlier and/or higher transcript accumulation of defence genes in bacterized plantlets upon low non-freezing temperatures according to the phenomenon of priming. Further investigation of several biochemical parameters reveals that bacterized grapevine plantlets are in a primed physiological state able to increase their sugar, starch and proline levels upon low non-freezing temperatures while the analysis of membrane lipid peroxidation markers indicates a faster degradation of aldehydes, malonaldehyde and hydrogen peroxide beyond one week, addressing the better adaptation of bacterized plantlets than non-bacterized plantlets to low non-freezing temperature. In addition, nine combinations of non-radioactive digoxigenine labelled-PstI and MseI primers were used to generate differentially expressed genes by cDNA-AFLP technology for further investigation of primed physiological state induced by PsJN and isolation of over-expressed genes upon low non-freezing temperatures. In conclusion, it is suggested that PsJN strain is an ISR-inducing PGPR able to stimulate grapevine defence mechanism by priming physiological responses critical to acclimation under low non-freezing temperatures.
Several grapevine varieties are grown in vineyards worldwide including interspecific (V... more Several grapevine varieties are grown in vineyards worldwide including interspecific (Vitis vinifera × Vitis spp),
intraspecific (V. viniferaL. × V. vinifera L.) and inter×intraspecific (interspecific×intraspecific) hybrids with unknown
origin, ambiguous naming and genetic identity. In this study, the genetic relations among eighteen grapevine hybrids
and original varieties (Vitis vinifera L.) which have mostly been described by ampelography data were analysed using
AFLP (Amplified Fragments Length Polymorphism) molecular marker technology. AFLP polymorphic fragments
generated by a combination of restriction digestion and PCR amplifications were assessed for analysis of the
polymorphisms among accessions. Polymorphic bands were scored and genetic similarity (GS) was calculated by Dice
coefficient. Cluster analysis and principle coordinate analyses (PCO) of the results addressed the genetic distance among inter-intraspecific hybrids and original grapevine varieties; detected the level of genetic similarity between varieties and specific mutant or clone; assessed the genetic relations among varieties involved in the same pedigree; recognized same genotypes under different names (synonymes) and proposed the genetic identity for an unknown, in ampelography data variety cultivated in UK vineyards.
Στη συγκεκριμένη μελέτη, μέσω της ανάπτυξης της AFLPs (Ανάλυση πολυμορφισμού ενισχυμένου μήκους θ... more Στη συγκεκριμένη μελέτη, μέσω της ανάπτυξης της AFLPs (Ανάλυση πολυμορφισμού ενισχυμένου μήκους θραυσμάτων) μοριακής τεχνικής, προσδιορίζονται οι γενετικές αποστάσεις των ποικιλιών της αμπέλου (Vitis vinifera L.) με τα διαειδικά υβρίδια διαστάυρωσης (Vitis vinifera L. x Vitis spp.) και αναλύονται οι γενετικές σχέσεις της ποικιλίας Riesling (Riesling Weiss) με συγγενικές ποικιλίες αποτέλεσμα είτε κλωνικής επιλογής είτε διαστάυρωσης με άλλες ποικιλίες του είδους V. vinifera L.. Για τον σκοπό αυτό χρησιμοποιήθηκαν 6 ζευγάρια εκκινητών για την απομόνωση 365 γενετικών τόπων, βάση των οποίων έγινε ο προσδιορισμός του βαθμού γενετικής ομοιότητας, καθορίζοντας τις γενετικές σχέσεις μεταξύ των ποικιλιών μέσω της φυλογενετικής ανάλυσης και της ανάλυσης κυρίων συντεταγμένων (PCO).
Talks by Andreas I. Theocharis (Ανδρέας Ι. Θεοχάρης)
Burkholderia phytofirmans strain PsJN is an endophytic Plant Growth Promoting Rhizobacteria (PGPR... more Burkholderia phytofirmans strain PsJN is an endophytic Plant Growth Promoting Rhizobacteria (PGPR) that enhances chilling tolerance of grapevine plants (Ait Barka et al.
2006). Molecular and biochemical approaches were investigated to explore several mechanisms by which this endophyte could improve cold tolerance by analyzing: (i) effect on expression of defence and cold related genes, (ii) modulation of H2O2 production and (iii) stimulation of plant primary metabolism. Before chilling exposure, bacterized plants displayed higher concentrations of carbohydrates
known to be involved in cryoprotection (starch, sucrose and raffinose). When exposed to chilling, bacterized plants exhibited priming of several defence related
genes (VvPAL, VvStSy, VvLOX…) as well as priming of the key cold regulator VvCBF4 (Theocharis et al. 2012). Furthermore, bacterized plants were characterized by a faster and stronger production of H2O2 and subsequent faster detoxication of this oxidative species. Overall, our results suggest that B. phytofirmans strain PsJN promotes grapevine chilling tolerance using several distinct pathways, whether existing or cold-induced mechanisms.
Future prospects include testing whether these variations also occurred in inflorescence of bacterized inflorescence, since this organ is especially sensitive to cold damages.
Induced defense mechanism has been succeeded by root colonization with plant growth promoting rhi... more Induced defense mechanism has been succeeded by root colonization with plant growth promoting rhizobacteria (PGPR), a phenomenon called Induced Systemic Resistance (ISR). Although ISR is linked to independent pathways of SAR, in some cases ISR, similarly to SAR, can be stimulated by systemic increase of salicylic acid levels in plant tissue and accumulation of pathogenesis related (PR) proteins. ISR and SAR have also been associated with an efficient activation of faster and/or stronger cellular defense responses against environmental stresses, a phenomenon known as priming. In the present study, ISR induced by PGPR Burkholderia phytofirmans strain PsJN, was analyzed in grapevine leaves by monitoring the expression pattern of defense-related genes coding for enzymes of phenylpropanoid pathway, the octadecanoid pathway, and PR proteins after root colonization. Priming was analyzed by studying the expression pattern of defence-related genes in non-bacterized and bacterized (6wks-colonized by strain PsJN) grapevine plantlets under low non-freezing temperature (4 ºC). Grapevine defense mechanism was stimulated by strain PsJN, inducing the characteristic ISR 12 and 24 h after root colonization. In addition, 6wks-bacterized plantlets showed earlier and higher expression of genes after 24, 48 and 72 h at 4ºC, compared to non-bacterized plantlets. Grapevine plantlets colonized by strain PsJN at 4ºC demonstrated an over-activation of several physiological responses related to cold acclimation showing not only an improved adaptation to chilling, but also a possible increased resistance to freezing. This study addresses strain PsJN as ISR-inducing PGPR that can prime the physiological responses of grapevine, suggesting priming as an enhanced protective mechanism to environmental stresses acting also as a save-energy defense model.
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Papers by Andreas I. Theocharis (Ανδρέας Ι. Θεοχάρης)
with cold stress, plant species have evolved several physiological and molecular adaptations to maximize cold tolerance by adjusting their metabolism. The regulation of some gene products represents an additional mechanism of cold tolerance. A consequence of these mechanisms is that plants are able to survive exposure to low temperature via a process known as cold acclimation. In this review, we briefly summarize recent progress in research and hypotheses on how sensitive plants perceive cold. We also explore how this perception is translated into changes within plants following exposure to low temperatures. Particular emphasis is placed on physiological parameters as well as transcriptional, post-transcriptional and post-translational regulation of cold-induced gene products that occur after exposure to low temperatures, leading to cold acclimation."
intraspecific (V. viniferaL. × V. vinifera L.) and inter×intraspecific (interspecific×intraspecific) hybrids with unknown
origin, ambiguous naming and genetic identity. In this study, the genetic relations among eighteen grapevine hybrids
and original varieties (Vitis vinifera L.) which have mostly been described by ampelography data were analysed using
AFLP (Amplified Fragments Length Polymorphism) molecular marker technology. AFLP polymorphic fragments
generated by a combination of restriction digestion and PCR amplifications were assessed for analysis of the
polymorphisms among accessions. Polymorphic bands were scored and genetic similarity (GS) was calculated by Dice
coefficient. Cluster analysis and principle coordinate analyses (PCO) of the results addressed the genetic distance among inter-intraspecific hybrids and original grapevine varieties; detected the level of genetic similarity between varieties and specific mutant or clone; assessed the genetic relations among varieties involved in the same pedigree; recognized same genotypes under different names (synonymes) and proposed the genetic identity for an unknown, in ampelography data variety cultivated in UK vineyards.
Talks by Andreas I. Theocharis (Ανδρέας Ι. Θεοχάρης)
2006). Molecular and biochemical approaches were investigated to explore several mechanisms by which this endophyte could improve cold tolerance by analyzing: (i) effect on expression of defence and cold related genes, (ii) modulation of H2O2 production and (iii) stimulation of plant primary metabolism. Before chilling exposure, bacterized plants displayed higher concentrations of carbohydrates
known to be involved in cryoprotection (starch, sucrose and raffinose). When exposed to chilling, bacterized plants exhibited priming of several defence related
genes (VvPAL, VvStSy, VvLOX…) as well as priming of the key cold regulator VvCBF4 (Theocharis et al. 2012). Furthermore, bacterized plants were characterized by a faster and stronger production of H2O2 and subsequent faster detoxication of this oxidative species. Overall, our results suggest that B. phytofirmans strain PsJN promotes grapevine chilling tolerance using several distinct pathways, whether existing or cold-induced mechanisms.
Future prospects include testing whether these variations also occurred in inflorescence of bacterized inflorescence, since this organ is especially sensitive to cold damages.
with cold stress, plant species have evolved several physiological and molecular adaptations to maximize cold tolerance by adjusting their metabolism. The regulation of some gene products represents an additional mechanism of cold tolerance. A consequence of these mechanisms is that plants are able to survive exposure to low temperature via a process known as cold acclimation. In this review, we briefly summarize recent progress in research and hypotheses on how sensitive plants perceive cold. We also explore how this perception is translated into changes within plants following exposure to low temperatures. Particular emphasis is placed on physiological parameters as well as transcriptional, post-transcriptional and post-translational regulation of cold-induced gene products that occur after exposure to low temperatures, leading to cold acclimation."
intraspecific (V. viniferaL. × V. vinifera L.) and inter×intraspecific (interspecific×intraspecific) hybrids with unknown
origin, ambiguous naming and genetic identity. In this study, the genetic relations among eighteen grapevine hybrids
and original varieties (Vitis vinifera L.) which have mostly been described by ampelography data were analysed using
AFLP (Amplified Fragments Length Polymorphism) molecular marker technology. AFLP polymorphic fragments
generated by a combination of restriction digestion and PCR amplifications were assessed for analysis of the
polymorphisms among accessions. Polymorphic bands were scored and genetic similarity (GS) was calculated by Dice
coefficient. Cluster analysis and principle coordinate analyses (PCO) of the results addressed the genetic distance among inter-intraspecific hybrids and original grapevine varieties; detected the level of genetic similarity between varieties and specific mutant or clone; assessed the genetic relations among varieties involved in the same pedigree; recognized same genotypes under different names (synonymes) and proposed the genetic identity for an unknown, in ampelography data variety cultivated in UK vineyards.
2006). Molecular and biochemical approaches were investigated to explore several mechanisms by which this endophyte could improve cold tolerance by analyzing: (i) effect on expression of defence and cold related genes, (ii) modulation of H2O2 production and (iii) stimulation of plant primary metabolism. Before chilling exposure, bacterized plants displayed higher concentrations of carbohydrates
known to be involved in cryoprotection (starch, sucrose and raffinose). When exposed to chilling, bacterized plants exhibited priming of several defence related
genes (VvPAL, VvStSy, VvLOX…) as well as priming of the key cold regulator VvCBF4 (Theocharis et al. 2012). Furthermore, bacterized plants were characterized by a faster and stronger production of H2O2 and subsequent faster detoxication of this oxidative species. Overall, our results suggest that B. phytofirmans strain PsJN promotes grapevine chilling tolerance using several distinct pathways, whether existing or cold-induced mechanisms.
Future prospects include testing whether these variations also occurred in inflorescence of bacterized inflorescence, since this organ is especially sensitive to cold damages.