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Olive tree growth and reproduction are severely affected by temperature extremes, compromising fruit yield. In that aspect, the olive varieties “Koroneiki” and “Mastoidis” were employed in a mild cold stress experiment, imitating night frost incidents to assess their biochemical, physiological and reproductive functions in relation to genotype. The physiological performance of the stressed plants was not significantly altered, suggesting that both cultivars were well adapted to mild cold night stress. The biochemical response of the plants, regarding antioxidant enzymes, H2O2 and TBARS accumulation, confirmed that both cultivars could cope with the stress applied. The mRNA levels of the PPO gene, which participates in hydroxytyrosol biosynthesis and plant defense, were elevated after 24-h stress at 0 °C, in both cultivars with “Mastoidis” plants exhibiting higher levels for a longer period. Three more genes involved in hydroxytyrosol biosynthesis upregulated their expression levels as a response to cold stress. The numerous plant phenology aspects measured reinforced the conclusion that both cultivars responded to the stress applied. The results of the present study may contribute to better understanding olive tree adaptive responses to low temperature events, an abiotic stress condition that is often present in an open plantation, thus assisting farmers on breeding and cultivar selection.
Niki Mougiou; Boushra Baalbaki; Georgios Doupis; Nektarios Kavroulakis; Stylianos Poulios; Konstantinos Vlachonasios; Georgios Koubouris. The Effect of Low Temperature on Physiological, Biochemical and Flowering Functions of Olive Tree in Relation to Genotype. Sustainability 2020, 12, 10065 .
AMA StyleNiki Mougiou, Boushra Baalbaki, Georgios Doupis, Nektarios Kavroulakis, Stylianos Poulios, Konstantinos Vlachonasios, Georgios Koubouris. The Effect of Low Temperature on Physiological, Biochemical and Flowering Functions of Olive Tree in Relation to Genotype. Sustainability. 2020; 12 (23):10065.
Chicago/Turabian StyleNiki Mougiou; Boushra Baalbaki; Georgios Doupis; Nektarios Kavroulakis; Stylianos Poulios; Konstantinos Vlachonasios; Georgios Koubouris. 2020. "The Effect of Low Temperature on Physiological, Biochemical and Flowering Functions of Olive Tree in Relation to Genotype." Sustainability 12, no. 23: 10065.
Avocado (Persea americana Mill) is a new and rapidly expanded crop in the Mediterranean basin. Due to environmental conditions, its cultivation in Greece, is restricted mainly to Chania prefecture (Crete island), and there is limited data on the fungal diseases which can affect the plantations. In the autumn of 2018, in an orchard in Alikianos district of Chania (35°27′05.03″N, 23°54′49.82″E), approximately 8% of fifty 5 to 6 years-old avocado trees (cv. Hass) showed symptoms consisting of branch and twig cankers with brownish bark discoloration, resulting in twig dieback with brown leaves remaining attached to the trees. Small symptomatic bark tissue pieces from diseased trees (10 tissue pieces originating from two branches of each of the four diseased trees) were surface disinfested in 0.5% sodium hypochlorite followed by 70% EtOH for 2 min each step, rinsed twice with sterile distilled water and dried prior to culturing on potato dextrose agar (PDA), amended with 1 ml of lactic acid 10% per 100 ml PDA (pH 4.5), and incubated in the dark at 25οC for 2 to 3 days. 27 isolates out of 40 isolations were recovered from eight branches (68% isolation frequency) and had identical colony morphology. Mycelial plugs from the actively grown colony margins were transferred onto fresh PDA plates in order to obtain pure cultures. The morphological identification of the fungus was determined based on the pure cultures. Colonies on PDA were white slow-growing with sparse aerial mycelium on which globose to subglobose, dark brown to black, and pycnidia (420-670 μm in diameter) with an elongated neck (up to 100 μm) were produced after 2 weeks. Conidiophores were hyaline, septate and branched (18.0 to 24.0 × 1.9 to 3.0 μm). Alpha-conidia were aseptate, hyaline and ellipsoidal or fusiform and measured 8.0 ± 0.8 × 2.5 ± 0.6 μm (n = 50). Beta-conidia were hyaline, aseptate, filiform and slightly curved, measuring 26.9 ± 1.8 × 1.3 ± 0.2 μm (n = 50) and presented in larger numbers than alpha-conidia. The morphological and cultural characteristics of the isolates were congruent with those of Diaporthe spp. (anamorph Phomopsis spp.). To confirm the morphological identification, DNA from mycelium of four isolates (Av-1, Av-2, Av-6, Av-8) was extracted using the NucleoSpin Plant II kit (Macherey-Nagel). The ITS1-5.8S-ITS2 region was amplified with primers ITS1/ITS4 (White et al., 1990). The PCR products were sequenced, and BLASTn analysis revealed 99.8% similarity with sequences of various D. foeniculina isolates (eg. chestnut [LN651172], citrus [KC843294], soybean [JF430495], apple [MK370623]). All sequences were identical and one representative (isolate Av-1) was deposited in GenBank (MT374094). Partial amplification of β-tubulin (tub2) and translation elongation factor 1-alpha (EF1-a) was performed with Bt2a/Bt2b and EF1-728F/EF1-986R primers, respectively, using the Av-1 isolate (Carbone & Kohn, 1999; Glass & Donaldson, 1995). The amplicons were sequenced, deposited in GenBank (EF1-a: MT374092; tub2: MT374093), and showed 100% homology with sequences of D. foeniculina isolates (tub2: MF418578; EF1-a: LN651178). Thus, the isolate was identified as D. foeniculina (Sacc.) Udayanga & Castl. (Udayanga et al. 2015). Pathogenicity tests were conducted using 15 1.5-year old avocado trees (cv. Hass) under greenhouse conditions. PDA plugs, 4 mm in diameter, with actively growing mycelium of a 7-day-old culture, were transferred onto wounds made by a cork borer on previously sterilized trunk surfaces, covered with sterile paper and sealed with parafilm. Five trees inoculated with noncolonized PDA disks were kept as controls. Five months after inoculation lesions with brownish bark discoloration had developed on all inoculated trees, while control plants remained symptomless. D. foeniculina was re-isolated on PDA from all artificially inoculated plants. Thirty isolations were performed and D. foeniculina was recovered from all symptomatic inoculated plants (100% isolation frequency) and their identity was morphologically reconfirmed. D. foeniculina was further molecularly identified by PCR amplification and sequencing of the ITS and EF1-a regions of two isolates derived from artificially inoculated plants. Koch’s postulates were thus fulfilled with the above described procedure. On avocado, canker symptoms on shoots, branches or trunks are caused by several fungal species belonging to Botryosphaeriaceae and Diaporthiaceae families, and to date, in Europe, there is one report of D. foeniculina in Italy causing avocado canker (Guarnaccia et al., 2016). To our knowledge, this is the first report of D. foeniculina causing branch canker disease on avocado in Crete, Greece. This record provides significant information as the disease poses a new threat to the widely cultivated avocado crops in the area and draws the attention for the application of preventive measures to control spread should be considered.
Matthaios M. Mathioudakis; Georgios T. Tziros; Nektarios Kavroulakis. First Report of Diaporthe foeniculina Associated with Branch Canker of Avocado in Greece. Plant Disease 2020, 104, 3057 .
AMA StyleMatthaios M. Mathioudakis, Georgios T. Tziros, Nektarios Kavroulakis. First Report of Diaporthe foeniculina Associated with Branch Canker of Avocado in Greece. Plant Disease. 2020; 104 (11):3057.
Chicago/Turabian StyleMatthaios M. Mathioudakis; Georgios T. Tziros; Nektarios Kavroulakis. 2020. "First Report of Diaporthe foeniculina Associated with Branch Canker of Avocado in Greece." Plant Disease 104, no. 11: 3057.
The potential of Ag-NPs to suppress Monilia fructicola isolates and to broaden the effectiveness of fungicides to overcome resistance was tested in vitro and in vivo. Twenty-three M. fructicola isolates were subjected to fungitoxicity screening with a number of fungicides in vitro, which resulted in the detection of 18 isolates resistant to benzimidazoles (BEN-R) thiophanare methyl (TM) and carbendazim (CARB). DNA sequencing revealed the E198A resistance mutation in the β-tubulin gene, target site of the benzimidazole fungicides in all resistant isolates. Ag-NPs effectively suppressed mycelial growth in both sensitive (BENS) and resistant isolates. The combination of Ag-NPs with TM led to a significantly enhanced fungitoxic effect compared to the individual treatments regardless resistant phenotype (BEN-R/S) both in vitro and when applied on apple fruit. The above observed additive/synergistic action is probably associated with an enhanced Ag-NPs activity/availability as indicated by the positive correlation between Ag-NPs and TM + Ag-NPs treatments. No correlation was found between AgNO3 and Ag-NPs suggesting that difference(s) exist in the fungitoxic mechanism of action between nanoparticles and their ionic counterparts. Synergy observed between Ag-NPs and the oxidative phosphorylation-uncoupler fluazinam (FM) against both resistance phenotypes indicates a possible role of energy (ATP) metabolism in the mode of action of Ag-NPs. Additionally, the role of released silver ions on the fungitoxic action of Ag-NPs against M. fructicola was found to be limited because the combination with NaCl revealed a synergistic rather than the antagonistic effect that would be expected from silver ion binding with chlorine ions. The results of this study suggested that Ag-NPs can be effectively used against M. fructicola and when used in combination with conventional fungicides they could provide the means for countering benzimidazole resistance and at the same time reduce the environmental impact of synthetic fungicides by reducing doses needed for the control of the pathogen.
Anastasios A. Malandrakis; Nektarios Kavroulakis; Constantinos V. Chrysikopoulos. Use of silver nanoparticles to counter fungicide-resistance in Monilinia fructicola. Science of The Total Environment 2020, 747, 141287 .
AMA StyleAnastasios A. Malandrakis, Nektarios Kavroulakis, Constantinos V. Chrysikopoulos. Use of silver nanoparticles to counter fungicide-resistance in Monilinia fructicola. Science of The Total Environment. 2020; 747 ():141287.
Chicago/Turabian StyleAnastasios A. Malandrakis; Nektarios Kavroulakis; Constantinos V. Chrysikopoulos. 2020. "Use of silver nanoparticles to counter fungicide-resistance in Monilinia fructicola." Science of The Total Environment 747, no. : 141287.
Cultivation of olive trees covers large coastal areas of land in Mediterranean regions, many of them characterized by low soil fertility and exposed to salinity and seasonal drought. In this frame, we developed mixed community inocula of arbuscular mycorrhizal fungi (AMF) derived from the extreme, seasonally arid environments of six Mediterranean sand dunes and evaluated their effects, in the form of community inocula, on rooted semi-woody olive tree cuttings (Olea europaea cv. Koroneiki). The plantlets were grown in the greenhouse for 10 months under 50 mM and 100 mM concentrations of NaCl, successively applied to induce osmotic stress. Inoculation had a positive effect on plant growth and nutrient uptake. However, the three best-performing inocula in early colonization and in plant growth enhancement also resulted in high plant sensitivity to high salinity, which was not observed for the other three inocula. This was expressed by decreased nutrient uptake and drastically lower plant growth, plant photosynthesis, and stomatal conductance (generally an over 50% reduction compared to no salinity application). Amplicon sequencing analysis of the olive plants under salinity stress showed that the AMF communities in the roots were clearly differentiated by inoculation treatment. We could not, however, consistently associate the plant responses observed under high salinity with specific shared AMF community membership or assembly attributes. The observed physiological overreaction to osmotic stress may be an adaptation trait, potentially brought about by host selection coupled to abiotic environmental filtering, in the harsh conditions from which the AMF inocula were derived. The overreaction may, however, be undesirable if conveyed to allochthonous plants at an agronomic level.
Nektarios Kavroulakis; M. Tsiknia; I. Ipsilantis; A. Kavadia; C. Stedel; G. Psarras; C. Tzerakis; G. Doupis; D. G. Karpouzas; K. K. Papadopoulou; C. Ehaliotis. Arbuscular mycorrhizal fungus inocula from coastal sand dunes arrest olive cutting growth under salinity stress. Mycorrhiza 2020, 30, 475 -489.
AMA StyleNektarios Kavroulakis, M. Tsiknia, I. Ipsilantis, A. Kavadia, C. Stedel, G. Psarras, C. Tzerakis, G. Doupis, D. G. Karpouzas, K. K. Papadopoulou, C. Ehaliotis. Arbuscular mycorrhizal fungus inocula from coastal sand dunes arrest olive cutting growth under salinity stress. Mycorrhiza. 2020; 30 (4):475-489.
Chicago/Turabian StyleNektarios Kavroulakis; M. Tsiknia; I. Ipsilantis; A. Kavadia; C. Stedel; G. Psarras; C. Tzerakis; G. Doupis; D. G. Karpouzas; K. K. Papadopoulou; C. Ehaliotis. 2020. "Arbuscular mycorrhizal fungus inocula from coastal sand dunes arrest olive cutting growth under salinity stress." Mycorrhiza 30, no. 4: 475-489.
Combating drug-resistance is a daunting task, especially due to the shortage of available drug alternatives with multisite modes of action. In this study, the potential of copper nanoparticles (Cu-NPs) to suppress 15 Botrytis cinerea isolates, which are sensitive or resistant to fungicides, alone or in combination with conventional fungicides, was tested in vitro and in vivo. Sensitivity screening in vitro revealed two fungicide resistance phenotypes, resulting from target site mutations. DNA sequencing revealed three B. cinerea isolates highly resistant to benzimidazoles (BEN-R), thiophanare methyl (TM), and carbendazim, bearing the E198A resistance mutation in the β-tubulin gene, and four isolates highly resistant to the QoI pyraclostrobin (PYR-R) with a G143A mutation in the cytb gene. Cu-NPs were equally effective against sensitive and resistant isolates. An additive/synergistic effect was observed between Cu-NPs and TM in the case of BEN-S isolates both in vitro and when applied in apple fruit. A positive correlation was observed between TM and TM + Cu-NPs treatments, suggesting that an increased TM availability in the target site could be related with the observed additive/synergistic action. No correlation between Cu(OH)2 and Cu-NPs sensitivity was found, indicating that different mechanisms govern the fungitoxic activity between nano and bulk counterparts. A synergistic profile was observed between Cu-NPs and fluazinam (FM) - an oxidative phosphorylation inhibitor - in all isolates regardless of resistance phenotype, suggesting that ATP metabolism could be involved in the mode of action of Cu-NPs. Furthermore, the observed cross sensitivity and antagonistic action between Cu-NPs and NaCl also provided evidence for copper ions contribution to the fungitoxic action of Cu-NPs. The results suggested that Cu-NPs in combination with conventional fungicides can provide the means for an environmentally safe, sustainable resistance management strategy by reducing fungicide use and combating resistance against B. cinerea.
Anastasios A. Malandrakis; Nektarios Kavroulakis; Constantinos Chrysikopoulos. Synergy between Cu-NPs and fungicides against Botrytis cinerea. Science of The Total Environment 2019, 703, 135557 .
AMA StyleAnastasios A. Malandrakis, Nektarios Kavroulakis, Constantinos Chrysikopoulos. Synergy between Cu-NPs and fungicides against Botrytis cinerea. Science of The Total Environment. 2019; 703 ():135557.
Chicago/Turabian StyleAnastasios A. Malandrakis; Nektarios Kavroulakis; Constantinos Chrysikopoulos. 2019. "Synergy between Cu-NPs and fungicides against Botrytis cinerea." Science of The Total Environment 703, no. : 135557.
Thiresia-Teresa Tzatzani; Nektarios Kavroulakis; Georgios Doupis; Georgios Psarras; Ioannis E. Papadakis. Nutritional status of ‘Hass’ and ‘Fuerte’ avocado (Persea americana Mill.) plants subjected to high soil moisture. Journal of Plant Nutrition 2019, 43, 327 -334.
AMA StyleThiresia-Teresa Tzatzani, Nektarios Kavroulakis, Georgios Doupis, Georgios Psarras, Ioannis E. Papadakis. Nutritional status of ‘Hass’ and ‘Fuerte’ avocado (Persea americana Mill.) plants subjected to high soil moisture. Journal of Plant Nutrition. 2019; 43 (3):327-334.
Chicago/Turabian StyleThiresia-Teresa Tzatzani; Nektarios Kavroulakis; Georgios Doupis; Georgios Psarras; Ioannis E. Papadakis. 2019. "Nutritional status of ‘Hass’ and ‘Fuerte’ avocado (Persea americana Mill.) plants subjected to high soil moisture." Journal of Plant Nutrition 43, no. 3: 327-334.
Demetrios J. Vakalounakis; Spyridon Ntougias; Nektarios Kavroulakis; Eftichios Protopapadakis. Neofusicoccum parvumandDiaporthe foeniculinaassociated with twig and shoot blight and branch canker of citrus in Greece. Journal of Phytopathology 2019, 167, 527 -537.
AMA StyleDemetrios J. Vakalounakis, Spyridon Ntougias, Nektarios Kavroulakis, Eftichios Protopapadakis. Neofusicoccum parvumandDiaporthe foeniculinaassociated with twig and shoot blight and branch canker of citrus in Greece. Journal of Phytopathology. 2019; 167 (9):527-537.
Chicago/Turabian StyleDemetrios J. Vakalounakis; Spyridon Ntougias; Nektarios Kavroulakis; Eftichios Protopapadakis. 2019. "Neofusicoccum parvumandDiaporthe foeniculinaassociated with twig and shoot blight and branch canker of citrus in Greece." Journal of Phytopathology 167, no. 9: 527-537.
Nano-fungicides are expected to play an important role in future plant disease management as eco-friendly alternatives of conventional synthetic fungicides. In the present study, the sensitivity of seven fungal species, known to cause foliar and soil-borne diseases, to nanoparticles (NPs) containing copper (Cu-NPs, CuO-NPs), silver (Ag-NPs) and zinc (ZnO-NPs) was assessed in vitro. Mycelial growth assays revealed that Cu-NPs with mean inhibition rates, EC50, ranging between 162 and 310 μg/mL were most effective among the NPs tested in inhibiting fungal growth, followed by ZnO-NPs with EC50 ranging between 235 and 848 μg/mL. All fungal species were practically insensitive to CuO-NPs and Ag-NPs except for B. cinerea, which was equally sensitive to Ag-NPs and Cu-NPs (EC50 = 307 μg/mL). Cu-NPs were more fungitoxic in terms of mycelial growth, to almost all species tested, than a protective fungicide containing Cu(OH)2, which was used as a reference. Fungitoxicity experiments with the NPs tested and bulk size reagents containing the respective metals revealed that ZnO-NPs were more toxic to all fungal species tested than ZnSO4, whereas Cu-NPs were more fungitoxic than CuSO4 in all cases, except for B. cinerea, A. alternata and M. fructicola. The existence of a positive correlation between Cu-NPs and CuO-NPs toxicity and, at the same time, the absence of any correlation between NPs tested and their respective bulk metal counterparts indicated potential differences in the mode of action between bulk and nanosized antifungal ingredients. Although there was considerable variation between fungal species, all NPs were generally 10 to 100 fold more fungitoxic to spores than hyphae and in the majority of cases more effective than Cu(OH)2, as revealed by colony formation bioassays. NPs significantly suppressed grey mold symptoms on plum fruit, especially Ag-NPs, which completely inhibited disease development. Consequently, tested NPs have the potential to be used as protective antifungal agents.
Anastasios A. Malandrakis; Nektarios Kavroulakis; Constantinos Chrysikopoulos. Use of copper, silver and zinc nanoparticles against foliar and soil-borne plant pathogens. Science of The Total Environment 2019, 670, 292 -299.
AMA StyleAnastasios A. Malandrakis, Nektarios Kavroulakis, Constantinos Chrysikopoulos. Use of copper, silver and zinc nanoparticles against foliar and soil-borne plant pathogens. Science of The Total Environment. 2019; 670 ():292-299.
Chicago/Turabian StyleAnastasios A. Malandrakis; Nektarios Kavroulakis; Constantinos Chrysikopoulos. 2019. "Use of copper, silver and zinc nanoparticles against foliar and soil-borne plant pathogens." Science of The Total Environment 670, no. : 292-299.
Plant cellular responses to endophytic filamentous fungi are scarcely reported, with the majority of described colonization processes in plant-fungal interactions referring to either pathogens or true symbionts. Fusarium solani strain K (FsK) is a root endophyte of Solanum lycopersicum, which protects against root and foliar pathogens. Here, we investigated the association of FsK with two legumes (Lotus japonicus and Medicago truncatula) and report on colonization patterns and plant responses during the establishment of the interaction. L. japonicus plants colonized by FsK complete their life cycle and exhibit no apparent growth defects under normal conditions. We followed the growth of FsK within root-inoculated plants spatiotemporally and showed the capability of the endophyte to migrate to the stem. In a bipartite system comprising of the endophyte and either whole plants or root organ cultures, we studied the plant sub-cellular responses to FsK recognition, using optical, confocal and transmission electron microscopy. A polarized reorganization of the root cell occurs: endoplasmic reticulum/cytoplasm accumulation and nuclear placement at contact sites, occasional development of papillae underneath hyphopodia and membranous material rearrangements towards penetrating hyphae. Fungal hyphae proliferate within the vascular bundle of the plant. Plant cell death is involved in fungal colonization of the root. Our data suggest that the establishment of FsK within legume tissues requires fungal growth adaptations and plant cell-autonomous responses, known to occur during both symbiotic and pathogenic plant-fungal interactions. We highlight the overlooked plasticity of endophytic fungi upon plant colonization, and introduce a novel plant-endophyte association.
Vasiliki Skiada; Antonella Faccio; Nektarios Kavroulakis; Andrea Genre; Paola Bonfante; Kalliope K. Papadopoulou. Colonization of legumes by an endophytic Fusarium solani strain FsK reveals common features to symbionts or pathogens. Fungal Genetics and Biology 2019, 127, 60 -74.
AMA StyleVasiliki Skiada, Antonella Faccio, Nektarios Kavroulakis, Andrea Genre, Paola Bonfante, Kalliope K. Papadopoulou. Colonization of legumes by an endophytic Fusarium solani strain FsK reveals common features to symbionts or pathogens. Fungal Genetics and Biology. 2019; 127 ():60-74.
Chicago/Turabian StyleVasiliki Skiada; Antonella Faccio; Nektarios Kavroulakis; Andrea Genre; Paola Bonfante; Kalliope K. Papadopoulou. 2019. "Colonization of legumes by an endophytic Fusarium solani strain FsK reveals common features to symbionts or pathogens." Fungal Genetics and Biology 127, no. : 60-74.
Beneficial microorganisms are known to promote plant growth and confer resistance to biotic and abiotic stressors. Soil-borne beneficial microbes in particular have shown potential in protecting plants against pathogens and herbivores via the elicitation of plant responses. In this study, we evaluated the role of Fusarium solani strain K (FsK) in altering plant responses to the two spotted spider mite Tetranychus urticae in tomato. We found evidence that FsK, a beneficial endophytic fungal strain isolated from the roots of tomato plants grown on suppressive compost, affects both direct and indirect tomato defenses against spider mites. Defense-related genes were differentially expressed on FsK-colonized plants after spider mite infestation compared to clean or spider mite-infested un-colonized plants. In accordance, spider mite performance was negatively affected on FsK-colonized plants and feeding damage was lower on these compared to control plants. Notably, FsK-colonization led to increased plant biomass to both spider mite-infested and un-infested plants. FsK was shown to enhance indirect tomato defense as FsK-colonized plants attracted more predators than un-colonized plants. In accordance, headspace volatile analysis revealed significant differences between the volatiles emitted by FsK-colonized plants in response to attack by spider mites. Our results highlight the role of endophytic fungi in shaping plant–mite interactions and may offer the opportunity for the development of a novel tool for spider mite control.
Maria L. Pappas; Maria Liapoura; Dimitra Papantoniou; Marianna Avramidou; Nektarios Kavroulakis; Alexander Weinhold; George D. Broufas; Kalliope K. Papadopoulou. The Beneficial Endophytic Fungus Fusariumsolani Strain K Alters Tomato Responses Against Spider Mites to the Benefit of the Plant. Frontiers in Plant Science 2018, 9, 1603 .
AMA StyleMaria L. Pappas, Maria Liapoura, Dimitra Papantoniou, Marianna Avramidou, Nektarios Kavroulakis, Alexander Weinhold, George D. Broufas, Kalliope K. Papadopoulou. The Beneficial Endophytic Fungus Fusariumsolani Strain K Alters Tomato Responses Against Spider Mites to the Benefit of the Plant. Frontiers in Plant Science. 2018; 9 ():1603.
Chicago/Turabian StyleMaria L. Pappas; Maria Liapoura; Dimitra Papantoniou; Marianna Avramidou; Nektarios Kavroulakis; Alexander Weinhold; George D. Broufas; Kalliope K. Papadopoulou. 2018. "The Beneficial Endophytic Fungus Fusariumsolani Strain K Alters Tomato Responses Against Spider Mites to the Benefit of the Plant." Frontiers in Plant Science 9, no. : 1603.
Wood decay caused primarily by Fomitiporia mediterranea is considered to be an emerging disease for citrus and olive trees in Mediterranean countries. The pathogen cannot be currently controlled by chemicals whereas there is no available information about the source and level of resistance even for the most important cultivars where the global citrus and olive industries are based on. In the present study, five of the most significant Greek olive cultivars (Amfissis, Chalkidikis, Kalamon, Koroneiki and Mastoidis) were evaluated for their resistance to F. mediterranea by conducting artificial inoculation experiments. Disease reactions were evaluated by measuring the length of bark and wood lesions, 33 months post inoculation. Trunk sections scanning and image pixel analysis were employed to estimate the total discoloration and decay area of infected wood, whereas positive re-isolation ratio of F. mediterranea was also taken into account in resistance evaluation. Data on symptom development along with wood tissue colonization by the pathogen indicated that the resistance of olive cultivars to F. mediterranea varied significantly. Based on the cumulative stress response index (CSRI), ‘Kalamon’ and ‘Koroneiki’ were classified as resistant, ‘Chalkidikis’ and ‘Mastoidis’ as intermediately resistant, whereas ‘Amfissis’ was susceptible. Determination of lignin in trunk wood showed that the resistance of olive cultivars to F. mediterranea could be associated with their lignin content. This is the first experimental evidence of differential susceptibility responses of olive cultivars against F. mediterranea, and reveals for the first time the potential exploitation of host resistance as a promising approach in the effort to control wood decay disease of olive in practice.
Emmanouil A. Markakis; Eleftherios K. Ligoxigakis; Peter A. Roussos; Chrysi K. Sergentani; Nektarios Kavroulakis; Emmanouil N. Roditakis; Georgios C. Koubouris. Differential susceptibility responses of Greek olive cultivars to Fomitiporia mediterranea. European Journal of Plant Pathology 2018, 153, 1055 -1066.
AMA StyleEmmanouil A. Markakis, Eleftherios K. Ligoxigakis, Peter A. Roussos, Chrysi K. Sergentani, Nektarios Kavroulakis, Emmanouil N. Roditakis, Georgios C. Koubouris. Differential susceptibility responses of Greek olive cultivars to Fomitiporia mediterranea. European Journal of Plant Pathology. 2018; 153 (4):1055-1066.
Chicago/Turabian StyleEmmanouil A. Markakis; Eleftherios K. Ligoxigakis; Peter A. Roussos; Chrysi K. Sergentani; Nektarios Kavroulakis; Emmanouil N. Roditakis; Georgios C. Koubouris. 2018. "Differential susceptibility responses of Greek olive cultivars to Fomitiporia mediterranea." European Journal of Plant Pathology 153, no. 4: 1055-1066.
Certain limitations of conventional chemical control strategies for disease management point out the need for alternative control measures towards an integrated disease management model. The potential of FsK, a non-pathogenic endophytic Fusarium solani strain, to be utilized as a biocontrol agent in combination with nine selected fungicides registered in tomato crops in Greece was evaluated. In vitro fungitoxicity tests revealed that FsK was insensitive to doses exceeding 100 μg/mL of thiophanate-methyl, fenhexamid, cyprodinil, boscalid and mancozeb. On the contrary, prochloraz, fludioxonil, pyraclostrobin and difenoconazole were the most toxic to FsK exhibiting EC50 values equal to 0.035, 0.065, 5 and 15 μg/mL respectively. None of the later tested fungicides affected conidial production in an adverse way. Drenching of tomato plants with commercial products containing the above fungicides at recommended doses did not significantly affect colonization of tomato roots by FsK as revealed by in vitro isolation and Real Time PCR quantification techniques. The disease suppressive ability of FsK against Fusarium oxysporum f.sp.radicis lycopersici (FORL) was not adversely affected by the post-inoculation application of commercial formulations of fludioxonil (Switch) and pyraclostrobin (Comet) at the recommended doses. Even more, the Comet - FsK combination resulted in an enhanced disease suppression compared to either of the two treatments applied individually. In conclusion, not only biocontrol agent FsK is suitable for use in tomato integrated disease management programs that include all tested fungicides in this study but also, some FsK –fungicide combinations can have additive effect against FORL disease incidence.
Anastasios Malandrakis; Efrosini Rafaella Daskalaki; Vasiliki Skiada; Kalliope K. Papadopoulou; Nektarios Kavroulakis. A Fusarium solani endophyte vs fungicides: Compatibility in a Fusarium oxysporum f.sp. radicis-lycopersici – tomato pathosystem. Fungal Biology 2018, 122, 1215 -1221.
AMA StyleAnastasios Malandrakis, Efrosini Rafaella Daskalaki, Vasiliki Skiada, Kalliope K. Papadopoulou, Nektarios Kavroulakis. A Fusarium solani endophyte vs fungicides: Compatibility in a Fusarium oxysporum f.sp. radicis-lycopersici – tomato pathosystem. Fungal Biology. 2018; 122 (12):1215-1221.
Chicago/Turabian StyleAnastasios Malandrakis; Efrosini Rafaella Daskalaki; Vasiliki Skiada; Kalliope K. Papadopoulou; Nektarios Kavroulakis. 2018. "A Fusarium solani endophyte vs fungicides: Compatibility in a Fusarium oxysporum f.sp. radicis-lycopersici – tomato pathosystem." Fungal Biology 122, no. 12: 1215-1221.
Belowground symbiosis of plants with beneficial microbes is known to confer resistance to aboveground pests such as herbivorous arthropods and pathogens. Similarly, microbe-induced plant responses may also impact natural enemies of pests via the elicitation of plant defense responses and/or alteration of plant quality and growth. Nesidiocoris tenuis is a zoophytophagous predator and an efficient biological control agent of greenhouse pests. Its usefulness in plant protection is often hindered by its ability to damage plants at high predator population densities or when prey is scarce. In this study, we investigated the effect of Fusarium solani strain K (FsK), an endophytic fungal isolate that colonizes tomato root tissues, on the capability of N. tenuis to cause necrotic rings, an easily discernible symptom, on tomato stems and leaves. We found significantly less necrotic rings formed on FsK-inoculated plants for all tomato cultivars tested. FsK has been previously shown to confer ethylene-mediated tomato resistance to both foliar and root fungal pathogens; thus, the ethylene-insensitive Never ripe (Nr) and epinastic (epi) tomato plant mutant lines were included in our study to assess the role of ethylene in the recorded FsK-mediated plant damage reduction. The jasmonic acid (JA)-biosynthesis tomato mutant def-1 was also used since JA is known to mediate major anti-herbivore plant responses. We show that ethylene and JA are required for FsK to efficiently protect tomato plants from N. tenuis feeding. No necrotic rings were recorded on FsK-inoculated epi plants suggesting that ethylene overproduction may be key to tomato resistance to N. tenuis feeding.
Nikolaos Garantonakis; Maria L. Pappas; Kyriaki Varikou; Vasiliki Skiada; George D. Broufas; Nektarios Kavroulakis; Kalliope K. Papadopoulou. Tomato Inoculation With the Endophytic Strain Fusarium solani K Results in Reduced Feeding Damage by the Zoophytophagous Predator Nesidiocoris tenuis. Frontiers in Ecology and Evolution 2018, 6, 1 .
AMA StyleNikolaos Garantonakis, Maria L. Pappas, Kyriaki Varikou, Vasiliki Skiada, George D. Broufas, Nektarios Kavroulakis, Kalliope K. Papadopoulou. Tomato Inoculation With the Endophytic Strain Fusarium solani K Results in Reduced Feeding Damage by the Zoophytophagous Predator Nesidiocoris tenuis. Frontiers in Ecology and Evolution. 2018; 6 ():1.
Chicago/Turabian StyleNikolaos Garantonakis; Maria L. Pappas; Kyriaki Varikou; Vasiliki Skiada; George D. Broufas; Nektarios Kavroulakis; Kalliope K. Papadopoulou. 2018. "Tomato Inoculation With the Endophytic Strain Fusarium solani K Results in Reduced Feeding Damage by the Zoophytophagous Predator Nesidiocoris tenuis." Frontiers in Ecology and Evolution 6, no. : 1.
Avocado (Persea americana) is an important fruit crop for the island of Crete, in which almost the total yield of the fruit in Greece is being produced. The total cultivation area is estimated at more than 400 ha (FAOSTAT 2015). During the growing season of 2016 fruits exhibiting depressed greenish yellow-white craters, which are typical symptoms of avocado sunblotch disease, were spotted on a single tree in an orchard located in the province of Chania, Crete. No symptoms were observed on the leaves or shoots of the tree nor on any other tree in the orchard. The causal agent of sunblotch disease is avocado sunblotch viroid (ASBVd-family Avsunviroidae). In order to determine if the viroid was present, total RNA preparations from leaves, fruit skin and pulp from the symptomatic tree were extracted (Maliogka et al. 2015) and tested by a two-step RT-PCR (Schnell et al. 1997), which amplifies the cDNA of the complete ASBVd genome. Leaves from nine non-symptomatic trees, from the same field, were also analyzed. The RT-PCR performed on all the tissues of the symptomatic sample yielded the expected unit-length amplicon, as well as the dimeric and polymeric forms of the viroid, whereas all the non-symptomatic samples were found negative. The unit-length amplicon was directly sequenced, whereas the dimeric amplicon was excised from the gel, purified and cloned into a pGEM®-T Easy vector (Promega) and subsequently sequenced (VBC-Biotech). The whole genome sequence of ASBVd (249 nucleotides) was determined from the monomeric RT-PCR product and from two dimeric clones and was deposited in European Nucleotide Archive (ENA). Two different variants were identified from the symptomatic fruit, AvoCr0-A and B (Acc. No. LT966069 and LT966070, respectively). BLASTn results showed that the Greek variants of ASBVd (AvoCr0-A and B) are 95-99% identical to the already characterized isolates of ASBVd. The presence of the viroid in the symptomatic tree was also confirmed by northern blot analysis (Torchetti et al. 2012). For this aim, total RNAs were separated by 5% PAGE electrophoresis in denaturing conditions, electro-transferred to a nylon membrane and hybridized with a DIG-labeled full-length RNA probe specific for the plus strand of ASBVd (provided by Dr. Ricardo Flores, UPV-CSIC, Spain). Circular and linear forms of ASBVd RNAs co-migrating with those of the positive control (also provided by Dr. R. Flores) were observed. The presence of additional infected trees in the same field is not excluded, but further investigation is needed to obtain conclusive data in this respect. To our knowledge, this is the first report of ASBVd in Greece. Given the importance of the sunblotch disease, future studies should be performed to determine the prevalence and the significance of this viroid in Greek orchards.
L. Lotos; N. Kavroulakis; B. Navarro; F. Di Serio; A. Olmos; Ana Belen Ruiz-Garcia; N. I. Katis; V. I. Maliogka. First Report of Avocado Sunblotch Viroid (ASBVd) Naturally Infecting Avocado (Persea americana) in Greece. Plant Disease 2018, 102, 1470 .
AMA StyleL. Lotos, N. Kavroulakis, B. Navarro, F. Di Serio, A. Olmos, Ana Belen Ruiz-Garcia, N. I. Katis, V. I. Maliogka. First Report of Avocado Sunblotch Viroid (ASBVd) Naturally Infecting Avocado (Persea americana) in Greece. Plant Disease. 2018; 102 (7):1470.
Chicago/Turabian StyleL. Lotos; N. Kavroulakis; B. Navarro; F. Di Serio; A. Olmos; Ana Belen Ruiz-Garcia; N. I. Katis; V. I. Maliogka. 2018. "First Report of Avocado Sunblotch Viroid (ASBVd) Naturally Infecting Avocado (Persea americana) in Greece." Plant Disease 102, no. 7: 1470.
Nektarios Kavroulakis; Georgios Doupis; Ioannis E. Papadakis; Constantinos Ehaliotis; Kalliope K. Papadopoulou. Tolerance of tomato plants to water stress is improved by the root endophyte Fusarium solani FsK. Rhizosphere 2018, 6, 77 -85.
AMA StyleNektarios Kavroulakis, Georgios Doupis, Ioannis E. Papadakis, Constantinos Ehaliotis, Kalliope K. Papadopoulou. Tolerance of tomato plants to water stress is improved by the root endophyte Fusarium solani FsK. Rhizosphere. 2018; 6 ():77-85.
Chicago/Turabian StyleNektarios Kavroulakis; Georgios Doupis; Ioannis E. Papadakis; Constantinos Ehaliotis; Kalliope K. Papadopoulou. 2018. "Tolerance of tomato plants to water stress is improved by the root endophyte Fusarium solani FsK." Rhizosphere 6, no. : 77-85.
A two-year survey was conducted to identify fungi associated with wood decay in a range of tree species and grapevine. Fifty-eight fungal strains isolated from plants of 18 species showing typical wood decay symptoms were characterized by morphological, physiological, and molecular analyses. By 5.8S rRNA gene-ITS sequencing analysis, these isolates were classified into 25 distinct operational taxonomic units, including important phytopathogenic species of the phyla Pezizomycotina and Agaricomycotina, such as Fomitiporia, Inonotus, Phellinus, Inocutis, Fuscoporia, Trametes, Fusarium, Eutypa, Phaeomoniella, Phaeoacremonium, and Pleurostomophora spp. The white rot basidiomycetes Fomitiporia mediterranea (20 isolates, 34.5%) and Inonotus hispidus (6 isolates, 10.3%) were the most prevalent. Pathogenicity tests revealed for the first time that certain fungal species of the genera Fomitiporia, Inonotus, Phellinus, Pleurostomophora, and Fusarium caused wood infection of various tree species in Greece and worldwide. To the best of our knowledge, this is the first report of F. mediterranea as the causal agent of wood decay in pear, pomegranate, kumquat, and silk tree. This is also the first record of Inonotus hispidus, Phellinus pomaceus, Pleurostomophora richardsiae, and Fusarium solani in apple, almond, avocado, and mulberry tree, respectively, whereas P. richardsiae was associated with wood infection of olive tree for the first time in Greece. Cross pathogenicity tests with F. mediterranea strains originated from grapevine applied on other woody hosts and from olive on grapevine demonstrated partial host specificity of the fungus. The potential of F. mediterranea to transinfect hosts other than those originated, along with the host range extension of the fungus, is discussed.
Emmanouil Markakis; Nektarios Kavroulakis; Spyridon Ntougias; Georgios Koubouris; Chrysi K. Sergentani; Eleftherios K. Ligoxigakis. Characterization of Fungi Associated With Wood Decay of Tree Species and Grapevine in Greece. Plant Disease 2017, 101, 1929 -1940.
AMA StyleEmmanouil Markakis, Nektarios Kavroulakis, Spyridon Ntougias, Georgios Koubouris, Chrysi K. Sergentani, Eleftherios K. Ligoxigakis. Characterization of Fungi Associated With Wood Decay of Tree Species and Grapevine in Greece. Plant Disease. 2017; 101 (11):1929-1940.
Chicago/Turabian StyleEmmanouil Markakis; Nektarios Kavroulakis; Spyridon Ntougias; Georgios Koubouris; Chrysi K. Sergentani; Eleftherios K. Ligoxigakis. 2017. "Characterization of Fungi Associated With Wood Decay of Tree Species and Grapevine in Greece." Plant Disease 101, no. 11: 1929-1940.
D.J. Vakalounakis; N. Kavroulakis. Occurrence of powdery mildew caused by Erysiphe betae on chard [Beta vulgaris L. subsp. cicla (L.) Koch] in Greece. Crop Protection 2017, 99, 128 -131.
AMA StyleD.J. Vakalounakis, N. Kavroulakis. Occurrence of powdery mildew caused by Erysiphe betae on chard [Beta vulgaris L. subsp. cicla (L.) Koch] in Greece. Crop Protection. 2017; 99 ():128-131.
Chicago/Turabian StyleD.J. Vakalounakis; N. Kavroulakis. 2017. "Occurrence of powdery mildew caused by Erysiphe betae on chard [Beta vulgaris L. subsp. cicla (L.) Koch] in Greece." Crop Protection 99, no. : 128-131.
‘Hass’ and ‘Fuerte’ avocado plants were grown under well-watered or waterlogged conditions. Results indicated significant effects on the majority of the allometric parameters in waterlogged plants, with ‘Fuerte’ displaying a more pronounced growth inhibition. Waterlogged conditions caused a progressive and simultaneous decline in net photosynthetic rate and stomatal conductance, earlier in ‘Fuerte’ than in ‘Hass’. Maximal potential quantum yield of PSII was unaffected by the soil water regime and/or variety and leaf water potential values in waterlogged plants were not more negative compared with control plants. ‘Fuerte’ waterlogged plants exhibited increased contents of thiobarbituric acid reactive substances, whereas oxidative injury was not detected in ‘Hass’. Finally, none of the two cultivars displayed valuable antioxidant potential, as evidenced by the decreased activities of the antioxidant enzymes superoxide dismutase, guaiacol peroxidase, glutathione peroxidase, and ascorbate peroxidase.
G. Doupis; N. Kavroulakis; G. Psarras; I. E. Papadakis. Growth, photosynthetic performance and antioxidative response of 'Hass' and 'Fuerte' avocado (Persea americana Mill.) plants grown under high soil moisture. Photosynthetica 2016, 55, 655 -663.
AMA StyleG. Doupis, N. Kavroulakis, G. Psarras, I. E. Papadakis. Growth, photosynthetic performance and antioxidative response of 'Hass' and 'Fuerte' avocado (Persea americana Mill.) plants grown under high soil moisture. Photosynthetica. 2016; 55 (4):655-663.
Chicago/Turabian StyleG. Doupis; N. Kavroulakis; G. Psarras; I. E. Papadakis. 2016. "Growth, photosynthetic performance and antioxidative response of 'Hass' and 'Fuerte' avocado (Persea americana Mill.) plants grown under high soil moisture." Photosynthetica 55, no. 4: 655-663.
In January 2015 a severe foliar disease of commercially grown Barbados aloe (Aloe barbadensis Miller) was observed after a heavy hail at an incidence of approximately 80% in two fields of 0.4 ha each in the Tympaki area of Crete, Greece. Symptoms were observed on lower and middle leaves of both surfaces in the form of small circular, brown to black and sunken necrotic spots, with an average diameter of 1.0 cm that could coalesce to form lesions up to 4 cm in diameter. A dark olivaceous fungus with profuse golden brown, branched, and septate hyphae was consistently isolated from the infected tissue on PDA. The fungus produced moderately long to long chains of 12 to 20 conidia on short conidiophores; branching of chains was minor or lucking. Based on morphological, molecular and pathogenicity data, the fungus was identified as belonging to Alternaria tenuissima (Nees & T. Nees: Fr.) Wiltshire. This is, to our knowledge, the first record of this pathogen on A. barbadensis in Greece and worldwide.
D. J. Vakalounakis; N. Kavroulakis; K. Lamprou. Occurrence of Leaf Spot Caused by Alternaria tenuissima on Aloe barbadensis in Greece. Plant Disease 2016, 100, 1015 -1015.
AMA StyleD. J. Vakalounakis, N. Kavroulakis, K. Lamprou. Occurrence of Leaf Spot Caused by Alternaria tenuissima on Aloe barbadensis in Greece. Plant Disease. 2016; 100 (5):1015-1015.
Chicago/Turabian StyleD. J. Vakalounakis; N. Kavroulakis; K. Lamprou. 2016. "Occurrence of Leaf Spot Caused by Alternaria tenuissima on Aloe barbadensis in Greece." Plant Disease 100, no. 5: 1015-1015.
K. Karantemiris; Nektarios Kavroulakis; K. Lamprou; D. J. Vakalounakis. First Report of Alternaria alternata Causing a Leaf Spot of Radicchio in Greece. Plant Disease 2015, 99, 1867 -1867.
AMA StyleK. Karantemiris, Nektarios Kavroulakis, K. Lamprou, D. J. Vakalounakis. First Report of Alternaria alternata Causing a Leaf Spot of Radicchio in Greece. Plant Disease. 2015; 99 (12):1867-1867.
Chicago/Turabian StyleK. Karantemiris; Nektarios Kavroulakis; K. Lamprou; D. J. Vakalounakis. 2015. "First Report of Alternaria alternata Causing a Leaf Spot of Radicchio in Greece." Plant Disease 99, no. 12: 1867-1867.