Georgios Tsaniklidis | Agricultural University of Athens (original) (raw)

Papers by Georgios Tsaniklidis

Agronomy

Under the economic pressure from the increase of fertilizers’ prices due to the recent energy cri... more Under the economic pressure from the increase of fertilizers’ prices due to the recent energy crisis, more efforts are needed to search for alternative and cheaper sources of nutrients for crops. The purpose of our study was to compare the effects of manure and inorganic amendments’ application to those derived from the application of a controlled-release fertilizer (CRF) on the growth, nutrition, physiology and fruit quality of pepper plants. For that reason, zeolite (ZEO) and vermiculite (VER) were applied either independently, or in combination between them, or with manure (MAN), in a pot experiment. Insignificant differences for plant growth among the treatments were recorded, while higher foliar N, Mg and Mn concentrations were determined in CRF. In contrast, a significantly higher K uptake was recorded in the ZEO and VER + ZEO treatments; the highest leaf P levels (0.47 and 0.44% D.W.) were recorded in the MAN + VER and ZEO treatments, respectively. The optimum photosynthetic ...

Scientific Reports

γ-Aminobutyric acid (GABA) is a non-protein amino acid with multifunctional roles in dynamic plan... more γ-Aminobutyric acid (GABA) is a non-protein amino acid with multifunctional roles in dynamic plant responses. To determine the effects of exogenous GABA application (0, 25 and 50 µM) on drought response, two chickpea cultivars with contrasting tolerance to water deficit were examined. Plants were exposed to four irrigation levels (irrigation to 100, 60, 40 and 20% field capacity). Water deficit decreased growth, chlorophyll content, and photosynthetic efficiency. It increased electrolyte leakage and lipid peroxidation owing to both higher ROS accumulation and lower antioxidant enzyme activity. These negative effects of water deficit and the alleviating role of GABA application were more prominent in the sensitive, as compared to the tolerant cultivar. Water deficit also increased proline and GABA contents more in the tolerant cultivar, whereas their content was more enhanced by GABA application in the sensitive one. This may confer an additional level of regulation that results in b...

Foods, 2022

The aim of this work was to investigate the effect of edible coatings (ECs) prepared from extract... more The aim of this work was to investigate the effect of edible coatings (ECs) prepared from extracts of Opuntia ficus-indica (OFI) cladodes in comparison with a commercial chitosan formulation on the quality of ‘Regina’ cherries packaged in macro-perforated bags and stored for up to 28 d (1 °C, 90% RH). The coating concentrations were 25% and 50% aqueous OFI extract (approximately 0.59 and 1.18% dry matter, respectively), 1% OFI alcohol insoluble polysaccharide and 1% chitosan. The variables evaluated included weight loss (WL), respiration rates (RR), peel color, firmness, microbial decay, total antioxidants (phenolics, flavonoids, anthocyanins, antioxidant capacity), individual phenolic compounds (anthocyanins, hydroxycinnamic acids, flavan-3-O-ols), and pedicel removal force. The main results show that all coatings reduced WL and RR similarly, enhanced firmness throughout storage and antioxidants after 28 d of storage compared to the controls. Among treatments, chitosan resulted in ...

Postharvest Biology and Technology, 2021

Abstract Polyamines are actively involved in diverse processes, including fruit ripening and stre... more Abstract Polyamines are actively involved in diverse processes, including fruit ripening and stress responses. The aim of this study was to investigate the role of storage temperature on polyamine metabolism of tomato fruit, which were either harvested at the turning stage or left to mature on-plant. The applied temperatures (5, 10 and 25 °C) and storage duration (7 d) are regularly employed in real-world scenarios. The metabolic profile of polyamines (putrescine, spermidine and spermine), gene transcription of the enzymes mediating polyamine biosynthesis and catabolism, protein accumulation of the putrescine synthesis enzyme and the putrescine-produced H2O2 were evaluated. Putrescine was the major polyamine in all cases, and its content generally increased during ripening, as well as in chilled fruit (stored at 5 °C). Increases in arginine decarboxylase protein content and in arginine decarboxylase transcription of both attached fruit and detached ones stored at either 10 or 25 °C showed that putrescine accumulation was mainly driven via the arginine decarboxylase biosynthetic pathway. Interestingly, putrescine catabolism by copper-containing amine oxidase was favored in parallel with increases in arginine decarboxylase and ornithine decarboxylase transcripts in fruit stored at 5 °C. However, the arginine decarboxylase protein accumulation suggests that ornithine decarboxylase is mainly responsible for putrescine accumulation at 5 °C. This study indicates that storage temperature modifies the homeostasis of polyamines in tomato fruit, which in turn orchestrates ripening-associated physiological processes.

Agronomy, 2021

Wild phytogenetic resources are threatened by overexploitation. This pressure on species and natu... more Wild phytogenetic resources are threatened by overexploitation. This pressure on species and natural ecosystems can be alleviated in part by recruiting and domesticating wild-growing species under pilot cultivation with tailor-made fertilization schemes. This study focused on the pilot cultivation of Origanum microphyllum—a critically endangered local endemic plant of Crete, Greece—investigating the effect of conventional and integrated nutrient management (ΙΝΜ) fertilizers by foliar or root application and biostimulant. Above-ground biomass together with leaf chlorophyll fluorescence and color (SPAD meter, DA meter, Chroma Meter) were determined. Leaf chlorophyll, antioxidant compound (carotenoids, phenols, flavonoids), and nutrient contents were also assessed. The results showed that fertilization did not significantly affect plant growth and leaf nutrient content. Root fertilization was associated with greener leaves compared to foliar. The same trend was generally evident for an...

Sustainability, 2021

The domestication of wild-growing plants, including cultivation and fertilization protocols, is a... more The domestication of wild-growing plants, including cultivation and fertilization protocols, is able to alleviate the ecological risks posed by the uncontrolled harvesting of range-restricted local endemic plants. In this field study focused on Verbascum arcturus, a vulnerable local endemic of Crete (Greece), the effect of two kinds of fertilization applied by two methods (foliar/root) was investigated. The foliar application included conventional or integrated nutrient management (INM) fertilization. Root application included the application of conventional fertilizers, biostimulants, or INM with biostimulants. Several properties of plant growth, physiology and nutrition were determined. The results showed that fertilization treatment affected neither leaf color and shape nor plant growth, morphology, dry mass partitioning or nutrient content. However, both kinds of foliar-applied fertilization enhanced Zn and B in leaves and soil-applied biostimulant increased leaf Ca. Considering...

Plants, 2021

Tomato (Solanum lycopersicum L.) is considered one of the most valuable and versatile vegetable c... more Tomato (Solanum lycopersicum L.) is considered one of the most valuable and versatile vegetable crops globally and also serves as a significant model species for fruit developmental biology. Despite its significance, a severe genetic bottleneck and intense selection of genotypes with specific qualitative traits have resulted in the prevalence of a restricted number of (geno)types, also causing a lack of diversity across widespread cultivated types. As a result, the re-emergence of landraces as well as traditional and heirloom varieties is largely acknowledged as a countermeasure to restore phenotypic, phytochemical and genetic diversity while enriching the aroma/taste tomato palette. On those grounds, the Cypriot tomato germplasm was assessed and characterized. Ten landrace accessions were evaluated under greenhouse conditions and data were collected for 24 IPGRI discrete phenotypic traits. Grouping of accessions largely reflected the fruit shape and size; four different fruit types...

Horticulturae, 2021

Plants develop a plethora of defense strategies during their acclimation and interactions with va... more Plants develop a plethora of defense strategies during their acclimation and interactions with various environmental stresses. Secondary metabolites play a pivotal role in the processes during stress acclimation, therefore deciphering their relevant responses exchange the interpretation of the underlying molecular mechanisms that may contribute to improved adaptability and efficacy. In the current study, tomato plants were exposed to short-term cold stress (5 °C for 16 h) or inoculated (20 d) with either Cucumber Mosaic Virus (CMV) or Potato Virus Y (PVY). Responses were recorded via the assessments of leaf total phenolic (TP) content, total flavonoid (TF) levels, and phenylalanine ammonia-lyase (PAL) enzyme activity. The transcription of the gene families regulating the core phenylpropanoid biosynthetic pathway (PBP) at an early (PAL, cinnamic acid 4-hydroxylase, 4-coumarate-CoA ligase) or late (chalcone synthase and flavonol synthase) stage was also evaluated. The results showed t...

Agronomy, 2021

Broccoli sprouts are rich in health-promoting bioactive compounds. Their content depends on both ... more Broccoli sprouts are rich in health-promoting bioactive compounds. Their content depends on both cultivation light quality and temperature. However, these effects have been previously addressed in isolation. Here, the dual inputs of cultivation light quality [blue (B), red (R), mixture of R and B (R+B), mixture of R and UVA (R+UVA)] and air temperature (15, 19, and 23 °C) on determining growth, external quality, and the cotyledon and hypocotyl content of five major bioactive compounds were investigated. The carbohydrate status at harvest and postharvest ratio of variable to maximum fluorescence (Fv/Fm) were also assessed. Hypocotyl length was generally enhanced under monochromatic light (R or B) and elevated temperature. Total phenolic, total flavonoid, and glucoraphanin contents were generally higher in cotyledon as compared to hypocotyl. Hypocotyl anthocyanin, total phenolic, total flavonoid, and ascorbic acid contents were generally enhanced by R+B, and were decreased by R. Cotyl...

International Journal of Molecular Sciences, 2021

To investigate the importance of light on healing and acclimatization, in the present study, graf... more To investigate the importance of light on healing and acclimatization, in the present study, grafted watermelon seedlings were exposed to darkness (D) or light, provided by blue (B), red (R), a mixture of R (68%) and B (RB), or white (W; 35% B, 49% intermediate spectra, 16% R) LEDs for 12 days. Survival ratio, root and shoot growth, soluble carbohydrate content, photosynthetic pigments content, and photosynthetic performance were evaluated. Seedling survival was not only strongly limited in D but the survived seedlings had an inferior shoot and root development, reduced chlorophyll content, and attenuated photosynthetic efficiency. RB-exposed seedlings had a less-developed root system. R-exposed seedlings showed leaf epinasty, and had the smallest leaf area, reduced chlorophyll content, and suppressed photosynthetic apparatus performance. The R-exposed seedlings contained the highest amount of soluble carbohydrate and together with D-exposed seedlings the lowest amount of chlorophyl...

International Journal of Molecular Sciences, 2020

Defensins are small and rather ubiquitous cysteine-rich anti-microbial peptides. These proteins m... more Defensins are small and rather ubiquitous cysteine-rich anti-microbial peptides. These proteins may act against pathogenic microorganisms either directly (by binding and disrupting membranes) or indirectly (as signaling molecules that participate in the organization of the cellular defense). Even though defensins are widespread across eukaryotes, still, extensive nucleotide and amino acid dissimilarities hamper the elucidation of their response to stimuli and mode of function. In the current study, we screened the Solanum lycopersicum genome for the identification of defensin genes, predicted the relating protein structures, and further studied their transcriptional responses to biotic (Verticillium dahliae, Meloidogyne javanica, Cucumber Mosaic Virus, and Potato Virus Y infections) and abiotic (cold stress) stimuli. Tomato defensin sequences were classified into two groups (C8 and C12). Our data indicate that the transcription of defensin coding genes primarily depends on the speci...

Agronomy, 2021

Boron (B) is an essential nutrient for plant growth and development, exhibiting extremely narrow ... more Boron (B) is an essential nutrient for plant growth and development, exhibiting extremely narrow margins between deficiency and toxicity. B toxicity is devastating for productivity and apparent for a continuously increasing part of agricultural land, under the influence of on-going climate change. In this study, the effects of increased B supply (by using H3BO3) were addressed by examining critical physiological responses of young and mature leaves, which were devoid of toxicity symptoms, in two melon varieties (Armenian cucumbers, cantaloupes). B was primarily translocated through the transpiration stream, and secondarily via the active cell membrane transport system. The B distribution pattern was independent of leaf age, and remained rather unchanged under increased B supply. Armenian cucumbers, exhibiting higher leaf B levels, underwent an enhanced adverse impact on (root and shoot) growth, photosynthetic pigment content, cellular membrane integrity, and also exhibited attenuate...

Plant Physiology and Biochemistry, 2020

High relative air humidity (RH ≥ 85%) is frequent in controlled environments, and not uncommon in... more High relative air humidity (RH ≥ 85%) is frequent in controlled environments, and not uncommon in nature. In this review, we examine the high RH effects on plants with a special focus on stomatal characters. All aspects of stomatal physiology are attenuated by elevated RH during leaf expansion (long-term) in C3 species. These include impaired opening and closing response, as well as weak diel oscillations. Consequently, the high RH-grown plants are not only vulnerable to biotic and abiotic stress, but also undergo a deregulation between CO2 uptake and water loss. Stomatal behavior of a single leaf is determined by the local microclimate during expansion, and may be different than the remaining leaves of the same plant. No effect of high RH is apparent in C4 and CAM species, while the same is expected for species with hydropassive stomatal closure. Formation of bigger stomata with larger pores is a universal response to high RH during leaf expansion, whereas the effect on stomatal density appears to be species- and leaf side-specific. Compelling evidence suggests that ABA mediates the high RH-induced stomatal malfunction, as well as the stomatal size increase. Although high RH stimulates leaf ethylene evolution, it remains elusive whether or not this contributes to stomatal malfunction. Most species lose stomatal function following mid-term (4-7 d) exposure to high RH following leaf expansion. Consequently, the regulatory role of ambient humidity on stomatal functionality is not limited to the period of leaf expansion, but holds throughout the leaf life span.

Plants, 2020

Cypriot vineyards are considered as one among the earliest niches of viticulture and a pivotal hu... more Cypriot vineyards are considered as one among the earliest niches of viticulture and a pivotal hub for the domestication and dissemination of grapevine. The millennial presence of Vitis spp. in this Eastern Mediterranean island has given rise to a plethora of biotypes that have not been adequately characterized, despite their unique attributes and stress tolerance. This ancient germplasm also has an additional value since it survived the phylloxera outbreak; hence, it possesses a large amount of genetic diversity that has been unnoticed. In order to provide useful insights to the lineage of Cypriot vineyards, a two-year-spanning collection of centennial grapevine cultivars mostly regarded to belong to four indigenous variety clusters (“Mavro”, “Xynisteri”, “Maratheftiko”, and “Veriko”) was initiated. There were 164 accessions across the broader Commandaria wine zone sampled and characterized using a universal microsatellite primer set. Genetic analysis indicated that considered indi...

Plants, 2020

Plant proteases, the proteolytic enzymes that catalyze protein breakdown and recycling, play an e... more Plant proteases, the proteolytic enzymes that catalyze protein breakdown and recycling, play an essential role in a variety of biological processes including stomatal development and distribution, as well as, systemic stress responses. In this review, we summarize what is known about the participation of proteases in both stomatal organogenesis and on the stomatal pore aperture tuning, with particular emphasis on their involvement in numerous signaling pathways triggered by abiotic and biotic stressors. There is a compelling body of evidence demonstrating that several proteases are directly or indirectly implicated in the process of stomatal development, affecting stomatal index, density, spacing, as well as, size. In addition, proteases are reported to be involved in a transient adjustment of stomatal aperture, thus orchestrating gas exchange. Consequently, the proteases-mediated regulation of stomatal movements considerably affects plants’ ability to cope not only with abiotic str...

Gene, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Horticultural Science, 2014

Ascorbate metabolism is an essential procedure for all plant cells that plays important roles in ... more 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 genesfollowed similar patterns. However, APX3 gene expression was considerably higher in reproductive organs, while plastidialAPX6 and DHAR2genes transcripts were barely detectable in root...

Scientia Horticulturae, 2018

Area (LA) estimation, based on individual leaf dimensions [length (L) and width (W)], was address... more Area (LA) estimation, based on individual leaf dimensions [length (L) and width (W)], was addressed in olive tree. Ten cultivars exposed to two watering regimes (irrigated versus rainfed) under field conditions were examined. Petiole length, leaf L, W, perimeter, base and apex angles, four shape indicators, together with LA were digitally assessed in fully-expanded leaves (480 leaves per treatment; 9.600 leaves in total). Large cultivar differences mainly in leaf size and secondarily in leaf shape were apparent. All parameters were affected by water deficit, but to a cultivar dependent extent. Leaf size was generally reduced by lack of irrigation in most cultivars. LA was estimated with higher accuracy by employing L alone, as compared to W alone, in eight cultivars. LA estimation was always improved by considering both L and W simultaneously, as compared to a single dimension. By studying each cultivar individually, LA estimation was within accepted limits (0.71 ≤ R 2 ≤ 0.92) in nine cultivars, whereas in the tenth one a moderate R 2 (0.63) was obtained. The accuracy of this estimation was not improved by pooling the data of all cultivars. Watering did not significantly affect the relation between estimated and measured LA. The obtained data indicate that a universal LA estimation model for olive tree carries the pitfall of moderate accuracy, owing only to cultivar differences, since environmental effects were trivial.

Scientia Horticulturae, 2017

Sweet cherry storage at 1°C significantly affected many biochemical parameters linked to anthocya... more Sweet cherry storage at 1°C significantly affected many biochemical parameters linked to anthocyanin concentration in fruits and subsequently their colour. While no significant differences in the concentration of total phenolics were detected among treatments, total anthocyanin concentration and phenylalanine ammonia-lyase enzyme activity, as well as the transcription of anthocyanidin synthase and flavonol 3-O-glucosyltransferase (genes coding for enzymes fundamental for the anthocyanin synthesis) were considerably lower in fruits stored at 1°C (with or without a 24-h period of storage at 20°C) in comparison to the initial fruits at harvest. In contrast, the fruits stored continuously at 20°C exhibited higher levels of total anthocyanins and Phenylalanine Ammonia-Lyase activity and also elevated expression of the genes coding for enzymes involved in the biosynthesis of anthocyanins in comparison to fruits that underwent cold storage. Our results suggest that cold storage of sweet cherries at low, but non-chilling temperatures, decelerates the accumulation of anthocyanins and consequently causes slower colour development in fruits.

Agronomy

Under the economic pressure from the increase of fertilizers’ prices due to the recent energy cri... more Under the economic pressure from the increase of fertilizers’ prices due to the recent energy crisis, more efforts are needed to search for alternative and cheaper sources of nutrients for crops. The purpose of our study was to compare the effects of manure and inorganic amendments’ application to those derived from the application of a controlled-release fertilizer (CRF) on the growth, nutrition, physiology and fruit quality of pepper plants. For that reason, zeolite (ZEO) and vermiculite (VER) were applied either independently, or in combination between them, or with manure (MAN), in a pot experiment. Insignificant differences for plant growth among the treatments were recorded, while higher foliar N, Mg and Mn concentrations were determined in CRF. In contrast, a significantly higher K uptake was recorded in the ZEO and VER + ZEO treatments; the highest leaf P levels (0.47 and 0.44% D.W.) were recorded in the MAN + VER and ZEO treatments, respectively. The optimum photosynthetic ...

Scientific Reports

γ-Aminobutyric acid (GABA) is a non-protein amino acid with multifunctional roles in dynamic plan... more γ-Aminobutyric acid (GABA) is a non-protein amino acid with multifunctional roles in dynamic plant responses. To determine the effects of exogenous GABA application (0, 25 and 50 µM) on drought response, two chickpea cultivars with contrasting tolerance to water deficit were examined. Plants were exposed to four irrigation levels (irrigation to 100, 60, 40 and 20% field capacity). Water deficit decreased growth, chlorophyll content, and photosynthetic efficiency. It increased electrolyte leakage and lipid peroxidation owing to both higher ROS accumulation and lower antioxidant enzyme activity. These negative effects of water deficit and the alleviating role of GABA application were more prominent in the sensitive, as compared to the tolerant cultivar. Water deficit also increased proline and GABA contents more in the tolerant cultivar, whereas their content was more enhanced by GABA application in the sensitive one. This may confer an additional level of regulation that results in b...

Foods, 2022

The aim of this work was to investigate the effect of edible coatings (ECs) prepared from extract... more The aim of this work was to investigate the effect of edible coatings (ECs) prepared from extracts of Opuntia ficus-indica (OFI) cladodes in comparison with a commercial chitosan formulation on the quality of ‘Regina’ cherries packaged in macro-perforated bags and stored for up to 28 d (1 °C, 90% RH). The coating concentrations were 25% and 50% aqueous OFI extract (approximately 0.59 and 1.18% dry matter, respectively), 1% OFI alcohol insoluble polysaccharide and 1% chitosan. The variables evaluated included weight loss (WL), respiration rates (RR), peel color, firmness, microbial decay, total antioxidants (phenolics, flavonoids, anthocyanins, antioxidant capacity), individual phenolic compounds (anthocyanins, hydroxycinnamic acids, flavan-3-O-ols), and pedicel removal force. The main results show that all coatings reduced WL and RR similarly, enhanced firmness throughout storage and antioxidants after 28 d of storage compared to the controls. Among treatments, chitosan resulted in ...

Postharvest Biology and Technology, 2021

Abstract Polyamines are actively involved in diverse processes, including fruit ripening and stre... more Abstract Polyamines are actively involved in diverse processes, including fruit ripening and stress responses. The aim of this study was to investigate the role of storage temperature on polyamine metabolism of tomato fruit, which were either harvested at the turning stage or left to mature on-plant. The applied temperatures (5, 10 and 25 °C) and storage duration (7 d) are regularly employed in real-world scenarios. The metabolic profile of polyamines (putrescine, spermidine and spermine), gene transcription of the enzymes mediating polyamine biosynthesis and catabolism, protein accumulation of the putrescine synthesis enzyme and the putrescine-produced H2O2 were evaluated. Putrescine was the major polyamine in all cases, and its content generally increased during ripening, as well as in chilled fruit (stored at 5 °C). Increases in arginine decarboxylase protein content and in arginine decarboxylase transcription of both attached fruit and detached ones stored at either 10 or 25 °C showed that putrescine accumulation was mainly driven via the arginine decarboxylase biosynthetic pathway. Interestingly, putrescine catabolism by copper-containing amine oxidase was favored in parallel with increases in arginine decarboxylase and ornithine decarboxylase transcripts in fruit stored at 5 °C. However, the arginine decarboxylase protein accumulation suggests that ornithine decarboxylase is mainly responsible for putrescine accumulation at 5 °C. This study indicates that storage temperature modifies the homeostasis of polyamines in tomato fruit, which in turn orchestrates ripening-associated physiological processes.

Agronomy, 2021

Wild phytogenetic resources are threatened by overexploitation. This pressure on species and natu... more Wild phytogenetic resources are threatened by overexploitation. This pressure on species and natural ecosystems can be alleviated in part by recruiting and domesticating wild-growing species under pilot cultivation with tailor-made fertilization schemes. This study focused on the pilot cultivation of Origanum microphyllum—a critically endangered local endemic plant of Crete, Greece—investigating the effect of conventional and integrated nutrient management (ΙΝΜ) fertilizers by foliar or root application and biostimulant. Above-ground biomass together with leaf chlorophyll fluorescence and color (SPAD meter, DA meter, Chroma Meter) were determined. Leaf chlorophyll, antioxidant compound (carotenoids, phenols, flavonoids), and nutrient contents were also assessed. The results showed that fertilization did not significantly affect plant growth and leaf nutrient content. Root fertilization was associated with greener leaves compared to foliar. The same trend was generally evident for an...

Sustainability, 2021

The domestication of wild-growing plants, including cultivation and fertilization protocols, is a... more The domestication of wild-growing plants, including cultivation and fertilization protocols, is able to alleviate the ecological risks posed by the uncontrolled harvesting of range-restricted local endemic plants. In this field study focused on Verbascum arcturus, a vulnerable local endemic of Crete (Greece), the effect of two kinds of fertilization applied by two methods (foliar/root) was investigated. The foliar application included conventional or integrated nutrient management (INM) fertilization. Root application included the application of conventional fertilizers, biostimulants, or INM with biostimulants. Several properties of plant growth, physiology and nutrition were determined. The results showed that fertilization treatment affected neither leaf color and shape nor plant growth, morphology, dry mass partitioning or nutrient content. However, both kinds of foliar-applied fertilization enhanced Zn and B in leaves and soil-applied biostimulant increased leaf Ca. Considering...

Plants, 2021

Tomato (Solanum lycopersicum L.) is considered one of the most valuable and versatile vegetable c... more Tomato (Solanum lycopersicum L.) is considered one of the most valuable and versatile vegetable crops globally and also serves as a significant model species for fruit developmental biology. Despite its significance, a severe genetic bottleneck and intense selection of genotypes with specific qualitative traits have resulted in the prevalence of a restricted number of (geno)types, also causing a lack of diversity across widespread cultivated types. As a result, the re-emergence of landraces as well as traditional and heirloom varieties is largely acknowledged as a countermeasure to restore phenotypic, phytochemical and genetic diversity while enriching the aroma/taste tomato palette. On those grounds, the Cypriot tomato germplasm was assessed and characterized. Ten landrace accessions were evaluated under greenhouse conditions and data were collected for 24 IPGRI discrete phenotypic traits. Grouping of accessions largely reflected the fruit shape and size; four different fruit types...

Horticulturae, 2021

Plants develop a plethora of defense strategies during their acclimation and interactions with va... more Plants develop a plethora of defense strategies during their acclimation and interactions with various environmental stresses. Secondary metabolites play a pivotal role in the processes during stress acclimation, therefore deciphering their relevant responses exchange the interpretation of the underlying molecular mechanisms that may contribute to improved adaptability and efficacy. In the current study, tomato plants were exposed to short-term cold stress (5 °C for 16 h) or inoculated (20 d) with either Cucumber Mosaic Virus (CMV) or Potato Virus Y (PVY). Responses were recorded via the assessments of leaf total phenolic (TP) content, total flavonoid (TF) levels, and phenylalanine ammonia-lyase (PAL) enzyme activity. The transcription of the gene families regulating the core phenylpropanoid biosynthetic pathway (PBP) at an early (PAL, cinnamic acid 4-hydroxylase, 4-coumarate-CoA ligase) or late (chalcone synthase and flavonol synthase) stage was also evaluated. The results showed t...

Agronomy, 2021

Broccoli sprouts are rich in health-promoting bioactive compounds. Their content depends on both ... more Broccoli sprouts are rich in health-promoting bioactive compounds. Their content depends on both cultivation light quality and temperature. However, these effects have been previously addressed in isolation. Here, the dual inputs of cultivation light quality [blue (B), red (R), mixture of R and B (R+B), mixture of R and UVA (R+UVA)] and air temperature (15, 19, and 23 °C) on determining growth, external quality, and the cotyledon and hypocotyl content of five major bioactive compounds were investigated. The carbohydrate status at harvest and postharvest ratio of variable to maximum fluorescence (Fv/Fm) were also assessed. Hypocotyl length was generally enhanced under monochromatic light (R or B) and elevated temperature. Total phenolic, total flavonoid, and glucoraphanin contents were generally higher in cotyledon as compared to hypocotyl. Hypocotyl anthocyanin, total phenolic, total flavonoid, and ascorbic acid contents were generally enhanced by R+B, and were decreased by R. Cotyl...

International Journal of Molecular Sciences, 2021

To investigate the importance of light on healing and acclimatization, in the present study, graf... more To investigate the importance of light on healing and acclimatization, in the present study, grafted watermelon seedlings were exposed to darkness (D) or light, provided by blue (B), red (R), a mixture of R (68%) and B (RB), or white (W; 35% B, 49% intermediate spectra, 16% R) LEDs for 12 days. Survival ratio, root and shoot growth, soluble carbohydrate content, photosynthetic pigments content, and photosynthetic performance were evaluated. Seedling survival was not only strongly limited in D but the survived seedlings had an inferior shoot and root development, reduced chlorophyll content, and attenuated photosynthetic efficiency. RB-exposed seedlings had a less-developed root system. R-exposed seedlings showed leaf epinasty, and had the smallest leaf area, reduced chlorophyll content, and suppressed photosynthetic apparatus performance. The R-exposed seedlings contained the highest amount of soluble carbohydrate and together with D-exposed seedlings the lowest amount of chlorophyl...

International Journal of Molecular Sciences, 2020

Defensins are small and rather ubiquitous cysteine-rich anti-microbial peptides. These proteins m... more Defensins are small and rather ubiquitous cysteine-rich anti-microbial peptides. These proteins may act against pathogenic microorganisms either directly (by binding and disrupting membranes) or indirectly (as signaling molecules that participate in the organization of the cellular defense). Even though defensins are widespread across eukaryotes, still, extensive nucleotide and amino acid dissimilarities hamper the elucidation of their response to stimuli and mode of function. In the current study, we screened the Solanum lycopersicum genome for the identification of defensin genes, predicted the relating protein structures, and further studied their transcriptional responses to biotic (Verticillium dahliae, Meloidogyne javanica, Cucumber Mosaic Virus, and Potato Virus Y infections) and abiotic (cold stress) stimuli. Tomato defensin sequences were classified into two groups (C8 and C12). Our data indicate that the transcription of defensin coding genes primarily depends on the speci...

Agronomy, 2021

Boron (B) is an essential nutrient for plant growth and development, exhibiting extremely narrow ... more Boron (B) is an essential nutrient for plant growth and development, exhibiting extremely narrow margins between deficiency and toxicity. B toxicity is devastating for productivity and apparent for a continuously increasing part of agricultural land, under the influence of on-going climate change. In this study, the effects of increased B supply (by using H3BO3) were addressed by examining critical physiological responses of young and mature leaves, which were devoid of toxicity symptoms, in two melon varieties (Armenian cucumbers, cantaloupes). B was primarily translocated through the transpiration stream, and secondarily via the active cell membrane transport system. The B distribution pattern was independent of leaf age, and remained rather unchanged under increased B supply. Armenian cucumbers, exhibiting higher leaf B levels, underwent an enhanced adverse impact on (root and shoot) growth, photosynthetic pigment content, cellular membrane integrity, and also exhibited attenuate...

Plant Physiology and Biochemistry, 2020

High relative air humidity (RH ≥ 85%) is frequent in controlled environments, and not uncommon in... more High relative air humidity (RH ≥ 85%) is frequent in controlled environments, and not uncommon in nature. In this review, we examine the high RH effects on plants with a special focus on stomatal characters. All aspects of stomatal physiology are attenuated by elevated RH during leaf expansion (long-term) in C3 species. These include impaired opening and closing response, as well as weak diel oscillations. Consequently, the high RH-grown plants are not only vulnerable to biotic and abiotic stress, but also undergo a deregulation between CO2 uptake and water loss. Stomatal behavior of a single leaf is determined by the local microclimate during expansion, and may be different than the remaining leaves of the same plant. No effect of high RH is apparent in C4 and CAM species, while the same is expected for species with hydropassive stomatal closure. Formation of bigger stomata with larger pores is a universal response to high RH during leaf expansion, whereas the effect on stomatal density appears to be species- and leaf side-specific. Compelling evidence suggests that ABA mediates the high RH-induced stomatal malfunction, as well as the stomatal size increase. Although high RH stimulates leaf ethylene evolution, it remains elusive whether or not this contributes to stomatal malfunction. Most species lose stomatal function following mid-term (4-7 d) exposure to high RH following leaf expansion. Consequently, the regulatory role of ambient humidity on stomatal functionality is not limited to the period of leaf expansion, but holds throughout the leaf life span.

Plants, 2020

Cypriot vineyards are considered as one among the earliest niches of viticulture and a pivotal hu... more Cypriot vineyards are considered as one among the earliest niches of viticulture and a pivotal hub for the domestication and dissemination of grapevine. The millennial presence of Vitis spp. in this Eastern Mediterranean island has given rise to a plethora of biotypes that have not been adequately characterized, despite their unique attributes and stress tolerance. This ancient germplasm also has an additional value since it survived the phylloxera outbreak; hence, it possesses a large amount of genetic diversity that has been unnoticed. In order to provide useful insights to the lineage of Cypriot vineyards, a two-year-spanning collection of centennial grapevine cultivars mostly regarded to belong to four indigenous variety clusters (“Mavro”, “Xynisteri”, “Maratheftiko”, and “Veriko”) was initiated. There were 164 accessions across the broader Commandaria wine zone sampled and characterized using a universal microsatellite primer set. Genetic analysis indicated that considered indi...

Plants, 2020

Plant proteases, the proteolytic enzymes that catalyze protein breakdown and recycling, play an e... more Plant proteases, the proteolytic enzymes that catalyze protein breakdown and recycling, play an essential role in a variety of biological processes including stomatal development and distribution, as well as, systemic stress responses. In this review, we summarize what is known about the participation of proteases in both stomatal organogenesis and on the stomatal pore aperture tuning, with particular emphasis on their involvement in numerous signaling pathways triggered by abiotic and biotic stressors. There is a compelling body of evidence demonstrating that several proteases are directly or indirectly implicated in the process of stomatal development, affecting stomatal index, density, spacing, as well as, size. In addition, proteases are reported to be involved in a transient adjustment of stomatal aperture, thus orchestrating gas exchange. Consequently, the proteases-mediated regulation of stomatal movements considerably affects plants’ ability to cope not only with abiotic str...

Gene, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Horticultural Science, 2014

Ascorbate metabolism is an essential procedure for all plant cells that plays important roles in ... more 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 genesfollowed similar patterns. However, APX3 gene expression was considerably higher in reproductive organs, while plastidialAPX6 and DHAR2genes transcripts were barely detectable in root...

Scientia Horticulturae, 2018

Area (LA) estimation, based on individual leaf dimensions [length (L) and width (W)], was address... more Area (LA) estimation, based on individual leaf dimensions [length (L) and width (W)], was addressed in olive tree. Ten cultivars exposed to two watering regimes (irrigated versus rainfed) under field conditions were examined. Petiole length, leaf L, W, perimeter, base and apex angles, four shape indicators, together with LA were digitally assessed in fully-expanded leaves (480 leaves per treatment; 9.600 leaves in total). Large cultivar differences mainly in leaf size and secondarily in leaf shape were apparent. All parameters were affected by water deficit, but to a cultivar dependent extent. Leaf size was generally reduced by lack of irrigation in most cultivars. LA was estimated with higher accuracy by employing L alone, as compared to W alone, in eight cultivars. LA estimation was always improved by considering both L and W simultaneously, as compared to a single dimension. By studying each cultivar individually, LA estimation was within accepted limits (0.71 ≤ R 2 ≤ 0.92) in nine cultivars, whereas in the tenth one a moderate R 2 (0.63) was obtained. The accuracy of this estimation was not improved by pooling the data of all cultivars. Watering did not significantly affect the relation between estimated and measured LA. The obtained data indicate that a universal LA estimation model for olive tree carries the pitfall of moderate accuracy, owing only to cultivar differences, since environmental effects were trivial.

Scientia Horticulturae, 2017

Sweet cherry storage at 1°C significantly affected many biochemical parameters linked to anthocya... more Sweet cherry storage at 1°C significantly affected many biochemical parameters linked to anthocyanin concentration in fruits and subsequently their colour. While no significant differences in the concentration of total phenolics were detected among treatments, total anthocyanin concentration and phenylalanine ammonia-lyase enzyme activity, as well as the transcription of anthocyanidin synthase and flavonol 3-O-glucosyltransferase (genes coding for enzymes fundamental for the anthocyanin synthesis) were considerably lower in fruits stored at 1°C (with or without a 24-h period of storage at 20°C) in comparison to the initial fruits at harvest. In contrast, the fruits stored continuously at 20°C exhibited higher levels of total anthocyanins and Phenylalanine Ammonia-Lyase activity and also elevated expression of the genes coding for enzymes involved in the biosynthesis of anthocyanins in comparison to fruits that underwent cold storage. Our results suggest that cold storage of sweet cherries at low, but non-chilling temperatures, decelerates the accumulation of anthocyanins and consequently causes slower colour development in fruits.