Effect of glutamic acid foliar applications on lettuce under water stress.

The yield and quality of leafy vegetables can be compromised by reduced water availability. Glutamic acid is involved in different biological processes and among them it plays an important role in chlorophyll and proline biosynthesis. The aim of this work was to evaluate the possible efficacy of glutamic acid in counteracting water stress in romaine lettuce. Lettuce plants were grown in pots filled with substrate and subjected to water deprivation. A glutamic acid solution (1.9 mM) was applied as foliar treatment, both in stressed and non-stressed plants. The effect of the treatment was evaluated at different time points during the experiment in order to evaluate changes at a molecular, physiological, biochemical and agronomic level. Yield was reduced by 35% in stressed plants, while no significant changes in quality parameters were observed, except for nitrate content, which increased under water stress. At a molecular level, the expression of genes encoding for ROS scavenging enzymes was monitored but, apparently, glutamic acid did not significantly prevent the water stress response. Slightly positive effects deriving from glutamic acid application were found for nitrate and proline contents, suggesting that a possible mode of action of glutamic acid would involve a role for these molecules. Further studies are required, also on other crop species, for confirming these results. Different concentrations and application modes should be also tested.

Borage extracts affect wild rocket quality and influence nitrate and carbon metabolism.

Market is increasingly demanding vegetables with high quality and nutraceutical characteristics. It was demonstrated that leafy vegetables can get benefit from biostimulants, for the reduction of nitrate concentration and the increment of antioxidants, with potential benefit for human health. The research purpose was to investigate on the role of a novel plant-based biostimulant in affecting nitrogen and carbon metabolism in wild rocket (Diplotaxis tenuifolia L.). Foliar spray treatments were performed with extracts obtained from borage (Borago officinalis L.) leaves and flowers. To evaluate the treatments effect, in vivo determinations (chlorophyll a fluorescence and chlorophyll content) were performed. At harvest, nitrate concentration, sucrose, total sugars, chlorophyll, and carotenoids levels were measured in leaves. In order to characterize the mechanism of action also at molecular level, a set of genes encoding for some of the key enzymes implicated in nitrate and carbon metabolism was selected and their expression was measured by qRT-PCR. Interesting results concerned the increment of sucrose, coherent with a high value of Fv/Fm, in addition to a significant reduction of nitrate and ABA than control, and an enhanced NR in vivo activity. Also, genes expression was influenced by extracts, with a more pronounced effect on N related genes.

Spatial and temporal transcriptome changes occurring during flower opening and senescence of the ephemeral hibiscus flower, Hibiscus rosa-sinensis.

Flowers are complex systems whose vegetative and sexual structures initiate and die in a synchronous manner. The rapidity of this process varies widely in flowers, with some lasting for months while others such as Hibiscus rosa-sinensis survive for only a day. The genetic regulation underlying these differences is unclear. To identify key genes and pathways that coordinate floral organ senescence of ephemeral flowers, we identified transcripts in H. rosa-sinensis floral organs by 454 sequencing. During development, 2053 transcripts increased and 2135 decreased significantly in abundance. The senescence of the flower was associated with increased abundance of many hydrolytic genes, including aspartic and cysteine proteases, vacuolar processing enzymes, and nucleases. Pathway analysis suggested that transcripts altering significantly in abundance were enriched in functions related to cell wall-, aquaporin-, light/circadian clock-, autophagy-, and calcium-related genes. Finding enrichment in light/circadian clock-related genes fits well with the observation that hibiscus floral development is highly synchronized with light and the hypothesis that ageing/senescence of the flower is orchestrated by a molecular clock. Further study of these genes will provide novel insight into how the molecular clock is able to regulate the timing of programmed cell death in tissues.

Effect of cytokinins on delaying petunia flower senescence: a transcriptome study approach.

Flower senescence is a fascinating natural process that represents the final developmental stage in the life of a flower. Plant hormones play an important role in regulating the timing of flower senescence. Ethylene is a trigger and usually accelerates the senescence rate, while cytokinins are known to delay it. The aim of this work was to study the effect of 6-benzylaminopurine (BA) on petal senescence by transcript profile comparison after 3 or 6 h using a cross-species method by hybridizing petunia samples to a 4 × 44 K Agilent tomato array. The relative content of ethylene, abscisic acid, anthocyanins, total carotenoids and total phenols that determine the physiological behaviours of the petal tissue were measured. BA treatment prolonged the flower life and increased the concentrations of phenols and anthocyanins, while total carotenoids did not increase and were lower than the control. The ethylene biosynthetic and perception gene expressions were studied immediately after treatment until 24 h and all genes were repressed, while ethylene production was strongly induced after 4 days. The microarray analyses highlighted that BA strongly affected gene regulation after 3 h, but only 14% of genes remained differentially expressed after 6 h. The most affected pathways and genes were those related to stress, such as heat shock proteins, abscisic acid (ABA) catabolism and its signalling pathway, lipid metabolism and antioxidant defence systems. A gene annotation enrichment analysis using DAVID showed that the most important gene clusters were involved in energy generation and conservation processes. In addition to the ethylene pathway, cytokinins seem to be strongly involved the regulation of the ABA response in flower tissues.

Methyl jasmonate affects phenolic metabolism and gene expression in blueberry (Vaccinium corymbosum).

Blueberry (Vaccinium corymbosum) is a fruit very much appreciated by consumers for its antioxidant potential and health-promoting traits. Its beneficial potential properties are mainly due to a high content of anthocyanins and their amount can change after elicitation with methyl jasmonate. The aim of this work is to evaluate the changes in expression of several genes, accumulation of phenolic compounds and alterations in antioxidant potential in two different blueberry cultivars ('Duke' and 'Blueray') in response to methyl jasmonate (0.1 mM). Results showed that 9 h after treatment, the expression of phenylalanine ammonium lyase, chalcone synthase and anthocyanidin synthase genes was stimulated more in the 'Blueray' variety. Among the phenols measured an increase was recorded also for epicatechin and anthocyanin concentrations. 'Duke' is a richer sourche of anthocyanins compared to 'Blueray', treatment with methyl jasmonate promoted in 'Blueray' an increase in pigments as well as in the antioxidant potential, especially in fully ripe berries, but treated 'Duke' berries had greater levels, which were not induced by methyl jasmonate treatment. In conclusion, methyl jasmonate was, in some cases, an effective elicitor of phenolic metabolism and gene expression in blueberry, though with different intensity between cultivars.

Ethylene: Management and breeding for postharvest quality in vegetable crops. A review.

Ethylene is a two-carbon gaseous plant growth regulator that involved in several important physiological events, including growth, development, ripening and senescence of fruits, vegetables, and ornamental crops. The hormone accelerates ripening of ethylene sensitive fruits, leafy greens and vegetables at micromolar concentrations, and its accumulation can led to fruit decay and waste during the postharvest stage. Several strategies of crops management and techniques of plant breeding have been attempted in the last decades to understand ethylene regulation pathways and ethylene-dependent biochemical and physiological processes, with the final aim to extend the produce shelf-life and improve the postharvest quality of fruits and vegetables. These investigation approaches involve the use of conventional and new breeding techniques, including precise genome-editing. This review paper aims to provide a relevant overview on the state of the art related to the use of modern breeding techniques focused on ethylene and ethylene-related metabolism, as well as on the possible postharvest technological applications for the postharvest management of ethylene-sensitive crops. An updated view and perspective on the implications of new breeding and management strategies to maintain the quality and the marketability of different crops during postharvest are given, with particular focus on: postharvest physiology (ethylene dependent) for mature and immature fruits and vegetables; postharvest quality management of vegetables: fresh and fresh cut products, focusing on the most important ethylene-dependent biochemical pathways; evolution of breeding technologies for facing old and new challenges in postharvest quality of vegetable crops: from conventional breeding and marker assisted selection to new breeding technologies focusing on transgenesis and gene editing. Examples of applied breeding techniques for model plants (tomato, zucchini and brocccoli) are given to elucidate ethylene metabolism, as well as beneficial and detrimental ethylene effects.

Benzothiadiazole enhances ascorbate recycling and polyphenols accumulation in blueberry in a cultivar-dependent manner.

Benzothiadiazole (BTH) is a functional analogue of salicylic acid able to induce systemic acquired resistance in many horticultural crops. The aim of the work was to investigate how BTH may affect i) fruit quality, ii) ascorbic acid (AsA) oxidation and recycling metabolism and iii) phenolic compounds accumulation, during development and ripening of berries from the two selected cultivars. Blueberry (Vaccinium corymbosum L.) plants (cv 'Brigitta' and 'Duke') were treated with 0.118 mM BTH every two weeks during ripening, then all fruits of each plant were harvested and divided in four developmental stages. Results indicated that BTH had no marked effects on fruit quality parameters. During the first developmental stage, BTH negatively affected dry matter in both cv, while soluble solids and AsA content were affected in 'Duke'. In fully ripe berries, BTH reduced dry matter in 'Duke' and enhanced soluble solids content in 'Brigitta', while diminishing titratable acidity. AsA content was positively affected by BTH in 'Duke', but not in 'Brigitta'. The effect of BTH on the enzymes involved in AsA recycling was recorded in berries at the third (fruit more than half pigmented) and fourth developmental stages. After treatment, in both cv ascorbate peroxidase (APX) activity increased in fully ripe berries, while monodehydroascorbate reductase (MDHAR) activity was stimulated at the third ripening stage. Conversely, the activities of dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were enhanced only in 'Brigitta' and in 'Duke', respectively. BTH stimulated total polyphenols, flavonoid and anthocyanin accumulation in 'Brigitta' and in 'Duke' at the third and fourth ripening stages. In fully ripe berries, BTH enhanced the accumulation of delphinidins, cyanidins, petunidins and peonidins in 'Brigitta', while in 'Duke' it increased all classes of anthocyanidins, including malvidin. On the contrary, the relative proportion of the individual anthocyanins was only slightly affected by BTH treatment, mainly regarding delphinidin and malvidin at the third and fourth stage of ripening of 'Duke' and 'Brigitta', respectively. These results show that preharvest BTH application can positively impact on fruit bioactive compounds levels, affecting AsA recycling and content and increasing polyphenols accumulation in fruit, but partly depending on cv and ripening stage.

Priming Treatments with Biostimulants to Cope the Short-Term Heat Stress Response: A Transcriptomic Profile Evaluation.

Plant stress induced by high temperature is a problem in wide areas of different regions in the world. The trend of global warming is going to enhance the effects of heat stress on crops in many cultivation areas. Heat stress impairs the stability of cell membranes and many biological processes involving both primary and secondary metabolism. Biostimulants are innovative agronomical tools that can be used as a strategy to counteract the detrimental effect of abiotic stresses, including heat stress. In this work, two biostimulants based on Ascophyllum nodosum extracts (named Phylgreen) and based on animal L-α amino acids (named Delfan Plus) were applied as priming treatments to Arabidopsis thaliana plants subjected to heat stress exposure. Plants at the vegetative stage were treated with biostimulants 12 h before high temperature exposure, which consisted of maintaining the plants at 37 ± 1 °C for 4 h. Transcriptional profiles, physiological, and biochemical analyses were performed to understand the mode of action of the biostimulants in protecting the plants exposed to short-term heat stress. At a physiological level, chlorophyll, chlorophyll a fluorescence, phenolic index, total anthocyanins, reactive oxygen species (ROS) were measured, and significant variations were observed immediately after stress. Both biostimulants were able to reduce the oxidative damage in leaves and cell membrane. Transcriptomic data revealed that upregulated genes were 626 in Phylgreen and 365 in Delfan Plus, while downregulated genes were 295 in Phylgreen and 312 in Delfan Plus. Bioinformatic analysis showed that the biostimulants protected the plants from heat stress by activating specific heat shock proteins (HPS), antioxidant systems, and ROS scavengers. The results revealed that the biostimulants effectively induced the activation of heat stress-associated genes belonging to different transcription factors and HSP families. Among the heat shock proteins, the most important was the AtHSP17 family and in particular, those influenced by treatments were AtHPS17.4 and AtHPS17.6A, B, showing the most relevant changes.

Assessment of Possible Application of an Atmospheric Pressure Plasma Jet for Shelf Life Extension of Fresh-Cut Salad.

Ready-to-eat salads are very perishable with quality losses within 6-7 days, and the extension of their shelf life is still a challenge. In this work, an atmospheric pressure plasma jet (APPJ) was applied for the surface decontamination of fresh-cut lettuce baby leaves. The APPJ antimicrobial efficiency on the natural microbiota and its impact on some physicochemical attributes of lettuce were evaluated as a function of the treatment duration (0-30 s). Then, the influence of plasma treatment on the salad shelf life was studied, following the growth of aerobic mesophilic bacteria in both untreated and plasma-treated samples during 9 days of storage at 4 °C, together with the plasma-induced changes in physicochemical parameters of lettuce leaves. The APPJ induced a fast (15 s) microbial decontamination (1.3 log10 CFU/g) of the salad surface. Exposure time and salad-plasma plume distance were the parameters that substantially affected the microbial inactivation. APPJ treatment retarded bacterial growth during the refrigerated storage, as plasma-treated samples were noticeably less contaminated than the non-treated ones in the first 3-4 days. No significant effect were observed on electrolyte leakage, pH, and dry matter content in both the set up phase and the shelf life study.

Towards Nutrition-Sensitive Agriculture: An evaluation of biocontrol effects, nutritional value, and ecological impact of bacterial inoculants.

Nutrition-Sensitive Agriculture (NSA) is a novel concept in agriculture that considers not only yield, but also nutritional value of produce, sustainability of production, and ecological impact of agriculture. In accordance with its goals, NSA would benefit from applying microbial-based products as they are deemed more sustainable than their synthetic counterparts. This study characterized 3 plant-beneficial bacterial strains (Paenibacillus pasadenensis strain R16, Pseudomonas syringae strain 260-02, Bacillus amyloliquefaciens strain CC2) on their biocontrol activity and effect on nutritional and texture quality of romaine lettuce plants (Lactuca sativa) in greenhouse. The pathogens used in the trials are Rhizoctonia solani and Pythium ultimum. The obtained results indicate that strain R16 had a significant ability to cause a statistically significant reduction in the symptoms caused by both P. ultimum (reduction of 32%) and R. solani (reduction of 42%), while the other two strains showed a less efficient biocontrol ability. Indices of the nutritional quality (content in phenols, carotenoids and chlorophyll) were unaffected by the treatments, indicating that the product was equivalent to that obtained without using the bacteria, while the texture of the leaves benefits from the biocontrol treatments. In particular, the mechanical resistance of the leaves was significantly higher in non-treated plants affected by R. solani but was restored to the values of healthy plants when the bacterial inoculants were present as well. The ecological impact was evaluated by characterizing the bacterial microbiota in bulk soil, rhizosphere, and root in the presence or absence of the inoculants. The composition of the microbiota, analyzed with a Unifrac model to describe beta-diversity, was radically different in the rhizosphere and the root endosphere among treatments, while the bulk soil formed a single cluster regardless of treatment, indicating that the use of these treatments did not have an ecological impact outside of the plant.

Transcriptional Regulation in Rocket Leaves as Affected by Salinity.

Salinity is one of the major abiotic stress causing yield losses and decreasing product quality. The beneficial effects of biostimulant products to enhance plant tolerance to abiotic stresses have been reported in several crops, but their mode of action is poorly understood. This work aims to better understand the effect of salt stress on wild rocket treated with a borage extract. The expression of some of the transcription factors (TFs) typically involved in salt stress response was studied within a 24 h period. Physiological parameters such as chlorophyll, chlorophyll a fluorescence, carotenoids, phenols, and anthocyanin were analyzed. Results obtained showed that salt stress induced a general increase in the expression levels of almost all TFs studied, whereas the treatment with the plant-base extract only induced an increase at specific time points. Moreover, the approach adopted allowed indagating the change in gene expression during time. Different pathways such as sugars metabolism, cuticular wax biosynthesis, and brassinosteroids signaling took part in plant responses.

Effect of Preharvest Abiotic Stresses on the Accumulation of Bioactive Compounds in Horticultural Produce.

The quality of horticultural products is the result of the interaction of different factors, including grower's crop management ability, genotype, and environment. Sub-optimal environmental conditions during plant growth can induce abiotic stresses and reduce the crop performance with yield reduction and quality losses. However, abiotic stresses can induce several physiological, biochemical, and molecular responses in plants, aiming to cope with the stressful conditions. It is well known that these abiotic stresses are also elicitors of the biosynthesis of many metabolites in plants, including a wide range of bioactive compounds, which firstly serve as functional molecules for crop adaptation, but they have also a great interest for their beneficial effects on human health. Nowadays, the consumer is oriented to low-energy foods with low fat content, but at the same time, growing attention is paid to the presence of bioactive molecules, which are recognized as health-related compounds and concur to the nutraceutical value of plant-derived foods. In this context, fruit and vegetables play an important role as sources of bioactive ingredients in the diet. At the cultivation level, the understanding of crop responses to abiotic stresses and how they act in the biosynthesis/accumulation of these bioactive compounds is crucial. In fact, controlled abiotic stresses can be used as tools for improving the nutraceutical value of fruit and vegetables. This review focuses on the quality of vegetables and fruits as affected by preharvest abiotic stressors, with particular attention to the effect on the nutraceutical aspects.

Short-Term Post-Harvest Stress that Affects Profiles of Volatile Organic Compounds and Gene Expression in Rocket Salad During Early Post-Harvest Senescence.

Once harvested, leaves undergo a process of senescence which shares some features with developmental senescence. These include changes in gene expression, metabolites, and loss of photosynthetic capacity. Of particular interest in fresh produce are changes in nutrient content and the aroma, which is dependent on the profile of volatile organic compounds (VOCs). Leafy salads are subjected to multiple stresses during and shortly after harvest, including mechanical damage, storage or transport under different temperature regimes, and low light. These are thought to impact on later shelf life performance by altering the progress of post-harvest senescence. Short term stresses in the first 24 h after harvest were simulated in wild rocket (Diplotaxis tenuifolia). These included dark (ambient temperature), dark and wounding (ambient temperature), and storage at 4 °C in darkness. The effects of stresses were monitored immediately afterwards and after one week of storage at 10 °C. Expression changes in two NAC transcription factors (orthologues of ANAC059 and ANAC019), and a gene involved in isothiocyanate production (thiocyanate methyltransferase, TMT) were evident immediately after stress treatments with some expression changes persisting following storage. Vitamin C loss and microbial growth on leaves were also affected by stress treatments. VOC profiles were differentially affected by stress treatments and the storage period. Overall, short term post-harvest stresses affected multiple aspects of rocket leaf senescence during chilled storage even after a week. However, different stress combinations elicited different responses.

A complex interaction between pre-harvest and post-harvest factors determines fresh-cut melon quality and aroma.

Melons are prized for their characteristic aroma, however, pre-harvest growth, stage of ripening at harvest, post-harvest processing and storage conditions lead to quality changes in fresh-cut fruit. We considered changes in metabolites and gene expression over 14 days storage to assess underlying mechanisms and identify potential quality markers. Overall, 99 volatile organic compounds (VOCs) were detected and VOC profiles discriminated between two melon seasons, cut-size, storage temperatures and storage time, although season affected their discriminatory power. Abundance of two VOCs fell rapidly and was not associated with cut size, indicating their use as markers for early changes post-processing. Non-acetate to acetate ester ratio differed between the seasons and correlated with changes in alcohol acyl-transferase (CmAAT1) gene expression. Furthermore, CmAAT1 expression clustered with two ester VOCs that may be potential new products of this enzyme. Season also strongly affected post-harvest sugar content, most likely attributable to meteorological differences during growth. Storage temperature and cut size affected expression of transcription factors ERF71, ERF106, and TINY, whose expression generally rose during storage, probably related to increased stress. Thus, although time × temperature of storage are key factors, pre-harvest conditions and fruit processing impact significantly gene expression and aroma loss post-harvest.

Effect of heat root stress and high salinity on glucosinolates metabolism in wild rocket.

Wild rocket (Diplotaxis tenuifolia L.) is a leafy vegetable appreciated for its characteristic sensory properties which are mainly due to the presence of glucosinolates (GSLs). Short-term exposure to abiotic stresses can induce physiological responses and transcriptional changes which involve GSLs. For this reason, the aim of this work was to study the mechanisms of regulation of GSLs metabolism in rocket subjected to heat stress (40 °C) and high salinity (200 mM NaCl) imposed for up to 48 h. GSLs levels and the expression of methylthioalkylmalate synthase1 (DtMAM1), cytochromeP79F1 (DtCYP79F1), cytochromeP45083A1 (DtCYP83A1), cytosolic-sulfotransferase5b (DtST5b), cytosolic-sulfotransferase5c (DtST5c), flavinmono-oxygenase (DtFMO), myrosinase (DtMyro) and thio-methyl transferase (DtTMT) were analyzed under stress conditions. In addition, the effect on chlorophyll and glucose levels, as well as on chlorophyll a fluorescence were evaluated. Chlorophyll and chlorophyll fluorescence were not affected by the short-term application of stresses. Glucose levels in roots were doubled in response to high salinity, while, in the same organ, GSLs were three fold lower in response to both stresses. The relative content of several aliphatic GSLs was significantly reduced in leaves as a response to both stresses. A key role in GSLs metabolism and in the response to salinity is hypothesized for the gene DtTMT, as it showed an increment in transcripts accumulation (three-fold) consistent with the decrement in the GSLs levels found in salt-exposed leaves and roots. The results obtained in this study can be used in breeding programmes aiming to enhance rocket sensory quality and to improve the resistance to abiotic stresses.

Gene expression analysis of rocket salad under pre-harvest and postharvest stresses: A transcriptomic resource for Diplotaxis tenuifolia.

Diplotaxis tenuifolia L. is of important economic value in the fresh-cut industry for its nutraceutical and sensorial properties. However, information on the molecular mechanisms conferring tolerance of harvested leaves to pre- and postharvest stresses during processing and shelf-life have never been investigated. Here, we provide the first transcriptomic resource of rocket by de novo RNA sequencing assembly, functional annotation and stress-induced expression analysis of 33874 transcripts. Transcriptomic changes in leaves subjected to commercially-relevant pre-harvest (salinity, heat and nitrogen starvation) and postharvest stresses (cold, dehydration, dark, wounding) known to affect quality and shelf-life were analysed 24h after stress treatment, a timing relevant to subsequent processing of salad leaves. Transcription factors and genes involved in plant growth regulator signaling, autophagy, senescence and glucosinolate metabolism were the most affected by the stresses. Hundreds of genes with unknown function but uniquely expressed under stress were identified, providing candidates to investigate stress responses in rocket. Dehydration and wounding had the greatest effect on the transcriptome and different stresses elicited changes in the expression of genes related to overlapping groups of hormones. These data will allow development of approaches targeted at improving stress tolerance, quality and shelf-life of rocket with direct applications in the fresh-cut industries.

Evaluation of Borage Extracts As Potential Biostimulant Using a Phenomic, Agronomic, Physiological, and Biochemical Approach.

Biostimulants are substances able to improve water and nutrient use efficiency and counteract stress factors by enhancing primary and secondary metabolism. Premise of the work was to exploit raw extracts from leaves (LE) or flowers (FE) of Borago officinalis L., to enhance yield and quality of Lactuca sativa 'Longifolia,' and to set up a protocol to assess their effects. To this aim, an integrated study on agronomic, physiological and biochemical aspects, including also a phenomic approach, has been adopted. Extracts were diluted to 1 or 10 mL L-1, sprayed onto lettuce plants at the middle of the growing cycle and 1 day before harvest. Control plants were treated with water. Non-destructive analyses were conducted to assess the effect of extracts on biomass with an innovative imaging technique, and on leaf photosynthetic efficiency (chlorophyll a fluorescence and leaf gas exchanges). At harvest, the levels of ethylene, photosynthetic pigments, nitrate, and primary (sucrose and total sugars) and secondary (total phenols and flavonoids) metabolites, including the activity and levels of phenylalanine ammonia lyase (PAL) were assessed. Moreover, a preliminary study of the effects during postharvest was performed. Borage extracts enhanced the primary metabolism by increasing leaf pigments and photosynthetic activity. Plant fresh weight increased upon treatments with 10 mL L-1 doses, as correctly estimated by multi-view angles images. Chlorophyll a fluorescence data showed that FEs were able to increase the number of active reaction centers per cross section; a similar trend was observed for the performance index. Ethylene was three-fold lower in FEs treatments. Nitrate and sugar levels did not change in response to the different treatments. Total flavonoids and phenols, as well as the total protein levels, the in vitro PAL specific activity, and the levels of PAL-like polypeptides were increased by all borage extracts, with particular regard to FEs. FEs also proved efficient in preventing degradation and inducing an increase in photosynthetic pigments during storage. In conclusion, borage extracts, with particular regard to the flower ones, appear to indeed exert biostimulant effects on lettuce; future work will be required to further investigate on their efficacy in different conditions and/or species.

Identification of innovative potential quality markers in rocket and melon fresh-cut produce.

Ready-to-eat fresh cut produce are exposed to pre- and postharvest abiotic stresses during the production chain. Our work aimed to identify stress responsive genes as new molecular markers of quality that can be widely applied to leaves and fruits and easily determined at any stage of the production chain. Stress responsive genes associated with quality losses were isolated in rocket and melon fresh-cut produce and their expression levels analyzed by quantitative real time PCR (qRT-PCR) at different time points after harvest at 20 °C and 4 °C. qRT-PCR results were supported by correlation analysis with physiological and biochemical determinations evaluated at the same conditions such as chlorophyll a fluorescence indices, total, reducing sugars, sucrose, ethylene, ascorbic acid, lipid peroxidation and reactive oxygen species. In both species the putative molecular markers increased their expression soon after harvest suggesting a possible use as novel and objective quality markers of fresh-cut produces.

The Antioxidants Changes in Ornamental Flowers during Development and Senescence.

The concentration of antioxidant compounds is constitutive and variable from species to species and is also variable considering the development of the plant tissue. In this review, we take into consideration the antioxidant changes and the physiological, biochemical and molecular factors that are able to modulate the accumulation of antioxidant compounds in ornamental flowers during the whole development process until the senescence. Many ornamental flowers are natural sources of very important bioactive compounds with benefit to the human health and their possible role as dietary components has been reported. The most part of antioxidants are flower pigments such as carotenoids and polyphenols, often present in higher concentration compared with the most common fruits and vegetables. The antioxidants content changes during development and during senescence many biochemical systems and molecular mechanisms are activated to counteract the increase of reactive oxygen species and free radicals. There is a tight correlation between antioxidants and senescence processes and this aspect is detailed and appropriately discussed.

Ascorbic acid metabolism during bilberry (Vaccinium myrtillus L.) fruit development.

Bilberry (Vaccinium myrtillus L.) possesses a high antioxidant capacity in berries due to the presence of anthocyanins and ascorbic acid (AsA). Accumulation of AsA and the expression of the genes encoding the enzymes of the main AsA biosynthetic route and of the ascorbate-glutathione cycle, as well as the activities of the enzymes involved in AsA oxidation and recycling were investigated for the first time during the development and ripening of bilberry fruit. The results showed that the AsA level remained relatively stable during fruit maturation. The expression of the genes encoding the key enzymes in the AsA main biosynthetic route showed consistent trends with each other as well as with AsA levels, especially during the first stages of fruit ripening. The expression of genes and activities of the enzyme involved in the AsA oxidation and recycling route showed more prominent developmental stage-dependent changes during the ripening process. Different patterns of activity were found among the studied enzymes and the results were, for some enzymes, in accordance with AsA levels. In fully ripe berries, both AsA content and gene expression were significantly higher in skin than in pulp.