The Role of Stress Modifier Biostimulants on Adaptive Strategy of Oregano Plant for Increasing Productivity under Water Shortage.

To investigate the influence of stress modulators on the adaptive physiological responses and biomass traits of oregano under water stress conditions, a two-year (2018 and 2019) randomized complete block-designed factorial research was performed. In this study, oregano plants were treated with five stress modulators levels (CHN: chitosan, AMA: amino acids, SEW: seaweed, ASA: ascorbic acid, SAA: salicylic acid, and CON: control) at three levels of irrigation regimes (Irr40 (40), Irr60 (60) and Irr75 (75) % field capacity). The effects of water shortage and biostimulant application were evaluated on total dry weight (TDW), relative water content (RWC), essential oil production, chlorophyll, nutrient (N, K, and P), proline, total soluble sugar, polyphenol and flavonoid content, and activity of antioxidant enzymes. The result showed that under optimal irrigation conditions, oregano plants sprayed with CHN exhibited the highest dry weight (141.23 g m-2) as a morphological trait, the highest relative water content (79.34%), the most consistent concentrations of nitrogen, phosphorus and potassium (3.14, 0.39, and 1.69%, respectively), chlorophylls a and b (3.02 and 1.95 mg g-1 FW, respectively), and total phenols and total flavonoids (30.72 and 3.17 mg g-1 DW, respectively). The water deficit increased the proline content, with the greatest amount (4.17 µg g-1 FW) observed in control plants. Moreover, under moisture shortage stress conditions, the application of CHN and SEW increased the soluble sugar (27.26 µmol g-1 FW) and essential oil yield (1.80%) production, the catalase, ascorbate peroxidase, and superoxide dismutase activities (3.17, 1.18, and 63.89 µmol min-1 g-1 FW, respectively) compared to control plants. In summary, the study demonstrated that oregano plants respond positively to stress modulator treatments when subjected to moisture shortage stress, especially when treated with chitosan. The results offer promising insights for developing sustainable adaptative strategies aimed at enhancing the oregano's tolerance to water shortage, ultimately improving its productivity and biochemical traits.

Resilience of Xanthoria parietina under Mars-like conditions: photosynthesis and oxidative stress response.

MAIN CONCLUSION: Xanthoria parietina survivability in Mars-like conditions was supported by water-lysis efficiency recovery and antioxidant content balancing with ROS production after 30 days of exposure. Xanthoria parietina (L.) Th. Fr. is a widespread lichen showing tolerance against air pollutants and UV-radiation. It has been tested under space-like and Mars-like conditions resulting in high recovery performances. Hereby, we aim to assess the mechanisms at the basis of the thalli resilience against multiple space stress factors. Living thalli of X. parietina were exposed to simulated Martian atmospheric conditions (Dark Mars) and UV radiation (Full Mars). Then, we monitored as vitality indicator the photosynthetic efficiency, assessed by in vivo chlorophyll emission fluorescence measurements (FM; FV/F0). The physiological defense was evaluated by analyzing the thalli antioxidant capacity. The drop of FM and FV/F0 immediately after the exposure indicated a reduction of photosynthesis. After 24 h from exposure, photosynthetic efficiency began to recover suggesting the occurrence of protective mechanisms. Antioxidant concentrations were higher during the exposure, only decreasing after 30 days. The recovery of photosynthetic efficiency in both treatments suggested a strong resilience by the photosynthetic apparatus against combined space stress factors, likely due to the boosted antioxidants at the beginning and their depletion at the end of the exposure. The overall results indicated that the production of antioxidants, along with the occurrence of photoprotection mechanisms, guarantee X. parietina survivability in Mars-like environment.

Light Quality Potentiates the Antioxidant Properties of Brassica rapa Microgreen Extracts against Oxidative Stress and DNA Damage in Human Cells.

Plants are an inexhaustible source of bioactive compounds beneficial for contrasting oxidative stress, leading to many degenerative pathologies. Brassica rapa L. subsp. rapa is well known for its nutraceutical properties among edible vegetable species. In our work, we aimed to explore an eco-friendly way to enhance the beneficial dietary phytochemicals in this vast world of crop-growing plants at selected light quality conditions. White broad-spectrum (W) and red-blue (RB) light regimes were used for growing brassica microgreens. The organic extracts were tested on keratinocytes upon oxidative stress to explore their capability to act as natural antioxidant cell protectors. Our results show that both W and RB extracts caused a notable reduction in reactive oxygen species (ROS) levels induced by H2O2. Interestingly, according to its higher contents of polyphenols and flavonoids, the RB was more efficient in reducing ROS amount and DNA damage than the W extract, particularly at the lowest concentration tested. However, at higher concentrations (up to 100 µg/mL), the antioxidant effect reached a plateau, and there was little added benefit. These findings confirm that RB light effectively increases the antioxidant compounds in Brassica rapa L. microgreens, thus contributing to their enhanced activity against oxidative-induced genotoxicity compared to microgreens grown under W light.

Canopy-forming macroalgae can adapt to marine heatwaves.

Seawater warming and marine heatwaves (MHWs) have a major role on the fragmentation and loss of coastal marine habitats. Understanding the resilience and potential for adaptation of marine habitat forming species to ocean warming becomes pivotal for predicting future changes, improving present conservation and restoration strategies. In this study, a thermo-tolerance experiment was conducted to investigate the physiological effects of short vs long MHWs occurring at different timing on recruits of Gongolaria barbata, a canopy-forming species widespread in the Mediterranean Sea. The recruits were collected from a population of the Marine Protected Area of Porto Cesareo (Apulia, Ionian Sea). Recruits length, PSII maximal photochemical efficiency (Fv/Fm), photosynthetic pigments content, concentrations of antioxidant compounds and total antioxidant activity (DPPH) were the response variables measured during the experiment. Univariate asymmetrical analyses highlighted that all physiological variables were significantly affected by both the duration and the timing of the thermal stress with the only exception of recruits length. The higher Fv/Fm ratio, chlorophylls and carotenoids content, and antioxidant compounds concentration in recruits exposed to long-term stress likely indicate an acclimation of thalli to the new environmental conditions and hence, an increased tolerance of G. barbata to thermal stress. Results also suggest that the mechanisms of adaptation activated in response to thermal stress did not affect the natural growth rate of recruits. Overall, this study supports the hypothesis that canopy-forming species can adapt to future climate conditions demonstrating a physiological acclimation to cope with MHWs, providing strong evidence that adaptation of marine species to thermal stress is more frequent than expected, this contributing to design tailored conservation and restoration strategies for marine coastal habitat.

Modulation of Antioxidant Compounds in Fruits of Citrus reticulata Blanco Using Postharvest LED Irradiation.

Phlegrean mandarin fruits are already known for health-promoting properties due to the high concentration of phytochemicals in peel, pulp, and seed. Biotic and abiotic factors, including light, may modulate their biosynthesis, metabolism, and accumulation. In this context, light-emitting diodes (LED) have recently been applied to control nutritional traits, ripening process, senescence, fruit shelf-life, and pathogenic microbial spoilage of fruits. This study investigated the effect of the seven-day exposure of Phlegrean mandarin fruits to two LED regimes, white (W) and red-blue (RB), to test the possibility that the storage under specific light wavelengths may be used as green preservation technology that enhances fruit phytochemical properties. To pursue this aim, the antioxidant activity and polyphenolic profile of the pulp and peel of mandarins under W and RB light regimes were evaluated and compared with Control fruits not exposed to LED treatment. Our results indicated that storage under W and RB treatments modulates the antioxidant content in pulp and peel differently. Compared to W, the RB regime increases the ascorbic acid, flavonoid, anthocyanin, and carotenoid concentrations, while the polyphenol profile analysis reveals that the number of important phytochemicals, i.e., quercetin rutinoside, chlorogenic acid, sinensetin, and rutin, are higher under W. The overall data demonstrated that postharvest LED irradiation is a valid tool for modifying fruit phytochemical properties, which also boosts specific bioactive compounds.

Impact of Different Fertilizer Sources under Supplemental Irrigation and Rainfed Conditions on Eco-Physiological Responses and Yield Characteristics of Dragon's Head (Lallemantia iberica).

The effects of the irrigation regime and different fertilizer sources on the eco-physiological responses and yield characteristics of dragon's head were explored in a factorial experiment based on a randomized complete block design with 12 treatments and 3 replications in the 2019 growing season. The treatments included six different fertilizer sources (animal manure, vermicompost, poultry manure, biofertilizer, chemical fertilizer, and control) and two irrigation regimes (rainfed and supplemental irrigation). The results indicated the positive effects of supplementary irrigation and the application of vermicompost, poultry manure, and animal manure by increasing the absorption of nutrients (phosphorus and potassium) and improving relative water contents, chlorophyll and carotenoid contents, and the fixed oil percentage of dragon's head. The activities of catalase, ascorbate peroxidase, and superoxide dismutase decreased in the rainfed plants, whereas organic fertilizer application increased the antioxidant enzyme activity. The highest grain yield (721 kg ha-1), biological yield (5858 kg ha-1), total flavonoids (1.47 mg g-1 DW), total phenol (27.90 mg g-1 DW), fixed oil yield (200.17 kg ha-1), and essential oil yield (1.18 kg ha-1) were noted in plants that were treated with vermicompost under supplemental irrigation. Therefore, it is recommended that organic fertilizers such as vermicompost and poultry manure be used to substitute chemical fertilizers. These practices can help popularize organic crops using rainfed and supplementary irrigation.

Plant-Growth Promoting Microbes Change the Photosynthetic Response to Light Quality in Spinach.

In this study, the combined effect of plant growth under different light quality and the application of plant-growth-promoting microbes (PGPM) was considered on spinach (Spinacia oleracea L.) to assess the influence of these factors on the photosynthetic performance. To pursue this goal, spinach plants were grown in a growth chamber at two different light quality regimes, full-spectrum white light (W) and red-blue light (RB), with (I) or without (NI) PGPM-based inoculants. Photosynthesis-light response curves (LRC) and photosynthesis-CO2 response curves (CRC) were performed for the four growth conditions (W-NI, RB-NI, W-I, and RB-I). At each step of LRC and CRC, net photosynthesis (PN), stomatal conductance (gs), Ci/Ca ratio, water use efficiency (WUEi), and fluorescence indexes were calculated. Moreover, parameters derived from the fitting of LRC, such as light-saturated net photosynthesis (PNmax), apparent light efficiency (Qpp), and dark respiration (Rd), as well as the Rubisco large subunit amount, were also determined. In not-inoculated plants, the growth under RB- regime improved PN compared to W-light because it increased stomatal conductance and favored the Rubisco synthesis. Furthermore, the RB regime also stimulates the processes of light conversion into chemical energy through chloroplasts, as indicated by the higher values of Qpp and PNmax in RB compared to W plants. On the contrary, in inoculated plants, the PN enhancement was significantly higher in W (30%) than in RB plants (17%), which showed the highest Rubisco content among all treatments. Our results indicate that the plant-growth-promoting microbes alter the photosynthetic response to light quality. This issue must be considered when PGPMs are used to improve plant growth performance in a controlled environment using artificial lighting.

Antioxidant Characterization of Six Tomato Cultivars and Derived Products Destined for Human Consumption.

The consumption of fresh tomatoes and processed tomato products is widespread in the Mediterranean diet. This fruit is a valuable source of antioxidants and plays an important role in preventing oxidative stress. This study aimed to investigate the content of antioxidants and measure the total antioxidant capacity (ABTS and DPPH assays) in the peel, pulp, and seed fractions of six tomato cultivars. Finally, some bioactive compounds and total antioxidant activity were also determined in homemade tomato purees, since such homemade production is commonplace in Southern Italy. The level of antioxidants and total antioxidant capacity in each fraction were also calculated based on their actual fresh weight in the whole tomato. The overall results indicated that the peel and seeds of all analysed tomato cultivars contribute significantly to the antioxidant charge of the fruits. Consequently, consuming tomatoes without peel and seeds results in a substantial loss of compounds beneficial for human health. Our results also showed that phenolic and lycopene content, as well as antioxidant activities in all purees are higher than in fresh tomatoes. Based on this evidence, producing homemade tomato puree is a good practice, and its consumption helps prevent oxidative stress damage.

Vernalization Procedure of Tuberous Roots Affects Growth, Photosynthesis and Metabolic Profile of Ranunculus asiaticus L.

In Ranunculus asiaticus L., vernalization of propagation material is a common practice for the production scheduling of cut flowers, however little is known about the plant physiology and metabolism of this species as affected by cold treatments. We investigated the influence of two hybrids, MBO and MDR, and three preparation procedures of tuberous roots, only rehydration (control, C), and rehydration plus vernalization at 3.5 °C for 2 weeks (V2) and for 4 weeks (V4), on plant growth and flowering, leaf photosynthesis, and leaf metabolic profile in plants grown in pot in a cold greenhouse. Net photosynthesis (NP) was higher in MDR than in MBO. In the two genotypes, the NP did not change in V2 and increased in V4 compared to C in MBO, while was unaffected by vernalization in MDR. Quantum yield of PSII electron transport (ΦPSII), linear electron transport rate (ETR) and non-photochemical quenching (NPQ) did not differ in the two hybrids, whereas maximal PSII photochemical efficiency (Fv/Fm) was higher in MBO than in MDR. Fluorescence indexes were unaffected by the preparation procedure, except for ETR, which decreased in V2 compared to C and V4 in MDR. A significant interaction between genotype and preparation procedure was found in plant leaf area, which was reduced only in V4 in MBO, while decreased in both the vernalization procedures in MDR. In Control plants, flowering started in 65 days in MBO and 69 days in MDR. Compared to controls, both the vernalization treatments anticipated flowering in MDR, while they were detrimental or only slightly efficient in promoting flowering in MBO. Vernalization always reduced the quality of flower stems in both the hybrids.

Photosynthetic, Molecular and Ultrastructural Characterization of Toxic Effects of Zinc in Caulerpa racemosa Indicate Promising Bioremediation Potentiality.

Caulerpaceae are unconventional green algae composed of multinucleated, single siphonous cells. The species of Caulerpa are acquiring major scientific interest for both their invasion in the Mediterranean ecological niche and for the production of valuable natural metabolites. Furthermore, the abilities of Caulerpa spp. in the biorecovery of polluted waters were recently investigated. Among heavy metal contaminants in marine systems, zinc (Zn) is considered a critical pollutant, progressively accumulating from plastic leachates. In this study, the responses of Caulerpa racemosa to different levels (5-10 mg L-1) of Zn were studied for 14 days under laboratory-controlled conditions. Effects of Zn were monitored by measuring the growth rate, photosynthetic efficiency and gene expression. Moreover, the ability of Caulerpa to remove Zn from seawater was monitored. Zn induced detrimental effects by decreasing the relative growth rate (RGR) and maximal PSII photochemical efficiency (Fv/Fm). Moreover, C. racemosa, grown in contaminated seawater, reduced the levels of Zn to a final concentration of 1.026 and 1.932 mg L-1 after 14 days, thus demonstrating efficient uptake. Therefore, our results characterized the effects of zinc on C. racemosa and the possible role of this alga as being effective in the bioremediation of marine seawater.

Radiation environment in exploration-class space missions and plants' responses relevant for cultivation in Bioregenerative Life Support Systems.

For deep space exploration, radiation effects on astronauts, and on items fundamental for life support systems, must be kept under a pre-agreed threshold to avoid detrimental outcomes. Therefore, it is fundamental to achieve a deep knowledge on the radiation spatial and temporal variability in the different mission scenarios as well as on the responses of different organisms to space-relevant radiation. In this paper, we first consider the radiation issue for space exploration from a physics point of view by giving an overview of the topics related to the spatial and temporal variability of space radiation, as well as on measurement and simulation of irradiation, then we focus on biological issues converging the attention on plants as one of the fundamental components of Bioregenerative Life Support Systems (BLSS). In fact, plants in BLSS act as regenerators of resources (i.e. oxygen production, carbon dioxide removal, water and wastes recycling) and producers of fresh food. In particular, we summarize some basic statements on plant radio-resistance deriving from recent literature and concentrate on endpoints critical for the development of Space agriculture. We finally indicate some perspective, suggesting the direction future research should follow to standardize methods and protocols for irradiation experiments moving towards studies to validate with space-relevant radiation the current knowledge. Indeed, the latter derives instead from experiments conducted with different radiation types and doses and often with not space-oriented scopes.

Plant Growth-Promoting Bacterial Consortia as a Strategy to Alleviate Drought Stress in Spinacia oleracea.

Drought stress is one of the most severe abiotic stresses affecting soil fertility and plant health, and due to climate change, it is destined to increase even further, becoming a serious threat to crop production. An efficient, eco-friendly alternative is the use of plant growth-promoting bacteria (PGPB), which can promote plant fitness through direct and indirect approaches, protecting plants from biotic and abiotic stresses. The present study aims to identify bacterial consortia to promote Spinacia oleracea L. cv Matador's seed germination and protect its seedlings from drought stress. Eight PGPB strains belonging to the Bacillus, Azotobacter, and Pseudomonas genera, previously characterized in physiological conditions, were analyzed under water-shortage conditions, and a germination bioassay was carried out by biopriming S. oleracea seeds with either individual strains or consortia. The consortia of B. amyloliquefaciens RHF6, B. amyloliquefaciens LMG9814, and B. sp. AGS84 displayed the capacity to positively affect seed germination and seedlings' radical development in both standard and drought conditions, ameliorating the plants' growth rate compared to the untreated ones. These results sustain using PGPB consortia as a valid ameliorating water stress strategy in the agro-industrial field.

Manipulation of light quality is an effective tool to regulate photosynthetic capacity and fruit antioxidant properties of Solanum lycopersicum L. cv. 'Microtom' in a controlled environment.

Light quality plays an essential role in setting plant structural and functional traits, including antioxidant compounds. This paper aimed to assess how manipulating the light spectrum during growth may regulate the photosynthetic activity and fruit bioactive compound synthesis in Solanum lycopersicum L. cv. 'Microtom' to improve plant physiological performance and fruit nutritional value. Plants were cultivated under three light quality regimes: red-green-blue LEDs (RGB), red-blue LEDs (RB) and white fluorescent lamps (FL), from sowing to fruit ripening. Leaf functional traits, photosynthetic efficiency, Rubisco and D1 protein expression, and antioxidant production in fruits were analyzed. Compared to FL, RGB and RB regimes reduced height and increased leaf number and specific leaf area, enhancing plant dwarf growth. The RGB regime improved photosynthesis and stomatal conductance despite lower biomass, favoring Rubisco synthesis and carboxylation rate than RB and FL regimes. The RB light produced plants with fewer flowers and fruits with a lower ascorbic acid amount but the highest polyphenol content, antioxidant capacity and SOD and CAT activities. Our data indicate that the high percentage of the green wavelength in the RGB regime promoted photosynthesis and reduced plant reproductive capacity compared to FL and RB. Conversely, the RB regime was the best in favoring the production of health-promoting compounds in tomato berries.

Light Quality Modulates Photosynthesis and Antioxidant Properties of B. vulgaris L. Plants from Seeds Irradiated with High-Energy Heavy Ions: Implications for Cultivation in Space.

Beta vulgaris L. is a crop selected for cultivation in Space for its nutritional properties. However, exposure to ionizing radiation (IR) can alter plant photosynthetic performance and phytochemical production in the extraterrestrial environment. This study investigated if plant growth under different light quality regimes (FL-white fluorescent; RGB-red-green-blue; RB-red-blue) modifies the photosynthetic behavior and bioactive compound synthesis of plants sprouted by dry seeds irradiated with carbon or titanium high-energy ions. The study evidenced that: (i) the plant response depends on the type of heavyion; (ii) control and C-ion-irradiated plants were similar for photosynthetic pigment content and PSII photochemical efficiency, regardless of the LQ regime; (iii) under FL, net photosynthesis (AN) and water use efficiency (iWUE) declined in C- and Ti-ion plants compared to control, while the growth of irradiated plants under RGB and RB regimes offset these differences; (iv) the interaction Ti-ion× RB improved iWUE, and stimulated the production of pigments, carbohydrates, and antioxidants. The overall results highlighted that the cultivation of irradiated plants under specific LQ regimes effectively regulates photosynthesis and bioactive compound amounts in leaf edible tissues. In particular, the interaction Ti-ion × RB improved iWUE and increased pigments, carbohydrates, and antioxidant content.

Role of Poly(ADP-Ribose) Polymerase (PARP) Enzyme in the Systemic Acquired Acclimation Induced by Light Stress in Phaseolus vulgaris L. Plants.

Plants are able to acclimate to environmental constraints through functional modifications that may also occur in tissues that are not directly exposed to stress. This process is termed "systemic acquired acclimation." The present study aims to evaluate the involvement of PolyADP-ribose) polymerase (PARP) protein in the acclimation process to high light (HL) stress in Phaseolus vulgaris plants. For this purpose, some leaves located at the top of the plant, in the apical position, were directly exposed to HL ("inducing" leaves), while others on the same plant, distal from the top, continued to be exposed to growth light ("receiving" leaves) to verify the hypothesis that an "alert" message may be transferred from injured tissues to distal ones. Biochemical and eco-physiological analyses, namely PARP activity, H2O2 and water- and fat-soluble antioxidants (i.e., ascorbic acid, tocopherol, glutathione (GSH), phenols, carotenoids, etc.) content, and chlorophyll fluorescence measurements were performed on both "inducing" and "receiving" leaves. Even if no change in PARP expression was found, its activity increased in "receiving" unstressed leaves in response to the light stress duration experimented by "inducing" leaves, while antioxidant capacity declined. When the "receiving" leaves were exposed to HL, the PARP activity returned to the control value, while antioxidant capacity photosynthetic electron transport rate (Jf) decreased and increased, respectively, compared to Control. Our results seem to show an acclimation pathway triggered in remote tissues not yet subjected to stress, likely involving a reactive oxygen species wave activating the PARP enzyme in a mechanism still to be clarified. In addition, the increased tolerance of plants directly exposed to HL could implicate a boosted synthesis of soluble antioxidants accompanied by a reduction of PARP activity to reduce excessive consumption of NAD(P).

How Leaf Vein and Stomata Traits Are Related with Photosynthetic Efficiency in Falanghina Grapevine in Different Pedoclimatic Conditions.

The increase in severe drought events due to climate change in the areas traditionally suitable for viticulture is enhancing the need to understand how grapevines regulate their photosynthetic metabolism in order to forecast specific cultivar adaptive responses to the changing environment. This study aims at evaluating the association between leaf anatomical traits and eco-physiological adjustments of the 'Falanghina' grapevine under different microclimatic conditions at four sites in southern Italy. Sites were characterized by different pedoclimatic conditions but, as much as possible, were similar for plant material and cultivation management. Microscopy analyses on leaves were performed to quantify stomata and vein traits, while eco-physiological analyses were conducted on vines to assess plant physiological adaptation capability. At the two sites with relatively low moisture, photosynthetic rate, stomatal conductance, photosystem electron transfer rate, and quantum yield of PSII, linear electron transport was lower compared to the other two sites. Stomata size was higher at the site characterized by the highest precipitation. However, stomatal density and most vein traits tended to be relatively stable among sites. The number of free vein endings per unit leaf area was lower in the two vineyards with low precipitation. We suggest that site-specific stomata and vein traits modulation in Falanghina grapevine are an acclimation strategy that may influence photosynthetic performance. Overall in-depth knowledge of the structure/function relations in Falanghina vines might be useful to evaluate the plasticity of this cultivar towards site-specific management of vineyards in the direction of precision viticulture.

Antioxidant Properties of Pulp, Peel and Seeds of Phlegrean Mandarin (Citrus reticulata Blanco) at Different Stages of Fruit Ripening.

In this work, we assess the potential of waste products of Phlegrean mandarin (Citrus reticulata Blanco), namely seeds and peel, to be reutilized as a source of bioactive compounds beneficial for the human diet. Starting from the evidence that the by-products of this specific cultivar are the most powerful sources of antioxidants compared to pulp, we have investigated if and how the bioactive compounds in peel and seeds may be affected by fruit ripening. Three stages of fruit ripening have been considered in our study: unripe fruits = UF, semi-ripe fruits = SRF, ripe fruits = RF. The overall results indicated that RF showed the highest concentration of antioxidants. Among fruit components, peel was the richest in total antioxidant capacity, total polyphenol content, total flavonoids, total chlorophylls and carotenoids, while seeds exhibited the highest concentration of total condensed tannins and ascorbic acid. The liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay indicates the occurrence, in peel extracts, of 28 phenolic compounds, mainly flavonoids (FLs); in seeds, 34 derivatives were present in the first stage (UF), which diminish to 24 during the ripening process. Our data indicated that the content of phytochemicals in citrus strongly varies among the fruit components and depends on the ripening stage. The higher antioxidant activity of peel and seeds, especially in RF, encourage a potential use of by-products of this specific citrus cultivar for industrial or pharmacological applications. However, to maximize the occurrence of desired bioactive compounds, it is important also to consider the ripening stage at which fruits must be collected.

Comparative Analysis of the Effect of Carbon- and Titanium-Ions Irradiation on Morpho-Anatomical and Biochemical Traits of Dolichos melanophthalmus DC. Seedlings Aimed to Space Exploration.

The realization of manned missions for space exploration requires the development of Bioregenerative Life Support Systems (BLSSs) to make human colonies self-sufficient in terms of resources. Indeed, in these systems, plants contribute to resource regeneration and food production. However, the cultivation of plants in space is influenced by ionizing radiation which can have positive, null, or negative effects on plant growth depending on intrinsic and environmental/cultivation factors. The aim of this study was to analyze the effect of high-LET (Linear Energy Transfer) ionizing radiation on seed germination and seedling development in eye bean. Dry seeds of Dolichos melanophthalmus DC. (eye bean) were irradiated with two doses (1 and 10 Gy) of C- and Ti-ions. Seedlings from irradiated seeds were compared with non-irradiated controls in terms of morpho-anatomical and biochemical traits. Results showed that the responses of eye bean plants to radiation are dose-specific and dependent on the type of ion. The information obtained from this study will be useful for evaluating the radio-resistance of eye bean seedlings, for their possible cultivation and utilization as food supplement in space environments.

Light Spectral Composition Influences Structural and Eco-Physiological Traits of Solanum lycopersicum L. cv. 'Microtom' in Response to High-LET Ionizing Radiation.

This study evaluated if specific light quality (LQ) regimes (white fluorescent, FL; full-spectrum, FS; red-blue, RB) during plant growth modified morphological and photosynthetic traits of Solanum lycopersicum L. 'Microtom' plants irradiated at the dry seed stage with 25 Gy 48Ca ions (IR). The irradiation reduced plant size while it increased leaf dry matter content (LDMC) and relative water content (RWC) compared to the control. FS and RB light regimes determined a decrease of plant height and a rise of RWC compared to FL plants. The irradiation under FS and RB regimes favoured the development of dwarf plants and improved the leaf water status. Under the FL regime, irradiated plants showed reduced photosynthesis and stomatal conductance. The opposite behavior was observed in RB irradiated plants in which gas exchanges were significantly stimulated. RB regime enhanced Rubisco expression in irradiated plants also inducing anatomical and functional adjustments (i.e., increase of leaf thickness and incidence of intercellular spaces). Finally, 48Ca ions did not prevent fruit ripening and the achievement of the 'seed-to seed' cycle, irrespective of the LQ regime. Overall, the present study evidenced that RB light regime was the most effective in optimising growth and photosynthetic efficiency of 'Microtom' irradiated plants. These outcomes may help to develop proper cultivation protocols for the growth of dwarf tomato in Controlled Ecological Life Support Systems (CELSS).