97 research outputs found
Origin, evolution, and future of isoprene and nitric oxide interactions within leaves
No full text: Photolytic generation of nitric oxide (NO), isoprene, and reactive oxygen species (ROS) pre-dated life on Earth (~4 billion years ago). However, isoprene-ROS-NO interactions became relevant to climate chemistry ~50 million years ago, after aquatic and terrestrial ecosystems became dominated by isoprene-emitting diatoms and angiosperms. Today, NO and NO2 (together referred to as NOx) are dangerous biogenic gaseous atmospheric pollutants. In plants, NO, with its multiple sources and sinks, acts as a secondary messenger that regulates development at low doses and induces cell death at high doses. Likewise, biogenic isoprene is a putative antioxidant and hormone 'enabler' that hastens plant (and leaf) growth and reproduction, and improves plant tolerance to transient abiotic stresses. Using examples from controlled-chamber simulation and field studies of isoprene oxidation, we discuss the likely nature and extent of isoprene oxidation within leaves. We argue that isoprene-NO interactions vary greatly among plant species, driven by differences in isoprene emission rate and nitrate assimilation capacity (i.e. NO sink strength), ROS availability, and the within-leaf ratio between free-NO and isoprene. In a warmer and CO2-fertilized future climate, antagonism between isoprene and NO within leaves will probably occur in a NO-rich (relative to present) environment, yielding a greater proportion of isoprene oxidation products, and inducing major changes in NO-mediated growth and stress responses
Harnessing Light Wavelengths to Enrich Health-Promoting Molecules in Tomato Fruits
No full textThe tomato (Solanum lycopersicum L.) is one of the most consumed crops worldwide and a source of antioxidants. Given the role the latter play against oxidative stress and free radical-related diseases, enhancing tomato bioactive compound production would be appealing for a wide range of applications in the fields of nutrition, pharmacy, and biotechnology. This study explores a sustainable and innovative approach: the modulation of specific light spectra to boost the production of bioactive compounds in tomatoes (cultivar ‘Microtom’). We investigated how three light regimes—white fluorescent (FL), full-spectrum (FS), and red-blue (RB)—influence the accumulation of polyphenols and other key nutraceuticals during plant growth. Our findings reveal that full-spectrum (FS) light significantly enhances the levels of polyphenols, flavonoids, tannins, ascorbic acid, and lycopene in tomato fruits, compared to those grown under RB or FL light. Interestingly, fruits from RB light-grown plants showed the highest carotenoid concentrations and antioxidant capacity. These results suggest that light quality actively modulates the expression of key enzymes in the phenylpropanoid and flavonoid biosynthetic pathways, shaping each fruit’s unique metabolic fingerprint. Cluster analysis confirmed that RB, FL, and FS conditions lead to distinct polyphenolic profiles, each with notable health-promoting potential. Our results highlight a promising avenue: tailoring light environments to enhance the functional value of crops, bridging agriculture, nutrition, and biomedicine in a sustainable way
Light Spectral Composition Influences Structural and Eco-Physiological Traits of <i>Solanum lycopersicum</i> L. cv. ‘Microtom’ in Response to High-LET Ionizing Radiation
No full textThis 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)
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
No full textBeta 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 (A(N)) 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
Isoprenoids and phenylpropanoids are part of the antioxidant defense orchestrated daily by drought-stressed Platanus × acerifolia plants during Mediterranean summers
No full textThe hypothesis was tested that isoprenoids and phenylpropanoids play a prominent role in countering photooxidative stress, following the depletion of antioxidant enzyme activity in plants exposed to severe drought stress under high solar irradiance and high temperatures. Platanus × acerifolia, a high isoprene-emitting species, was drought-stressed during summer (WS) and compared with unstressed controls (WW). Water relations and photosynthetic parameters were measured under mild, moderate, and severe drought stress conditions. Volatile and nonvolatile isoprenoids, antioxidant enzymes, and phenylpropanoids were measured with the same time course, but in four different periods of the day. Drought severely inhibited photosynthesis, whereas it did not markedly affect the photochemical machinery. Isoprene emission and zeaxanthin concentration were higher in WS than in WW leaves, particularly at mild and moderate stresses, and during the hottest hours of the day. The activities of catalase and ascorbate peroxidase steeply declined during the day, while the activity of guaiacol peroxidase and the concentration of quercetin increased during the day, peaking in the hottest hours in both WW and WS plants. Our experiment reveals a sequence of antioxidants that were used daily by plants to orchestrate defense against oxidative stress induced by drought and associated high light and high temperature. Secondary metabolites seem valuable complements of antioxidant enzymes to counter oxidative stress during the hottest daily hours
An integrated overview of physiological and biochemical responses of Celtis australis to drought stress
No full textTrees in Mediterranean areas frequently face severe drought stress events, due to sudden decreases in soil water availability associated to intense heat waves. The knowledge of strategies adopted by plants to cope with the environmental pressures associated to Mediterranean climate is crucial for reforestation strategies and planning future urban greening. Here we investigated the physiological and biochemical adjustments activated by Celtis australis in response to drought stress during summer. Despite widely used for reforestation in Southern Mediterranean, how C. australis responds to the severe challenges imposed by Mediterranean climate has not investigated yet. In our study, we performed analyses of water relations, gas exchange and PSII performance, the concentration of photosynthetic pigments, the activity and the concentration of primary antioxidants in plants exposed to drought stress of increasing severity. Data of our study reveal that C. australis displays both conservative water use and isohydric behavior in response to drought, and diffusive resistance mostly limits photosynthesis even at severe drought. Our study also reveals an effective down-regulation rather than permanent impairment of PSII photochemistry in response to drought stress of increasing severity, since excess electron transport due to declines in photosynthesis (-61% at severe stress, compared to control) was matched by an increase in nonphotochemical quenching (+71% at severe stress, compared to control). However, our study highlights that under severe drought, zeaxanthin (and neoxanthin) increased by 75% (and 25%), likely served an important function as chloroplast antioxidant, other than sustaining nonphotochemical quenching. Antioxidant enzymes and ascorbate also increased (+132% on average for superoxide dismutase, ascorbate peroxidase, and catalase) and contributed in countering oxidative stress in severely droughted plants. Large adjustments in the suite of physiological and biochemical traits may effectively enable C. australis to gain carbon at appreciable rates while avoiding irreversible damage to the photosynthetic apparatus even when challenged by severe drought stress, thereby making this species an excellent candidate for forest and urban plantings in sites experiencing extended periods of drought stress
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
No full textLight 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
Physiological and structural adjustments of two ecotypes of Platanus orientalis L. from different habitats in response to drought and re-watering
No full textPlatanus orientalis covers a very fragmented area in Europe and, at the edge of its natural distribution, is considered a relic endangered species near extinction. In our study, it was hypothesized that individuals from the edge of the habitat, with stronger climate constrains (drier and warmer environment, Italy, IT ecotype), developed different mechanisms of adaptation than those growing under optimal conditions at the center of the habitat (more humid and colder environment, Bulgaria, BG ecotype). Indeed, the two P. orientalis ecotypes displayed physiological, structural and functional differences already under control (unstressed) conditions. Adaptation to a dry environment stimulated constitutive isoprene emission, determined active stomatal behavior, and modified chloroplast ultrastructure, ultimately allowing more effective use of absorbed light energy for photochemistry. When exposed to short-term acute drought stress, IT plants showed active stomatal control that enhanced instantaneous water use efficiency, and stimulation of isoprene emission that sustained photochemistry and reduced oxidative damages to membranes, as compared to BG plants. None of the P. orientalis ecotypes recovered completely from drought stress after re-watering, confirming the sensitivity of this mesophyte to drought. Nevertheless, the IT ecotype showed less damage and better stability at the level of chloroplast membrane parameters when compared to the BG ecotype, which we interpret as possible adaptation to hostile environments and improved capacity to cope with future, likely more recurrent, drought stress
The role of isoprene emission in two Arundineae species exposed to progressive drought stress
No full textIsoprene is the most abundant biogenic volatile organic compound emitted
from vegetation and has been suggested to have protective role in plants under
different kinds of stress. In this study we compared the responses to drought
stress of two Arundineae species which differ in their ability to emit isoprene –
Arundo donax, a promising biofuel crop and isoprene emitter, and Hakonechloa
macra, a non-emitting ornamental plant. Our results showed better recovery
of photosynthesis in A. donax after rehydration in comparison to H. macra.
H. macra had lower photosystem II (PSII) photochemical efficiency, increased
non-photochemical quenching (NPQ) and high levels of leaf malondialdehyde
(MDA) and proline content when exposed to drought stress. The isoprene emitting
species A. donax showed enhanced drought tolerance and better recovery
after rewatering than the non-emitting H. macra. Our results confirm the idea
that in isoprene emitting species, the function of isoprene is closely associated
with functioning of the photosynthetic apparatus
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