Ratio Of Carotenoids Research Articles

THE SIGNIFICANCE OF CHLOROPHYLLS AND CAROTENOIDS IN ENHANCING SEED TOLERANCE TO ABIOTIC STRESS

the degradation of chlorophylls during seed ripening, residual levels are detectable in mature seeds, affecting their stress tolerance. Carotenoids, predominantly lutein and β-carotene, accumulate in seeds under accelerated aging conditions and high-temperature germination, influencing stress response. The ratio of carotenoid to chlorophyll content (Car/Chl) emerges as a potential indicator of seed stress tolerance, with higher ratios correlating with enhanced resilience to stressors. Objective: This study aims to elucidate the significance of chlorophylls and carotenoids in enhancing seed tolerance to abiotic stressors by investigating their roles and interactions within seeds under stress conditions. Methods: Physiologically mature seeds containing residual chlorophylls were subjected to stress treatments, and carotenoid levels were assessed during seed aging and germination experiments. The Car/Chl ratio was calculated to evaluate its relationship with seed stress tolerance. Results: Seeds with elevated Car/Chl ratios exhibited higher tolerance to stress treatments, suggesting a protective role of carotenoids against oxidative stress induced by chlorophylls under abiotic stress conditions. Carotenoid accumulation during aging and germination further underscored their role in stress response, influencing seed resilience. Conclusion: although residual in mature seeds, chlorophylls contribute to oxidative stress under abiotic stressors. Conversely, carotenoids act as antioxidants, mitigating stress-induced damage and enhancing seed tolerance. The Car/Chl ratio is valuable for assessing seed stress resilience, providing insights into seed physiology under adverse environmental conditions.

Фотосинтетическая активность подроста хвойных в связи с промышленными рубками

The functioning of coniferous undergrowth of preliminary and subsequent generations after industrial felling was considered in the middle taiga subzone of the Komi Republic. Using spectrophotometric and gasometric methods we analyzed the pigment activity, photosynthetic, and respiratory abilities of the assimilation apparatus of pine (Pinus sylvestris L.) and spruce (Picea obovata Ledeb.) undergrowth at the 3- and 10-year old clearings. The pigment apparatus functional rearrangement of the preliminary generation spruce undergrowth at clearings was found. Needles adapt to environmental conditions at the pigment system level by changing the content and ratio of chlorophylls and carotenoids. Changes in plastids in the spruce undergrowth at the 3-year clearings occurred due to a decrease in chlorophyll and carotenoid concentrations, and at the 10-year clearings due to activation of pigment synthesis which affects the carbon dioxide absorption in chloroplasts. The assimilation apparatus of spruce undergrowth at clearing absorbs CO2 by 1.4 and 1.8 time more actively than that under the forest canopy. The photosynthetic and respiratory abilities of spruce needles at clearings do not differ. This indicates a stable level of important vital processes for the studied undergrowth at clearings during ten years after felling. Pine and spruce undergrowth needles are able to absorb CO2 at a fairly high rate up to 5.73 and 2.7 μmol CO2/(m2 · s) respectively. This rate contributes to the accumulation of assimilates in pine needles and their use for growth which logically increases the productivity of undergrowth at clearings. In general, the functional organization of spruce and pine undergrowth assimilating organs ensures their growth and favors the successful restoration of conifers at clearings in the middle taiga subzone of the European North-East.

Excluding sunscald from long-term storage of ‘Granny Smith’ apples

Sunscald is a postharvest apple and pear peel disorder primarily caused by excessive light exposure during the growing season. Symptoms are not apparent at-harvest but develop during storage as superficial brown or gray discolored patches on the exposed portion of the apple. A novel protocol using hyperspectral imaging (HSI) was developed to identify apples at- harvest that are more likely to develop the disorder and reduce sunscald in the cold chain by eliminating at-risk apples from long-term storage. PLS-DA and LOGISTIC models and an index summarizing the chlorophyll to carotenoid ratio were tested for this purpose using two populations selected for different sun exposure levels and four populations harvested from whole trees. The accuracy of models varied seasonally. However, detection of sunburn and estimation of sunscald risk based on index values was a more consistent approach. Summarizing peel area according to this index was the basis for categorizing whole apples as rejected (sunburned), high (sunscald) risk, or low-risk. Categorization segregated apples nearly entirely into these categories with only an insignificant frequency of misclassification. The frequency of high-risk apples without sunburn symptoms in the populations harvested from whole trees fell below 20 %, although actual sunscald incidence within this category ranged from 55 % to 81 % among populations harvested from whole trees, highlighting that other factors beyond elevated sun exposure contribute to sunscald incidence. The classification model for low and high-risk categories had an accuracy of 83–93 % in four independent populations, with 99.9 % sensitivity to classify non-sunscalded fruit into the low-risk category. Sorting by sunburn presence and sunscald risk allows for apples that have sunburn symptoms to be excluded and those that are marketable but most likely to develop sunscald to be pushed to market rather than storage. With the appropriate source/sensor array, this approach is readily adaptable to sorting lines or even robotic harvesters. Challenges include adapting this approach for other apple and pear cultivars and extending capabilities for additional uses, including sorting fruit into additional categories representative of relative sunlight exposure.

Temperature-Caused Changes in Raman Pattern and Protein Profiles of Winter Triticale (x Triticosecale, Wittm.) Field-Grown Seedlings.

Climate change, which causes periods with relatively high temperatures in winter in Poland, can lead to a shortening or interruption of the cold hardening of crops. Previous research indicates that cold acclimation is of key importance in the process of acquiring cereal tolerance to stress factors. The objective of this work was to verify the hypothesis that both natural temperature fluctuations and the plant genotype influence the content of metabolites as well as proteins, including antioxidant enzymes and photosystem proteins. The research material involved four winter triticale genotypes, differing in their tolerance to stress under controlled conditions. The values of chlorophyll a fluorescence parameters and antioxidant activity were measured in their seedlings. Subsequently, the contribution of selected proteins was verified using specific antibodies. In parallel, the profiling of the contents of chlorophylls, carotenoids, phenolic compounds, and proteins was carried out by Raman spectroscopy. The obtained results indicate that a better PSII performance along with a higher photosystem II proteins content and thioredoxin reductase abundance were accompanied by a higher antioxidant activity in the field-grown triticale seedlings. The Raman studies showed that the cold hardening led to a variation in photosynthetic dyes and an increase in the phenolic to carotenoids ratio in all DH lines.

МЕТОДОЛОГИЯ УПРАВЛЕНИЯ АГРОБИОЛОГИЧЕСКОЙ, АДАПТИВНОЙ И ПРОДУКЦИОННОЙ УСТОЙЧИВОСТЬЮ НАСАЖДЕНИЙ ВИНОГРАДА В НЕСТАБИЛЬНЫХ ПОГОДНЫХ УСЛОВИЯХ И ТЕХНОГЕННОЙ ИНТЕНСИФИКАЦИИ ПРОИЗВОДСТВА

The article presents the results of agrobiological and physiological-biochemical studies to ensure the stability of grape plantations in unstable weather conditions and anthropogenic intensification of production. Studies in the agroecological conditions of the Krasnodar region on the southern chernozems revealed the most productive norm of loading of grape bushes with shoots for the technical varieties Kurchanskiy, Dmitriy, Vladimir, Granatovyi, Antaris and Alkor, on leached chernozems – for the table seedless variety Centennial Seedless. According to the results of electrophoretic separation of peroxidases in polyacrylamide gel and an increased content of ascorbic acid, increased frost resistance was established in the varieties Kristall, Vostorg, Krasnostop AZOS. The Vostorg and Zarif varieties proved to be more adaptive to the stresses of the summer period in terms of leaf hydration, bound water content, the ratio of chlorophylls and carotenoids, the amount of proline and water-soluble sugars, membrane permeability. The role of physiologically active substances in increasing the adaptive potential of grape plants has been established. The treatment of Merlot vines with methyl jasmonate and epibrassinolide during deep dormancy period, as well as proline, salicylic acid and epibrassinolide during induced dormancy period had a positive effect on the condition of the vine: there was a decrease in electrolyte yield. Sustainable grape cultivation is achieved with the systemic use of the «Bioconcentrate-Z» effluent by the non-root method. Against the background of nonroot treatments of Merlot and Cabernet Sauvignon varieties, a higher level of plant water supply, an increase in potassium content, green pigments, organic acids and grape yields were established. Physiologically active compounds and the preparation Turinbash have a positive effect in intensive own-root plantations of native and promising introduced grape varieties against the background of phylloxera infection in the southern part of Dagestan. The created yield forecasting method based on the NDVI of the grape plant and the actual data of multispectral images of the phenophases of flowering and growth allows to increase the accuracy of the calculated yield capacity to the actual one with a deviation from 0 to 0.8 kg per bush, the accuracy of the forecast increases by 2 times by the end of the growth phase and by the beginning of the maturation phase. Key words: GRAPES, METHODS, MANAGEMENT, SUSTAINABILITY, PRODUCTIVITY, QUALITY, FORECASTING

MINERAL STATUS OF GREEN PEAS GROWTH BY DROUGHT AND AMINO ACID SPRAYING

A greenhouse pot experiment was conducted 2023 at the National Research Centre in Dokki, Cairo, Egypt to investigate the impact of proline and glutamic acid on the growth, photosynthetic pigments, and mineral levels of Green Peas plants. The absence of irrigation has a detrimental impact on the growth of Green Peas plants, namely in terms of plant height, number of green leaves and stem, as well as the dry weight of leaves and top. The depressing impact was greater when irrigation was absent during the blossoming stage compared to the filling stage. This statement holds true for the conditions indicated earlier. In general, the utilization of amino acids (namely glutamic and proline) enhanced development characteristics. The application of glutamic acid resulted in greater plant height, leaf count, and dry weight of both stems and tops compared to the effects of proline spraying. The absence of irrigation at any growth stage in the study had no impact on the concentration of Chlorophyll (Ch. A and Ch. A + Ch. B). However, there was a modest effect on the concentrations of carotenoids and total Chlorophyll. Nevertheless, the concentration of (Ch. B) exhibited an increase during the fruiting phase under drought treatment. However, this rise needed to be more substantial to reach a statistically significant level. The ratio of Chlorophyll A to Ch. B increased exclusively during the dry period. The utilization of glutamic acid resulted in the highest levels of Ch.A, Ch.B total chlorophyll concentrations, with just a modest impact on carotenoid levels. In addition, the ratios of carotenoids in Ch. A and Ch. B, as well as the combined ratios of Ch.A and Ch.B exhibited similar reactions.

Evidence for tropospheric ozone effects on rice production in Bangladesh

Although Bangladesh is known to be burdened with elevated tropospheric ozone levels, little is known about its effects on food security. We conducted field experiments in four highly polluted rice growing environments of Bangladesh in three cropping seasons (2020−2022), in which we grew 20 different rice varieties with or without application of the ozone protectant ethylene diurea (EDU). The average daytime ozone concentrations at the study sites during the rice growing seasons ranged from 53 ppb to 84 ppb, with the lowest concentrations occurring in the year 2020. EDU increased rice grain yields significantly by an average of 10.4 % across all seasons and locations, indicating that plants were stressed under ambient ozone concentrations. EDU was effective in distinguishing ozone-tolerant from ozone-sensitive varieties, in which yield increased by up to 21 %. Likewise, the EDU treatment positively affected vegetation indices representing chlorophyll (NDVI), the chorophyll:carotenoid ratio (Lic2), and pigments of the xanthophyll cycle (PRI). Stomatal conductance was increased significantly by an average of around 10 % among all varieties when plants were treated with EDU. In all physiological traits, significant genotype by treatment interactions occurred, indicating that different varieties varied in their responses to ozone stress. Our study demonstrates that rice production in Bangladesh is severely affected by tropospheric ozone, and calls for the breeding of tolerant rice varieties as well as mitigation measures to reduce air pollution.

Culture-free identification of fast-growing cyanobacteria cells by Raman-activated gravity-driven encapsulation and sequencing

By directly converting solar energy and carbon dioxide into biobased products, cyanobacteria are promising chassis for photosynthetic biosynthesis. To make cyanobacterial photosynthetic biosynthesis technology economically feasible on industrial scales, exploring and engineering cyanobacterial chassis and cell factories with fast growth rates and carbon fixation activities facing environmental stresses are of great significance. To simplify and accelerate the screening for fast-growing cyanobacteria strains, a method called Individual Cyanobacteria Vitality Tests and Screening (iCyanVS) was established. We show that the 13C incorporation ratio of carotenoids can be used to measure differences in cell growth and carbon fixation rates in individual cyanobacterial cells of distinct genotypes that differ in growth rates in bulk cultivations, thus greatly accelerating the process screening for fastest-growing cells. The feasibility of this approach is further demonstrated by phenotypically and then genotypically identifying individual cyanobacterial cells with higher salt tolerance from an artificial mutant library via Raman-activated gravity-driven encapsulation and sequencing. Therefore, this method should find broad applications in growth rate or carbon intake rate based screening of cyanobacteria and other photosynthetic cell factories.

Photoprotective responses of three intertidal Antarctic macroalgae to short-term temperature stress

The Antarctic Peninsula is experiencing one of the highest warming rates globally. In polar regions, macroalgae thrive under extreme environmental conditions, which could worsen because of future climate change scenarios, including increased ultraviolet exposure, extremely low light availability, and fluctuating temperatures, particularly in the intertidal zones. To investigate the potential role of photoprotective and antioxidant mechanisms in response to future increases in sea surface temperatures caused by climate change, we conducted laboratory experiments using three intertidal macroalgae model species: Adenocystis utricularis (Ochrophyta, Phaeophyceae), Pyropia endiviifolia (Rhodophyta, Bangiophyceae), and Monostroma hariotii (Chlorophyta, Ulvophyceae). These algae were collected in Punta Artigas (King George Island, Antarctica) and acclimated at 2°C for 48 h. They were then assessed in laboratory experiments for up to 5 days under two treatments: (1) control conditions at 2°C and (2) elevated tem.perature conditions at 8°C, representing the most negative increment in SSTs estimated by the end of the 21st century. Carbon, nitrogen, pigments (chlorophylls and carotenoids), mycosporine-like amino acids (MAAs), and phenolic compounds were quantified after 3 and 5 days of exposure. For M. hariotii, elevated temperatures led to an increase in the C/N ratio, total antioxidant capacity, and levels of nitrogen, total carotenoids, chlorophyll-a, pigments (chlorophyll-b and violaxanthin), and phenolic compounds. For A. utricularis, elevated temperatures led to elevated C/N ratio and levels of chlorophyll-a and carotenoids (fucoxanthin and β-carotene). For P. endiviifolia, elevated temperatures resulted in elevated levels of carotenoids (lutein and β-carotene), phenolic compounds, and MAAs (porphyra-334, shinorine, and palythine). Thus, our study suggests that increasing water temperatures due to global warming can enhance the photoprotective abilities of three Antarctic intertidal macroalgae (M. hariotii, A. utricularis, and P. endiviifolia), with each species showing specific responses.

Cultivar-dependent and drought-induced modulation of secondary metabolites, adaptative defense in Fagopyrum esculentum L

The present study investigates the biochemical responses of buckwheat to drought stress, particularly focusing on phenolic acids and flavonoids, abundant in this crop. We hypothesize that distinct genotypic responses to drought stress will lead to variations in phenolic acid accumulation. Two common buckwheat cultivars, Panda (East European origin) and PI 482597 (originating from Zimbabwe), were subjected to drought treatment, with biochemical traits, relative water content, and photosynthetic pigments regularly assessed. While chlorophyll content remained unaffected by dehydration, total carotenoid content decreased. The unique increase in the chlorophyll to carotenoid ratio suggests a specific role of carotenoids in buckwheat's metabolic stress response. While most phenolic acids and flavonoids exhibited increasing trends during progressive dehydration, their dynamics differed. Notably, rutin content increased early in drought stress, while chlorogenic acid and kaempferol showed enhanced levels only under severe dehydration. Genotypic differences were observed in chlorogenic acid, neochlorogenic acid, cryptochlorogenic acid, 4-hydroxybenzoic acid, and quercetin. Conversely, trans-p-coumaric acid, trans-ferulic acid, vanillic acid, rutin, and kaempferol showed similar trends in both cultivars. By aligning observed drought-induced changes in phenolic compound contents with biosynthesis pathways, trade-offs between individual compounds were identified, contributing to the mechanistic understanding of varied stress responses.

Molecular mechanism of lycopene cyclases regulating carotenoids ratio in different branches during tea leaf and flower development

Carotenoids are essential components in tea quality, contributing to leaf color and aroma. However, little information about carotenoids in different tea cultivars and their biosynthesis regulation mechanism during leaf development is known. Here we analyzed carotenoids by HPLC in the buds and leaves of 113 tea cultivars harvested on the same day. By profile clustering, carotenoids were divided into five groups. Same group cultivars displayed divergence in the total content of carotenoids but a similar molar ratio. To figure out the molecular mechanisms of this phenomenon, we further characterized all functional lycopene cyclases, which are the branch point of the carotenoid biosynthesis pathway. Two β-lycopene cyclases (CsLCYB1 and CsLCYB2) and one ε-lycopene cyclase (CsLCYE1) were cloned. Subcellular localization analysis showed that all cloned CsLCYs were localized in plastids. Enzyme activity assays in E. coli indicated both CsLCYBs catalyzed lycopene into β-carotene, and CsLCYE1 produced δ-carotene and ε-carotene. We found CsLCYB1 and CsLCYE1 predominantly expressed in leaf, while CsLCYB2 was mainly expressed during flowering stages. Suppression by antisense oligonucleotides reduced CsLCYB1 and CsLCYE1 transcripts and led to reduction of both β,β-branch and β,ε-branch carotenoids in leaf. The expression levels of CsLCYB1 showed a significant positive correlation with β,β-branch carotenoids in leaf. Our study provides carotenoid profiles of different tea cultivars, which can assist tea producers in selecting cultivars of interest. Meanwhile, we proposed the molecular mechanism of carotenoids reflecting the tenderness of tea plant leaf from a metabolic flux perspective, and suggested lycopene cyclase that could be applied to the breeding of tea varieties with different branch carotenoids.

Pigment assemblages in subtropical bloom-forming cyanobacteria strains

Abstract Pigments are powerful indicators for chemotaxonomy and remote sensing studies, which are the approaches used for cyanobacterial bloom monitoring. Cyanobacterial pigments include high concentrations of phycobilins and diverse carotenoids. Filamentous nitrogen-fixing species (Nostocales) are frequent in cyanobacterial blooms of warm climate lakes, and more information about pigments can be useful for improving management. We analyzed the carotenoid ratios to chlorophyll a of nine subtropical cyanobacterial strains (orders: Synechococcales, Chroococcales, Oscillatoriales and Nostocales), for some of which we also characterized the in vivo absorption spectra (aph). The main carotenoids were β,β-carotene, echinenone, hydroxy-echinenone-like, zeaxanthin and myxoxanthophyll (including aphanizophyll and unknown myxoxanthophyll-like myxol-glycoside carotenoids); however, proportions diverged greatly between orders, a trend also observed for the aph. Zeaxanthin ratios were highest in the picocyanobacterium. Nostocales species were rich in myxoxanthophyll and echinenone, with low zeaxanthin signals. We identified four pigment assemblages differentiating the strains according to their phylogenetic orders, information that needs to be considered for tracking cyanobacterial groups, particularly Nostocales.

Characterizing carotenoids in cyanobacterial cultures – Opportunities and implications for paleolimnological studies

Cyanobacterial blooms are increasing in frequency and intensity globally, impacting lake ecosystem health and posing a risk to human and animal health due to the toxins they can produce. Cyanobacterial pigments preserved in lake sediments provide a useful means of understanding the changes that have led to cyanobacterial blooms in lakes. However, there is some uncertainty as to whether specific carotenoids are unique to certain genera or types of cyanobacteria. To fill this knowledge gap, we analyzed pigments in 34 cyanobacteria cultures and applied the findings to sediments from three New Zealand lakes. The cyanobacterial carotenoids canthaxanthin, echinenone and zeaxanthin were detected in all cultures, whereas myxoxanthophyll was only detected in ten cultures (Microcoleus, Planktothrix and the picocyanobacteria cultures; Synechococcaceae). The sum of the individual carotenoid concentrations provided the strongest relationship with cyanobacterial biomass (R2 = 0.58) and could be used in paleolimnology studies to evaluate general cyanobacterial abundance. Ratios of canthaxanthin, zeaxanthin and myxoxanthophyll relative to echinenone indicated that carotenoid ratios could be used to differentiate picocyanobacteria and bloom-forming cyanobacteria, to some degree. High zeaxanthin/echinenone ratios were measured in picocyanobacteria and low zeaxanthin/echinenone ratios were measured in bloom-forming cyanobacteria. The zeaxanthin/echinenone ratio was applied to sediment core samples where the cyanobacterial community was also evaluated by 16S rRNA gene metabarcoding, with the zeaxanthin/echinenone ratios showing similar patterns to those observed in the cultures. The preliminary assessment described here suggests that zeaxanthin/echinenone ratios could provide a valuable paleoecological proxy for evaluating historical shifts in cyanobacterial communities and warrants further exploration.

A new vegetation index combination for leaf carotenoid-to-chlorophyll ratio: minimizing the effect of their correlation

ABSTRACT The ratio of leaf carotenoid to chlorophyll (Car/Chl) is an indicator of vegetation photosynthesis, development and responses to stress. However, the correlation between Car and Chl, and their overlapping absorption in the visible spectral domain pose a challenge for optical remote sensing of their ratio. This study aims to investigate combinations of vegetation indices (VIs) to minimize the influence of Car-Chl correlation, thus being more sensitive to the variability in the ratio across vegetation species and sites. VIs sensitive to Car and Chl variability were combined into four candidates of combinations, using a simulated dataset from the PROSPECT model. The VI combinations were then tested using six simulated datasets with different Car-Chl correlations, and evaluated against four independent datasets. The ratio of the carotenoid triangle ratio index (CTRI) with the red-edge chlorophyll index (CIred-edge) was found least influenced by the Car-Chl correlation and demonstrated a superior ability for estimating Car/Chl variability. Compared with published VIs and two machine learning algorithms, CTRI/CIred-edge also showed the optimal performance in the four field datasets. This new VI combination could be useful to provide insights in spatiotemporal variability in the leaf Car/Chl ratio, applicable for assessing vegetation physiology, phenology, and response to environmental stress. Trial registration: Clinical Trials Registry India identifier: CTRI/..

The ability of supercritical CO2 carrot and pumpkin extracts to counteract inflammation and oxidative stress in RAW 264.7 macrophages stimulated with LPS or MDA-MB-231 cell-conditioned media.

Supercritical fluid extraction with CO2 (SFE) is an alternative technology to conventional solvent extraction (CSE), to obtain food-grade bioactives from plants. Here, SFE and CSE extracts from carrot and pumpkin matrices, impregnated with hempseed or flaxseed oil as co-solvents, were characterized by HPLC and GC-MS, and their ability to counteract the inflammatory and oxidative phenomena underlying the onset of several pathologies was assessed in vitro. All extracts showed dose-dependent anti-inflammatory potential and demonstrated an ability to interfere with the pro-inflammatory effects of breast cancer cell-conditioned media, and to inhibit reactive oxygen species (ROS) accumulation and nitrite production (NP) in lipopolysaccharide-stimulated macrophages. Nuclear factor-erythroid-2-related factor 2 (Nrf2) is involved in these response mechanisms, as highlighted by the increased mRNA levels of its target genes revealed by quantitative real-time PCR analyses. NP and ROS concentrations negatively correlated with α-tocopherol and most carotenoids, but positively with the total tocopherol/total carotenoid ratio, suggesting an idiosyncratic effect of these bioactives on cell responses and emphasizing the need to focus on extract constituents' interactions.

Chlorophyll Pigment and Leaf Macronutrient Trait Variation of Four Salix Species in Elevated CO2, under Soil Moisture Stress and Fertilization Treatments

Leaf chlorophyll pigment and macronutrient concentrations were quantified for four willow species (Salix cordata (COR), S. discolor (DIS), S. eriocephala (ERI) and S. interior (INT)) while growing under 2 × 2 factorial of ambient and elevated CO2 and well-watered and drought-stressed soil moisture treatments (Expt. 1). After the first year, we saw no difference in stem biomass between CO2 treatments. In the following year, a second experiment was conducted on a subset of well-watered willows as a 2 × 2 factorial of atmospheric CO2 and soil fertilization (FERT). For both years of Expt. 1, chlorophyll a, b, a + b (TCC) and carotenoids (CAR) significantly downregulated in response to elevated CO2 (eCO2) and upregulated in response to drought (DRT). In Expt. 2, FERT mitigated CO2 downregulation of TCC and CAR, and upregulated TCC and CAR. Across species, ERI had the greatest pigment concentrations followed by either COR or DIS. Except for one case, INT had the lowest pigment concentrations. A significant species x FERT interaction was due to magnitude effects. The CHLa:b ratio was not affected by CO2 or DRT but did increase in response to FERT. INT had the greatest CHLa:b ratio followed by DIS, then either ERI or COR. In the second year, TCC:CAR ratio decreased in response to eCO2 and increased in response to DRT and FERT. In Expt. 1, leaf N was the only nutrient to significantly downregulate in response to eCO2; whereas all other nutrient levels remained unchanged. In response to DRT, leaf N and Mg upregulated; whereas leaf P, K, and Ca were downregulated. In response to eCO2 in Expt. 2, again only leaf N downregulated; whereas all other nutrients remained unchanged. All leaf nutrients upregulated in response to FERT. Of the four species, INT had the greatest leaf N and K, and the lowest Ca. Species variation was important, but so to was clonal variation in response to change. Indeed, INT leaf chlorophyll and macronutrients are significantly different or segregated from the other three willow species and this may be related to the evolutionary origins of INT, and other species of the taxonomic section Longifoliae, in the arid southwest USA and Mexico. Furthermore, under low nutrient conditions, it may be necessary to fertilize the plants to see a biomass response to eCO2.

Using leaf spectroscopy and pigment estimation to monitor indoor grown lettuce dynamic response to spectral light intensity.

Rising urban food demand is being addressed by plant factories, which aim at producing quality food in closed environment with optimised use of resources. The efficiency of these new plant production systems could be further increased by automated control of plant health and nutritious composition during cultivation, allowing for increased produce value and closer match between plant needs and treatment application with potential energy savings. We hypothesise that certain leaf pigments, including chlorophylls, carotenoids and anthocyanins, which are responsive to light, may be good indicator of plant performance and related healthy compounds composition and, that the combination of leaf spectroscopy and mathematical modelling will allow monitoring of plant cultivation through noninvasive estimation of leaf pigments. Plants of two lettuce cultivars (a green- and a red-leaf) were cultivated in hydroponic conditions for 18 days under white light spectrum in climate controlled growth chamber. After that period, plant responses to white light spectrum ('W') with differing blue wavelengths ('B', 420 - 450 nm) percentage (15% 'B15', and 40% 'B40') were investigated for a 14 days period. The two light spectral treatments were applied at photon flux densities (PFDs) of 160 and 240 µmol m-2 s-1, resulting in a total of four light treatments (160WB15, 160WB40, 240WB15, 240WB40). Chlorophyll a fluorescence measurements and assessment of foliar pigments, through destructive (in vitro) and non-destructive (in vivo) spectrophotometry, were performed at 1, 7 and 14 days after treatment initiation. Increase in measured and estimated pigments in response to WB40 and decrease in chlorophyll:carotenoid ratio in response to higher PFD were found in both cultivars. Cultivar specific behavior in terms of specific pigment content stimulation in response to time was observed. Content ranges of modelled and measured pigments were comparable, though the correlation between both needs to be improved. In conclusion, leaf pigment estimation may represent a potential noninvasive and real-time technique to monitor, and control, plant growth and nutritious quality in controlled environment agriculture.

Combined analysis of metabolome and transcriptome provides insights into metabolisms of chlorophylls, carotenoids, and flavonoids in the yellowing leaves of ‘HAES344’ macadamia

Macadamia variety ‘HAES344’ is widely popularized in macadamia producing areas around the world due to its premium edible kernels. However, ‘HAES344’ is prone to generate the etiolated leaves under high temperature, but the molecular and metabolic mechanisms of leaf yellowing remain unclear. In this study, an integrative analysis of the metabolome and transcriptome profiles was performed for the ‘HAES344’ leaves at four different stages. We found that the ratio of carotenoids to chlorophylls increased in the yellowing leaves. A total of 131 differential accumulated metabolites had been obtained, of which 35 were flavonoids, and 27 out of 35 flavonoids were identified between the green and the etiolated leaves. The major flavonoids including 10 flavonols, 10 flavones, and 5 flavanones were significantly up-regulated in the yellowing leaves. RNA-Seq revealed 10,301 differential expressed genes, of which 5, 4, and 58 genes involved in the metabolism of chlorophylls, carotenoids, and flavonoids, respectively. Transcription factors AP2/ERFs (20), WRKY (17), MYBs (17), bHLH (12), C2H2 (12), NAC (10), HD-ZIP (8), HSF (7), bZIP (4) and C3H (4), with significant difference, were also analyzed. The increasing expression of CHS, CHS1, CHS2, CHS7, CYP75A2, F3H, UGT75L6, UGT78D2, and RhGT1 might play a key role in the flavonoid accumulation, and a regulatory network of flavonoid biosynthesis was established. The AP2/ERFs, WRKY, MYBs, NAC, bHLH, and C2H2 families were commonly involved in chlorophyll, carotenoids, and flavonoid metabolism. This result of the differentially expressed genes and metabolites showed that the metabolome and transcriptome data were positively connected with the leaf yellowing of ‘HAES344’ macadamia.

Drought-tolerance of transgenic winter wheat with partial suppression of the proline dehydrogenase gene

The global climate changes and the consequent increase in the number of soil and air droughts during the vegetation period of grain crops require the development of new strategies to adapt plants to those yield-decreasing stressors. A relevant way of increasing drought-tolerance of cereals is the use of biotechnological methods, particularly RNA interference, which can down-regulate the activity of plants’ genes and increase concentration of stress metabolites that perform osmoprotective functions during drought. We studied the tolerance to soil moisture shortage in transgenic plants of winter wheat with partial suppression of the proline dehydrogenase gene, obtained using the technology of short interfering RNAs. We analyzed physiological and biochemical parameters and structural elements of yield productivity of 4 wild genotypes and their transgenic lines with reduced activity of proline dehydrogenase in the conditions of 7-day drought during the late booting–ear emergence. We determined that the presence of double-stranded RNA suppressor of the proline dehydrogenase gene in transgenic lines led to increase in the level of accumulation of free proline in flag leaves. At the same time, its concentration in transgenic lines was higher than in untransformed plants of the wild genotypes in both drought conditions and conditions of sufficient moisture. We found that against the background of water deficiency, the total chlorophyll content in leaves of plants of transgenic lines was significantly higher, and the ratio of carotenoids to chlorophyll was lower than in plants of the wild genotypes, suggesting mitigation of the negative impact of drought on the plants of transgenic lines. Lacking soil moisture, genetically altered lines of wheat had significantly higher parameters of the structure of grain yield compared with untransformed genotypes. At the same time, we observed genotypic difference according to grain productivity in biotechnological plants. Therefore, the results we obtained confirm the perspectives of using the technology of short interfering RNAs to increase tolerance of winter wheat to water deficiency.

Physio-biochemical responses of grafted tomatoes differing in thermotolerance to heat stress and recovery

The aim of this study was to evaluate the physiological and biochemical heat responses of grafted tomato (Solanum lycopersicum L.) seedlings and their changes during the post-stress recovery period. Heat-tolerant ‘Celebrity’ and heat-sensitive ‘Arkansas Traveler’ tomatoes were grafted onto a commercial ‘Maxifort’ rootstock, and transplants were grown in growth chambers for 14 days of heat treatment (38/30 °C, day/night) followed by 7 days of recovery (25/18 °C). Results showed significant differences between ‘Maxifort’-grafted and ungrafted seedlings in antioxidant enzyme activities with increased leaf ascorbate peroxidase (APX), root superoxide dismutase (SOD) and catalase (CAT), and decreased root guaiacol peroxidase (POD) in ‘Maxifort’-grafted plants when heat stress was imposed. ‘Maxifort’-grafted plants had lower chlorophyll:carotenoid ratios and higher leaf total soluble protein than ungrafted controls under heat stress. Heat stress increased leaf chlorophyll, carotenoid, electrolyte leakage (EL), malondialdehyde (MDA) and leaf and root proline content, and reduced leaf chlorophyll fluorescence (Fv/Fm) during the stress period. Antioxidant enzymes were up-regulated by heat stress in leaves, while those in roots were selectively regulated with increased glutathione reductase (GR) and CAT, and decreased POD and APX activities in heat stressed plants. After the recovery period, chlorophyll, carotenoid, EL and proline contents showed partial or full recovery from the stress, whereas the heat responses of MDA and Fv/Fm remained constant. Cultivar effects were detected in leaf antioxidant enzyme activities of heat stressed plants after recovery as ‘Arkansas Traveler’ had higher POD, GR, CAT and lower SOD activities than ‘Celebrity’. These results demonstrate the potential for using ‘Maxifort’ rootstocks to enhance the thermotolerance of tomato plants during the vegetative stage, although the beneficial traits did not lead to a significant alleviation of heat stress.