Violaxanthin Content Research Articles

Wax treatment delays the coloration of postharvest citrus fruit by retarding the carotenoid biosynthesis pathway

Wax coating is a widely used method to delay fruit maturation, especially for postharvest citrus fruit. Although treatment of citrus fruits with wax delays the color change process, the underlying mechanism is poorly understood. This study investigated the effect of SP-1 commercial wax on the peel coloration of postharvest Miyagawa Wase (Citrus unshiu Marc.) fruit. Results showed that wax treatment retarded the coloration of citrus fruit. Transcriptomic analysis revealed that multiple genes involved in cell wall, photosynthetic light reaction, lipid metabolism, primary metabolism and secondary metabolisms were differentially expressed after wax treatment. Specifically, genes involved in carotenoid biosynthesis including phytoene desaturase (PDS), ζ-carotene desaturase (ZDS), lycopene β-cyclase (LCYb), β-carotene hydroxylase (CHY), violaxanthin de-epoxidase (VDE), xanthoxin dehydrogenase (ABA2) and 9-cis-epoxycarotenoid dioxygenase (NCED) were all down-regulated after wax treatment. Correspondingly, the contents of total carotenoid, violaxanthin (two isomers, tran- and cis-), β, β-xanthophylls (β-cryptoxanthin and antheraxanthin), luteoxanthin, lutein and abscisic acid (ABA) in wax-treated peels were all decreased. Collectively, our results suggest that SP-1 commercial wax can delay citrus fruit coloration by retarding the carotenoid biosynthetic pathway thus providing basis for future studies on the possible effects of waxing on the coloration of a wide range of fruits.

Carotenoid and transcriptome profiles of a novel citrus cultivar ‘Jinlegan’ reveal mechanisms of yellowish fruit formation

Citrus fruit coloration is one of the vital quality traits that is determined primarily by the composition and content of carotenoids. Natural citrus fruit pigment mutants are available to study diverse and complex carotenoid metabolism. Here, ‘Jinlegan’ (MT) tangor is a spontaneous bud mutant derived from ‘Shiranuhi’ (WT) with distinctive bright yellow fruit. High performance liquid chromatography (HPLC) analysis revealed that the yellowish MT flavedo and pulp were primarily caused by the decrease in total carotenoid content. The total carotenoid content in MT flavedo was reduced by 75% (79.98 μg/g DW) compared with that in WT (318.40 μg/g DW), including approximately 84%, 80%, and 60% reductions in the contents of β-cryptoxanthin, violaxanthin and zeaxanthin, respectively. The total carotenoid content in MT pulp was 60% lower (10.09 μg/g DW) than that in WT pulp (26.61 μg/g DW), which was mainly due to a 70% and 30% decrease in the contents of β-cryptoxanthin and zeaxanthin, respectively. To explore the molecular mechanism underlying carotenoid variation in MT, RNA-seq analyses were performed on the flavedo and pulp of WT and MT at five developmental stages. The reduced expression of phytoene synthase (CrPSY) and β-carotenehydroxylase 1 (CrBCH1) in the flavedo and pulp of MT at the breaker stage might be the major cause of the reduction in carotenoids. Weighted gene co-expression network analysis (WGCNA) further identified 23 key transcription factors that are closely associated with carotenoid accumulation. This study demonstrated a comprehensive picture of the metabolic and transcriptional alterations of a unique yellowish citrus fruit mutant, which provides new insights into the molecular regulation of carotenoid accumulation in citrus fruit.

Effect of long-term drought and waterlogging stress on photosynthetic pigments in potato

In potato tubers of four cultivars, the impact of drought and waterlogging stress on total carotenoid content (TCC) and individual carotenoids profile variance and total carotenoids, chlorophylls (a, b, a + b) content in leaves during period 71 days of stress in two-year pot greenhouse experiments were investigated. The different response between potato cultivars was observed after exposure to drought stress (an increase of TCC was in Marabel and Laura cultivars) and after waterlogging stress (in Milva and Marabel cultivars). On average, of all cultivars, both drought and waterlogging stresses caused total carotenoid content to increase with a higher impact of drought stress. In potato tubers, eight carotenoids were identified with the most represented violaxanthin, luteoxanthin, antheroxanthin and lutein. Significant differences in individual carotenoid amounts between cultivars have been determined. On average, drought and waterlogging stresses of all cultivars significantly increased contents of violaxanthin, 9'-(Z)-neoxanthin and luteoxanthin, while antheraxanthin, lutein and zeaxanthin levels decreased. In leaves, both abiotic stresses decreased chlorophyll contents (a, b, a + b) with a very destructive impact of drought stress. While carotenoids accumulated in tubers as a result of stress, the opposite trend was characteristic in leaves, where their content decreased depending on the duration of stress.

Frequent antibiotic exposure stabilized the associated bacterial community while altering physiological and biochemical characteristics of the coccolithophore Chrysotila roscoffensis

The application of microalgae-based techniques in antibiotic-contaminated wastewater treatment frequently exposes the mass-cultured microalgae to antibiotics. The effects of frequent antibiotic exposure on the physiological processes and biochemical metabolites of microalgae remain to be determined. In addition, the response of the associated bacteria is unclear. A strain of coccolithophore, Chrysotila roscoffensis, which was frequently treated with antibiotics for several research purposes, was applied in the present study. The final biomass from a batch culture was sampled to detect how another fresh antibiotic treatment affected growth, photosynthetic performance, pigment and phytohormone production, and nutrient absorption. Changes in the associated bacteria in the cultures were comparatively studied. Compared with the control of the non-treated group, the growth rate, maximum biomass maintenance and photosynthetic performance were significantly improved in the antibiotic-treated group. The microalgae with antibiotics were less stressed according to the data from chlorophyll fluorescence parameters. No significant differences were observed in the contents of pigments such as chlorophyll a, diatoxanthin, zeaxanthin, prasinoxanthin, and fucoxanthin. However, the violaxanthin content decreased significantly by 61.36 %, and the diadinoxanthin content increased significantly by 28.02 %, showing that xanthophyll cycling for photoprotection, both violaxanthin cycle and diadinoxanthin cycle, was probably changed by the antibiotic treatments. The contents of phytohormones in the microalgae, such as indole acetic acid, salicylic acid, jasmonic acid, strigolactone and isopentenyl adenine, were not different, except for the concentration of 6-benzylaminopurine (decreased significantly by 43.51 %) and abscisic acid (undetectable in the antibiotic-treated group while the concentration in the non-treated group was 18.20 ± 2.15 ng/1010cells). Absorption of nutrients PO43−-P and SiO32−-Si was relatively inhibited, while NO3−-N absorption was promoted. Phosphorus limitation was probably alleviated in the antibiotic-treated group. No significant differences in the bacterial biomass and community were observed between the antibiotic-treated and untreated group. However, final associated bacterial communities in both groups differed significantly from the initial bacterial community. This phenomenon showed that although repeated antibiotic treatment did not change the associated bacterial community, the growth of C. roscoffensis exerted a considerable impact on the community. The present study provided new insights into the application of a microalgae-based strategy in wastewater treatment for the removal of antibiotic contaminants.

Enhancement of violaxanthin accumulation in Nannochloropsis oceanica by overexpressing a carotenoid isomerase gene from Phaeodactylum tricornutum.

Nannochloropsis has been considered as a promising feedstock for the industrial production of violaxanthin. However, a rational breeding strategy for the enhancement of violaxanthin content in this microalga is still vacant, thereby limiting its industrial application. All-trans-lycopene locates in the first branch point of carotenogenesis. The carotenoid isomerase (CRTISO), catalyzing the lycopene formation, is thus regarded as a key enzyme for carotenogenesis. Phaeodactylum tricornutum can accumulate high-level carotenoids under optimal conditions. Therefore, it is feasible to improve violaxanthin level in Nannochloropsis by overexpression of PtCRTISO. Protein targeting analysis of seven PtCRTISO candidates (PtCRTISO1–6 and PtCRTISO-like) demonstrated that PtCRTISO4 was most likely the carotenoid isomerase of P. tricornutum. Moreover, the transcriptional pattern of PtCRTISO4 at different cultivation periods was quite similar to other known carotenogenesis genes. Thus, PtCRTISO4 was transformed into N. oceanica. Compared to the wild type (WT), all three transgenic lines (T1–T3) of N. oceanica exhibited higher levels of total carotenoid and violaxanthin. Notably, T3 exhibited the peak violaxanthin content of 4.48 mg g–1 dry cell weight (DCW), which was 1.68-folds higher than WT. Interestingly, qRT-polymerase chain reaction (PCR) results demonstrated that phytoene synthase (NoPSY) rather than ζ-carotene desaturase (NoZDS) and lycopene β-cyclase (NoLCYB) exhibited the highest upregulation, suggesting that PtCRTISO4 played an additional regulatory role in terms of carotenoid accumulation. Moreover, PtCRTISO4 overexpression increased C18:1n-9 but decreased C16:1n-7, implying that C18:1 may serve as a main feedstock for xanthophyll esterification in Nannochloropsis. Our results will provide valuable information for the violaxanthin production from Nannochloropsis.

Fatty acid profile, secondary compounds and antioxidant activities in the fresh forage, hay and silage of sainfoin (Onobrychis viciifolia) and sulla (Hedysarum coronarium).

BackgroundSainfoin (Onobrychis viciifolia) and sulla (Hedysarum coronarium) are forage legumes usually preserved to optimize their utilization as feedstuffs. However, the method of preservation modifies the chemical composition differently in both legume species. Secondary compounds (such as proanthocyanidins, fatty acids, carotenoids and tocopherols) present in forages affect the quality of animal products. Therefore, the effect of preservation on the contents of secondary compounds should be investigated. Accoridngly, samples of sainfoin and sulla were directly freeze‐dried (fresh), dried at ambient temperature (hay) and vacuum‐packaged for 82 days (silage).ResultsIn both legumes, the total fatty acid and C18:3 n‐3 contents decreased and C16:0 increased with preservation (P < 0.001), with a greater effect for the hays than for the silages. For both legumes, the lutein, neoxanthin and violaxanthin contents decreased to a greater extent in the silages than in the hays (P < 0.001). Both hays exhibited the lowest β‐carotene concentrations (P < 0.001). The α‐tocopherol contents decreased in hays, but not in silages, compared to the fresh forages of both legumes (P < 0.001). The antioxidant activities were lower in the silages than in the hays and fresh forages (P < 0.001) and were very strongly related to the contents of polyphenols and proanthocyanidins (P < 0.001).ConclusionHaymaking affected the fatty acid, carotenoid and α‐tocopherol contents to a greater extent but had a lesser effect on the antioxidant activities than silage‐making, which were very strongly related to their contents of polyphenols and proanthocyanidins. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A cytochrome P450 superfamily gene, IbCYP82D47, increases carotenoid contents in transgenic sweet potato

The cytochrome P450 superfamily (CYP450) is one of the largest protein families in plants, and its members play diverse roles in primary and secondary metabolic biosynthesis. In this study, the CYP450 family gene IbCYP82D47 was cloned from the high carotenoid line HVB-3 of sweet potato (Ipomoea batatas). The IbCYP82D47 protein harbored two transmembrane domains and dynamically localized between plastid stroma and membrane. Overexpression of IbCYP82D47 not only increased total carotenoid, lutein, zeaxanthin and violaxanthin contents by 32.2–48.0%, 10.5–13.3%, 40.2–136% and 82.4–106%, respectively, but also increased the number of carotenoid globules in sweet potato storage roots. Furthermore, genes associated with the carotenoid biosynthesis (IbDXS, IbPSY, IbLCYE, IbBCH, IbZEP) were upregulated in transgenic sweet potato. In addition, IbCYP82D47 physically interacts with geranylgeranyl diphosphate synthase 12 (IbGGPPS12). Our findings suggest that IbCYP82D47 increases carotenoid contents by interacting with the carotenoid biosynthesis related protein IbGGPPS12, and influencing the expressions of carotenoid biosynthesis related genes in transgenic sweet potato.

COMPARATIVE STUDY ON THE EFFECTS OF WHEAT PLANTS EXPOSURE TO GIBBERELLIC ACID AND SALICYLIC ACID

We set out to characterize some aspects of growth and metabolism of wheat seedlings that have grown for 7 days on media supplemented with gibberellic acid (GA3) or salicylic acid (SA), at concentrations of 10 μmol∙L-1 and 100 μmol∙L-1. Compared to control plants, increased concentration of glucose and lipid peroxidation products were observed in GA3 series, while higher levels of soluble proteins, glucose, acid phosphatase and peroxidase activity were measured in SA series. Data from photosynthetic pigment analysis pointed out minor differences regarding chlorophylls and carotenoids content in plants’ leaves, both within and between the groups. Although total carotenoid content didn’t vary markedly among the experimental variants, certain changes of the relative contribution of the pigments in the carotenoid pool were observed, mainly a decrease of neoxanthin content paralleled by an increase of violaxanthin content. However, as the biometric data have shown, plant growth was neither inhibited nor stimulated, irrespective of the growth conditions. The observed modulation of certain biochemical parameters may be considered as part of the plants’ adaptive responses to an environmental challenge, where the differences between GA3 and SA regarding bioavailability, mobility and specific mechanisms of action underlie the different outcomes.

COMPARATIVE STUDY ON THE EFFECTS OF WHEAT PLANTS EXPOSURE TO GIBBERELLIC ACID AND SALICYLIC ACID

We set out to characterize some aspects of growth and metabolism of wheat seedlings that have grown for 7 days on media supplemented with gibberellic acid (GA3) or salicylic acid (SA), at concentrations of 10 μmol∙L-1 and 100 μmol∙L-1. Compared to control plants, increased concentration of glucose and lipid peroxidation products were observed in GA3 series, while higher levels of soluble proteins, glucose, acid phosphatase and peroxidase activity were measured in SA series. Data from photosynthetic pigment analysis pointed out minor differences regarding chlorophylls and carotenoids content in plants’ leaves, both within and between the groups. Although total carotenoid content didn’t vary markedly among the experimental variants, certain changes of the relative contribution of the pigments in the carotenoid pool were observed, mainly a decrease of neoxanthin content paralleled by an increase of violaxanthin content. However, as the biometric data have shown, plant growth was neither inhibited nor stimulated, irrespective of the growth conditions. The observed modulation of certain biochemical parameters may be considered as part of the plants’ adaptive responses to an environmental challenge, where the differences between GA3 and SA regarding bioavailability, mobility and specific mechanisms of action underlie the different outcomes.

Optimum Parameters for Extracting Three Kinds of Carotenoids from Pepper Leaves by Response Surface Methodology

To determine the optimum parameters for extracting three carotenoids including zeaxanthin, lutein epoxide, and violaxanthin from pepper leaves by response surface methodology (RSM), a solvent of acetone and ethyl acetate (1:2) was used to extract carotenoids with four independent factors: ultrasound time (20–60 min); ratio of sample to solvent (1:12–1:4); saponification time (10–50 min); and concentration of saponification solution (KOH–methanol) (10–30%). A second-order polynomial model produced a satisfactory fitting of the experimental data with regard to zeaxanthin (R2 = 75.95%, p &lt; 0.0197), lutein epoxide (R2 = 90.24%, p &lt; 0.0001), and violaxanthin (R2 = 73.84%, p &lt; 0.0809) content. The optimum joint extraction conditions of zeaxanthin, lutein epoxide, and violaxanthin were 40 min, 1:8, 32 min, and 20%, respectively. The optimal predicted contents for zeaxanthin (0.823022 µg/g DW), lutein epoxide (4.03684 µg/g dry; DW—dry weight), and violaxanthin (16.1972 µg/g DW) in extraction had little difference with the actual experimental values obtained under the optimum extraction conditions for each response: zeaxanthin (0.8118 µg/g DW), lutein epoxide (3.9497 µg/g DW), and violaxanthin (16.1590 µg/g DW), which provides a theoretical basis and method for cultivating new varieties at low temperatures and weak light resistance.

Content of Carotenoids, Violaxanthin and Neoxanthin in Leaves of Triticum aestivum Exposed to Persistent Environmental Pollutants.

Persistent pollutants such as pharmaceuticals, pesticides, musk fragrances, and dyes are frequently detected in different environmental compartments and negatively impact the environment and humans. Understanding the impacts of diffuse environmental pollutants on plants is still limited, especially at realistic environmental concentrations of contaminants. We studied the effects of key representatives of two major classes of environmental pollutants (nine different antibiotics and six different textile dyes) on the leaf carotenoid (violaxanthin and neoxanthin) content in wheat (Triticum aestivum L.) using different pollutant concentrations and application times. The wheat plants were watered with solutions of selected environmental pollutants in two different concentrations of 0.5 mg L−1 and 1.5 mg L−1 for one week (0.5 L) and two weeks (1 L). Both categories of pollutants selected for this study negatively influenced the content of violaxanthin and neoxanthin, whereas the textile dyes represented more severe stress to the wheat plants. The results demonstrate that chronic exposure to common diffusively spread environmental contaminants constitutes significant stress to the plants.

Fine mapping and candidate gene analysis of the orange petal colour gene Bnpc2 in spring rapeseed (Brassica napus)

AbstractPetal colour is considered as an important trait and major visual signal for insect‐pollinated plants and landscaping. In previous study, we isolated and identified two genes (BnPC1 and BnPC2) that control the orange petal colour (OPC) in rapeseed. To identify the molecular markers linked to the orange petal colour, we constructed a B. napus linkage map with four newly developed simple sequence repeat (SSR) markers and nine insertion–deletion (InDel) markers using BC5II, a near isogenic line population segregated at the BnPC2 locus. The BnPC2 gene was flanked by Indel‐3 and Indel‐20 and was found to represent a 27‐kb (3.721–3.748 Mb) region on A09 of B. napus. High‐pressure liquid chromatography analysis revealed that, compared to yellow petals, orange petals exhibit significantly increased zeaxanthin, β‐carotene and lutein contents and a relatively decreased violaxanthin content. Expression profiling confirmed that BnaA09.ZEP (zeaxanthin epoxidase) is an important candidate gene for BnPC2 and is predominantly expressed in floral tissues. Overall, our results provide a basis for understanding the molecular mechanisms underlying the orange petal colour trait in B. napus.

Development of a novel nannochloropsis strain with enhanced violaxanthin yield for large\u2010scale production

BackgroundNannochloropsis is a marine microalga that has been extensively studied. The major carotenoid produced by this group of microalgae is violaxanthin, which exhibits anti-inflammatory, anti-photoaging, and antiproliferative activities. Therefore, it has a wide range of potential applications. However, large-scale production of this pigment has not been much studied, thereby limiting its industrial application.ResultsTo develop a novel strain producing high amount of violaxanthin, various Nannochloropsis species were isolated from seawater samples and their violaxanthin production potential were compared. Of the strains tested, N. oceanica WS-1 exhibited the highest violaxanthin productivity; to further enhance the violaxanthin yield of WS-1, we performed gamma-ray-mediated random mutagenesis followed by colorimetric screening. As a result, Mutant M1 was selected because of its significant higher violaxanthin content and biomass productivity than WS-1 (5.21 ± 0.33 mg g− 1 and 0.2101 g L− 1 d− 1, respectively). Subsequently, we employed a 10 L-scale bioreactor to confirm the large-scale production potential of M1, and the results indicated a 43.54 % increase in violaxanthin production compared with WS-1. In addition, comparative transcriptomic analysis performed under normal light condition identified possible mechanisms associated with remediating photo-inhibitory damage and other key responses in M1, which seemed to at least partially explain enhanced violaxanthin content and delayed growth.ConclusionsNannochloropsis oceanica mutant (M1) with enhanced violaxanthin content was developed and its physiological characteristics were investigated. In addition, enhanced production of violaxanthin was demonstrated in the large-scale cultivation. Key transcriptomic responses that are seemingly associated with different physiological responses of M1 were elucidated under normal light condition, the details of which would guide ongoing efforts to further maximize the industrial potential of violaxanthin producing strains.

Gene silencing of BnaA09.ZEP and BnaC09.ZEP confers orange color in Brassica napus flowers.

Brassica napus is currently cultivated as an important ornamental crop in China. Flower color has attracted much attention in rapeseed genetics and breeding. Here, we characterize an orange-flowered mutant of B. napus that exhibits an altered carotenoid profile in its petals. As revealed by map-based cloning, the change in color from yellow to orange is attributed to the loss of BnaC09.ZEP (zeaxanthin epoxidase) and a 1695-bp deletion in BnaA09.ZEP. HPLC analysis, genetic complementation and CRISPR/Cas9 experiments demonstrated that BnaA09.ZEP and BnaC09.ZEP have similar functions, and the abolishment of both genes led to a substantial increase in lutein content and a sharp decline in violaxanthin content in petals but not leaves. BnaA09.ZEP and BnaC09.ZEP are predominantly expressed in floral tissues, whereas their homologs, BnaA07.ZEP and BnaC07.ZEP, mainly function in leaves, indicating redundancy and tissue-specific diversification of BnaZEP function. Transcriptome analysis in petals revealed differences in the expression of carotenoid and flavonoid biosynthesis-related genes between the mutant and its complementary lines. Flavonoid profiles in the petals of complementary lines were greatly altered compared to the mutant, indicating potential cross-talk between the regulatory networks underlying the carotenoid and flavonoid pathways. Additionally, our results indicate that there is functional compensation by BnaA07.ZEP and BnaC07.ZEP in the absence of BnaA09.ZEP and BnaC09.ZEP. Cloning and characterization of BnaZEPs provide insights into the molecular mechanisms underlying flower pigmentation in B. napus and would facilitate breeding of B. napus varieties with higher ornamental value.

Effect of hot water treatment of seeds on quality indicators of alfalfa sprouts

The aim of this study was to evaluate the effect of soaking seeds in hot water on the content of selected bioactive compounds in alfalfa sprouts. Temperature and time regimes were: 85 °C, for 10 and 40 s; 90 °C and 100 °C, for 10 s. Sprouts were examined for the contents of ascorbic acid, chlorophylls a and b, α- and β-carotene, neoxanthin, violaxanthin, lutein and total phenolics. In most cases, the treatment applied had no significant effect on the contents of lutein, violaxanthin, neoxanthin, β-carotene and total phenolics. However, disinfection at 100 °C caused a significant reduction in ascorbic acid content, an increase in total phenolic content and a rise in the proportion of cotyledons in the mass of sprouts. The treatment variants applied did not significantly affect the total chlorophyll content in cotyledons. This study revealed that seed treatment with hot water may, depending on the applied parameters, affect sprout morphology, ascorbic acid content and total phenolic content.

The impact of LED lighting on the yield, morphological structure and some bioactive components in alfalfa (Medicago sativa L.) sprouts

The aim of this study was to evaluate the impact of selected types of LED (light emitting diodes) lighting on the quality of alfalfa sprouts. In the experiment, cold white, warm white and multicolour: (red, green, blue-RGB) LEDs were applied, and dispersed sunlight was used as a control. The product was examined for the yield and the contents of dry matter, total polyphenols, ascorbic acid, chlorophylls, β-carotene, lutein, neoxanthin and violaxanthin. Cotyledons’ mass in the whole plant increased under LED illumination and was up to 50% greater for sprouts grown in RGB light compared to those cultivated in dispersed sunlight. The highest chlorophyll and carotenoid pigment contents in cotyledons were observed under RGB LED and cold white treatments. Similarly, RGB LEDs allows one to obtain the product with the highest level of total phenolic compounds. The highest ascorbic acid content was observed in sprouts growing under sunlight, followed by RGB.

Effect of high hydrostatic pressure applied to a Mexican honey to increase its microbiological and functional quality

High hydrostatic pressure (HHP) applied at 600MPa (0, 2, 5, 8, 12 and 15min) was used as an alternative method to reduce the microbial population, preserving bioactivity (antioxidant activity (AOA), vitamin C, total phenolic and carotenoid contents) and other quality factors (diastase activity, 5-hydroxymethylfurfural, fructose and glucose contents and rheological behavior) of a Mexican honey. HHP processing reduces viable microorganisms in honey and the treatment for 15min reduced the total microbial count below detection limit. AOA and total phenolic content were increased by 30% and 6%, respectively, after 2min processing. The vitamin C, fructose, glucose and maltose contents in HHP treated honey were retained at all processing times. The total carotenoid content was maintained at processing times up to 8min, while violaxanthin content was reduced by 56% after 15min. HHP did not change the contents of 5-hydroxymethylfurfural, while the diastase activity decreased by 10% after 12min treatment. Honey exhibited a Newtonian behavior and its viscosity was decreased at all HHP processing conditions. HHP treatment at 600MPa for 2min offers an opportunity to enhance the antioxidant properties of honey while reducing its microbiological load and preserving its the general quality parameters of honey.

High Hydrostatic Pressure and Temperature Applied to Preserve the Antioxidant Compounds of Mango Pulp (Mangifera indica L.)

High hydrostatic pressure (HHP) processes combined with moderate heating can be used to preserve foods while maintaining general quality. The effect of these conditions on the total phenolic (TP), vitamin C (L-ascorbic acid (AA)), carotenoids, and antioxidant activity (AOA) of mango purees was evaluated. Purees were processed at 400–550 MPa/34 and 59 °C at different holding times. Unprocessed puree had TP of 26.6 mg gallic acid/100 g, 21.1 mg L-ascorbic acid/100 g, AOA of 885 μmol trolox equivalents/100 g, and total carotenoids of 6.0 mg β-carotene/100 g. HHP treatments increased the phenolic concentrations up to 34% (550 MPa/59 °C/2 and 4 min) compared with the initial content, probably due to improvement of their extraction. AA content was reduced significantly (10–45%) after all HHP processes performed at 59 °C, while at 34 °C, they were diminished only after 8 and 16 min of treatment (13–26%). At 34 °C and lower times, AA concentration increased in average 18%. Total carotenoid retention in HHP-treated samples varies from 77 to 98%, being the higher the temperature the lower the retention observed. The concentration of most individual carotenoids remains unchanged, but violaxanthin content was reduced (21–26%) and 9-cis-violaxanthin was increased by about 10%. The AOA was also increased (up to 39%) at some processing conditions. A linear correlation between the TP and AOA was obtained. HHP at 550 MPa combined with moderate temperature (34 °C) at processing times up to 8 min is recommended for the maximum retention of the antioxidant compounds of mango puree.

Chlorophyll fluorescence lifetime imaging provides new insight into the chlorosis induced by plant virus infection.

Leaf chlorosis induced by plant virus infection has a short fluorescence lifetime, which reflects damaged photosynthetic complexes and degraded chloroplasts. Plant viruses often induce chlorosis and necrosis, which are intimately related to photosynthetic functions. Chlorophyll fluorescence lifetime measurement is a valuable noninvasive tool for analyzing photosynthetic processes and is a sensitive indicator of the environment surrounding the fluorescent molecules. In this study, our central goal was to explore the effect of viral infection on photosynthesis by employing chlorophyll fluorescence lifetime imaging (FLIM), steady-state fluorescence, non-photochemical quenching (NPQ), transmission electron microscopy (TEM), and pigment analysis. The data indicated that the chlorophyll fluorescence lifetime of chlorotic leaves was significantly shorter than that of healthy control leaves, and the fitted short lifetime component of chlorophyll fluorescence of chlorotic leaves was dominant. This dominant short lifetime component may result from damage to the structure of thylakoid, which was confirmed by TEM. The NPQ value of chlorotic leaves was slightly higher than that of healthy green leaves, which can be explained by increased neoxanthin, lutein and violaxanthin content relative to chlorophyll a. The difference in NPQ is slight, but FLIM can provide simple and direct characterization of PSII structure and photosynthetic function. Therefore, this technique shows great potential as a simple and rapid method for studying mechanisms of plant virus infection.

Carotenoid Composition and Changes in Sweet and Field Corn (Zea mays) During Kernel Development

Kernels of two carotenoid‐rich cultivars, sweet corn Jingtian 5 and field corn Suyu 29, were compared in terms of carotenoid composition during corn kernel development. The results showed that eight principal carotenoids were characterized by HPLC with diode array detection and atmospheric pressure chemical ionization tandem mass spectrometry with a C30 column. During kernel development, there was a similar trend in the change of total carotenoids for both corn cultivars, and the variation of individual carotenoids was also somewhat similar; violaxanthin, zeaxanthin, lutein, α‐cryptoxanthin, and β‐cryptoxanthin contents had upward trends, whereas neoxanthin content declined all the time, and α‐carotene and β‐carotene had no significant changes. However, the highest levels of the major carotenoids lutein (41.61 µg/g, dry weight) and zeaxanthin (39.59 µg/g, dry weight) obtained in field corn Suyu 29 during the milk stage were higher than those in sweet corn Jingtian 5, whereas the other individual carotenoid levels were significantly lower. Compared with the grain color, highly significant positive correlations were observed between zeaxanthin, lutein, and violaxanthin contents and deeper yellow/orange coloration indicators for field corn Suyu 29, but these relationships were weak for sweet corn Jingtian 5. Potential genetic variation might exist for carotenoid accumulation in sweet and field corn kernels.