Carotenoid content and expression of phytoene synthase and phytoene desaturase genes in bitter melon (Momordica charantia)

Effect of microwave heating on the phenolic and carotenoid composition and antioxidant properties of Momordica charantia

Momordica charantia L. (MC) is a widely consumed vegetable known for its nutritional benefits, as it is a rich source of carotenoids and phenolic compounds. Various cooking methods are use in domestic settings, including microwave cooking. Therefore, it is crucial to investigate the impact of microwave cooking on the bioactive composition of MC. MC fruits were subjected to microwave heat for 5-, 10-, and 15-min. High performance liquid chromatography was used to identify of carotenoids and phenolic compounds, and total bioactive composition and antioxidant assays were conducted using spectroscopic techniques. There were 17 carotenoids and chlorophylls identified in MC fruit, including lutein, violaxanthin, antheraxanthin, pheophytin a, and all-E-β-carotene. The levels of these compounds significantly increased upon exposure to microwave heating. Similarly, 16 phenolic compounds were identified, and their amounts increased during the treatments, except for 3-hydroxyphloretin-6'-hexoside, quercetin-3-(6″-acetyl)-glucoside, petunidin-3-(6″-acetyl)-glucoside and petunidin-3-(6″-acetyl)-glucoside. The sample subjected to microwave treatment for 15 min exhibited the highest concentration of total phenolic compounds (TPC) at 754.5 mg/100g. The total flavonoid content (TFC) reached 94.6 mg/100g after 10 min of treatment. Additionally, the maximum total anthocyanin content, reported as 54.8 mg/L, was observed in the sample exposed to microwave heating for 15 min.

Potential locus W and candidate gene McPRR2 associated with pericarp pigment accumulation in bitter gourd (Momordica charantia L.) revealed via BSA-seq analysis

Pericarp color is a prominent agronomic trait that exerts a significant impact on consumer and breeder preferences. Genetic analysis has revealed that the pericarp color of bitter gourd is a quantitative trait. However, the underlying mechanism for this trait in bitter gourd remains largely unknown. In the present study, we employed bulked segregant analysis (BSA) to identify the candidate genes responsible for bitter gourd pericarp color (specifically, dark green versus white) within F2 segregation populations resulting from the crossing of B07 (dark green pericarp) and A06 (white pericarp). Through genomic variation, genetic mapping, and expression analysis, we identified a candidate gene named McPRR2, which was a homolog of Arabidopsis pseudo response regulator 2 (APRR2) encoded by LOC111023472. Sequence alignment of the candidate gene between the two parental lines revealed a 15-bp nucleotide insertion in the coding region of LOC111023472, leading to a premature stop codon and potentially causing a loss-of-function mutation. qRT-PCR analysis demonstrated that the expression of McPRR2 was significantly higher in B07 compared to A06, and it was primarily expressed in the immature fruit pericarp. Moreover, overexpression of McPRR2 in tomato could enhance the green color of immature fruit pericarp by increasing the chlorophyll content. Consequently, McPRR2 emerged as a strong candidate gene regulating the bitter gourd pericarp color by influencing chlorophyll accumulation. Finally, we developed a molecular marker linked to pericarp color, enabling the identification of genotypes in breeding populations. These findings provided valuable insights into the genetic improvement of bitter gourd pericarp color.

Effects of long-term blue light irradiation on carotenoid biosynthesis and antioxidant activities in Chinese cabbage (Brassica rapa L. ssp. pekinensis)

The aim of this study was to investigate the impact of long-term exposure to blue light-emitting diodes (LEDs) on the accumulation of indolic glucosinolates and carotenoids, as well as the plant growth and antioxidant activities in both orange and common Chinese cabbage (Brassica rapa L. ssp. pekinensis). Blue light treatment also induced higher ferric-reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl by 20.66 % and 30.82 % and antioxidant enzyme activities catalase, peroxidase, superoxide dismutase, and the accumulation of non-enzymatic antioxidant substances (total phenols and total flavonoids) in the orange Chinese cabbage. Furthermore, long-term exposure to blue light had negative effects on the net photosynthetic rate and chlorophyll fluorescence levels. Meanwhile, blue light promoted accumulation of Indol-3-ylmethyl glucosinolate (I3M), β-carotene, lutein and zeaxanthin due to the high expression of regulatory and biosynthetic genes of the above metabolic pathways. In particular, lycopene and β-carotene content in orange Chinese cabbage increased by 60.14 % and 65.33 % compared to the ones in common line. The accumulation of carotenoid and increasing antioxidant levels in the orange cabbage line was influenced by long-term blue light irradiation, leading to better tolerance to low temperature and drought stresses. The up-regulation of transcription factors such as BrHY5-2, BrPIF4 and BrMYB12 may also contribute to the increased tolerance in orange Chinese cabbage to extreme environmental stresses. The BrHY5-2 gene could activate carotenoid biosynthetic genes and induce the accumulation of carotenoids. These findings suggested that long-term blue light irradiation could be a promising technique for increasing the nutrition value and enhancing tolerance to low temperature and drought stresses in Chinese cabbage.

Combined transcriptome and metabolome analysis reveal that the white and yellow mango pulp colors are associated with carotenoid and flavonoid accumulation, and phytohormone signaling

Mango (Mangifera indica L.) is a widely appreciated tropical fruit for its rich color and nutrition. However, knowledge on the molecular basis of color variation is limited. Here, we studied HY3 (yellowish-white pulp) and YX4 (yellow pulp), reaped with 24 h gap from the standard harvesting time. The carotenoids and total flavonoids increased with the advance of harvest time (YX4 > HY34). Transcriptome sequencing showed that higher expressions of the core carotenoid biosynthesis genes and flavonoid biosynthesis genes are correlated to their respective contents. The endogenous indole-3-acetic acid and jasmonic acid contents decreased but abscisic acid and ethylene contents increased with an increase in harvesting time (YX4 > HY34). Similar trends were observed for the corresponding genes. Our results indicate that the color differences are related to carotenoid and flavonoid contents, which in turn are influenced by phytohormone accumulation and signaling.

Accumulation of Antioxidative Phenolics and Carotenoids Using Thermal Processing in Different Stages of Momordica charantia Fruit

The bitter taste of M. charantia fruit limits its consumption, although the health benefits are well known. The thermal drying process is considered as an alternative method to reduce the bitterness. However, processing studies have rarely investigated physiochemical changes in fruit stages. The antioxidant activities and physiochemical properties of various fruit stages were investigated using different thermal treatments. The color of the thermally treated fruit varied depending on the temperature. When heat-treated for 3 days, the samples from the 30 °C and 90 °C treatments turned brown, while the color of the 60 °C sample did not change significantly. The antioxidant activities were increased in the thermally processed samples in a temperature-dependent manner, with an increase in phenolic compounds. In the 90 °C samples, the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity presented a 6.8-fold higher level than that of nonthermal treatment in mature yellow fruit (S3), whereas the activity showed about a 3.1-fold higher level in immature green (S1) and mature green (S2) fruits. Regardless of the stages, the carotenoid content tended to decrease with increasing temperature. In terms of antioxidant activities, these results suggested that mature yellow fruit is better for consumption using thermal processing.

Telomere-to-telomere genome assembly of bitter melon (Momordica charantia L. var. abbreviata Ser.) reveals fruit development, composition and ripening genetic characteristics

Momordica charantia L. var. abbreviata Ser. (Mca), known as bitter gourd or bitter melon, is a Momordica variety with medicinal value and belongs to the Cucurbitaceae family. In view of the lack of genomic information on bitter gourd and other Momordica species and to promote Mca genomic research, we assembled a 295.6-Mb telomere-to-telomere (T2T) high-quality Mca genome with six gap-free chromosomes after Hi-C correction. This genome is anchored to 11 chromosomes, which is consistent with the karyotype information, and comprises 98 contigs (N50 of 25.4 Mb) and 95 scaffolds (N50 of 25.4 Mb). The Mca genome harbors 19 895 protein-coding genes, of which 45.59% constitute predicted repeat sequences. Synteny analysis revealed variations involved in fruit quality during the divergence of bitter gourd. In addition, assay for transposase-accessible chromatin by high-throughput sequencing and metabolic analysis showed that momordicosides and other substances are characteristic of Mca fruit pulp. A combined transcriptomic and metabolomic analysis revealed the mechanisms of pigment accumulation and cucurbitacin biosynthesis in Mca fruit peels, providing fundamental molecular information for further research on Mca fruit ripening. This report provides a new genetic resource for Momordica genomic studies and contributes additional insights into Cucurbitaceae phylogeny.

Purified Saponins in Momordica charantia Treated with High Hydrostatic Pressure and Ionic Liquid-Based Aqueous Biphasic Systems

Momordica charantia L. (Cucurbitaceae) is rich in saponins, which have multiple biological effects. In this study, the total saponins of M. charantia were extracted by high hydrostatic pressure (HHP) technology. The optimal extraction process was determined (ethanol concentration 68%, pressure-holding time 8 min, ratio of material to solvent 1:35 and pressure 510 MPa), and the extraction amount of saponins reached 127.890 mg/g. On this basis, an ionic liquid-based aqueous biphasic system was constructed to purify the total saponins. Under the optimized conditions, the purity of M. charantia saponins was 76.06%. Liquid chromatography–mass spectrometry (LC/MS) was used to characterize the saponins in the purified extract of M. charantia. It was found that there were four kinds of saponins in the extract of M. charantia: kuguaglycoside A, momordicoside L, kuguacin B and kuguacin J, providing a basis for the study of the biological activity of saponins.

Identification, In Silico Characterization, and Differential Expression Profiles of Carotenoid, Xanthophyll, Apocarotenoid Biosynthetic Pathways Genes, and Analysis of Carotenoid and Xanthophyll Accumulation in Heracleum moellendorffii Hance

Heracleum moellendorffii Hance is a non-woody forest plant widely used in China, Korea, and Japan because of its various therapeutic properties. However, the genetic details of the carotenoid pathway (CP), xanthophyll pathway (XP), and apocarotenoid pathway (AP) genes have not been studied. Thus, the CP, XP, and AP genes of H. moellendorffii were detected and analyzed. A total of fifteen genes were identified, of which eight, four, and three belonged to CP, XP, and AP, respectively. All identified genes possessed full open reading frames. Phylogenetic characterization of the identified gene sequences showed the highest similarity with other higher plants. Multiple alignments and 3D dimensional structures showed several diverse conserved motifs, such as the carotene-binding motif, dinucleotide-binding motif, and aspartate or glutamate residues. The results of real-time PCR showed that the CP, XP, and AP genes were highly expressed in leaves, followed by the stems and roots. In total, eight different individual carotenoids were identified using HPLC analysis. The highest individual and total carotenoid content were achieved in the leaves, followed by the stems and roots. This study will provide more information on the gene structure of the CP, XP, and AP genes, which may help to increase the accumulation of carotenoids in H. moellendorffii through genetic engineering. These results could be helpful for further molecular and functional studies of CP, XP, and AP genes.

Site-Directed Mutagenesis of the Carotenoid Isomerase Gene BnaCRTISO Alters the Color of Petals and Leaves in Brassica napus L

The diversity of petal and leaf color can improve the ornamental value of rapeseed and promote the development of agriculture and tourism. The two copies of carotenoid isomerase gene (BnaCRTISO) in Brassica napus (BnaA09.CRTISO and BnaC08.CRTISO) was edited using the CRISPR/Cas9 system in the present study. The mutation phenotype of creamy white petals and yellowish leaves could be recovered only in targeted mutants of both BnaCRTISO functional copies, indicating that the redundant roles of BnaA09.CRTISO and BnaC08.CRTISO are vital for the regulation of petal and leaf color. The carotenoid content in the petals and leaves of the BnaCRTISO double mutant was significantly reduced. The chalcone content, a vital substance that makes up the yellow color, also decreased significantly in petals. Whereas, the contents of some carotenes (lycopene, α-carotene, γ-carotene) were increased significantly in petals. Further, transcriptome analysis showed that the targeted mutation of BnaCRTISO resulted in the significant down-regulation of important genes BnaPSY and BnaC4H in the carotenoid and flavonoid synthesis pathways, respectively; however, the expression of other genes related to carotenes and xanthophylls synthesis, such as BnaPDS3, BnaZEP, BnaBCH1 and BCH2, was up-regulated. This indicates that the molecular mechanism regulating petal color variation in B. napus is more complicated than those reported in Arabidopsis and other Brassica species. These results provide insight into the molecular mechanisms underlying flower color variation in rapeseed and provides valuable resources for rapeseed breeding.

Cucurbitaceae genome evolution, gene function and molecular breeding

The Cucurbitaceae is one of the most genetically diverse plant families in the world. Many of them are important vegetables or medicinal plants and are widely distributed worldwide. The rapid development of sequencing technologies and bioinformatic algorithms has enabled the generation of genome sequences of numerous important Cucurbitaceae species. This has greatly facilitated research on gene identification, genome evolution, genetic variation and molecular breeding of cucurbit crops. So far, genome sequences of 18 different cucurbit species belonging to tribes Benincaseae, Cucurbiteae, Sicyoeae, Momordiceae and Siraitieae have been deciphered. This review summarizes the genome sequence information, evolutionary relationship, and functional genes associated with important agronomic traits (e.g., fruit quality). The progress of molecular breeding in cucurbit crops and prospects for future applications of Cucurbitaceae genome information are also discussed.

Molecular Characterization, Expression Analysis of Carotenoid, Xanthophyll, Apocarotenoid Pathway Genes, and Carotenoid and Xanthophyll Accumulation in Chelidonium majus L

Chelidonium majus L. is a perennial herbaceous plant that has various medicinal properties. However, the genomic information about its carotenoid biosynthesis pathway (CBP), xanthophyll biosynthesis pathway (XBP), and apocarotenoid biosynthesis pathway (ABP) genes were limited. Thus, the CBP, XBP, and ABP genes of C. majus were identified and analyzed. Among the 15 carotenoid pathway genes identified, 11 full and 4 partial open reading frames were determined. Phylogenetic analysis of these gene sequences showed higher similarity with higher plants. Through 3D structural analysis and multiple alignments, several distinct conserved motifs were identified, including dinucleotide binding motif, carotene binding motif, and aspartate or glutamate residues. Quantitative RT-PCR showed that CBP, XBP, and ABP genes were expressed in a tissue-specific manner; the highest expression levels were achieved in flowers, followed by those in leaves, roots, and stems. The HPLC analysis of the different organs showed the presence of eight different carotenoids. The highest total carotenoid content was found in leaves, followed by that in flowers, stems, and roots. This study provides information on the molecular mechanisms involved in CBP, XBP, and ABP genes, which might help optimize the carotenoid production in C. majus. The results could also be a basis of further studies on the molecular genetics and functional analysis of CBP, XBP, and ABP genes.

Transcription activation of β-carotene biosynthetic genes at the initial stage of stresses as an indicator of the increased β-carotene accumulation in isolated Dunaliella salina strain GY-H13

β-carotene is an efficient antioxidant and its accumulation is an oxidative response to stressors. Dunaliella salina strain GY-H13 is rich in β-carotene under environmental stresses, which was selected as material to understand the molecular mechanism underlying β-carotene biosynthesis. Seven full length cDNA sequences in β-carotene biosynthesis pathway were cloned, including geranylgeranyl pyrophosphate synthase (GGPS), phytoene synthase (PSY), phytoene desaturase (PDS), 15-cis-zeta-carotene isomerase (ZISO), zeta-carotene desaturase (ZDS), prolycopene isomerase (CRTISO), lycopene beta-cyclase (LCYb). The seven protein sequences from the strain GY-H13 showed the highest similarity with other D. salina strains. Especially, PSY, PDS and LCYb protein sequences shared 100 % identity. Phylogenetic analysis indicated all proteins from GY-H13 firstly clustered with those from other D. salina strains with a bootstrap of 100 %. Multiple alignment indicated several distinct conserved motifs such as aspartate-rich domain (ARD), dinucleotide binding domain (DBD), and carotene binding domain (CBD). These motifs are located near ligand-binding pocket, which may be required for the activity of enzyme. Expression levels of these genes and β-carotene content were measured over 24-h cycle, showing clear daily dynamics. All genes were dramatically up-regulated in the morning but the highest accumulation of β-carotene was observed at noon, suggesting a lag-effect between gene transcription and biological response. Furthermore, the accumulation of β-carotene increased under nitrogen deficiency, Cd exposure and high light and decreased under high salinity in a time-dependent manner. No gene of β-carotene biosynthesis was up-regulated by high salinity while most genes were activated by the other stresses at the beginning stage of exposure. Growth inhibition and oxidative damage were also observed under high salinity. Overall, transcription activation of β-carotene biosynthetic genes at the initial stage of stress exposure is a determinant of the increased accumulation of β-carotene in microalgae, which help their survive under harsh environments. The newly isolated D. salina strain GY-H13 would be a promising microalgae model for investigating the molecular mechanism of stress-induced β-carotene biosynthesis.

Anti-Inflammatory Effect of Crude Momordica charantia L. Extract on 2,4,6-Trinitrobenzene Sulfonic Acid-Induced Colitis Model in Rat and the Bioaccessibility of its Carotenoid Content

Momordica charantia L., known as bitter melon (BM), is a plant that belongs to the family Cucurbitaceae. Aims of this study are to investigate the anti-inflammatory effect of crude BM extract on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced experimental colitis model in rat. It was also aimed to determine the content and bioaccessibility of carotenoids of BM. BM was purchased from local markets in Izmir, Turkey. Fruits of BM were lyophilized, powdered, and used in the experiment. Carotenoids were determined by high-performance liquid chromatography. To determine the bioaccessibility of β-carotene, in vitro digestion was performed. Wistar albino rats were divided into four groups: group A (BM+TNBS), group B (BM), group C (TNBS), and group D (control). BM solution was given 300 mg/(kg·day) for 6 weeks orally. Colitis was induced by 0.25 mL of a solution containing 100 mg/kg 5% (w/v) TNBS in 50% ethanol (w/v) intrarectally after 6 weeks. After sacrification, macroscopic and microscopic evaluations were performed. Myeloperoxidase, cytokines levels (interleukin-17 [IL-17], TNF-alpha, and interleukin-10 [IL-10]) were measured in serum and colonic samples by ELISA test. Institutional Animal Ethics Committee approval was obtained. Total carotenoid content of BM was determined 11.7 mg/g dry weight as β-carotene equivalents. Bioaccessibility of total carotenoids was determined as 2.1% with in vitro digestion. Pretreatment with crude BM extract significantly reduced weight loss, macroscopic, and microscopic colitis damages in colonic samples (P = .000), (P = .015), and (P = .026), respectively. Serum anti-inflammatory cytokine IL-10 increased significantly in both treatment groups (P = .000). BM is a rich source of carotenoids, but the bioaccessibility of its carotenoids is low. This study displays that BM has protective anti-inflammatory effects on TNBS-induced colitis.

Metabolite profiling and in vitro biological activities of two commercial bitter melon (Momordica charantia Linn.) cultivars

The current study was designed to characterize the metabolite profile and bioactivity of two commercial bitter melon (Momordica charantia Linn.) genotypes. UPLC-high resolution mass spectrometry (HRMS) was used to identify 15 phenolic and 46 triterpenoids in various bitter melon extracts. Total phenolic levels were the highest (57.28 ± 1.02) in methanolic extract of the inner tissue of Indian Green cultivar, which also correlated to the highest DPPH radical scavenging activity (30.48 ± 2.49 ascorbic acid equivalents (mg of AAE)/g of FD). In addition, highest levels of total saponins were observed in chloroform extract of the Chinese bitter melon pericarp (75.73 mg ± 4.67 diosgenin equivalents (DE)/g of FD). Differential inhibition of α-amylase and α-glucosidase activity was observed in response to polarity of extract, cultivar and tissue type. These results suggest that consumption of whole bitter melon may have potential health benefits to manage diabetes.

Expression of Carotenoid Biosynthetic Genes and Carotenoid Biosynthesis during Seedling Development of Momordica charantia

Carotenoids belong to a large group of secondary metabolites, and have pivotal roles in plants, including photosynthesis and phytohormone synthesis, pigmentation, and membrane stabilization. Additionally, carotenoids are potent antioxidants, and their health benefits are becoming increasingly prominent. In recent years, carotenoids have been studied in many plants. Furthermore, gene expression, as well as carotenoid accumulation in different parts of the bitter melon, has been investigated; however, it has not been studied in bitter melon seedlings. In this study, carotenoid accumulation and transcript levels of McGGPPS1, McGGPPS2, McPSY, McPDS, McZDS, McLCYB, McLCYE1, McLCYE2, McCXHB, and McZEP, involved in carotenoid biosynthesis, were analyzed during seedling development using HPLC and qRT-PCR. The major carotenoids that accumulated in the bitter melon seedlings were lutein and E-β-carotene. The expression of most carotenoid biosynthetic genes increased during seedling development, consistent with the accumulation of violaxanthin, lutein, zeaxanthin, β-cryptoxanthin, 13Z-β-carotene, E-β-carotene, and 9Z-β-carotene in bitter melon seedlings. The results of this study provide a firm basis for comprehending the link between gene expression and carotenoid concentration in bitter melon seedlings.

Medically important carotenoids from Momordica charantia and their gene expressions in different organs

Carotenoids, found in the fruit and different organs of bitter melon (Momordica charantia), have attracted great attention for their potential health benefits in treating several major chronic diseases. Therefore, study related to the identification and quantification of the medically important carotenoid metabolites is highly important for the treatment of various disorderes. The present study involved in the identification and quantification of the various carotenoids present in the different organs of M. charantia and the identification of the genes responsible for the accumulation of the carotenoids with respect to the transcriptome levels were investigated. In this study, using the transcriptome database of bitter melon, a partial-length cDNA clone encoding geranylgeranyl pyrophosphate synthase (McGGPPS2), and several full-length cDNA clones encoding geranylgeranyl pyrophosphate synthase (McGGPPS1), zeta-carotene desaturase (McZDS), lycopene beta-cyclase (McLCYB), lycopene epsilon cyclases (McLCYE1 and McLCYE2), beta-carotene hydroxylase (McCHXB), and zeaxanthin epoxidase (McZEP) were identified in bitter melon. The expression levels of the mRNAs encoding these eight putative biosynthetic enzymes, as well as the accumulation of lycopene, α-carotene, lutein, 13Z-β-carotene, E-β-carotene, 9Z-β-carotene, β-cryptoxanthin, zeaxanthin, antheraxanthin, and violaxanthin were investigated in different organs from M. charantia as well as in the four different stages of its fruit maturation. Transcripts were found to be constitutively expressed at high levels in the leaves where carotenoids were also found at the highest levels. Collectively, these results indicate that the putative McGGPPS2, McZDS, McLCYB, McLCYE1, McLCYE2, and McCHXB enzymes might be key factors in controlling carotenoid content in bitter melon. In conclusion, the over expression of the carotenoid biosynthetic genes from M. charantia crops to increase the yield of these medically important carotenoids.

Molecular Cloning and Characterization of Carotenoid Pathway Genes and Carotenoid Content in Ixeris dentata var. albiflora

Ixeris dentata var. albiflora is considered as a potential therapeutic agent against mithridatism, calculous, indigestion, pneumonia, hepatitis, and tumors as well as good seasoned vegetable in Far East countries. Phytoene synthase (PSY), phytoene desaturase (PDS) ξ-carotene desaturase (ZDS), lycopene β-cyclase (LCYB), lycopene ε-cyclase (LCYE), ε-ring carotene hydroxylase (CHXB), and zeaxanthin epoxidase (ZDS) are vital enzymes in the carotenoid biosynthesis pathway. We have examined these seven genes from I. dentata that are participated in carotenoid biosynthesis utilizing an Illumina/Solexa HiSeq 2000 platform. In silico analysis of the seven deduced amino acid sequences were revealed its closest homology with other Asteracea plants. Further, we explored transcript levels and carotenoid accumulation in various organs of I. dentata using quantitative real time PCR and high-performance liquid chromatography, respectively. The highest transcript levels were noticed in the leaf for all the genes while minimal levels were noticed in the root. The maximal carotenoid accumulation was also detected in the leaf. We proposed that these genes expressions are associated with the accumulation of carotenoids. Our findings may suggest the fundamental clues to unravel the molecular insights of carotenoid biosynthesis in various organs of I. dentata.

Accumulation of Carotenoids and Metabolic Profiling in Different Cultivars of Tagetes Flowers

Species of Tagetes, which belong to the family Asteraceae show different characteristics including, bloom size, shape, and color; plant size; and leaf shape. In this study, we determined the differences in primary metabolites and carotenoid yields among six cultivars from two Tagetes species, T. erecta and T. patula. In total, we detected seven carotenoids in the examined cultivars: violaxanthin, lutein, zeaxanthin, α-carotene, β-carotene, 9-cis-β-carotene, and 13-cis-β-carotene. In all the cultivars, lutein was the most abundant carotenoid. Furthermore, the contents of each carotenoid in flowers varied depending on the cultivar. Principal component analysis (PCA) facilitated metabolic discrimination between Tagetes cultivars, with the exception of Inca Yellow and Discovery Orange. Moreover, PCA and orthogonal projection to latent structure-discriminant analysis (OPLS-DA) results provided a clear discrimination between T. erecta and T. patula. Primary metabolites, including xylose, citric acid, valine, glycine, and galactose were the main components facilitating separation of the species. Positive relationships were apparent between carbon-rich metabolites, including those of the TCA cycle and sugar metabolism, and carotenoids.

Transcriptome and metabolome analysis in shoot and root of Valeriana fauriei

BACKGROUND

Valeriana fauriei is commonly used in the treatment of cardiovascular diseases in many countries. Several constituents with various pharmacological properties are present in the roots of Valeriana species. Although many researches on V. fauriei have been done since a long time, further studies in the discipline make a limit due to inadequate genomic information. Hence, Illumina HiSeq 2500 system was conducted to obtain the transcriptome data from shoot and root of V. fauriei.

RESULTS

A total of 97,595 unigenes were noticed from 346,771,454 raw reads after preprocessing and assembly. Of these, 47,760 unigens were annotated with Uniprot BLAST hits and mapped to COG, GO and KEGG pathway. Also, 70,013 and 88,827 transcripts were expressed in root and shoot of V. fauriei, respectively. Among the secondary metabolite biosynthesis, terpenoid backbone and phenylpropanoid biosynthesis were large groups, where transcripts was involved. To characterize the molecular basis of terpenoid, carotenoid, and phenylpropanoid biosynthesis, the levels of transcription were determined by qRT-PCR. Also, secondary metabolites content were measured using GC/MS and HPLC analysis for that gene expression correlated with its accumulation respectively between shoot and root of V. fauriei.

CONCLUSIONS

We have identified the transcriptome using Illumina HiSeq system in shoot and root of V. fauriei. Also, we have demonstrated gene expressions associated with secondary metabolism such as terpenoid, carotenoid, and phenylpropanoid.

Development of carotenoid storage cells in Bixa orellana L. seed arils

The arils of Bixa orellana L. seeds contain carotenoid storage cells (CSCs). The main compounds in these cells include bixin and norbixin, which are important pigments in the food and pharmaceutical industries. Although many studies have been conducted on these chemical constituents, the cellular events that occur during the development of the carotenoid-accumulating cells in the arils and their relationship with the final carotenoid accumulation in the vacuoles remain unknown. In this study, the development of the CSCs in B. orellana arils was analyzed by light and transmission electron microscopy. Carotenoids formed in specialized cells, whose number and size increased during aril development. At various stages of development, the cytoplasm of the CSCs contained chromoplasts that held an extensive network of tubules and plastoglobules. Next to the chromoplasts, lipid droplets may fuse one another to form osmiophilic bodies. In addition, vesicles were observed next to the tonoplast. At the final stages of development, both the osmiophilic bodies and vesicles, which became quadrangular or rectangular, were stored in the vacuoles of the CSCs. This study reported for the first time the occurrence of different storage unit types within the vacuole of carotenoid storage cells.

Carotenoid metabolism and regulation in horticultural crops

Carotenoids are a diverse group of pigments widely distributed in nature. The vivid yellow, orange, and red colors of many horticultural crops are attributed to the overaccumulation of carotenoids, which contribute to a critical agronomic trait for flowers and an important quality trait for fruits and vegetables. Not only do carotenoids give horticultural crops their visual appeal, they also enhance nutritional value and health benefits for humans. As a result, carotenoid research in horticultural crops has grown exponentially over the last decade. These investigations have advanced our fundamental understanding of carotenoid metabolism and regulation in plants. In this review, we provide an overview of carotenoid biosynthesis, degradation, and accumulation in horticultural crops and highlight recent achievements in our understanding of carotenoid metabolic regulation in vegetables, fruits, and flowers.

Changes in carotenoid profiles and in the expression pattern of the genes in carotenoid metabolisms during fruit development and ripening in four watermelon cultivars

Changes in carotenoid profiles during fruit ripening were investigated in four watermelon cultivars: red-fleshed "CN66", pink-fleshed "CN62", yellow-fleshed "ZXG381" and white-fleshed "ZXG507". The expression pattern of twelve genes (GGPS, PSY, PSY-A, PDS, ZDS, CRTISO, LCYB, CHYB, ZEP, NCED1, NCED2 and NCED3) was analysed. In "CN66" and "CN62", lycopene appeared at 12 DAP and became a main carotenoid increased at the later stages. The transcript levels of carotenogenic genes in "CN66" sharply increased during 18-30 DAP, and concomitantly, fruit accumulated the massive amounts of carotenoids. In "ZXG381", violaxanthin and lutein contents were positively correlated, respectively, with CHYB and ZEP transcript levels during fruit ripening. The trace amounts of carotenoids in "ZXG507" were accompanied with the low transcript levels of most biosynthetic genes. The results suggest that differential transcriptional regulation of carotenoid metabolic genes is very important in determining the amount and type of specific carotenoids accumulated during fruit development and ripening.

Molecular characterization of carotenoid biosynthetic genes and carotenoid accumulation in Scutellaria baicalensis Georgi

Scutellaria baicalensis has a wide range of biological activities and has been considered as an important traditional drug in Asia and North America for centuries. A partial-length cDNA clone encoding phytoene synthase (SbPSY) and full-length cDNA clonesencoding phytoene desaturase (SbPDS), ξ-carotene desaturase (SbZDS), β-ring carotene hydroxylase (SbCHXB), and zeaxanthin epoxidase (SbZEP)were identifiedin S. baicalensis. Sequence analyses revealed that these proteins share high identity and conserved domains with their orthologous genes. SbPSY, SbPDS, SbZDS, SbCHXB, and SbZEP were constitutively expressed in the roots, stems, leaves, and flowers of S.baicalensis. SbPSY, SbPDS, and SbZDS were highly expressed in the stems, leaves, and flowers and showed low expression in the roots, where only trace amounts of carotenoids were detected. SbCHXB and SbZEP transcripts were expressed at relatively high levels in the roots, stems, and flowers and were expressed at low levels in the leaves, where carotenoids were mostly distributed. The predominant carotenoids in S.baicalensiswere lutein and β-carotene, with abundant amounts found in the leaves (517.19 and 228.37 μg g^-1 dry weight, respectively). Our study on the biosynthesis of carotenoids in S. baicalensis will provide basic data for elucidating the contribution of carotenoids to the considerable medicinal properties of S. baicalensis.

Molecular characterization of carotenoid biosynthetic genes and carotenoid accumulation in Lycium chinense

Lycium chinense is a shrub that has health benefits and is used as a source of medicines in Asia. In this study, a full-length cDNA clone encoding β-ring carotene hydroxylase (LcCHXB) and partial-length cDNA clones encoding phytoene synthase (LcPSY), phytoene desaturase (LcPDS), ξ-carotene desaturase (LcZDS), lycopene β-cyclase (LcLCYB), lycopene ε-cyclase (LcLCYE), ε-ring carotene hydroxylase (LcCHXE), zeaxanthin epoxidase (LcZEP), carotenoid cleavage dioxygenase (LcCCD1), and 9-cis epoxycarotenoid dioxygenase (LcNCED) were identified in L. chinense. The transcripts were constitutively expressed at high levels in leaves, flowers and red fruits, where the carotenoids are mostly distributed. In contrast, most of the carotenoid biosynthetic genes were weakly expressed in the roots and stems, which contained only small amounts of carotenoids. The level of LcLCYE transcripts was very high in leaves and correlated with the abundance of lutein in this plant tissue. During maturation, the levels of lutein and zeaxanthin in L. chinense fruits dramatically increased, concomitant with a rise in the level of β-cryptoxanthin. LcPSY, LcPDS, LcZDS, LcLCYB, and LcCHXE were highly expressed in red fruits, leading to their substantially higher total carotenoid content compared to that in green fruits. Total carotenoid content was high in both the leaves and red fruits of L. chinense. Our findings on the biosynthesis of carotenoids in L. chinense provide insights into the molecular mechanisms involved in carotenoid biosynthesis and may facilitate the optimization of carotenoid production in L. chinense.

In vivo hypoglycemic effect of methanolic fruit extract of Momordica charantia L

BACKGROUND

Momordica charantia L. is a medicinal plant commonly used in the management of diabetes mellitus.

OBJECTIVES

We investigated the blood glucose lowering effect of the methanolic fruit extract of the Ugandan variety of M. charantia L. in alloxan-induced diabetic albino rats.

METHODS

500g of M. charantia powder were macerated in methanol and the extract administered to two groups of alloxan-induced diabetic rats. The first group received 125mg/kg, the second 375mg/kg and a third group 7mg/kg of metformin. A fourth group received 1ml normal saline. Fasting blood glucose (FBG) levels were measured at 0.5,1,2,3,5,8 and 12 hours and compared using one-way ANOVA.

RESULTS

There was an initial rise in FBG for 1 hour after administration of extracts followed by steep reductions. Significant reduction in FBG occurred at 2 hours for 125mg/kg of extract (-3.2%, 313±25.9 to 303±25.0mg/dL, p = 0.049), 375mg/kg of extract (-3.9%, 356±19.7 to 342±20.3mg/dL, p = 0.001), and metformin (-2.6%, 344±21.7 to 335±21.1mg/dL, p = 0.003) when compared to normal saline. The maximum percentage reduction in FBG by both extracts occurred between 3 and 12 hours post dose.

CONCLUSIONS

The methanolic fruit extract of M. charantia exhibits dose dependent hypoglycaemic activity in vivo.

Molecular cloning and characterization of cDNAs encoding carotenoid cleavage dioxygenase in bitter melon (Momordica charantia)

Carotenoid cleavage dioxygenases (CCDs) are a family of enzymes that catalyze the oxidative cleavage of carotenoids at various chain positions to form a broad spectrum of apocarotenoids, including aromatic substances, pigments and phytohormones. Using the rapid amplification of cDNA ends (RACE) PCR method, we isolated three cDNA-encoding CCDs (McCCD1, McCCD4, and McNCED) from Momordica charantia. Amino acid sequence alignments showed that they share high sequence identity with other orthologous genes. Quantitative real-time RT PCR (reverse transcriptase PCR) analysis revealed that the expression of McCCD1 and McCCD4 was highest in flowers, and lowest in roots and old leaves (O-leaves). During fruit maturation, the two genes displayed differential expression, with McCCD1 peaking at mid-stage maturation while McCCD4 showed the lowest expression at that stage. The mRNA expression level of McNCED, a key enzyme involved in abscisic acid (ABA) biosynthesis, was high during fruit maturation and further increased at the beginning of seed germination. When first-leaf stage plants of M. charantia were exposed to dehydration stress, McNCED mRNA expression was induced primarily in the leaves and, to a lesser extend, in roots and stems. McNCED expression was also induced by high temperature and salinity, while treatment with exogenous ABA led to a decrease. These results should be helpful in determining the substrates and cleavage sites catalyzed by CCD genes in M. charantia, and also in defining the roles of CCDs in growth and development, and in the plant's response to environmental stress.

Riboflavin accumulation and characterization of cDNAs encoding lumazine synthase and riboflavin synthase in bitter melon (Momordica charantia)

Riboflavin (vitamin B2) is the universal precursor of the coenzymes flavin mononucleotide and flavin adenine dinucleotide--cofactors that are essential for the activity of a wide variety of metabolic enzymes in animals, plants, and microbes. Using the RACE PCR approach, cDNAs encoding lumazine synthase (McLS) and riboflavin synthase (McRS), which catalyze the last two steps in the riboflavin biosynthetic pathway, were cloned from bitter melon (Momordica charantia), a popular vegetable crop in Asia. Amino acid sequence alignments indicated that McLS and McRS share high sequence identity with other orthologous genes and carry an N-terminal extension, which is reported to be a plastid-targeting sequence. Organ expression analysis using quantitative real-time RT PCR showed that McLS and McRS were constitutively expressed in M. charantia, with the strongest expression levels observed during the last stage of fruit ripening (stage 6). This correlated with the highest level of riboflavin content, which was detected during ripening stage 6 by HPLC analysis. McLS and McRS were highly expressed in the young leaves and flowers, whereas roots exhibited the highest accumulation of riboflavin. The cloning and characterization of McLS and McRS from M. charantia may aid the metabolic engineering of vitamin B2 in crops.

De novo transcriptome sequencing of Momordica cochinchinensis to identify genes involved in the carotenoid biosynthesis

The ripe fruit of Momordica cochinchinensis Spreng, known as gac, is featured by very high carotenoid content. Although this plant might be a good resource for carotenoid metabolic engineering, so far, the genes involved in the carotenoid metabolic pathways in gac were unidentified due to lack of genomic information in the public database. In order to expedite the process of gene discovery, we have undertaken Illumina deep sequencing of mRNA prepared from aril of gac fruit. From 51,446,670 high-quality reads, we obtained 81,404 assembled unigenes with average length of 388 base pairs. At the protein level, gac aril transcripts showed about 81.5% similarity with cucumber proteomes. In addition 17,104 unigenes have been assigned to specific metabolic pathways in Kyoto Encyclopedia of Genes and Genomes, and all of known enzymes involved in terpenoid backbones biosynthetic and carotenoid biosynthetic pathways were also identified in our library. To analyze the relationship between putative carotenoid biosynthesis genes and alteration of carotenoid content during fruit ripening, digital gene expression analysis was performed on three different ripening stages of aril. This study has revealed putative phytoene synthase, 15-cis-phytone desaturase, zeta-carotene desaturase, carotenoid isomerase and lycopene epsilon cyclase might be key factors for controlling carotenoid contents during aril ripening. Taken together, this study has also made availability of a large gene database. This unique information for gac gene discovery would be helpful to facilitate functional studies for improving carotenoid quantities.