Search Results (59)

Rapid advancements in biotechnology have enabled biomanufacturing to emerge as a feasible approach for industrial chemical production. By harnessing synthetic biology and metabolic engineering, engineered microbial cell factories can convert renewable resources into valuable chemicals, providing a sustainable alternative to traditional chemical methods. This study focuses on the microbial production of retinal, an important retinoid used in pharmaceuticals, food, and cosmetics. The oleaginous yeast Rhodotorula toruloides NP11 was genetically modified to synthesize retinal by incorporating and optimizing three β-carotene 15,15′-dioxygenase genes from various sources. Several genetic modifications were made to enhance retinal yield, including the overexpression of isopentenyl-diphosphate isomerase (IDI1), geranylgeranyl diphosphate synthase (BTS1), phytoene synthase (CARRP), and phytoene dehydrogenase (CARB), which led to increased β-carotene levels and boosted retinal production. Furthermore, fermentation conditions such as temperature, antioxidants, and extractants were fine-tuned. The engineered strain Rt13 ultimately achieved a maximum retinal concentration of 20.38 mg/L through fed-batch fermentation. This study highlights the potential of R. toruloides as a cell factory for terpenoid biosynthesis, providing valuable insights for future metabolic engineering endeavors. Full article

The SQS_PSY family (Squalene/phytoene synthase family), with squalene synthase (SQS) and phytoene synthase (PSY) as core members, comprises enzymes that catalyze the head-to-head condensation of isoprenoid precursors. These enzymes play pivotal roles in mediating plant responses to both biotic and abiotic stresses; nevertheless, their specific functions in soybean defense against Phytophthora sojae infection remain elusive. In the present study, a comprehensive bioinformatics approach was utilized to identify 12 SQS_PSY family members in the soybean genome, followed by subsequent analyses of chromosomal distribution, phylogenetic relationships, gene structures, conserved motifs, and cis-acting regulatory elements within promoter regions. Notably, multiple cis-elements responsive to biotic and abiotic stresses were detected in the promoter regions of SQS_PSY genes in soybean, implying their potential involvement in stress-responsive pathways. To elucidate their roles in defense, resistant and susceptible soybean cultivars were inoculated with P. sojae, and RNA-seq was conducted on sampled tissues. Integrated with quantitative real-time PCR (qRT-PCR) validation, our findings demonstrated that GmSQS1 exhibited differential expression patterns between resistant and susceptible cultivars at multiple time points post-inoculation. Furthermore, the functional role of GmSQS1 in enhancing soybean resistance to P. sojae was confirmed using a transgenic hairy root system. Collectively, this study preliminarily validated the functions of the SQS_PSY genes in soybean and offers novel insights into their potential application for improving resistance against Phytophthora root rot. Full article

The oleaginous yeast Rhodotorula glutinis is a promising industrial host for the simultaneous production of lipids and carotenoids, yet the transcriptional regulation governing carbon flux toward these metabolites is poorly understood. As a foundational step, we performed a comparative transcriptomic analysis on bioreactor cultures under optimized fed-batch conditions with varying carbon-to-nitrogen (C/N) ratios and metal supplementation, comparing a nutrient-replete control (C) with conditions favoring high lipid (HLP) or high carotenoid (HCP) production. This study was designed as a preliminary, in-depth case study using single, well-controlled bioreactor runs per condition, with the goal of generating a comprehensive transcriptional map to identify key candidate genes for future validation. The data delineates two distinct presumptive metabolic strategies. The HLP regime was associated with broad transcriptional downregulation, channeling carbon toward lipogenesis via specific upregulation of the fatty acid synthase complex (FAS1/2, Log₂FC(HLP/HCP) > 2.99) and concerted suppression of β-oxidation genes (Log₂FC < −9.70). Conversely, the HCP condition was characterized by significant upregulation of NADPH-supplying pathways, including the pentose phosphate pathway (e.g., rpiA, Log₂FC(HCP/C) = 11.39) and an NADP⁺-dependent glyceraldehyde-3-phosphate dehydrogenase (gapN, Log₂FC(HCP/C) = 12.24). Notably, a putative beta-carotene hydroxylase (CrtZ) was uniquely sustained in the HCP condition (Log₂FC(HLP/HCP) = −10.65), strongly correlating with torularhodin accumulation and suggesting its novel role in torulene hydroxylation. This exploratory study reveals prospective transcriptional determinants of carbon partitioning in R. glutinis and provides a prioritized genetic blueprint for future hypothesis-driven research with full biological replication. Full article

Rosa rugosa (R. rugosa) is a commercially important ornamental species within the genus Rosa, highly valued in the horticultural market. With the increasing availability and improved annotation of Rosa genomes, establishing an efficient genetic transformation system has become essential for validating candidate gene functions. As a common intermediate tissue in plant regeneration, callus has been successfully used to establish genetic transformation systems in numerous species. In this study, we characterized the morphological and physiological differences between embryogenic and non-embryogenic calli in R. rugosa. The embryogenic callus exhibited significantly higher catalase (CAT) activity and proline (PRO) content than the non-embryogenic callus. However, its growth rate was markedly slower. Antibiotic sensitivity assays identified the optimal selection concentrations for non-embryogenic callus as 35 mg/L for kanamycin and 13 mg/L for hygromycin. We subsequently introduced the phytoene synthase (RrPSY1) gene into non-embryogenic callus, with positive transformants identified using GFP fluorescence detection and PCR analysis. The overexpression of RrPSY1 significantly increased the yellow pigment substances in the callus, confirming the establishment of an effective genetic transformation system for non-embryogenic calli in R. rugosa. This system provides a useful technical platform for the manipulation of metabolic products and the verification of related gene functions in rose. Full article

Rosa rugosa is an important ornamental and edible species that is valued for its floral colors and essential oils in the cosmetic and pharmaceutical industries. Carotenoids, beyond their health-promoting roles, function as accessory pigments that influence petal coloration, flower quality, and stress responses. However, their accumulation patterns and molecular biosynthesis in R. rugosa remain poorly understood. Here, UPLC-APCI-MS/MS analysis across three developmental stages (bud, semi-open, and full bloom) revealed stage-specific carotenoid accumulation, with phytoene and phytofluene markedly increasing at the semi-open stage. In total, 11 carotenoids were identified, comprising four carotenes and seven xanthophylls. Differential accumulation of metabolites (DAMs) analysis indicated shifts in compounds, including (E/Z)-phytoene, phytofluene, and β-carotene across stages. Genetic complementation assays in Escherichia coli and transient overexpression in rose petals confirmed that RrPSY1 functions as a phytoene synthase. qRT-PCR results showed its upregulation under salt treatment, suggesting a role in enhancing stress tolerance through carotenoid-mediated antioxidant protection. Furthermore, sub-cellular localization experiments confirmed plastid targeting of RrPSY1. Together, these findings clarify the role of RrPSY1 in carotenoid biosynthesis and provide a foundation for future studies on metabolic regulation and biosynthesis of carotenoids in R. rugosa. Full article

Phytoene synthase (PSY) is a multimeric enzyme that serves as the first enzyme in carotenoid synthesis within plant tissues and plays a crucial role in the production of carotenoids in plants. To understand the function of the PSY gene in Panax japonicus C. A. Meyer. fruit, the gene’s transcript was obtained by analyzing the transcriptome sequencing data of Panax japonicus fruit. The CDS sequence of the gene was cloned from Panax japonicus fruit using the RT-PCR cloning technique and named PjPSY1, which was then subjected to biosynthetic analysis and functional verification. The results showed that the open reading frame of the gene was 1269 bp, encoding 423 amino acids, with a protein molecular mass of 47,654.67 KDa and an isoelectric point (pI) of 8.63; the protein encoded by these amino acids was hydrophilic and localized in chloroplasts, and its three-dimensional structure was predicted by combining the pymol software to annotate the N site of action and active centre of the protein. Phylogenetic analysis demonstrated that PjPSY1 had the closest affinity to DcPSY from Daucus carota. Overexpression of PjPSY1 led to a significant increase in the content of carotenoid-related monomers in Arabidopsis thaliana, with Violaxanthin being synthesized in transgenic Arabidopsis thaliana but not in wild-type Arabidopsis thaliana. The PjPSY1 clone obtained in this study was able to promote carotenoid synthesis in the fruits of Panax japonicus, revealing that the mode of action of PjPSY1 in the carotenoid biosynthesis pathway of Panax japonicus fruits has a positive regulatory effect. Full article

During fruit ripening in Capsicum species, substantial amounts of carotenoids accumulate in the pericarp. While the carotenoid biosynthesis pathway in Capsicum species has been extensively investigated from various angles, the transcriptional regulation of genes encoding carotenoid biosynthetic enzymes remains less understood in this non-climacteric horticultural crop compared to tomato, a climacteric fruit. In the present study, we investigated the function of the NAM, ATAF1/2 or CUC2 81 (CaNAC81) transcription factor gene. This gene was selected through RNA-Seq co-expression analysis based on the correlation between expressed transcription factor gene profiles and those of carotenoid structural genes. To determine its role in regulating the expression of biosynthetic-related carotenogenic genes, we performed Virus-Induced Gene Silencing (VIGS) assays in the Serrano-type C. annuum ‘Tampiqueño 74’. Fruits from plants infected with a pTRV2:CaNAC81 construct (silenced fruits) exhibited altered carotenoid pigmentation accumulation, manifested as yellow-orange spots, in contrast to fruits from non-agroinfected controls (NTC) and fruits from plants infected with the empty TRV2 construct (red fruits). Quantitative real-time PCR (qPCR) assays confirmed decreased transcript levels of CaNAC81 in fruits displaying altered pigmentation, along with reduced transcription of the PSY gene, which encodes the carotenoid biosynthetic enzyme phytoene synthase (PSY). High-performance liquid chromatography (HPLC) analysis revealed a distinct carotenoid pigment accumulation pattern in fruits from plants showing silencing symptoms, characterized by low concentrations of capsanthin and zeaxanthin and trace amounts of capsorubin, compared to control plants (NTC). These findings suggest the involvement of CaNAC81 in the regulatory network of the carotenoid biosynthetic pathway in chili pepper fruits. Full article

Background: Myxol, a monocyclic carotenoid with β- and ψ-end groups, has been identified in only a limited number of bacteria, such as flavobacteria and cyanobacteria. Despite its biological significance, the biosynthetic pathway of myxol is not well understood, and studies on its physiological functions and biological activities are limited because of its rarity. Methods: BLAST homology searches for carotenoid biosynthesis genes in the genome of Nonlabens were performed. The carotenogenesis-related genes in the genome of the marine flavobacteria Nonlabens spongiae were individually cloned and functionally characterized using a heterologous Escherichia coli expression system. Carotenoids from N. spongiae were identified using an LC-MS analysis. Results: We identified a gene cluster involved in carotenoid biosynthesis in the genome of N. spongiae. This cluster includes genes encoding phytoene synthase (CrtB), phytoene desaturase (CrtI), lycopene cyclase (CrtY), carotenoid 1,2-hydratase (CruF), carotenoid 3,4-desaturase (ψ-end group) (CrtD), carotenoid 2-hydroxylase (ψ-end group) (CrtA-OH), and carotene hydro-xylase (CrtZ). Based on the characteristics of these enzymes, the primary products were predicted to be myxol and/or zeaxanthin. A spectroscopic analysis confirmed that myxol was the primary carotenoid. Furthermore, a plasmid containing a reconstructed gene cluster and geranylgeranyl pyrophosphate synthase (CrtE) located outside the cluster was introduced into E. coli. This system predominantly accumulated myxol, indicating that the reconstructed gene cluster enabled efficient myxol production in E. coli. Conclusions: This study highlighted the potential biotechnological applications of the carotenoid biosynthesis gene clusters for myxol production. Full article

Auricularia heimuer is a valuable traditional Chinese fungus used as food and medicine. Hei29 is a strain derived from wild A. heimuer through systematic domestication and selection. It has been the primary A. heimuer variety in Northeast China for 30 years and offers the advantages of high yield, good commercial property, and stable traits. This study used protoplast nucleation on Hei29 to produce two amiable and paired monokaryons, Hei29-D1 and Hei29-D2. The genome of Hei29 was sequenced utilizing the Illumina PE150 and PacBio Sequel sequencing platforms. Hei29-D1 and Hei29-D2 had genomic sizes of 47.54 Mb and 47.49 Mb, GC contents of 56.95% and 56.99%, and an N50 of 2.37 Mb and 4.28 Mb, respectively. Hei29’s genome possessed two phytoene synthase (PSY) protein genes, one of which—PSY encoded by g894—has a transmembrane domain. The phylogenetic tree showed that Hei29 shared the closest evolutionary relationship with Auricularia subglabra TFB-10046 SS5. Collinearity analysis showed that the correlation between the two monokaryons was as high as 90.81%. Cluster analysis revealed that Hei29 contains 12,362 core genes, 223 unique genes in Hei29-D1, and 228 unique genes in Hei29-D2. This study is the first to sequence two related and paired monokaryons from A. heimuer, which is critical for fully understanding the genetic composition and information of the characteristic strain of A. heimuer in Northeast China. It establishes the data and theoretical foundation for gene mining, usage, and molecular breeding. It further promotes the genetic breeding and active substance utilization of A. heimuer. Full article

Dunaliella salina is an important source of natural β-carotene (containing 9-cis and all trans isomers) for industrial production. The phytohormone salicylic acid (SA) has been proven to have impacts on the stress resistance of higher plants, but research on microalgae is currently unclear. In this study, the effects of SA on the growth, biochemical composition, antioxidant enzyme activity, key enzymes of β-carotene synthesis, and cis-and trans-isomers of β-carotene in D. salina under different salt concentrations were investigated. The results were shown that at concentrations of 1.5, 2, and 2.5 M NaCl, the antioxidant enzyme activity and key enzymes for β-carotene synthesis in algal cells were significantly increased, but the content and proportion of 9-cis isomer in β-carotene isomers decreased. The addition of SA significantly increased the growth and antioxidant enzyme (SOD, MDA) activity, as well as the synthesis of key enzyme phytoene synthase (PSY), phytoene desaturase (PDS), and lycopene β cyclase (LCYB) of D. salina under high-salinity conditions. It is worth noting that under the treatment of SA, the proportion of 9-cis isomer in the three salt concentrations (1.5, 2, 2.5 M NaCl) significantly increased by 32.09%, 20.30%, and 11.32%, respectively. Moreover, SA can not only improve the salt tolerance of D. salina, but also increase the proportion of 9-cis isomer, with higher physiological activity in β-carotene, thereby enhancing the application value of D. salina. Full article

Chromochloris zofingiensis, a unicellular green alga, is a potential source of natural carotenoids. In this study, the mutant LUT-4 was acquired from the chemical mutagenesis pool of C. zofingiensis strain. The biomass yield and lutein content of LUT-4 reached 9.23 g·L⁻¹, and 0.209% of dry weight (DW) on Day 3, which was 49.4%, and 33% higher than that of wild-type (WT), respectively. The biomass yields of LUT-4 under 100, 300, and 500 µmol/m²/s reached 8.4 g·L⁻¹, 7.75 g·L⁻¹, and 6.6 g·L⁻¹, which was 10.4%, 21%, and 29.6% lower compared with the control, respectively. Under mixotrophic conditions, the lutein yields were significantly higher than that obtained in the control. The light intensity of 300 µmol/m²/s was optimal for lutein biosynthesis and the content of lutein reached 0.294% of DW on Day 3, which was 40.7% more than that of the control. When LUT-4 was grown under 300 µmol/m²/s, a significant increase in expression of genes implicated in lutein biosynthesis, including phytoene synthase (PSY), phytoene desaturase (PDS), and lycopene epsilon cyclase (LCYe) was observed. The changes in biochemical composition, Ace-CoA, pyruvate, isopentenyl pyrophosphate (IPP), and geranylgeranyl diphosphate (GGPP) contents during lutein biosynthesis were caused by utilization of organic carbon. It was thereby concluded that 300 µmol/m²/s was the optimal culture light intensity for the mutant LUT-4 to synthesize lutein. The results would be helpful for the large-scale production of lutein. Full article

The formation of phytoene by condensing two geranylgeranyl diphosphate molecules catalyzed by phytoene synthase (PSY) is the first committed and rate-limiting step in carotenoid biosynthesis, which has been extensively investigated in bacteria, land plants and microalgae. However, this step in macroalgae remains unknown. In the present study, a gene encoding putative phytoene synthase was cloned from the economic red alga Pyropia yezoensis—a species that has long been used in food and pharmaceuticals. The conservative motifs/domains and the tertiary structure predicted using bioinformatic tools suggested that the cloned PyPSY should encode a phytoene synthase; this was empirically confirmed by pigment complementation in E. coli. This phytoene synthase was encoded by a single copy gene, whose expression was presumably regulated by many factors. The phylogenetic relationship of PSYs from different organisms suggested that red algae are probably the progeny of primary endosymbiosis and plastid donors of secondary endosymbiosis. Full article

This study investigates the relationship between nitrogen fertilization and pepper fruit color by employing five different nitrogen treatments (N1: 750 kg/hm², N2: 562.5 kg/hm², N3: 375 kg/hm², N4: 187.5, and N0: 0 kg/hm²). Fruits were harvested at 30 (S1: green ripening stage), 45 (S2: color transition stage), and 60 days (S3: red ripening stage) after flowering. Subsequently, pigment content, carotenoid component content, carotenoid enzyme activity, and transcriptome sequence were analyzed, and CA12g04950 function was validated through virus-induced gene silencing (VIGS). The results indicate that a reduction in nitrogen application led to an earlier onset of fruit color breakdown, and increased the contents of total carotenoid, capsanthin, phytoene and PSY (phytoene synthase) activity, LCYB (lycopene β-cyclase) activity and CCS (capsanthin/capsorubin synthase) activity. The analysis of different expression genes indicated that the most differently expressed genes were enriched in the N1 vs. N4 comparison, with 18 genes involved in carotenoid metabolism and 16 genes involved in nitrogen metabolism. Most DE genes were enriched in the pathways of photosynthesis, porphyrin, carotenoid biosynthesis, seleno-compounds, and nitrogen metabolism. There were numerous differential transcription factor families, including ERF, bHLH, MYB, C2H2, and NAC. Pearson correlation analysis revealed a significant positive correlation between CA12g04950 expression and 11 carotenoid genes in the N4 treatment. Subsequent silencing of CA12g04950 using VIGS resulted in delayed color ripening while a significant decrease in total carotenoid content and the expression levels of carotenoid genes. In conclusion, nitrogen reduction led to an increase in carotenoid content in pigment pepper fruits. Furthermore, under nitrogen reduction, CA12g04950 positively influenced the redness of the fruits. Full article

Fruit color affects its commercial value. β-carotene is the pigment that provides color for many fruits and vegetables. However, the molecular mechanism of β-carotene metabolism during apricot ripening is largely unknown. Here, we investigated whether β-carotene content affects apricot fruit color. First, the differences in β-carotene content between orange apricot ‘JTY’ and white apricot ‘X15’ during nine developmental stages (S1–S9) were compared. β-carotene contents highly significantly differed between ‘JTY’ and ‘X15’ from S5 (color transition stage) onwards. Whole-transcriptome analysis showed that the β-carotene synthesis genes 15-cis-phytoene desaturase (PaPDS) and 15-cis-phytoene synthase (PaPSY) significantly differed between the two cultivars during the color transition stage. There was a 5 bp deletion in exon 11 of PaPDS in ‘X15’, which led to early termination of amino acid translation. Gene overexpression and virus-induced silencing analysis showed that truncated PaPDS disrupted the β-carotene biosynthesis pathway in apricot pulp, resulting in decreased β-carotene content and a white phenotype. Furthermore, virus-induced silencing analysis showed that PaPSY was also a key gene in β-carotene biosynthesis. These findings provide new insights into the molecular regulation of apricot carotenoids and provide a theoretical reference for breeding new cultivars of apricot. Full article

The fruit flesh of watermelons differs depending on the distinct carotenoid composition. Orange-colored flesh relates to the accumulation of β-carotene, which is beneficial to human health. Canary-yellow-fleshed OTO-DAH and orange-β-fleshed (orange-fleshed with high β-carotene) NB-DAH near-isogenic lines (NILs) were used to determine the genetic mechanism attributed to orange watermelon flesh. For genetic mapping, an F₂ population was developed by crossing the two NILs. The segregation ratio of flesh color in the F₂ population indicated that the orange-β flesh of the NB-DAH NIL was controlled by a single incompletely dominant gene. Through a comparative analysis of the whole-genome sequences of the parent lines and NILs, a major introgression region unique to the NB-DAH NIL was detected on Chr. 1; this was considered a candidate region for harboring genes that distinguish orange from canary-yellow and red flesh. Among the 13 genes involved in the carotenoid metabolic pathway in watermelons, only ClPSY1 (ClCG01G008470), which encodes phytoene synthase 1, was located within the introgression region. The genotyping of F₂ plants using a cleaved amplified polymorphic sequence marker developed from a non-synonymous SNP in ClPSY1 revealed its relationship with orange-β flesh. The insights gained in this study can be applied to marker-assisted breeding for this desirable trait. Full article