Anthocyanin Biosynthesis Pathway Research Articles

High-quality genome of black wolfberry (Lycium ruthenicum Murr.) provides insights into the genetics of anthocyanin biosynthesis regulation

Abstract Black wolfberry (Lycium ruthenicum Murr.) is an important plant for ecological preservation. In addition, its fruits are rich in anthocyanins and have important edible and medicinal value. However, a high quality chromosome-level genome for this species is not yet available, and the regulatory mechanisms involved in the biosynthesis of anthocyanins are unclear. In this study, haploid material was used to assemble a high-quality chromosome-level reference genome of Lycium ruthenicum, resulting in a genome size of 2,272 Mb with contig N50 of 92.64 Mb, and 38,993 annotated gene models. In addition, the evolution of this genome and large-scale variations compared with the Ningxia wolfberry Lycium barbarum were determined. Importantly, homology annotation identified 86 genes involved in the regulatory pathway of anthocyanin biosynthesis, five of which [LrCHS1 (evm.TU.Chr05.295), LrCHS2 (evm.TU.Chr09.488), LrAOMT (evm.TU.Chr09.809), LrF3'5'H (evm.TU.Chr06.177) and LrAN2.1 (evm.TU.Chr05.2618)] were screened by differential expression analysis and correlation analysis using a combination of transcriptome and metabolome testing. Overexpression of these genes could significantly up- or downregulate anthocyanin-related metabolites. These results will help accelerate the functional genomic research of L. ruthenicum, and the elucidation of the genes involved in anthocyanin synthesis will be beneficial for breeding new varieties and further exploring its ecological conservation potential.

Transcriptomic and metabolomic analysis of poplar response to feeding by Hyphantria cunea

Populus cathayana × canadansis ‘Xinlin 1’ (‘P.‘xin lin 1’) with the characteristics of rapid growth and high yield, is frequently attacked by herbivorous insects. However, little is known about how it defenses against Hyphantria cunea (H. cunea) at molecular and biochemical levels. Differences in the transcriptome and metabolome were analyzed after ‘P. ‘xin lin 1’ leaves were fed to H. cunea for 0h, 2h, 4h, 8h, 16h and 24h. In the five comparison groups including 2h vs. CK, 4h vs. CK, 8h vs. CK, 16h vs. CK, and 24h vs. CK, a total of 8925 genes and 842 metabolites were differentially expressed. A total of 825 transcription factors (TFs) were identified, which encoded 56 TF families. The results showed that the top four families with the highest number of TFs were AP2/ERF, MYB, C2C2, bHLH. Analyses of leaves which were fed to H. cunea showed that the differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) were significantly enriched in plant hormone signal transduction pathway, MAPK signaling pathway, flavonoid, flavone and flavonol and anthocyanin biosynthesis pathway. Additionally, there were a number of genes significantly up-regulated in MAPK signaling pathway. Some compounds involved in plant hormone signal transduction and flavonoid/flavone and flavonol/ anthocyanin pathways such as jasmonic acid (JA), jasmonoyl-L-Isoleucine (JA-Ile), kaempferol and cyanidin-3-O-glucoside were induced in infested ‘P.‘xin lin 1’. This study provides a new understanding for exploring the dynamic response mechanism of poplar to the infestation of H. cunea.

Role of anthocyanin metabolic diversity in bract coloration of Curcuma alismatifolia varieties

Anthocyanins are one of the key metabolites influencing the coloration of ornamental bracts in plants. Curcuma alismatifolia is an emerging ornamental plant, known for the rich diversity in the coloration of its bracts and the variety of anthocyanins present. However, the specific anthocyanin metabolites contributing to this diversity are not entirely clear. This study examines the bract color variation across 19 C. alismatifolia varieties using colorimetric analysis and spectrophotometric determination of total anthocyanin content. The 19 accessions were categorized into four color groups: white, light pink, pink, and purple. Further analysis using anthocyanin metabolomics and transcriptomics was conducted on five C. alismatifolia varieties with significant differences in coloration and total anthocyanin content. In addition to previously reported anthocyanins, delphinidin-3-O-glucoside and peonidin-3-O-rutinoside were identified for the first time as important contributors to the diverse bract coloration in C. alismatifolia. Fifty-three differentially expressed genes (DEGs) were identified in the anthocyanin biosynthesis pathway, and two significant gene modules were determined through WGCNA analysis. Correlation network analysis revealed two BZ1 genes that may be key terminal enzyme genes affecting anthocyanin synthesis in C. alismatifolia bracts. Multiple transcription factors, including MYB, NAC, WRKY, ERF, and bHLH, may be involved in regulating the accumulation of different anthocyanin contents in the bracts. This research sheds light on the genetic and metabolic factors that influence bract coloration in C. alismatifolia.

Transcriptome Analysis Identified PyNAC42 as a Positive Regulator of Anthocyanin Biosynthesis Induced by Nitrogen Deficiency in Pear (Pyrus spp.)

Anthocyanins are important secondary metabolites in plants, which contribute to fruit color and nutritional value. Anthocyanins can be regulated by environmental factors such as light, low temperature, water conditions, and nutrition limitations. Nitrogen (N) is an essential macroelement for plant development, its deficiency as a kind of nutrition limitation often induces anthocyanin accumulation in many plants. However, there is a lack of reports regarding the effect of nitrogen deficiency on anthocyanin biosynthesis in pears. In this study, we found that N deficiency resulted in anthocyanin accumulation in pear callus and upregulated the expression of anthocyanin biosynthesis pathway structural genes (PyPAL, PyCHS, PyCHI, PyF3H, PyDFR, PyANS, and PyUFGT) and key regulatory factors (PyMYB10, PyMYB114, and PybHLH3). Through analysis of transcriptome data of treated pear callus and RT-qPCR assay, a differentially expressed gene PyNAC42 was identified as significantly induced by the N deficiency condition. Overexpression of PyNAC42 promoted anthocyanin accumulation in “Zaosu” pear peels. Additionally, dual luciferase assay and yeast one-hybrid assay demonstrated that PyNAC42 could not directly activate the expression of PyDFR, PyANS, and PyUFGT. Furthermore, yeast two-hybrid and pull-down assays confirmed that PyNAC42 interacted with PyMYB10 both in vivo and in vitro. Co-expression of PyNAC42 and PyMYB10 significantly enhanced anthocyanin accumulation in “Zaosu” pear peels. Dual luciferase assay showed that PyNAC42 significantly enhanced the activation of PyDFR, PyANS, and PyUFGT promoters by interacting with PyMYB10, which suggests that PyNAC42 can form the PyNAC42-PyMYB10 complex to regulate anthocyanin biosynthesis in pear. Thus, the molecular mechanism underlying anthocyanin biosynthesis induced by N deficiency is preliminarily elucidated. Our finding has expanded the regulatory network of anthocyanin biosynthesis and enhanced our understanding of the mechanisms underlying nutrient deficiency modulates anthocyanin biosynthesis in pear.

Transcriptomics and metabolomics revealed the molecular basis of the color formation in the roots of Panax notoginseng

Panax notoginseng is a traditional Chinese medicine rich in many pharmacological components. The root of the ‘Miaoxiang Sanqi No. 2’ is yellow or greenish yellow, while a novel cultivar-‘Wenyuan Ziqi No. 1’ shows purple root and is thought to have high medicinal value. Little information is available about the anthocyanin biosynthesis in P. notoginseng root. In this study, we compared the ‘Miaoxiang Sanqi No. 2’ and ‘Wenyuan Ziqi No. 1’ in morphological, transcriptional and metabolic levels. The results showed that purple rich in the periderm, rhizome and phloem around cambium of the ‘Wenyuan Ziqi No. 1’ root and cyanidin 3-O-galactoside was the main anthocyanin causing purple. Moreover, ‘Wenyuan Ziqi No. 1’ highly accumulated in 155 metabolites, including flavones, phenylpropanoids and lipids. Transcriptome data showed that phenylpropanoid biosynthesis pathway genes are highly expressed in ‘Wenyuan Ziqi No. 1’. Conjoint analysis showed that anthocyanin biosynthesis pathway substances were highly accumulated in ‘Wenyuan Ziqi No. 1’, and the expression level of structural genes involved in anthocyanin biosynthesis pathway was higher in ‘Wenyuan Ziqi No. 1’. Meanwhile, eight R2R3-MYB genes that might be involved in anthocyanin biosynthesis were identified. The comprehensive analysis of two cultivars provides new insights into the understanding of root coloration in P. notoginseng.

Elucidation of AsANS controlling pigment biosynthesis in Angelica sinensis through hormonal and transcriptomic analysis.

Angelica sinensis, a traditional Chinese medicinal plant, has been primarily reported due to its nutritional value. Pigmentation in this plant is an important appearance trait that directly affects its commercial value. To understand the mechanism controlling purpleness in A. sinensis, hormonal and transcriptomic analyses were performed in three different tissues (leave, root and stem), using two cultivars with contrasting colors. The two-dimensional data set provides dynamic hormonal and gene expression networks underpinning purpleness in A. sinensis. We found abscisic acid as a crucial hormone modulating anthocyanin biosynthesis in A. sinensis. We further identified and validated 7 key genes involved in the anthocyanin biosynthesis pathway and found a specific module containing ANS as a hub gene in WGCNA. Overexpression of a candidate pigment regulatory gene, AsANS (AS08G02092), in transgenic calli of A. sinensis resulted in increased anthocyanin production and caused purpleness. Together, these analyses provide an important understanding of the molecular networks underlying A. sinensis anthocyanin production and its correlation with plant hormones, which can provide an important source for breeding.

A first de novo transcriptome assembly of feijoa (Acca sellowiana [Berg] Burret) reveals key genes involved in flavonoid biosynthesis.

Acca sellowiana [Berg] Burret, a cultivated fruit tree originating from South America, is gaining the attention of the nutraceutical and pharmaceutical industries due to their high content of flavonoids and other phenolic compounds in fruits, leaves, and flowers. Flavonoids are a diverse group of secondary metabolites with antioxidant, anti-inflammatory, and antimicrobial properties. They also play a crucial role in plant immune response. Despite their importance, the lack of research on A. sellowiana genomics and transcriptomics hinders a deeper understanding of the molecular mechanisms behind flavonoid biosynthesis and its regulation. Here, we de novo assembled and benchmarked 11 A. sellowiana transcriptomes from leaves and floral tissues at three developmental stages using high-throughput sequencing. We selected and annotated the best assembly according to commonly used metrics and databases. This reference transcriptome consisted of 221,649 nonredundant transcripts, of which 107,612 were functionally annotated. We then used this reference transcriptome to explore the expression profiling of key secondary metabolite genes. Transcripts from genes involved in the flavonoid and anthocyanin biosynthesis pathways were identified. We also identified 4068 putative transcription factors, with the most abundant families being bHLH, C2H2, NAC, MYB, and MYB-related. Transcript expression profiling revealed distinct patterns of gene expression during flower development. Particularly, we found 71 differentially expressed transcripts representing 14 enzymes of the flavonoid pathway, suggesting major changes in flavonoid accumulation across floral stages. Our findings will contribute to understanding the genetic basis of flavonoids and provide a foundation for further research and exploitation of the economic potential of this species.

Methyl jasmonate-induced bHLH42 mediates tissue-specific accumulation of anthocyanins via regulating flavonoid metabolism-related pathways in Caitai.

Anthocyanin is a type of plant secondary metabolite beneficial to human health. The anthocyanin content of vegetable and fruit crops signifies their nutritional quality. However, the molecular mechanism of anthocyanin accumulation, especially tissue-specific accumulation, in Caitai, as well as in other Brassica rapa varieties, remains elusive. In the present study, taking advantage of three kinds of Caitai cultivars with diverse colour traits between leaves and stems, we conducted a comparative transcriptome analysis and identified the molecular pathway of anthocyanin biosynthesis in Caitai leaves and stems, respectively. Our further investigations demonstrate that bHLH42, which is robustly induced by MeJA, closely correlates with tissue-specific accumulation of anthocyanins in Caitai; bHLH42 upregulates the expression of flavonoid/anthocyanin biosynthetic pathway genes to activate anthocyanin biosynthesis pathway, importantly, overexpression of bHLH42 significantly improves the anthocyanin content of Caitai. Our analysis convincingly suggests that bHLH42 induced by jasmonic acid signalling plays a crucial role in tissue-specific accumulation of anthocyanins in Caitai.

Metabolic and molecular mechanisms of spine color formation in Chinese red chestnut.

The spines of Chinese red chestnut are red and the depth of their color gradually increases with maturity. To identify the anthocyanin types and synthesis pathways in red chestnut and to identify the key genes regulating the anthocyanin biosynthesis pathway, we obtained and analyzed the transcriptome and anthocyanin metabolism of red chestnut and its control variety with green spines at 3 different periods. GO and KEGG analyses revealed that photosynthesis was more highly enriched in green spines compared with red spines, while processes related to defense and metabolism regulation were more highly enriched in red spines. The analysis showed that the change in spine color promoted photoprotection in red chestnut, especially at the early growth stage, which resulted in the accumulation of differentially expressed genes involved in the defense metabolic pathway. The metabolome results revealed 6 anthocyanins in red spines. Moreover, red spines exhibited high levels of cyanidin, peonidin and pelargonidin and low levels of delphinidin, petunidin and malvidin. Compared with those in the control group, the levels of cyanidin, peonidin, pelargonidin and malvidin in red spines were significantly increased, indicating that the cyanidin and pelargonidin pathways were enriched in the synthesis of anthocyanins in red spines, whereas the delphinidin pathways were inhibited and mostly transformed into malvidin. During the process of flower pigment synthesis, the expression of the CHS, CHI, F3H, CYP75A, CYP75B1, DFR and ANS genes clearly increased, that of CYP73A decreased obviously, and that of PAL, 4CL and LAR both increased and decreased. Notably, the findings revealed that the synthesized anthocyanin can be converted into anthocyanidin or epicatechin. In red spines, the upregulation of BZ1 gene expression increases the corresponding anthocyanidin content, and the upregulation of the ANR gene also promotes the conversion of anthocyanin to epicatechin. The transcription factors involved in color formation included 4 WRKYs.

CRISPR/Cas editing of a <i>CPC gene in Arabidopsis thaliana</i>

BACKGROUND: Identification of target genes responsible for visible phenotypic effect may contribute to the development of transgene-free bioengineering strategies and application of crop varieties with edited genome. CAPRICE (CPC) is a single-repeat R3 MYB transcription factor, involved in anthocyanin biosynthesis and trichome formation. It is assumed that CPC controls the expression of Dihydroflavonol-4-reductase (DFR), a key gene of anthocyanin biosynthesis. AIM: The aim of the study was to determine whether knockout of the CPC gene using CRISPR/Cas9 results in visible anthocyanin accumulation. MATERIALS AND METHODS: Three guide RNAs were designed to excise a MYB domain from the CPC gene of Arabidopsis thaliana. Anthocyanin content and expression of CPC and DFR genes were studied in edited plants. RESULTS: The expected 662 bp deletion was detected in 2,7% of glufosinate-resistant plants, however none of the mutations were homozygous. Four edited lines were studied in four generations. An upregulation of the DFR gene was observed in edited lines, however CPC gene expression, anthocyanin content and trichome development were not significantly different from those in control plants. Moreover, in A. thaliana pigmentation did not directly depend on DFR or CPC gene expression. CONCLUSIONS: Our results suggest that CPC gene is involved in regulation of DFR gene expression and anthocyanin biosynthesis pathway, however in case of mutations plants might utilize other transcription factors to maintain homeostasis. Therefore, CPC gene is not a suitable target for CRISPR/Cas studies in Arabidopsis.

Identification of a candidate gene for the I locus determining the dominant white bulb color in onion (Allium cepa L.).

Through a map-based cloning approach, a gene coding for an R2R3-MYB transcription factor was identified as a causal gene for the I locus controlling the dominant white bulb color in onion. White bulb colors in onion (Allium cepa L.) are determined by either the C or I loci. The causal gene for the C locus was previously isolated, but the gene responsible for the I locus has not been identified yet. To identify candidate genes for the I locus, an approximately 7-Mb genomic DNA region harboring the I locus was obtained from onion and bunching onion (A. fistulosum) whole genome sequences using two tightly linked molecular markers. Within this interval, the AcMYB1 gene, known as a positive regulator of anthocyanin production, was identified. No polymorphic sequences were found between white and red AcMYB1 alleles in the 4,860-bp full-length genomic DNA sequences. However, a 4,838-bp LTR-retrotransposon was identified in the white allele, in the 79-bp upstream coding region from the stop codon. The insertion of this LTR-retrotransposon created a premature stop codon, resulting in the replacement of 26 amino acids with seven different residues. A molecular marker was developed based on the insertion of this LTR-retrotransposon to genotype the I locus. A perfect linkage between bulb color phenotypes and marker genotypes was observed among 5,303 individuals of segregating populations. The transcription of AcMYB1 appeared to be normal in both red and white onions, but the transcription of CHS-A, which encodes chalcone synthase and is involved in the first step of the anthocyanin biosynthesis pathway, was inactivated in the white onions. Taken together, an aberrant AcMYB1 protein produced from the mutant allele might be responsible for the dominant white bulb color in onions.

Laser capture microdissection transcriptome (LCM RNA-seq) reveals BcDFR is a key gene in anthocyanin synthesis of non-heading Chinese cabbage

BackgroundPurple non-heading Chinese cabbage [Brassica campestris (syn. Brassica rapa) ssp. chinensis] has become popular because of its richness in anthocyanin. However, anthocyanin only accumulates in the upper epidermis of leaves. Further studies are needed to investigate the molecular mechanisms underlying the specific accumulation of it.ResultsIn this study, we used the laser capture frozen section method (LCM) to divide purple (ZBC) and green (LBC) non-heading Chinese cabbage leaves into upper and lower epidermis parts (Pup represents the purple upper epidermis, Plow represents the purple lower epidermis, Gup represents the green upper epidermis, Glow represents the green lower epidermis). Through transcriptome sequencing, we found that the DIHYDROFLAVONOL 4-REDUCTASE-encoding gene BcDFR, is strongly expressed in Pup but hardly in others (Plow, Gup, Glow). Further, a deletion and insertion in the promoter of BcDFR in LBC were found, which may interfere with BcDFR expression. Subsequent analysis of gene structure and conserved structural domains showed that BcDFR is highly conserved in Brassica species. The predicted protein-protein interaction network of BcDFR suggests that it interacts with almost all functional proteins in the anthocyanin biosynthesis pathway. Finally, the results of the tobacco transient expression also demonstrated that BcDFR promotes the synthesis and accumulation of anthocyanin.ConclusionsBcDFR is specifically highly expressed on the upper epidermis of purple non-heading Chinese cabbage leaves and regulates anthocyanin biosynthesis and accumulation. Our study provides new insights into the functional analysis and transcriptional regulatory network of anthocyanin-related genes in purple non-heading Chinese cabbage.

Transcriptomic and metabolomic analyses reveal the importance of ethylene networks in mulberry fruit ripening

Mulberry (Morus alba L.) is a climacteric and highly perishable fruit. Ethylene has been considered to be an important trigger of fruit ripening process. However, the role of ethylene in the mulberry fruit ripening process remains unclear. In this study, we performed a comprehensive analysis of metabolomic and transcriptomic data of mulberry fruit and the physiological changes accompanying the fruit ripening process. Our study revealed that changes in the accumulation of specific metabolites at different stages of fruit development and ripening were closely correlated to transcriptional changes as well as underlying physiological changes and the development of taste biomolecules. The ripening of mulberry fruits was highly associated with the production of endogenous ethylene, and further application of exogenous ethylene assisted the ripening process. Transcriptomic analysis revealed that differential expression of diverse ripening-related genes was involved in sugar metabolism, anthocyanin biosynthesis, and cell wall modification pathways. Network analysis of transcriptomics and metabolomics data revealed that many transcription factors and ripening-related genes were involved, among which ethylene-responsive transcription factor 3 (MaERF3) plays a crucial role in the ripening process. The role of MaERF3 in ripening was experimentally proven in a transient overexpression assay in apples. Our study indicates that ethylene plays a vital role in modulating mulberry fruit ripening. The results provide a basis for guiding the genetic manipulation of mulberry fruits towards sustainable agricultural practices and improve post-harvest management, potentially enhancing the quality and shelf life of mulberry fruits for sustainable agriculture and forestry.

Genome-Wide Identification and Expression Analysis of Fifteen Gene Families Involved in Anthocyanin Synthesis in Pear

Anthocyanins play a crucial role in imparting red coloration to pear fruits. However, the specific number and expression patterns of each member within the anthocyanin biosynthesis-related gene families in pears require systematic exploration. In this study, based on the pear genome we identified 15 gene families involved in the anthocyanin biosynthesis pathway using the BLASTP and Hidden Markov Model search methods, comprising a total of 94 enzyme genes. Through phylogenetic analysis, conserved domains, motif, and gene structure analysis, these gene families were further categorized into eight distinct lineages. Subsequent collinearity analysis revealed that the expansion of anthocyanin synthesis-related gene families primarily originated from segmental duplications. Analysis of cis-element in the promoter regions of genes related to anthocyanin synthesis unveiled the presence of light-responsive elements and various hormone-responsive elements. This suggests that changes in light stimulation and hormone levels may influence anthocyanin synthesis. RNA-Seq and qRT-PCR analyses indicated differential expression of anthocyanin biosynthesis-related genes between the peel and flesh tissues. During the accumulation of anthocyanins in red-fleshed pears, upstream genes in the anthocyanin biosynthesis pathway such as PbrPAL2, PbrC4H2, PbrC4H3, Pbr4CL2, Pbr4CL17, PbrF3H5, and PbrF3H6 exhibited high expression levels, likely contributing significantly to the red coloration of pear flesh. In summary, we have identified the number of gene family members involved in pear anthocyanin biosynthesis and analyzed the expression patterns of the genes related to pear anthocyanin biosynthesis. These findings provide a solid foundation for further research on the regulatory mechanisms underlying pear anthocyanin biosynthesis and the breeding of red pear varieties.

Integrated transcriptomic and metabolomic analyses reveals anthocyanin biosynthesis in leaf coloration of quinoa (Chenopodium quinoa Willd.)

BackgroundQuinoa leaves demonstrate a diverse array of colors, offering a potential enhancement to landscape aesthetics and the development of leisure-oriented sightseeing agriculture in semi-arid regions. This study utilized integrated transcriptomic and metabolomic analyses to investigate the mechanisms underlying anthocyanin synthesis in both emerald green and pink quinoa leaves.ResultsIntegrated transcriptomic and metabolomic analyses indicated that both flavonoid biosynthesis pathway (ko00941) and anthocyanin biosynthesis pathway (ko00942) were significantly associated with anthocyanin biosynthesis. Differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) were analyzed between the two germplasms during different developmental periods. Ten DEGs were verified using qRT-PCR, and the results were consistent with those of the transcriptomic sequencing. The elevated expression of phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), 4-coumarate CoA ligase (4CL) and Hydroxycinnamoyltransferase (HCT), as well as the reduced expression of flavanone 3-hydroxylase (F3H) and Flavonol synthase (FLS), likely cause pink leaf formation. In addition, bHLH14, WRKY46, and TGA indirectly affected the activities of CHS and 4CL, collectively regulating the levels of cyanidin 3-O-(3’’, 6’’-O-dimalonyl) glucoside and naringenin. The diminished expression of PAL, 4CL, and HCT decreased the formation of cyanidin-3-O-(6”-O-malonyl-2”-O-glucuronyl) glucoside, leading to the emergence of emerald green leaves. Moreover, the lowered expression of TGA and WRKY46 indirectly regulated 4CL activity, serving as another important factor in maintaining the emerald green hue in leaves N1, N2, and N3.ConclusionThese findings establish a foundation for elucidating the molecular regulatory mechanisms governing anthocyanin biosynthesis in quinoa leaves, and also provide some theoretical basis for the development of leisure and sightseeing agriculture.

Melatonin foliar application promoted anthocyanin accumulation boosted reactive oxygen scavenging by upregulating the key enzymes activities and genes expression of anthocyanin biosynthesis pathway in green and purple mustard under vanadium stress

Heavy metal vanadium (V) is poisonous to both plants and animals. Plant resistance to heavy metals stress can be conferred by the multifunctional signaling molecule melatonin, although the underlying mechanisms are still largely understood. We elucidated the significant contribution of the secondary metabolite anthocyanin to the enhancement of V stress tolerance by melatonin in both green and purple mustard genotypes. The effects of excessive V were leaf yellowing, slowed development, decreased photosynthetic activity, and an increase in the buildup of reactive oxygen species and malondialdehyde in both mustard genotypes. It interesting to note that during V stress, key anthocyanin biosynthetic pathway enzymes activities and leaf anthocyanin concentration increased while exogenous melatonin applied as foliar further boosted activities of key anthocyanin biosynthetic pathway enzymes and leaf anthocyanin concentration in both green and purple mustards. Furthermore, the application of exogenous melatonin increased the levels of endogenous melatonin and mitigated V toxicity. Conversely, the suppression of melatonin intensified V-induced phytotoxicity and delayed the accumulation of anthocyanin by downregulating the transcript levels of essential structural genes. Under V stress conditions, the genes expression related to anthocyanin production, antioxidant enzymes activities, and stress resistance was significantly higher in purple mustard than green mustard genotype. Additionally, melatonin decreased V deposition in roots and leaves. The results recommended that melatonin foliar application to mustard plants inhibited the availability of V to plant and promote V stress tolerance.

Chromosome-level genome assemblies of Musa ornata and Musa velutina provide insights into pericarp dehiscence and anthocyanin biosynthesis in banana.

Musa ornata and Musa velutina are members of the Musaceae family and are indigenous to the South and Southeast Asia. They are very popular in the horticultural market, but the lack of genomic sequencing data and genetic studies has hampered efforts to improve their ornamental value. In this study, we generated the first chromosome-level genome assemblies for both species by utilizing Oxford Nanopore long reads and Hi-C reads. The genomes of M. ornata and M. velutina were assembled into 11 pseudochromosomes with genome sizes of 427.85Mb and 478.10Mb, respectively. Repetitive sequences comprised 46.70% and 50.91% of the total genomes for M. ornata and M. velutina, respectively. Differentially expressed gene (DEG) and Gene Ontology (GO) enrichment analyses indicated that upregulated genes in the mature pericarps of M. velutina were mainly associated with the saccharide metabolic processes, particularly at the cell wall and extracellular region. Furthermore, we identified polygalacturonase (PG) genes that exhibited higher expression level in mature pericarps of M. velutina compared to other tissues, potentially being accountable for pericarp dehiscence. This study also identified genes associated with anthocyanin biosynthesis pathway. Taken together, the chromosomal-level genome assemblies of M. ornata and M. velutina provide valuable insights into the mechanism of pericarp dehiscence and anthocyanin biosynthesis in banana, which will significantly contribute to future genetic and molecular breeding efforts.

Roles of CcDFR and CcOMT9 in the cyanidin biosynthesis and development of Cordyceps cicadae.

Cordyceps cicadae is a traditional Chinese medicinal fungus known for its rich production of bioactive substances, particularly cyanidin, an anthocyanin commonly found in plants with notable anti-inflammatory, anti-tumor, antiviral, and antibacterial properties. This study revealed two key genes, CcDFR and CcOMT9, affecting cyanidin biosynthesis in C. cicadae. The roles of these genes in cyanidin production, growth, and development were elucidated through the gene knockout method, phenotypic analysis, transcriptomics, and metabolomics. CcDFR deletion led to reduced cyanidin-3-O-glucoside (C3G), suppressed expression of cyanidin biosynthesis genes, impaired synnemata formation, decreased polysaccharide and adenosine content, and diminished chitinase activity. Meanwhile, the ΔCcOMT9 mutant exhibited an increase in C3G production, promoted expression of cyanidin biosynthesis genes and rising bioactive compounds, suppressed RNA methylation, and led to phenylalanine accumulation with no effect on fruiting body formation. We revealed a distinct anthocyanin biosynthesis pathway in C. cicadae and identified two genes with opposite functions, laying the foundation for future genetic modification of cyanidin-producing strains using modern biological techniques. This will shorten the production period of this valuable compound, facilitating the industrial-scale production of cyanidin.

Molecular mechanisms of regulation of anthocyanine biosynthesis, photosynthesis, and frost resistance of winter wheat seedlings treated with the 5-aminolevulic acid

It was found that in anthocyanin-enriched coleoptiles of winter wheat EtW5 variety, the exogenous 5-aminolevulinic acid (ALA) increased the content of anthocyanins by a factor of 1.5 and the expression level of structural (PAL, CHS) and regulatory (PAP-1) genes of the anthocyanin biosynthesis pathway. In coleoptiles of Vladi plants containing 33 times less anthocyanins compared to EtW5, the expression of CHS and PAP-1 was reduced and additionally inhibited by ALA. Thus, the genetic activity of the phenylpropanoid and flavonoid sites of the anthocyanin biosynthesis pathway shows distinct variety specificity and a dependence on the level of anthocyanins. ALA significantly reduced the thermal dissipation of excitation energy in PSII complexes in the EtW5 variety enriched with anthocyanins and significantly increased the level of these processes in the Vladi variety. Variety-specificity was noted in the levels of frost resistance of two varieties – high (88 % of surviving plants exposed to a temperature of –8 °С for 5 hours) in the EtW5 variety and lower (80 %) in the Vladi variety. ALA increased the frost resistance of both varieties due to an increase in the content of anthocyanins and proline in the coleoptiles of the EtW5 variety and a higher proline content in the Vladi variety.

Transcriptomics and metabolomics reveal the underlying mechanism of drought treatment on anthocyanin accumulation in postharvest blood orange fruit

BackgroundAnthocyanins are the most important compounds for nutritional quality and economic values of blood orange. However, there are few reports on the pre-harvest treatment accelerating the accumulation of anthocyanins in postharvest blood orange fruit. Here, we performed a comparative transcriptome and metabolomics analysis to elucidate the underlying mechanism involved in seasonal drought (SD) treatment during the fruit expansion stage on anthocyanin accumulation in postharvest ‘Tarocco’ blood orange fruit.ResultsOur results showed that SD treatment slowed down the fruit enlargement and increased the sugar accumulation during the fruit development and maturation period. Obviously, under SD treatment, the accumulation of anthocyanin in blood orange fruit during postharvest storage was significantly accelerated and markedly higher than that in CK. Meanwhile, the total flavonoids and phenols content and antioxidant activity in SD treatment fruits were also sensibly increased during postharvest storage. Based on metabolome analysis, we found that substrates required for anthocyanin biosynthesis, such as amino acids and their derivatives, and phenolic acids, had significantly accumulated and were higher in SD treated mature fruits compared with that of CK. Furthermore, according to the results of the transcriptome data and weighted gene coexpression correlation network analysis (WGCNA) analysis, phenylalanine ammonia-lyase (PAL3) was considered a key structural gene. The qRT-PCR analysis verified that the PAL3 was highly expressed in SD treated postharvest stored fruits, and was significantly positively correlated with the anthocyanin content. Moreover, we found that other structural genes in the anthocyanin biosynthesis pathway were also upregulated under SD treatment, as evidenced by transcriptome data and qRT-PCR analysis.ConclusionsThe findings suggest that SD treatment promotes the accumulation of substrates necessary for anthocyanin biosynthesis during the fruit ripening process, and activates the expression of anthocyanin biosynthesis pathway genes during the postharvest storage period. This is especially true for PAL3, which co-contributed to the rapid accumulation of anthocyanin. The present study provides a theoretical basis for the postharvest quality control and water-saving utilization of blood orange fruit.