The Transcription Factor MiMYB8 Suppresses Peel Coloration in Postharvest 'Guifei' Mango in Response to High Concentration of Exogenous Ethylene by Negatively Modulating MiPAL1.

Anthocyanin accumulation is regulated by specific genes during fruit ripening. Currently, peel coloration of mango fruit in response to exogenous ethylene and the underlying molecular mechanism remain largely unknown. The role of MiMYB8 on suppressing peel coloration in postharvest 'Guifei' mango was investigated by physiology detection, RNA-seq, qRT-PCR, bioinformatics analysis, yeast one-hybrid, dual-luciferase reporter assay, and transient overexpression. Results showed that compared with the control, low concentration of exogenous ethylene (ETH, 500 mg·L-1) significantly promoted peel coloration of mango fruit (cv. Guifei). However, a higher concentration of ETH (1000 mg·L-1) suppressed color transformation, which is associated with higher chlorophyll content, lower a* value, anthocyanin content, and phenylalanine ammonia-lyase (PAL) activity of mango fruit. M. indica myeloblastosis8 MiMYB8 and MiPAL1 were differentially expressed during storage. MiMYB8 was highly similar to those found in other plant species related to anthocyanin biosynthesis and was located in the nucleus. MiMYB8 suppressed the transcription of MiPAL1 by binding directly to its promoter. Transient overexpression of MiMYB8 in tobacco leaves and mango fruit inhibited anthocyanin accumulation by decreasing PAL activity and down-regulating the gene expression. Our observations suggest that MiMYB8 may act as repressor of anthocyanin synthesis by negatively modulating the MiPAL gene during ripening of mango fruit, which provides us with a theoretical basis for the scientific use of exogenous ethylene in practice.

Effect of Light Conditions, Trichoderma Fungi and Food Polymers on Growth and Profile of Biologically Active Compounds in Thymus vulgaris and Thymus serpyllum.

The research investigates the influence of different lighting conditions and soil treatments, in particular the application of food polymers separately and in combination with spores of Trichoderma consortium, on the growth and development of herbs-Thymus vulgaris and Thymus serpyllum. The metabolic analysis focuses on detecting changes in the levels of biologically active compounds such as chlorophyll a and b, anthocyanins, carotenoids, phenolic compounds (including flavonoids), terpenoids, and volatile organic compounds with potential health-promoting properties. By investigating these factors, the study aims to provide insights into how environmental conditions affect the growth and chemical composition of selected plants and to shed light on potential strategies for optimising the cultivation of these herbs for the improved quality and production of bioactive compounds. Under the influence of additional lighting, the growth of T. vulgaris and T. serpyllum seedlings was greatly accelerated, resulting in an increase in shoot biomass and length, and in the case of T. vulgaris, an increase in carotenoid and anthocyanin contents. Regarding secondary metabolites, the most pronounced changes were observed in total antioxidant capacity and flavonoid content, which increased significantly under the influence of additional lighting. The simultaneous or separate application of Trichoderma and food polymers resulted in an increase in flavonoid content in the leaves of both Thymus species. The increase in terpenoid content under supplemental light appears to be related to the presence of Trichoderma spores as well as food polymers added to the soil. However, the nature of these changes depends on the thyme species. Volatile compounds were analysed using an electronic nose (E-nose). Eight volatile compounds (VOCs) were tentatively identified in the vapours of T. vulgaris and T. serpyllum: α-pinene, myrcene, α-terpinene, γ-terpinene; 1,8-cineole (eucalyptol), thymol, carvacrol, and eugenol. Tendencies to increase the percentage of thymol and γ-terpinene under supplemental lighting were observed. The results also demonstrate a positive effect of food polymers and, to a lesser extent, Trichoderma fungi on the synthesis of VOCs with health-promoting properties. The effect of Trichoderma and food polymers on individual VOCs was positive in some cases for thymol and γ-terpinene.

Integrative analysis of transcriptome and target metabolites uncovering flavonoid biosynthesis regulation of changing petal colors in Nymphaea 'Feitian 2'.

BACKGROUND: Nymphaea (waterlily) is known for its rich colors and role as an important aquatic ornamental plant globally. Nymphaea atrans and some hybrids, including N. 'Feitian 2,' are more appealing due to the gradual color change of their petals at different flower developmental stages. The petals of N. 'Feitian 2' gradually change color from light blue-purple to deep rose-red throughout flowering. The mechanism of the phenomenon remains unclear. RESULTS: In this work, flavonoids in the petals of N. 'Feitian 2' at six flowering stages were examined to identify the influence of flavonoid components on flower color changes. Additionally, six cDNA libraries of N. 'Feitian 2' over two blooming stages were developed, and the transcriptome was sequenced to identify the molecular mechanism governing petal color changes. As a result, 18 flavonoid metabolites were identified, including five anthocyanins and 13 flavonols. Anthocyanin accumulation during flower development is the primary driver of petal color change. A total of 12 differentially expressed genes (DEGs) in the flavonoid biosynthesis pathway were uncovered, and these DEGs were significantly positively correlated with anthocyanin accumulation. Six structural genes were ultimately focused on, as their expression levels varied significantly across different flowering stages. Moreover, 104 differentially expressed transcription factors (TFs) were uncovered, and three MYBs associated with flavonoid biosynthesis were screened. The RT-qPCR results were generally aligned with high-throughput sequencing results. CONCLUSIONS: This research offers a foundation to clarify the mechanisms underlying changes in the petal color of waterlilies.

Comparative transcriptomic and metabolomic profiles reveal fruit peel color variation in two red pomegranate cultivars.

Pomegranate (Punica granatum L.) which belongs to family Lythraceae, is one of the most important fruit crops of many tropical and subtropical regions. A high variability in fruit color is observed among different pomegranate accessions, which arises from the qualitative and quantitative differences in anthocyanins. However, the mechanism of fruit color variation is still not fully elucidated. In the present study, we investigated the red color mutation between a red-skinned pomegranate 'Hongbaoshi' and a purple-red-skinned cultivar 'Moshiliu', by using transcriptomic and metabolomic approaches. A total of 51 anthocyanins were identified from fruit peels, among which 3-glucoside and 3,5-diglucoside of cyanidin (Cy), delphinidin (Dp), and pelargonidin (Pg) were dominant. High proportion of Pg in early stages of 'Hongbaoshi' but high Dp in late stages of 'Moshiliu' were characterized. The unique high levels of Cy and Dp anthocyanins accumulating from early developmental stages accounted for the purple-red phenotype of 'Moshiliu'. Transcriptomic analysis revealed an early down-regulated and late up-regulated of anthocyanin-related structure genes in 'Moshiliu' compared with 'Hongbaoshi'. Alao, ANR was specially expressed in 'Hongbaoshi', with extremely low expression levels in 'Moshiliu'. For transcription factors R2R3-MYB, the profiles demonstrated a much higher transcription levels of three subgroup (SG) 5 MYBs and a sharp decrease in expression of SG6 MYB LOC116202527 in high-anthocyanin 'Moshiliu'. SG4 MYBs exhibited two entirely different patterns, LOC116203744 and LOC116212505 were down-regulated whereas LOC116205515 and LOC116212778 were up-regulated in 'Moshiliu' pomegranate. The results indicate that specific SG members of the MYB family might promote the peel coloration in different manners and play important roles in color mutation in pomegranate.

Promoter replication of grape MYB transcription factor is associated with a new red flesh phenotype.

KEY MESSAGE: In our study, we discovered a fragment duplication autoregulation mechanism in 'ZS-HY', which may be the reason for the phenotype of red foliage and red flesh in grapes. In grapes, MYBA1 and MYBA2 are the main genetic factors responsible for skin coloration which are located at the color loci on chromosome 2, but the exact genes responsible for color have not been identified in the flesh. We used a new teinturier grape germplasm 'ZhongShan-HongYu' (ZS-HY) which accumulate anthocyanin both in skin and flesh as experimental materials. All tissues of 'ZS-HY' contained cyanidin 3-O-(6″-p-coumaroyl glucoside), and pelargonidins were detected in skin, flesh, and tendril. Through gene expression analysis at different stage of flesh, significant differences in the expression levels of VvMYBA1 were found. Gene amplification analysis showed that the VvMYBA1 promoter is composed of two alleles, VvMYBA1a and 'VvMYBA1c-like'. An insertion of a 408 bp repetitive fragment was detected in the allele 'VvMYBA1c-like'. In this process, we found the 408 bp repetitive fragment was co-segregated with red flesh and foliage phenotype. Our results revealed that the 408 bp fragment replication insertion in promoter of 'VvMYBA1c-like' was the target of its protein, and the number of repeat fragments was related to the increase of trans-activation of VvMYBA1 protein. The activation of promoter by VvMYBA1 was enhanced by the addition of VvMYC1. In addition, VvMYBA1 interacted with VvMYC1 to promote the expression of VvGT1 and VvGST4 genes in 'ZS-HY'. The discovery of this mutation event provides new insights into the regulation of VvMYBA1 on anthocyanin accumulation in red-fleshed grape, which is of great significance for molecular breeding of red-fleshed table grapes.

Do red and yellow autumn leaves make use of different photoprotective strategies during autumn senescence?

Our goal was to determine whether anthocyanin-producing species (red) use different photoprotective strategies to cope with excess light during fall senescence compared with non-anthocyanin-producing species (yellow). In a previous study, we found that a yellow species retained the photoprotective PsbS protein in late autumn, while a red species did not. Specifically, we tested the hypothesis that red species make less use of zeaxanthin and PsbS-mediated thermal dissipation, as they rely on anthocyanins for photoprotection. We monitored four red (Acer ginnala, Rhus typhnia, Parenthocissus quinquefolia, Viburnum dentatum) and four yellow species (Acer negundo, Ostrya virginiana, Vitis riparia, Zanthoxylum americanum) throughout autumn senescence and analyzed pigments, protein content, and chlorophyll fluorescence. We found yellow species retained the PsbS protein at higher levels, and had higher dark retention of zeaxanthin in late autumn relative to red species. All species retained lutein and the pool of xanthophyll cycle pigments in higher amounts than other carotenoids in late autumn. Our data support the hypothesis that red species use anthocyanins as a photoprotective strategy during autumn senescence, and therefore make less use of PsbS and zeaxanthin-mediated thermal dissipation. We also found species-specific variation in the particular combination of photoprotective strategies used.

A Fruit-Expressed MYB Transcription Factor Regulates Anthocyanin Biosynthesis in Atropa belladonna.

Anthocyanins are water-soluble flavonoid pigments that play a crucial role in plant growth and metabolism. They serve as attractants for animals by providing plants with red, blue, and purple pigments, facilitating pollination and seed dispersal. The fruits of solanaceous plants, tomato (Solanum lycopersicum) and eggplant (Solanum melongena), primarily accumulate anthocyanins in the fruit peels, while the ripe fruits of Atropa belladonna (Ab) have a dark purple flesh due to anthocyanin accumulation. In this study, an R2R3-MYB transcription factor (TF), AbMYB1, was identified through association analysis of gene expression and anthocyanin accumulation in different tissues of A. belladonna. Its role in regulating anthocyanin biosynthesis was investigated through gene overexpression and RNA interference (RNAi). Overexpression of AbMYB1 significantly enhanced the expression of anthocyanin biosynthesis genes, such as AbF3H, AbF3'5'H, AbDFR, AbANS, and Ab3GT, leading to increased anthocyanin production. Conversely, RNAi-mediated suppression of AbMYB1 resulted in decreased expression of most anthocyanin biosynthesis genes, as well as reduced anthocyanin contents in A. belladonna. Overall, AbMYB1 was identified as a fruit-expressed R2R3-MYB TF that positively regulated anthocyanin biosynthesis in A. belladonna. This study provides valuable insights into the regulation of anthocyanin biosynthesis in Solanaceae plants, laying the foundation for understanding anthocyanin accumulation especially in the whole fruits of solanaceous plants.

Genome-Wide Identification of Glutathione S-Transferase Genes in Eggplant (Solanum melongena L.) Reveals Their Potential Role in Anthocyanin Accumulation on the Fruit Peel.

Anthocyanins are ubiquitous pigments derived from the phenylpropanoid compound conferring red, purple and blue pigmentations to various organs of horticultural crops. The metabolism of flavonoids in the cytoplasm leads to the biosynthesis of anthocyanin, which is then conveyed to the vacuoles for storage by plant glutathione S-transferases (GST). Although GST is important for transporting anthocyanin in plants, its identification and characterization in eggplant (Solanum melongena L.) remains obscure. In this study, a total of 40 GST genes were obtained in the eggplant genome and classified into seven distinct chief groups based on the evolutionary relationship with Arabidopsis thaliana GST genes. The seven subgroups of eggplant GST genes (SmGST) comprise: dehydroascorbate reductase (DHAR), elongation factor 1Bγ (EF1Bγ), Zeta (Z), Theta(T), Phi(F), Tau(U) and tetra-chlorohydroquinone dehalogenase TCHQD. The 40 GST genes were unevenly distributed throughout the 10 eggplant chromosomes and were predominantly located in the cytoplasm. Structural gene analysis showed similarity in exons and introns within a GST subgroup. Six pairs of both tandem and segmental duplications have been identified, making them the primary factors contributing to the evolution of the SmGST. Light-related cis-regulatory elements were dominant, followed by stress-related and hormone-responsive elements. The syntenic analysis of orthologous genes indicated that eggplant, Arabidopsis and tomato (Solanum lycopersicum L.) counterpart genes seemed to be derived from a common ancestry. RNA-seq data analyses showed high expression of 13 SmGST genes with SmGSTF1 being glaringly upregulated on the peel of purple eggplant but showed no or low expression on eggplant varieties with green or white peel. Subsequently, SmGSTF1 had a strong positive correlation with anthocyanin content and with anthocyanin structural genes like SmUFGT (r = 0.9), SmANS (r = 0.85), SmF3H (r = 0.82) and SmCHI2 (r = 0.7). The suppression of SmGSTF1 through virus-induced gene silencing (VIGs) resulted in a decrease in anthocyanin on the infiltrated fruit surface. In a nutshell, results from this study established that SmGSTF1 has the potential of anthocyanin accumulation in eggplant peel and offers viable candidate genes for the improvement of purple eggplant. The comprehensive studies of the SmGST family genes provide the foundation for deciphering molecular investigations into the functional analysis of SmGST genes in eggplant.

Molecular mechanism of abscisic acid signaling response factor VcbZIP55 to promote anthocyanin biosynthesis in blueberry (Vaccinium corymbosum).

A high content of anthocyanin in blueberry (Vaccinium corymbosum) is an important indicator to evaluate fruit quality. Abscisic acid (ABA) can promote anthocyanin biosynthesis, but since the molecular mechanism is unclear, clarifying the mechanism will improve for blueberry breeding and cultivation regulation. VcbZIP55 regulating anthocyanin synthesis in blueberry were screened and mined using the published Isoform-sequencing, RNA-Seq and qRT-PCR at different fruit developmental stages. Blueberry genetic transformation and transgenic experiments confirmed that VcbZIP55 could promote anthocyanin biosynthesis in blueberry adventitious buds, tobacco leaves, blueberry leaves and blueberry fruit. VcbZIP55 responded to ABA signals and its expression was upregulated in blueberry fruit. In addition, using VcbZIP55 for Yeast one hybrid assay (Y1H) and transient expression in tobacco leaves demonstrated an interaction between VcbZIP55 and a G-Box motif on the VcMYB1 promoter to activate the expression of VcMYB1. This study will lay the theoretical foundation for the molecular mechanisms of phytohormone regulation responsible for anthocyanin synthesis and provide theoretical support for blueberry quality improvement.

Identification of Hsp20 gene family in Malus domestica and functional characterization of Hsp20 class I gene MdHsp18.2b.

Heat shock protein 20 (Hsp20) is a small molecule heat shock protein that plays an important role in plant growth, development, and stress resistance. Little is known about the function of Hsp20 family genes in apple (Malus domestica). Here, we performed a genome-wide analysis of the apple Hsp20 gene family, and a total of 49 Hsp20s genes were identified from the apple genome. Phylogenetic analysis revealed that the 49 genes were divided into 11 subfamilies, and MdHsp18.2b, a member located in the CI branch, was selected as a representative member for functional characterization. Treatment with NaCl and Botryosphaeria dothidea (B. dothidea), the causal agent of apple ring rot disease, significantly induced MdHsp18.2b transcription level. Further analysis revealed that overexpressing MdHsp18.2b reduced the resistance to salt stress but enhanced the resistance to B. dothidea infection in apple calli. Moreover, MdHsp18.2b positively regulated anthocyanin accumulation in apple calli. Physiology assays revealed that MdHsp18.2b promoted H2O2 production, even in the absence of stress factors, which might contribute to its functions in response to NaCl and B. dothidea infection. Hsps usually function as homo- or heterooligomers, and we found that MdHsp18.2b could form a heterodimer with MdHsp17.9a and MdHsp17.5, two members from the same branch with MdHsp18.2b in the phylogenetic tree. Therefore, we identified 49 Hsp20s genes from the apple genome and found that MdHsp18.2b was involved in regulating plant resistance to salt stress and B. dothidea infection, as well as in regulating anthocyanin accumulation in apple calli.

Effects of appropriate low-temperature treatment on the yield and quality of pigmented potato (Solanum tuberosum L.) tubers.

Temperature is one of the important environmental factors affecting plant growth, yield and quality. Moreover, appropriately low temperature is also beneficial for tuber coloration. The red potato variety Jianchuanhong, whose tuber color is susceptible to temperature, and the purple potato variety Huaxinyangyu, whose tuber color is stable, were used as experimental materials and subjected to 20 °C (control check), 15 °C and 10 °C treatments during the whole growth period. The effects of temperature treatment on the phenotype, the expression levels of structural genes related to anthocyanins and the correlations of each indicator were analyzed. The results showed that treatment at 10 °C significantly inhibited the potato plant height, and the chlorophyll content and photosynthetic parameters in the leaves were reduced, and the enzyme activities of SOD and POD were significantly increased, all indicating that the leaves were damaged. Treatment at 10 °C also affected the tuberization of Huaxinyangyu and reduced the tuberization and coloring of Jianchuanhong, while treatment at 15 °C significantly increased the stem diameter, root-to-shoot ratio, yield and content of secondary metabolites, especially anthocyanins. Similarly, the expression of structural genes were enhanced in two pigmented potatoes under low-temperature treatment conditions. In short, proper low temperature can not only increase yield but also enhance secondary metabolites production. Previous studies have not focused on the effects of appropriate low-temperature treatment during the whole growth period of potato on the changes in metabolites during tuber growth and development, these results can provide a theoretical basis and technical guidance for the selection of pigmented potatoes with better nutritional quality planting environment and the formulation of cultivation measures.

Integrated metabolome and transcriptome analyses reveal the role of BoGSTF12 in anthocyanin accumulation in Chinese kale (Brassica oleracea var. alboglabra).

BACKGROUND: The vivid red, purple, and blue hues that are observed in a variety of plant fruits, flowers, and leaves are produced by anthocyanins, which are naturally occurring pigments produced by a series of biochemical processes occurring inside the plant cells. The purple-stalked Chinese kale, a popular vegetable that contains anthocyanins, has many health benefits but needs to be investigated further to identify the genes involved in the anthocyanin biosynthesis and translocation in this vegetable. RESULTS: In this study, the purple- and green-stalked Chinese kale were examined using integrative transcriptome and metabolome analyses. The content of anthocyanins such as cyanidin-3-O-(6″-O-feruloyl) sophoroside-5-O-glucoside, cyanidin-3,5-O-diglucoside (cyanin), and cyanidin-3-O-(6″-O-p-hydroxybenzoyl) sophoroside-5-O-glucoside were considerably higher in purple-stalked Chinese kale than in its green-stalked relative. RNA-seq analysis indicated that 23 important anthocyanin biosynthesis genes, including 3 PAL, 2 C4H, 3 4CL, 3 CHS, 1 CHI, 1 F3H, 2 FLS, 2 F3'H, 1 DFR, 3 ANS, and 2 UFGT, along with the transcription factor BoMYB114, were significantly differentially expressed between the purple- and green-stalked varieties. Results of analyzing the expression levels of 11 genes involved in anthocyanin production using qRT-PCR further supported our findings. Association analysis between genes and metabolites revealed a strong correlation between BoGSTF12 and anthocyanin. We overexpressed BoGSTF12 in Arabidopsis thaliana tt19, an anthocyanin transport mutant, and this rescued the anthocyanin-loss phenotype in the stem and rosette leaves, indicating BoGSTF12 encodes an anthocyanin transporter that affects the accumulation of anthocyanins. CONCLUSION: This work represents a key step forward in our understanding of the molecular processes underlying anthocyanin production in Chinese kale. Our comprehensive metabolomic and transcriptome analyses provide important insights into the regulatory system that controls anthocyanin production and transport, while providing a foundation for further research to elucidate the physiological importance of the metabolites found in this nutritionally significant vegetable.

An R2R3-MYB Transcriptional Factor LuMYB314 Associated with the Loss of Petal Pigmentation in Flax (Linum usitatissimum L.).

The loss of anthocyanin pigments is one of the most common evolutionary transitions in petal color, yet the genetic basis for these changes in flax remains largely unknown. In this study, we used crossing studies, a bulk segregant analysis, genome-wide association studies, a phylogenetic analysis, and transgenic testing to identify genes responsible for the transition from blue to white petals in flax. This study found no correspondence between the petal color and seed color, refuting the conclusion that a locus controlling the seed coat color is associated with the petal color, as reported in previous studies. The locus controlling the petal color was mapped using a BSA-seq analysis based on the F2 population. However, no significantly associated genomic regions were detected. Our genome-wide association study identified a highly significant QTL (BP4.1) on chromosome 4 associated with flax petal color in the natural population. The combination of a local Manhattan plot and an LD heat map identified LuMYB314, an R2R3-MYB transcription factor, as a potential gene responsible for the natural variations in petal color in flax. The overexpression of LuMYB314 in both Arabidopsis thaliana and Nicotiana tabacum resulted in anthocyanin deposition, indicating that LuMYB314 is a credible candidate gene for controlling the petal color in flax. Additionally, our study highlights the limitations of the BSA-seq method in low-linkage genomic regions, while also demonstrating the powerful detection capabilities of GWAS based on high-density genomic variation mapping. This study enhances our genetic insight into petal color variations and has potential breeding value for engineering LuMYB314 to develop colored petals, bast fibers, and seeds for multifunctional use in flax.

Metabolomics reveals the importance of metabolites in Mussaenda pubescens for antioxidant properties and quality traits.

Mussaenda pubescens (Mp) is a valuable medicinal plant that has traditionally been used for medicinal purposes or as a tea substitute. However, there are few studies on the comprehensive and dynamic evaluation of Mp metabolites. This study used an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) approach and biochemical analysis to investigate substance changes in leaves at three different stages and elucidate the relationship between metabolites and antioxidant capacity. The findings showed that Mp leaves contained 957 metabolites, the majority of which were phenolic acids, lipids, and terpenoids. The metabolite profiling of Mp leaves was significantly influenced by their growth and development at different stages. A total of 317 differentially accumulated metabolites (DAMs) were screened, including 150 primary metabolites and 167 secondary metabolites, with 202 DAMs found in bud leaf vs. tender leaf, 54 DAMs in tender leaf vs. mature leaf, and 254 DAMs in bud leaf vs. mature leaf. Total phenolics, flavonoids, and anthocyanin concentrations decreased as Mp leaves grew and developed, whereas terpenoids increased significantly. The secondary metabolites also demonstrated a positive correlation with antioxidant activity. Phenolics, flavonoids, terpenoids, and anthocyanins were the primary factors influencing the antioxidant activity of leaves. These findings provide new insights into the metabolite formation mechanism, as well as the development and utilization of Mp tea.

Chalcone-Synthase-Encoding RdCHS1 Is Involved in Flavonoid Biosynthesis in Rhododendron delavayi.

Flower color is an important ornamental feature that is often modulated by the contents of flavonoids. Chalcone synthase is the first key enzyme in the biosynthesis of flavonoids, but little is known about the role of R. delavayi CHS in flavonoid biosynthesis. In this paper, three CHS genes (RdCHS1-3) were successfully cloned from R. delavayi flowers. According to multiple sequence alignment and a phylogenetic analysis, only RdCHS1 contained all the highly conserved and important residues, which was classified into the cluster of bona fide CHSs. RdCHS1 was then subjected to further functional analysis. Real-time PCR analysis revealed that the transcripts of RdCHS1 were the highest in the leaves and lowest in the roots; this did not match the anthocyanin accumulation patterns during flower development. Biochemical characterization displayed that RdCHS1 could catalyze p-coumaroyl-CoA and malonyl-CoA molecules to produce naringenin chalcone. The physiological function of RdCHS1 was checked in Arabidopsis mutants and tobacco, and the results showed that RdCHS1 transgenes could recover the color phenotypes of the tt4 mutant and caused the tobacco flower color to change from pink to dark pink through modulating the expressions of endogenous structural and regulatory genes in the tobacco. All these results demonstrate that RdCHS1 fulfills the function of a bona fide CHS and contributes to flavonoid biosynthesis in R. delavayi.

Vineyard microclimate alterations induced by black inter-row mulch through transcriptome reshaped the flavoromics of cabernet sauvignon grapes.

BACKGROUND: Weed control is essential for agricultural floor management in vineyards and the inter-row mulching is an eco-friendly practice to inhibit weed growth via filtering out photosynthetically active radiation. Besides weed suppression, inter-row mulching can influence grapevine growth and the accumulation of metabolites in grape berries. However, the complex interaction of multiple factors in the field challenges the understanding of molecular mechanisms on the regulated metabolites. In the current study, black geotextile inter-row mulch (M) was applied for two vintages (2016-2017) from anthesis to harvest. Metabolomics and transcriptomics analysis were conducted in two vintages, aiming to provide insights into metabolic and molecular responses of Cabernet Sauvignon grapes to M in a semi-arid climate. RESULTS: Upregulation of genes related to photosynthesis and heat shock proteins confirmed that M weakened the total light exposure and grapes suffered heat stress, resulting in lower sugar-acid ratio at harvest. Key genes responsible for enhancements in phenylalanine, glutamine, ornithine, arginine, and C6 alcohol concentrations, and the downward trend in ε-viniferin, anthocyanins, flavonols, terpenes, and norisoprenoids in M grapes were identified. In addition, several modules significantly correlated with the metabolic biomarkers through weighted correlation network analysis, and the potential key transcription factors regulating the above metabolites including VviGATA11, VviHSFA6B, and VviWRKY03 were also identified. CONCLUSION: This study provides a valuable overview of metabolic and transcriptomic responses of M grapes in semi-arid climates, which could facilitate understanding the complex regulatory network of metabolites in response to microclimate changes.

A 224-bp Indel in the Promoter of PeMYB114 Accounts for Anthocyanin Accumulation of Skin in Passion Fruit (Passiflora spp.).

Passion fruit (Passiflora spp.) is an important fruit tree in the family Passifloraceae. The color of the fruit skin, a significant agricultural trait, is determined by the content of anthocyanin in passion fruit. However, the regulatory mechanisms behind the accumulation of anthocyanin in different passion fruit skin colors remain unclear. In the study, we identified and characterized a R2R3-MYB transcription factor, PeMYB114, which functions as a transcriptional activator in anthocyanin biosynthesis. Yeast one-hybrid system and dual-luciferase analysis showed that PeMYB114 could directly activate the expression of anthocyanin structural genes (PeCHS and PeDFR). Furthermore, a natural variation in the promoter region of PeMYB114 alters its expression. PeMYB114purple accessions with the 224-bp insertion have a higher anthocyanin level than PeMYB114yellow accessions with the 224-bp deletion. The findings enhance our understanding of anthocyanin accumulation in fruits and provide genetic resources for genome design for improving passion fruit quality.

Deciphering the interaction mechanism between soy protein isolate and fat-soluble anthocyanin on experiments and molecular simulations.

In this work, the acylated anthocyanin (Ca-An) was prepared by enzymatic modification of black rice anthocyanin with caffeic acid, and the binding mechanism of Ca-An to soybean protein isolate (SPI) was investigated by experiments and computer simulation to expand the potential application of anthocyanin in food industry. Multi-spectroscopic studies revealed that the stable binding of Ca-An to SPI induced the folding of protein polypeptide chain, which transformed the secondary structure of SPI trended to be flexible. The microenvironment of protein was transformed from hydrophobic to hydrophilic, while tyrosine played dominant role in quenching process. The binding sites and forces of the complexes were determined by computer simulation for further explored. The protein conformation of the 7S and 11S binding regions to Ca-An changed, and the amino acid microenvironment shifted to hydrophilic after binding. The results showed that more non-polar amino acids existed in the binding sites, while in binding process van der Waals forces and hydrogen bonding played a major role hydrophobicity played a minor role. Based on MM-PBSA analysis, the binding constants of 7S-Ca-An and 11S-Ca-An were 0.518 × 106 mol-1 and 5.437 × 10-3 mol-1, respectively. This information provides theoretical guidance for further studying the interaction between modified anthocyanins and biomacromolecules.

Effect of Far-Red Light on Biomass Accumulation, Plant Morphology, and Phytonutrient Composition of Ruby Streaks Mustard at Microgreen, Baby Leaf, and Flowering Stages.

Far-red (FR) light influences plant development significantly through shade avoidance response and photosynthetic modulation, but there is limited knowledge on how FR treatments influence the growth and nutrition of vegetables at different maturity stages in controlled environment agriculture (CEA). Here, we comprehensively investigated the impacts of FR on the yield, morphology, and phytonutrients of ruby streaks mustard (RS) at microgreen, baby leaf, and flowering stages. Treatments including white control, white with supplementary FR, white followed by singularly applied FR, and enhanced white (WE) matching the extended daily light integral (eDLI) of FR were designed for separating the effects of light intensity and quality. Results showed that singular and supplemental FR affected plant development and nutrition similarly throughout the growth cycle, with light intensity and quality playing varying roles at different stages. Specifically, FR did not affect the fresh and dry weight of microgreens but increased those values for baby leaves, although not as effectively as WE. Meanwhile, FR caused significant morphological change and accelerated the development of leaves, flowers, and seedpods more dramatically than WE. With regard to phytonutrients, light treatments affected the metabolomic profiles for baby leaves more dramatically than microgreens and flowers. FR decreased the glucosinolate and anthocyanin contents in microgreens and baby leaves, while WE increased the contents of those compounds in baby leaves. This study illustrates the complex impacts of FR on RS and provides valuable information for selecting optimal lighting conditions in CEA.

Integrated transcriptome and metabolome analysis reveals anthocyanin biosynthesis mechanisms in pepper (Capsicum annuum L.) leaves under continuous blue light irradiation.

BACKGROUND: Different metabolic compounds give pepper leaves and fruits their diverse colors. Anthocyanin accumulation is the main cause of the purple color of pepper leaves. The light environment is a critical factor affecting anthocyanin biosynthesis. It is essential that we understand how to use light to regulate anthocyanin biosynthesis in plants. RESULT: Pepper leaves were significantly blue-purple only in continuous blue light or white light (with a blue light component) irradiation treatments, and the anthocyanin content of pepper leaves increased significantly after continuous blue light irradiation. This green-to-purple phenotype change in pepper leaves was due to the expression of different genes. We found that the anthocyanin synthesis precursor-related genes PAL and 4CL, as well as the structural genes F3H, DFR, ANS, BZ1, and F3'5'H in the anthocyanin synthesis pathway, had high expression under continuous blue light irradiation. Similarly, the expression of transcription factors MYB1R1-like, MYB48, MYB4-like isoform X1, bHLH143-like, and bHLH92-like isoform X3, and circadian rhythm-related genes LHY and COP1, were significantly increased after continuous blue light irradiation. A correlation network analysis revealed that these transcription factors and circadian rhythm-related genes were positively correlated with structural genes in the anthocyanin synthesis pathway. Metabolomic analysis showed that delphinidin-3-O-glucoside and delphinidin-3-O-rutinoside were significantly higher under continuous blue light irradiation relative to other light treatments. We selected 12 genes involved in anthocyanin synthesis in pepper leaves for qRT-PCR analysis, and the accuracy of the RNA-seq results was confirmed. CONCLUSIONS: In this study, we found that blue light and 24-hour irradiation together induced the expression of key genes and the accumulation of metabolites in the anthocyanin synthesis pathway, thus promoting anthocyanin biosynthesis in pepper leaves. These results provide a basis for future study of the mechanisms of light quality and photoperiod in anthocyanin synthesis and metabolism, and our study may serve as a valuable reference for screening light ratios that regulate anthocyanin biosynthesis in plants.