Higher anthocyanin accumulation associated with higher transcription levels of anthocyanin biosynthesis genes in spinach

Sugar and anthocyanins: A scientific exploration of sweet signals and natural pigments

The presence of anthocyanins imparts vibrant hues to plants, whose biosynthesis and accumulation is a complex process and are influenced by numerous factors. In plants, sugar acts as a primary energy source and signaling molecule regulating anthocyanins biosynthesis. In this review, we provides a comprehensive overview of the relationship between sugar and anthocyanin. We delved into the intricate biosynthetic pathway of anthocyanins, outlining the key structural genes involved and their functions. Furthermore, we summarized how various environmental factors such as sugar, light, abiotic stresses, etc., affect anthocyanin biosynthesis. Notably, Most notably, we emphasized that sugars can independently regulate anthocyanin biosynthesis by modulating the expression of the MBW complex or structural genes, as well as through cascades involving hormones. These findings offer valuable insights into understanding the molecular mechanisms underlying anthocyanin accumulation and present potential avenues for enhancing anthocyanin content in plants through targeted manipulations that could have applications in agriculture and nutrition.

Spinach genomes reveal migration history and candidate genes for important crop traits

Spinach (Spinacia oleracea) is an important leafy crop possessing notable economic value and health benefits. Current genomic resources include reference genomes and genome-wide association studies. However, the worldwide genetic relationships and the migration history of the crop remained uncertain, and genome-wide association studies have produced extensive gene lists related to agronomic traits. Here, we re-analysed the sequenced genomes of 305 cultivated and wild spinach accessions to unveil the phylogeny and history of cultivated spinach and to explore genetic variation in relation to phenotypes. In contrast to previous studies, we employed machine learning methods (based on Extreme Gradient Boosting, XGBoost) to detect variants that are collectively associated with agronomic traits. Variant-based cluster analyses revealed three primary spinach groups in the Middle East, Asia and Europe/US. Combining admixture analysis and allele-sharing statistics, migration routes of spinach from the Middle East to Europe and Asia are presented. Using XGBoost machine learning models we predict genomic variants influencing bolting time, flowering time, petiole color, and leaf surface texture and propose candidate genes for each trait. This study enhances our understanding of the history and phylogeny of domesticated spinach and provides valuable information on candidate genes for future genetic improvement of the crop.

Genetic mapping, transcriptomic sequencing and metabolic profiling indicated a glutathione S-transferase is responsible for the red-spot-petals in Gossypium arboreum

A GST for red-spot-petals in Gossypium arboreum was identified as the candidate under the scope of multi-omics approaches. Colored petal spots are correlated with insect pollination efficiency in Gossypium species. However, molecular mechanisms concerning the formation of red spots on Gossypium arboreum flowers remain elusive. In the current study, the Shixiya1-R (SxyR, with red spots) × Shixiya1-W (SxyW, without red spots) segregating population was utilized to determine that the red-spot-petal phenotype was levered by a single dominant locus. This phenotype was expectedly related to the anthocyanin metabolites, wherein the cyanidin and delphinidin derivatives constituted the major partition. Subsequently, this dominant locus was narrowed to a 3.27 Mb range on chromosome 7 by genomic resequencing from the two parents and the two segregated progeny bulks that have spotted petals or not. Furthermore, differential expressed genes generated from the two bulks at either of three sequential flower developmental stages that spanning the spot formation were intersected with the annotated ones that allocated to the 3.27 Mb interval, which returned eight genes. A glutathione S-transferase-coding gene (Gar07G08900) out of the eight was the only one that exhibited simultaneously differential expression among all three developmental stages, and it was therefore considered to be the probable candidate. Finally, functional validation upon this candidate was achieved by the appearance of scattered petal spots with inhibited expression of Gar07G08900. In conclusion, the current report identified a key gene for the red spotted petal in G. arboreum under the scope of multi-omics approaches, such efforts and embedded molecular resources would benefit future applications underlying the flower color trait in cotton.

Anthocyanins accumulation analysis of correlated genes by metabolome and transcriptome in green and purple peppers (Capsicum annuum)

BACKGROUND

In order to clarify the the molecular mechanism of anthocyanin accumulation in green and purple fruits of pepper using metabolomics and transcriptomics,to identify different anthocyanin metabolites,and to analyze the differentially expressed genes involved in anthocyanin biosynthesis..

RESULTS

We analyzed the anthocyanin metabolome and transcriptome data of the fruits of 2 purple pepper and 1 green pepper. A total of 5 anthocyanin metabolites and 2224 differentially expressed genes were identified between the green and purple fruits of pepper. Among the 5 anthocyanin metabolites,delphin chloride was unique to purple pepper fruits,which is the mainly responsible for the purple fruit color of pepper. A total of 59 unigenes encoding 7 enzymes were identified as candidate genes involved in anthocyanin biosynthesis in pepper fruit. The six enzymes (PAL,C4H,CHI,DFR,ANS,UFGT) had higher expression levels except the F3H gene in purple compared with green fruits. In addition,seven transcription factors were also found in this study. These transcription factors may contribute to anthocyanin metabolite biosynthesis in the fruits of pepper. One of differentially expressed gene novel.2098 was founded. It was not annotated in NCBI. Though blast analysis we preliminarily considered that this gene related to MYB transcription factor and was involved in anthocyanin biosynthesis in pepper fruit.

CONCLUSIONS

Overall, the results of this study provide useful information for understanding anthocyanin accumulation and the molecular mechanism of anthocyanin biosynthesis in peppers.

Selection and Validation of Reference Genes for RT-qPCR Analysis in Spinacia oleracea under Abiotic Stress

Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) is an accurate and convenient method for mRNA quantification. Selection of optimal reference gene(s) is an important step in RT-qPCR experiments. However, the stability of housekeeping genes in spinach (Spinacia oleracea) under various abiotic stresses is unclear. Evaluating the stability of candidate genes and determining the optimal gene(s) for normalization of gene expression in spinach are necessary to investigate the gene expression patterns during development and stress response. In this study, ten housekeeping genes, 18S ribosomal RNA (18S rRNA), actin, ADP ribosylation factor (ARF), cytochrome c oxidase subunit 5C (COX), cyclophilin (CYP), elongation factor 1-alpha (EF1α), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), histone H3 (H3), 50S ribosomal protein L2 (RPL2), and tubulin alpha chain (TUBα) from spinach, were selected as candidates in roots, stems, leaves, flowers, and seedlings in response to high temperature, CdCl₂, NaCl, NaHCO₃, and Na₂CO₃ stresses. The expression of these genes was quantified by RT-qPCR and evaluated by NormFinder, BestKeeper, and geNorm. 18S rRNA, actin, ARF, COX, CYP, EF1α, GAPDH, H3, and RPL2 were detected as optimal reference genes for gene expression analysis of different organs and stress responses. The results were further confirmed by the expression pattern normalized with different reference genes of two heat-responsive genes. Here, we optimized the detection method of the gene expression pattern in spinach. Our results provide the optimal candidate reference genes which were crucial for RT-qPCR analysis.

Integrated metabolomic and transcriptomic analysis of the anthocyanin regulatory networks in Salvia miltiorrhiza Bge. flowers

BACKGROUND

The objectives of this study were to reveal the anthocyanin biosynthesis metabolic pathway in white and purple flowers of Salvia miltiorrhiza using metabolomics and transcriptomics, to identify different anthocyanin metabolites, and to analyze the differentially expressed genes involved in anthocyanin biosynthesis.

RESULTS

We analyzed the metabolomics and transcriptomics data of S. miltiorrhiza flowers. A total of 1994 differentially expressed genes and 84 flavonoid metabolites were identified between the white and purple flowers of S. miltiorrhiza. Integrated analysis of transcriptomics and metabolomics showed that cyanidin 3,5-O-diglucoside, malvidin 3,5-diglucoside, and cyanidin 3-O-galactoside were mainly responsible for the purple flower color of S. miltiorrhiza. A total of 100 unigenes encoding 10 enzymes were identified as candidate genes involved in anthocyanin biosynthesis in S. miltiorrhiza flowers. Low expression of the ANS gene decreased the anthocyanin content but enhanced the accumulation of flavonoids in S. miltiorrhiza flowers.

CONCLUSIONS

Our results provide valuable information on the anthocyanin metabolites and the candidate genes involved in the anthocyanin biosynthesis pathways in S. miltiorrhiza.

Application of cucumber mosaic virus to efficient induction and long-term maintenance of virus-induced gene silencing in spinach

Virus-induced gene silencing (VIGS) is a useful tool for functional genomics in plants. In this study, we tried to apply cucumber mosaic virus (CMV) to efficient induction of VIGS in spinach. Although VIGS for spinach had been previously developed based on two viruses (beet curly top virus and tobacco rattle virus), they still have some problems with systemic movement and long-term maintenance of VIGS in spinach. Although ordinary CMV strains infect spinach inducing distinct mosaic symptoms, using a CMV pseudorecombinant, we can modify the viral pathogenicity to attenuate viral symptoms that may mask the silencing phenotype. We here successfully demonstrated the viral ability to silence the phytoene desaturase (PDS) and the dihydroflavonol 4-reductase (DFR) genes in spinach. Because CMV could quickly induce VIGS even at 7-10 days postinoculation and the virus did not disappear even at the flowering stage, this CMV-based VIGS system would contribute to functional genomics in spinach and especially to the elucidation of molecular mechanisms for some properties unique to spinach such as plasticity of sex expression; the CMV-induced VIGS can last until the flowering stage after the virus was inoculated onto the seedling.

Transcriptome analysis revealed expression of genes related to anthocyanin biosynthesis in eggplant (Solanum melongena L.) under high-temperature stress

BACKGROUND

Anthocyanin synthesis is affected by many factors, among which temperature is an important environmental factor. Eggplant is usually exposed to high temperatures during the cultivation season in Shanghai, China. Therefore,RNA -seq analysis was used to determine the effects of high-temperature stress on gene expression in the anthocyanin biosynthetic pathway of eggplant (Solanum melongena L.).

RESULTS

We tested the heat-resistant cultivar 'Tewangda'. The plants were incubated at 38 °C and 45 °C, and the suitable temperature for eggplant growth was used as a control. The treatment times were 3 h and 6 h. The skin of the eggplant was taken for transcriptome sequencing, qRT-PCR assays and bioinformatic analysis. The results showed that 770 genes were differentially expressed between different treatments. Gene Ontology (GO) database and Kyoto Encyclopedia of Genes and Genomes (KEGG) database analyses identified 16 genes related to anthocyanin biosynthesis, among which CHSB was upregulated. Other genes, including BHLH62, MYB380, CHI3, CHI, CCOAOMT, AN3, ACT-2, HST, 5MA-T1, CYP75A2, ANT17, RT, PAL2, and anthocyanin 5-aromatic acyltransferase were downregulated. In addition, the Myb family transcription factor PHL11 was upregulated in the CK 3 h vs 45 °C 3 h, CK 3 h vs 38 °C 3 h, and CK 6 h vs 38 °C 6 h comparisons, and the transcription factor bHLH35 was upregulated in the CK 3 h vs 38 °C 3 h and CK 6 h vs 38 °C 6 h comparisons.

CONCLUSION

These results indicated that high temperature will downregulate most of the genes in the anthocyanin biosynthetic pathway of eggplant. Our data have a reference value for the heat resistance mechanism of eggplant and can provide directions for molecular breeding of heat-resistant germplasm with anthocyanin content in eggplant.

Accumulation of Anthocyanin and Its Associated Gene Expression in Purple Tumorous Stem Mustard ( Brassica juncea var. tumida Tsen et Lee) Sprouts When Exposed to Light, Dark, Sugar, and Methyl Jasmonate

Tumorous stem mustard is a characteristic vegetable in Southeast Asia, as are its sprouts. The purple color of the purple variety 'Zi Ying' leaves is because of anthocyanin accumulation. The ways in which this anthocyanin accumulation is affected by the environment and hormones has remained unclear. Here, the impacts of sucrose, methyl jasmonate (MeJA), light, and dark on the growth and anthocyanin production of 'Zi Ying' sprouts were explored. The results showed that anthocyanins can be enhanced by sucrose in sprouts under light condition, and MeJA can promote anthocyanins production under light and dark conditions in sprouts. The anthocyanin biosynthetic regulatory genes BjTT8, BjMYB1, BjMYB2 and BjMYB4, and the EBGs and LBGs were upregulated under light conditions, while BjTT8, BjMYB1, and BjMYB2 and anthocyanin biosynthetic genes BjF3H and BjF3'H were upregulated under DM condition. These results indicate that sucrose and methyl jasmonate can stimulate the expression of genes encoding components of the MBW complex (MYB, bHLH, and WD40) and that they transcriptional activated the expression of LBGs and EBGs to promote the accumulation of anthocyanins in 'Zi Ying' sprouts. Our findings enhance our understanding of anthocyanin accumulation regulated by sucrose and MeJA in 'Zi Ying', which will help growers to produce anthocyanin-rich foods with benefits to human health.

Looking at Flavonoid Biodiversity in Horticultural Crops: A Colored Mine with Nutritional Benefits

Flavonoids represent a wide group of plant secondary metabolites implicated in many physiological roles, from the attraction of pollinators to the protection against biotic or abiotic stresses. Flavonoids are synthetized in a number of horticultural crops that are important components of our daily diet. In the last decades, the consumption of vegetables rich in antioxidants has been strongly promoted from the perspective of prevention/protection against chronic diseases. Therefore, due to their nutritional importance, several attempts have been made to enhance flavonoid levels in species of agronomic interest. In this review, we focus on the flavonoid biodiversity among the major horticultural species, which is responsible of differences among closely related species and influences the qualitative/quantitative composition. We also review the role of flavonoids in the nutritional quality of plant products, contributing to their organoleptic and nutritional properties, and the main strategies of biofortification to increase their content.