Correction to: Functional analysis of GhCHS, GhANR and GhLAR in colored fiber formation of Gossypium hirsutum L

VdCHS2 Overexpression Enhances Anthocyanin Biosynthesis, Modulates the Composition Ratio, and Increases Antioxidant Activity in Vitis davidii Cells

Anthocyanins are significant secondary metabolites that are essential for plant growth and development, possessing properties such as antioxidant, anti-inflammatory, and anti-cancer activities and cardiovascular protection. They offer significant potential for applications in food, medicine, and cosmetics. However, since anthocyanins are mainly obtained through plant extraction and chemical synthesis, they encounter various challenges, including resource depletion, ecological harm, environmental pollution, and the risk of toxic residuals. To address these issues, this study proposes a plant cell factory approach as a novel alternative solution for anthocyanin acquisition. In this study, the VdCHS2 gene was successfully transformed into spine grape cells, obtaining a high-yield anthocyanin cell line designated as OE1. Investigations of the light spectrum demonstrated that white light promoted spine grape cell growth, while short-wavelength blue light significantly boosted anthocyanin production. Targeted metabolomics analysis revealed that the total anthocyanin content in the OE1 cell line reached 11 mg/g, representing a 60% increase compared to the WT. A total of 54 differentially accumulated metabolites were identified, among which 44 were upregulated. Overexpression of the CHS gene enhanced the expression of downstream genes involved in anthocyanin biosynthesis, resulting in the differential expression of CHI, F3Hb, F3'5'H, DFR4, and LDOX. This led to the differential accumulation of anthocyanin monomers, predominantly consisting of 3-O-glucosides and 3-O-galactosides, thereby causing alterations in anthocyanin levels and composition. Furthermore, the OE1 cell line increased the activity of various antioxidant enzymes, improved the clearance of reactive oxygen species, and reduced the levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA). The subsequent cultivation of the transformed OE1 cell line, in conjunction with cell suspension culture, established a plant cell factory for anthocyanin production, significantly increasing anthocyanin yield while shortening the culture duration. This study elucidates the molecular mechanisms through which the VdCHS2 gene influenced anthocyanin accumulation and compositional variations. Additionally, it established a model for a small-scale anthocyanin plant cell factory, thereby providing a theoretical and practical foundation for the targeted synthesis of anthocyanin components and the development and utilization of plant natural products.

Fine Mapping of the "black" Peel Color in Pomegranate (Punica granatum L.) Strongly Suggests That a Mutation in the Anthocyanidin Reductase (ANR) Gene Is Responsible for the Trait

Anthocyanins are important dietary and health-promoting substances present in high quantities in the peel and arils of the pomegranate (Punica granatum L.) fruit. Yet, there is a high variation in the content of anthocyanin among different pomegranate varieties. The 'Black' pomegranate variety (P.G.127-28) found in Israel contains exceptionally high levels of anthocyanins in its fruit peel which can reach up to two orders of magnitude higher content as compared to that of other pomegranate varieties' peel anthocyanins. Biochemical analysis reveals that delphinidin is highly abundant in the peel of 'Black' variety. The pattern of anthocyanin accumulation in the fruit peel during fruit development of 'Black' variety differs from that of other pomegranates. High anthocyanin levels are maintained during all developmental stages. Moreover, the accumulation of anthocyanin in the fruit peel of 'Black' variety is not dependent on light. Genetic analysis of an F₂ population segregating for the "black" phenotype reveals that it is determined by a single recessive gene. Genetic mapping of the F₂ population using single nucleotide polymorphism (SNP) markers identified few markers tightly linked to the "black" phenotype. Recombination analysis of the F₂ population and F₃ populations narrowed the "black" trait to an area of 178.5 kb on the draft genome sequence of pomegranate cv. 'Dabenzi.' A putative anthocyanidin reductase (ANR) gene is located in this area. Only pomegranate varieties displaying the "black" trait carry a base pair deletion toward the end of the gene, causing a frame shift resulting in a shorter protein. We propose that this mutation in the ANR gene is responsible for the different anthocyanin composition and high anthocyanin levels of the "black" trait in pomegranate.