Higher Anthocyanin Accumulation Research Articles

Overexpression of oilseed rape trehalose-6-phosphate synthesis gene BnaC02.TPS8 confers sensitivity to low nitrogen and high sucrose-induced anthocyanin accumulation in Arabidopsis.

Overexpression of BnaC02.TPS8 increased low N and high sucrose-induced anthocyanin accumulation. Anthocyanin plays a crucial role in safeguarding photosynthetic tissues against high light, UV radiation, and oxidative stress. Their accumulation is triggered by low nitrogen (N) stress and elevated sucrose levels in Arabidopsis. Trehalose-6-phosphate (T6P) serves as a pivotal signaling molecule, sensing sucrose availability, and carbon (C) metabolism. However, the mechanisms governing the regulation of T6P synthase (TPS) genes responsible for anthocyanin accumulation under conditions of low N and high sucrose remain elusive. In a previous study, we demonstrated the positive impact of a cytoplasm-localized class II TPS protein 'BnaC02.TPS8' on photosynthesis and seed yield improvement in Brassica napus. The present research delves into the biological role of BnaC02.TPS8 in response to low N and high sucrose. Ectopic overexpression of BnaC02.TPS8 in Arabidopsis seedlings resulted in elevated shoot T6P levels under N-sufficient conditions, as well as an increased carbon-to-nitrogen (C/N) ratio, sucrose accumulation, and starch storage under low N conditions. Overexpression of BnaC02.TPS8 in Arabidopsis heightened sensitivity to low N stress and high sucrose levels, accompanied by increased anthocyanin accumulation and upregulation of genes involved in flavonoid biosynthesis and regulation. Metabolic profiling revealed increased levels of intermediate products of carbon metabolism, as well as anthocyanin and flavonoid derivatives in BnaC02.TPS8-overexpressing Arabidopsis plants under low N conditions. Furthermore, yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) analyses demonstrated that BnaC02.TPS8 interacts with both BnaC08.TPS9 and BnaA01.TPS10. These findings contribute to our understanding of how TPS8-mediated anthocyanin accumulation is modulated under low N and high sucrose conditions.

The MpNAC72/MpERF105-MpMYB10b module regulates anthocyanin biosynthesis in Malus 'Profusion' leaves infected with Gymnosporangium yamadae.

Apple rust is a serious fungal disease affecting Malus plants worldwide. Infection with the rust pathogen Gymnosporangium yamadae induces the accumulation of anthocyanins in Malus to resist rust disease. However, the mechanism of anthocyanin biosynthesis regulation in Malus against apple rust is still unclear. Here, we show that MpERF105 and MpNAC72 are key regulators of anthocyanin biosynthesis via the ethylene-dependent pathway in M. 'Profusion' leaves under rust disease stress. Exogenous ethephon treatment promoted high expression of MpERF105 and MpNAC72 and anthocyanin accumulation in G. yamadae-infected M. 'Profusion' leaves. Overexpression of MpERF105 increased the total anthocyanin content of Malus plant material and acted by positively regulating its target gene, MpMYB10b. MpNAC72 physically interacted with MpERF105 in vitro and in planta, and the two form a protein complex. Coexpression of the two leads to higher transcript levels of MpMYB10b and higher anthocyanin accumulation. In addition, overexpression of MpERF105 or MpNAC72 enhanced the resistance of M. 'Profusion' leaves to apple rust. In conclusion, our results elucidate the mechanism by which MpERF105 and MpNAC72 are induced by ethylene in G. yamadae-infected M. 'Profusion' leaves and promote anthocyanin accumulation by mediating the positive regulation of MpMYB10b expression.

The telomere-to-telomere gap-free reference genome of wild blueberry (Vaccinium duclouxii) provides its high soluble sugar and anthocyanin accumulation.

Vaccinium duclouxii, endemic to southwestern China, is a berry-producing shrub or small tree belonging to the Ericaceae family, with high nutritive, medicinal, and ornamental value, abundant germplasm resources, and good edible properties. In addition, V. duclouxii exhibits strong tolerance to adverse environmental conditions, making it a promising candidate for research and offering wide-ranging possibilities for utilization. However, the lack of V. duclouxii genome sequence has hampered its development and utilization. Here, a high-quality telomere-to-telomere genome sequence of V. duclouxii was de novo assembled and annotated. All of 12 chromosomes were assembled into gap-free single contigs, providing the highest integrity and quality assembly reported so far for blueberry. The V. duclouxii genome is 573.67Mb, which encodes 41 953 protein-coding genes. Combining transcriptomics and metabolomics analyses, we have uncovered the molecular mechanisms involved in sugar and acid accumulation and anthocyanin biosynthesis in V. duclouxii. This provides essential molecular information for further research on the quality of V. duclouxii. Moreover, the high-quality telomere-to-telomere assembly of the V. duclouxii genome will provide insights into the genomic evolution of Vaccinium and support advancements in blueberry genetics and molecular breeding.

Polyvinyl alcohol film with chlorine dioxide microcapsules can be used for blueberry preservation by slow-release of chlorine dioxide gas.

Chlorine dioxide (ClO2) is a safe and efficient bactericide with unique advantages in reducing foodborne illnesses, inhibiting microbial growth, and maintaining the nutritional quality of food. However, gaseous ClO2 is sensitive to heat, vibration, and light, which limits its application. In this study, a ClO2 precursor-stabilized ClO2 aqueous solution was encapsulated by the double emulsion method, and a high-performance ClO2 self-releasing polyvinyl alcohol (PVA) film was prepared to investigate its performance and effect on blueberry quality during storage. The self-releasing films had the best overall performance when the microcapsule content was 10% as the film's mechanical properties, thermal stability, and film barrier properties were significantly improved. The inhibition rates of Listeria monocytogenes and Escherichia coli were 93.69% and 95.55%, respectively, and the mycelial growth of Staphylococcus griseus was successfully inhibited. The resulting ClO2 self-releasing films were used for blueberry preservation, and an experimental study found that the ClO2 self-releasing antimicrobial film group delayed the quality decline of blueberries. During the 14-day storage period, no mold contamination was observed in the ClO2 self-releasing film group, and blueberries in the antibacterial film group had higher anthocyanin accumulation during the storage period. Research analysis showed that films containing ClO2 microcapsules are promising materials for future fruit and vegetable packaging.

Gap-free genome assembly and comparative analysis reveal the evolution and anthocyanin accumulation mechanism of Rhodomyrtus tomentosa.

Rhodomyrtus tomentosa is an important fleshy-fruited tree and a well-known medicinal plant of the Myrtaceae family that is widely cultivated in tropical and subtropical areas of the world. However, studies on the evolution and genomic breeding of R. tomentosa were hindered by the lack of a reference genome. Here, we presented a chromosome-level gap-free T2T genome assembly of R. tomentosa using PacBio and ONT long read sequencing. We assembled the genome with size of 470.35Mb and contig N50 of ~43.80Mb with 11 pseudochromosomes. A total of 33 382 genes and 239.31Mb of repetitive sequences were annotated in this genome. Phylogenetic analysis elucidated the independent evolution of R. tomentosa starting from 14.37MYA and shared a recent WGD event with other Myrtaceae species. We identified four major compounds of anthocyanins and their synthetic pathways in R. tomentosa. Comparative genomic and gene expression analysis suggested the coloring and high anthocyanin accumulation in R. tomentosa tends to be determined by the activation of anthocyanin synthesis pathway. The positive selection and up-regulation of MYB transcription factors were the implicit factors in this process. The copy number increase of downstream anthocyanin transport-related OMT and GST gene were also detected in R. tomentosa. Expression analysis and pathway identification enriched the importance of starch degradation, response to stimuli, effect of hormones, and cell wall metabolism during the fleshy fruit development in Myrtaceae. Our genome assembly provided a foundation for investigating the origins and differentiation of Myrtaceae species and accelerated the genetic improvement of R. tomentosa.

Study of <i>Myb114</i> Gene Polymorphism in the Cole Crops (<i>Brassica oleracea</i> L.) in Connection with Anthocyanin Biosynthesis Regulation Based on Comparison with the MYB Factors of Vegetable Nightshades (Solanaceae)

In order to study a regulation mechanism for one of the most ancient processes of anthocyanin biosynthesis in plants based on comparison of R2R3-MYB genes in Solanaceae (S. lycopersicum: An1, An2; S. melongena: Myb1; C. annuum: Myb113-like1 и Myb113-like2) and Brassicaeae crops, a search for orthologous sequences in Brassica oleracea was performed. A sequence encoding MYB114 TF was found to be the closest in a nucleotide structure to the previously investigated genes in Solanaceae. Primers were selected and a comparative analysis of Myb114 gene sequences was performed in B. oleracea varieties (white cabbage, red cabbage, kale, cauliflower, broccoli, and kohlrabi) with a wide intraspecies diversity by the anthocyanin accumulation in leaves and various food organs: heads, curds and stems. Alignment of Myb114 sequences revealed a number of gene polymorphisms that closely correlate with high anthocyanin accumulation in B. oleracea leaves, including 3 SNPs in exon regions and a 271 bp deletion in the 1st intron. The identified SNPs lead to the replacement of two amino acids located in the region of DNA-binding domains, which leads to a change in the binding efficiency of this transcription factor with the promoters of structural biosynthesis genes and a decrease in their expression level in the forms without anthocyanin accumulation in leaves compared with the forms with their accumulation in vegetative plant parts. A molecular marker MYB114.2 has been proposed that may be used for the identification of headed cabbages and kales with high/low anthocyanin accumulation. By the amino acid structure and phenotypic manifestation (regulation of anthocyanin accumulation in leaves), Myb114 B. oleracea is the closest to Ant2 tomato, Myb2 eggplant and Myb113-like2 pepper alleles. A high degree of conservatism of the SANT DNA-binding domains of MYB114 TF of B. oleracea and R2R3-MYB TF of nightshades was established.

Comprehensive analysis of a red-peel kiwi berry mutant reveals key genes are responsible for anthocyanin biosynthesis in fruit

Actinidia arguta is an important kind of kiwifruit species with good fruit quality and high economic value. New cultivars of kiwi berry and kiwifruit with high accumulation of anthocyanins in fruit are becoming more and more popular mainly due to the benefit of anthocyanins to human health. Here, a red-peel A. arguta mutant, CG 1, was identified, and its fruit quality was determined. The genetic variation of CG 1 was confirmed by kiwifruit Simple Sequence Repeats (SSR) molecular marker analysis. The peel color of mature fruit in this mutant changed into red, while it was green for the wild type. In addition, the total contents of anthocyanins in peel and pulp tissues of the mutant were both significantly higher when comparing with that of the wild type. Especially, the amount of anthocyanins in fruit peel of CG 1 was 7.49 mg g−1 fresh weight (FW), almost 9.4 times higher than that of the wild type. Further study by transcriptome sequencing and quantitative real-time PCR (qRT-PCR) analysis indicated that the expression patterns of five genes involved in anthocyanin biosynthesis were highly consistent with the anthocyanins contents in peel tissues of the two genotypes. We deduce that those five candidate genes are responsible for the high accumulation of anthocyanins in fruit of the red-peel kiwi berry mutant. This research provides useful methods to identify new kiwi berry mutant. And the comprehensive analysis reveals that the promoted anthocyanins accumulation in the mutant is dependent on the high transcriptional regulations of several key genes involved in anthocyanin biosynthesis pathway.

Identification of a BAHD Acyltransferase Gene Involved in Plant Growth and Secondary Metabolism in Tea Plants.

Plant acyl-CoA dominated acyltransferases (named BAHD) comprise a large appointed protein superfamily and play varied roles in plant secondary metabolism like synthesis of modified anthocyanins, flavonoids, volatile esters, etc. Tea (Camellia sinensis) is an important non-alcoholic medicinal and fragrancy plant synthesizing different secondary metabolites, including flavonoids. In the tea (C.A sinensis) cultivar Longjing 43 (LJ43), eight samples were performed into three groups for transcriptome analysis under three biological replications. Among the BAHD acyltransferase genes in tea cultivars, the expression of TEA031065 was highest in buds and young leaves following the RNA sequencing data, which was coincident with the tissue rich in catechins and other flavonoids. We then transformed this gene into wild-type Arabidopsis as an over-expression (OX) line 1 and line 2 in ½ MS media to verify its function. In the wild types (WT), the primary root length, number of secondary roots, and total root weight were significantly higher at 24%, 15%, and 53.92%, respectively, compared to the transgenic lines (OX1 and OX2). By contrast, the leaves displayed larger rosettes (21.58%), with higher total leaf weight (32.64%) in the transgenic lines than in the wild type (WT). This result is consistent with DCR mutant At5g23940 gene in Arabidopsis thaliana. Here, anthocyanin content in transgenic lines was also increased (21.65%) as compared to WT. According to the RNA sequencing data, a total of 22 growth regulatory genes and 31 structural genes with TFs (transcription factors) that are correlative with plant growth and anthocyanin accumulation were identified to be differentially expressed in the transgenic lines. It was found that some key genes involved in IAA (Auxin) and GA (Gibberellin) biosynthesis were downregulated in the transgenic lines, which might be correlated with the phenotype changes in roots. Moreover, the upregulation of plant growth regulation genes, such as UGT73C4 (zeatin), ARR15, GH3.5, ETR2, ERS2, APH4, and SAG113 might be responsible for massive leaf growth. In addition, transgenic lines shown high anthocyanin accumulation due to the upregulation of the (1) 3AT1 and (3) GSTF, particularly, GSTF12 genes in the flavonoid biosynthesis pathway. However, the TFs such as, CCoAMT, bHLH, WRKY, CYP, and other MYBs were also significantly upregulated in transgenic lines, which increased the content of anthocyanins in A. thaliana seedlings. In conclusion, a BAHD acyltransferase (TEA031065) was identified, which might play a vital role in tea growth and secondary metabolites regulation. This study increases our knowledge concerning the combined functionality of the tea BAHD acyltransferase gene (TEA031065).

Investigating of the polymorphism of <i>Solanaceae</i> R2R3 Myb and <i>Brassica Myb114</i> genes of transcription factors in connection with the anthocyanin biosynthesis regulation

Based on comparison of R2R3 Myb genes in Solanaceae (S. lycopersicum: Ant1, Ant2, S. melongena: Myb1, C. annuum: Myb113-like1 and Myb113-like2) and Brassicaceae crops, a search for orthologous sequences was The sequences encoding Myb114 TF in Brassica oleracea and Brassica rapa was found to be the closest in a nucleotide structure to the previously investigated genes in Solanaceae. Тhе polymorphism in the promoter region of the Capsicum annuum Myb113-like1 gene that regulates anthocyanin biosynthesis: an additional 148 bp repeat and 2(1) bp insertion in the forms with impaired anthocyanin synthesis in fruits was studied. A relationship between the presence of an insert in the promoter (Myb113-like1pr+148) and polymorphisms in the exon regions of Myb113-like1delTand Myb113-like2C/Аgenes associated with impaired anthocyanin synthesis was established. A number of polymorphisms of the Myb114 gene in vegetable crops of the cabbage family (Brassica oleracea, Brassica rapa), which closely correlate with high/low accumulation of anthocyanins in leaves, were identified. In B. oleracea, SNPs that lead to the replacement of two amino acids located in the region of DNAbinding domains were found, which leads to a change in the efficiency of binding of this transcription factor and the promoters of structural biosynthesis genes. A protein sequence encoded by the Myb114 gene in accessions of the leafy turnip (B. rapa) with a high accumulation of anthocyanins in the leaves differed from the accessions without anthocyanin accumulation in the leaves by five amino acids, while the regions of DNA-binding domains were the same in the forms with various anthocyanin accumulation.

Genetic effects of Red Lettuce Leaf genes on red coloration in leaf lettuce under artificial lighting conditions.

Some cultivars of lettuce accumulate anthocyanins, which act as functional food ingredients. Leaf lettuce has been known to be erratic in exhibiting red color when grown under artificial light, and there is a need for cultivars that more stably exhibit red color in artificial light cultivation. In this study, we aimed to dissect the genetic architecture for red coloring in various leaf lettuce cultivars grown under artificial light. We investigated the genotype of Red Lettuce Leaf (RLL) genes in 133 leaf lettuce strains, some of which were obtained from publicly available resequencing data. By studying the allelic combination of RLL genes, we further analyzed the contribution of these genes to producing red coloring in leaf lettuce. From the quantification of phenolic compounds and corresponding transcriptome data, we revealed that gene expression level-dependent regulation of RLL1 (bHLH) and RLL2 (MYB) is the underlying mechanism conferring high anthocyanin accumulation in red leaf lettuce under artificial light cultivation. Our data suggest that different combinations of RLL genotypes cause quantitative differences in anthocyanin accumulation among cultivars, and some genotype combinations are more effective at producing red coloration even under artificial lighting.

Topolin cytokinins enhanced shoot proliferation, reduced hyperhydricity and altered cytokinin metabolism in Pistacia vera L. seedling explants

The effect of 10 µM meta-topolin (mT) and meta-topolin riboside (mTR) on in vitro proliferation and anomalies of Pistacia vera L. were evaluated and compared to that of 6-benzylaminopurine (BA). The highest proliferation rate (15.6) was recorded in the mT-medium, with a value 6 times higher than in BA-medium. Moreover, the lowest percentage of hyperhydric usable shoots (58,9%) and callus weight (46,9%) were found in mTR-treated shoots. Shoot tip as well as leaf necrosis were not influenced by cytokinin (CK) type. Image analysis was used to evaluate photosynthetic efficiency as well as anthocyanin index. Photosynthesis was more efficient with BA and mTR but the higher anthocyanin accumulation in BA-treated shoots suggests more stress. Endogenous CKs and their metabolites were determined in seedlings and, for the first time, the metabolism of exogenous BA, mT and mTR was studied in pistachio. The stimulating effect on cis-zeatin and its riboside and the appearance of BA and traces of ortho-topolin and para-topolin as natural CKs are discussed. The quantitative and qualitative CK metabolite analyses provides some initial clues as to why topolin would be superior to BA in terms of proliferation rate and avoiding hyperhydricity and allowed a better understanding of the effect of exogenous administration of CK.

Transcriptome Analysis Reveals Roles of Sucrose in Anthocyanin Accumulation in 'Kuerle Xiangli' (Pyrus sinkiangensis Yü).

Pear (Pyrus L.) is one of the most important temperate fruit crops worldwide, with considerable economic value and significant health benefits. Red-skinned pears have an attractive appearance and relatively high anthocyanin accumulation, and are especially favored by customers. Abnormal weather conditions usually reduce the coloration of red pears. The application of exogenous sucrose obviously promotes anthocyanins accumulation in ‘Kuerle Xiangli’ (Pyrus sinkiangensis Yü); however, the underlying molecular mechanism of sucrose-mediated fruit coloration remains largely unknown. In this study, comprehensive transcriptome analysis was performed to identify the essential regulators and pathways associated with anthocyanin accumulation. The differentially expressed genes enriched in Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes items were analyzed. The transcript levels of some anthocyanin biosynthetic regulatory genes and structural genes were significantly induced by sucrose treatment. Sucrose application also stimulated the expression of some sugar transporter genes. Further RT-qPCR analysis confirmed the induction of anthocyanin biosynthetic genes. Taken together, the results revealed that sucrose promotes pear coloration most likely by regulating sugar metabolism and anthocyanin biosynthesis, and this study provides a comprehensive understanding of the complex molecular mechanisms underlying the coloration of red-skinned pear.

Arabidopsis alkaline ceramidase ACER functions in defense against insect herbivory.

Plant sphingolipids are important membrane components and bioactive molecules in development and defense responses. However, the function of sphingolipids in plant defense, especially against herbivores, is not fully understood. Here, we report that Spodoptera exigua feeding affects sphingolipid metabolism in Arabidopsis, resulting in increased levels of sphingoid long-chain bases, ceramides, and hydroxyceramides. Insect-induced ceramide and hydroxyceramide accumulation is dependent on the jasmonate signaling pathway. Loss of the Arabidopsis alkaline ceramidase ACER increases ceramides and decreases long-chain base levels in plants; in this work, we found that loss of ACER enhances plant resistance to S. exigua and improves response to mechanical wounding. Moreover, acer-1 mutants exhibited more severe root-growth inhibition and higher anthocyanin accumulation than wild-type plants in response to methyl jasmonate treatment, indicating that loss of ACER increases sensitivity to jasmonate and that ACER functions in jasmonate-mediated root growth and secondary metabolism. Transcript levels of ACER were also negatively regulated by jasmonates, and this process involves the transcription factor MYC2. Thus, our findings reveal that ACER is involved in mediating jasmonate-related plant growth and defense and that jasmonates function in regulating the expression of ACER.

Systems biology-based analysis indicates that PHO1;H10 positively modulates high light-induced anthocyanin biosynthesis in Arabidopsis leaves

Arabidopsis PHO1;H10 is a member of the PHO1 gene family with SPX and EXS domains, and its functions remain largely unknown. As shown in PCSD database, the upstream region of PHO1;H10 gene is in the active chromatin states, with high DHS accessibility and binding sites of multiple transcription factors, especially ABI5, SPCH and HY5. Co-expression network and data-mining analyses showed PHO1;H10 and co-expression genes were with activation under high light stress. We did wet-lab experiments, and found that the detached leaves of PHO1;H10 overexpression lines accumulated more anthocyanin than those of WT and mutant under high light treatment. RNA-seq results showed overexpression of PHO1;H10 up-regulated many anthocyanin biosynthetic genes. The GSEA analysis result showed that the functional module related to anthocyanin pathway was significantly enriched. In summary, we conducted systems biology approach, combining dry- and wet-lab analyses, and discovered that PHO1;H10 might play an essential role during modulating high light-induced anthocyanin accumulation in the Arabidopsis detached leaves.

Leaf Coloration in Acer palmatum Is Associated with a Positive Regulator ApMYB1 with Potential for Breeding Color-Leafed Plants.

Anthocyanin biosynthesis and accumulation is closely associated with tissue/organ coloring in plants. To gain insight into the physiological and molecular mechanisms of leaf coloring in Acer palmatum, a deciduous tree during autumnal senescence, we first investigated concentration dynamics of pigments (i.e., chlorophyll, carotenoid and anthocyanin) in leaves with differential coloring. It was found that compared to green leaves (GN), anthocyanins were accumulated actively in semi-red (SR) and total-red (TR) leaves, accompanied with chlorophyll and carotenoid degradation. Then transcriptional profiling on GN and SR leaves identified thousands of transcripts with differential expression in SR compared to GN leaves. An annotation search showed that the entire flavonoid/anthocyanin biosynthesis pathway from the production of naringenin chalcone to modification of flavonoid backbone was extensively activated at the transcriptional level in SR leaves. Phylogenetic analysis of putative MYB proteins identified ApMYB1 as a putative regulator promoting anthocyanin biosynthesis. Expression of ApMYB1 in leaves was induced by exogenous hormones including abscisic acid. Stable overexpression of ApMYB1 in tobacco resulted in leaves with higher accumulation of anthocyanins. Collectively, our results identified ApMYB1 as a positive regulator associated with leaf coloring in Acer palmatum during autumnal senescence, which may be regarded a potential target for breeding color-leafed plants.

Rootstock Effects on Anthocyanin Accumulation and Associated Biosynthetic Gene Expression and Enzyme Activity during Fruit Development and Ripening of Blood Oranges

Blood orange (Citrus sinensis L. Osbeck) is a rare commercial citrus fruit containing abundant anthocyanins and has numerous health benefits. Blood orange rootstock determines the fruit yield and quality. This study evaluated the effect of the three most commonly used rootstocks on the fruit features, color index, physicochemical parameters, anthocyanin accumulation, the anthocyanin biosynthetic gene expression, and the associated enzymes during the fruit development and ripening of ‘Tarocco’ blood orange. The highest anthocyanin content at harvest was found in blood orange trees grafted onto ‘Trifoliate orange’ (Poncirus trifoliata L. Raf., Pt) rootstock. Molecular analyses revealed that the rootstock affects the anthocyanin accumulation in the blood orange. Additionally, there was a strong correlation between the anthocyanin content and the expression and the activity of related genes and enzymes, respectively. Based on gene expression and enzymatic activity analyses, Pt rootstock promotes a very high anthocyanin accumulation in ‘Tarocco’ blood orange fruit. Accordingly, Pt is the promising rootstock for producing good quality and highly nutritious ‘Tarocco’ blood orange fruit for commercial purposes.

Production of purple Ma bamboo (Dendrocalamus latiflorus Munro) with enhanced drought and cold stress tolerance by engineering anthocyanin biosynthesis.

Overexpression of the leaf color (Lc) gene in Ma bamboo substantially increased the accumulation level of anthocyanin, and improved plant tolerance to cold and drought stresses, probably due to the increased antioxidant capacity. Most bamboos, including Ma bamboo (Dendrocalamus latiflorus Munro), are naturally evergreen and sensitive to cold and drought stresses, while it's nearly impossible to make improvements through conventual breeding due to their long and irregular flowering habit. Moreover, few studies have reported bamboo germplasm innovation through genetic engineering as bamboo genetic transformation remains difficult. In this study, we have upregulated anthocyanin biosynthesis in Ma bamboo, to generate non-green Ma bamboo with increased abiotic stress tolerance. By overexpressing the maize Lc gene, a bHLH transcription activator involved in the anthocyanin biosynthesis in Ma bamboo, we generated purple bamboos with increased anthocyanin levels including cyanidin-3-O-rutinoside, peonidin 3-O-rutinoside, and an unknown cyanidin pentaglycoside derivative. The expression levels of 9 anthocyanin biosynthesis genes were up-regulated. Overexpression of the Lc gene improved the plant tolerance to cold and drought stress, probably due to increased antioxidant capacity. The levels of the cold- and drought-related phytohormone jasmonic acid in the transgenic plants were also enhanced, which may also contribute to the plant stress-tolerant phenotypes. High anthocyanin accumulation level did not affect plant growth. Transcriptomic analysis showed higher expressions of genes involved in the flavonoid pathway in Lc transgenic bamboos compared with those in wild-type ones. The anthocyanin-rich bamboos generated here provide an example of ornamental and multiple agronomic trait improvements by genetic engineering in this important grass species.

In vitro study of the antioxidant activity of extracts from dried biomass of callus, cell suspension, and root cultures

The most promising sources of antioxidants are plant objects that contain natural antioxidants such as polyphenols, carotenoids, and vitamins. The paper studies the antioxidant activity of extracts from dried biomass of callus, suspension cell cultures, and root cultures in vitro. The study of the antioxidant activity of plant extracts showed that the maximum antioxidant activity (250.6 mg AA/g) is possessed by extracts from the dried biomass of in vitro hyssop root cultures. According to this indicator, extracts from dried biomass of hyssop hairy exceed extracts from dried biomass of Amur maakia root cultures by 2.23 times, and extracts from dried biomass of Siler root cultures by 5.61 times. Extracts from the dried biomass of in vitro callus, cell suspension, and root cultures of Siler do not possess high antioxidant activity, which varies from 16.56 to 44.66 mg AA/g. The maximum indicator of antioxidant activity for this medicinal plant is observed in extracts from dried biomass of in vitro root cultures. For extracts from dried biomass of in vitro callus, cell suspension and root cultures of Amur maakia, the range of antioxidant activity indices is from 85.40 mg AA/g to 112.33 mg AA/g. The maximum antioxidant activity was observed in extracts from dried biomass of in vitro root cultures. A higher accumulation of anthocyanins was also found in the callus culture of Malus sieversii f. niedzwetzkyana cultured on a nutrient medium containing both auxins and cytokinins.

The role of VvMYBA2r and VvMYBA2w alleles of the MYBA2 locus in the regulation of anthocyanin biosynthesis for molecular breeding of grape (Vitis spp.) skin coloration.

SummaryIn grape, MYBA1 and MYBA2 at the colour locus are the major genetic determinants of grape skin colour, and the mutation of two functional genes (VvMYBA1 and VvMYBA2) from these loci leads to white skin colour. This study aimed to elucidate the regulation of grape berry coloration by isolating and characterizing VvMYBA2w and VvMYBA2r alleles. The overexpression of VvMYBA2r up‐regulated the expression of anthocyanin biosynthetic genes and resulted in higher anthocyanin accumulation in transgenic tobacco than wild‐type (WT) plants, especially in flowers. However, the ectopic expression of VvMYBA2w inactivated the expression of anthocyanin biosynthetic genes and could not cause obvious phenotypic modulation in transgenic tobacco. Unlike in VvMYBA2r, CA dinucleotide deletion shortened the C‐terminal transactivation region and disrupted the transcriptional activation activity of VvMYBA2w. The results indicated that VvMYBA2r positively regulated anthocyanin biosynthesis by forming the VvMYBA2r‐VvMYCA1‐VvWDR1 complex, and VvWDR1 enhanced anthocyanin accumulation by interacting with the VvMYBA2r‐VvMYCA1 complex; however, R44L substitution abolished the interaction of VvMYBA2w with VvMYCA1. Meanwhile, both R44L substitution and CA dinucleotide deletion seriously affected the efficacy of VvMYBA2w to regulate anthocyanin biosynthesis, and the two non‐synonymous mutations were additive in their effects. Investigation of the colour density and MYB haplotypes of 213 grape germplasms revealed that dark‐skinned varieties tended to contain HapC‐N and HapE2, whereas red‐skinned varieties contained high frequencies of HapB and HapC‐Rs. Regarding ploidy, the higher the number of functional alleles present in a variety, the darker was the skin colour. In summary, this study provides insight into the roles of VvMYBA2r and VvMYBA2w alleles and lays the foundation for the molecular breeding of grape varieties with different skin colour.

Spectral Composition of Light Affects Sensitivity to UV-B and Photoinhibition in Cucumber.

Ultraviolet B (UV-B) (280–315 nm) and ultraviolet A (UV-A) (315–400 nm) radiation comprise small portions of the solar radiation but regulate many aspects of plant development, physiology and metabolism. Until now, how plants respond to UV-B in the presence of different light qualities is poorly understood. This study aimed to assess the effects of a low UV-B dose (0.912 ± 0.074 kJ m–2 day–1, at a 6 h daily UV exposure) in combination with four light treatments (blue, green, red and broadband white at 210 μmol m–2 s–1 Photosynthetically active radiation [PAR]) on morphological and physiological responses of cucumber (Cucumis sativus cv. “Lausanna RZ F1”). We explored the effects of light quality backgrounds on plant morphology, leaf gas exchange, chlorophyll fluorescence, epidermal pigment accumulation, and on acclimation ability to saturating light intensity. Our results showed that supplementary UV-B significantly decreased biomass accumulation in the presence of broad band white, blue and green light, but not under red light. UV-B also reduced the photosynthetic efficiency of CO2 fixation (α) when combined with blue light. These plants, despite showing high accumulation of anthocyanins, were unable to cope with saturating light conditions. No significant effects of UV-B in combination with green light were observed for gas exchange and chlorophyll fluorescence parameters, but supplementary UV-B significantly increased chlorophyll and flavonol contents in the leaf epidermis. Plants grown under red light and UV-B significantly increased maximum photosynthetic rate and dark respiration compared to pure red light. Additionally, red and UV-B treated plants exposed to saturating light intensity showed higher quantum yield of photosystem II (PSII), fraction of open PSII centres and electron transport rate and showed no effect on the apparent maximum quantum efficiency of PSII photochemistry (Fv/Fm) or non-photochemical quenching, in contrast to solely red-light conditions. These findings provide new insights into how plants respond to UV-B radiation in the presence of different light spectra.