Anthocyanin Induction Research Articles

Omics Analysis Unveils the Pathway Involved in the Anthocyanin Biosynthesis in Tomato Seedling and Fruits.

The purple tomato variety 'Indigo Rose' (InR) is favored due to its bright appearance, abundant anthocyanins and outstanding antioxidant capacity. SlHY5 is associated with anthocyanin biosynthesis in 'Indigo Rose' plants. However, residual anthocyanins still present in Slhy5 seedlings and fruit peel indicated there was an anthocyanin induction pathway that is independent of HY5 in plants. The molecular mechanism of anthocyanins formation in 'Indigo Rose' and Slhy5 mutants is unclear. In this study, we performed omics analysis to clarify the regulatory network underlying anthocyanin biosynthesis in seedling and fruit peel of 'Indigo Rose' and Slhy5 mutant. Results showed that the total amount of anthocyanins in both seedling and fruit of InR was significantly higher than those in the Slhy5 mutant, and most genes associated with anthocyanin biosynthesis exhibited higher expression levels in InR, suggesting that SlHY5 play pivotal roles in flavonoid biosynthesis both in tomato seedlings and fruit. Yeast two-hybrid (Y2H) results revealed that SlBBX24 physically interacts with SlAN2-like and SlAN2, while SlWRKY44 could interact with SlAN11 protein. Unexpectedly, both SlPIF1 and SlPIF3 were found to interact with SlBBX24, SlAN1 and SlJAF13 by yeast two-hybrid assay. Suppression of SlBBX24 by virus-induced gene silencing (VIGS) retarded the purple coloration of the fruit peel, indicating an important role of SlBBX24 in the regulation of anthocyanin accumulation. These results deepen the understanding of purple color formation in tomato seedlings and fruits in an HY5-dependent or independent manner via excavating the genes involved in anthocyanin biosynthesis based on omics analysis.

MYB transcription factors-master regulators of phenylpropanoid biosynthesis and diverse developmental and stress responses.

Phenylpropanoids, the largest class of natural products including flavonoids, anthocyanins, monolignols and tannins perform multiple functions ranging from photosynthesis, nutrient uptake, regulating growth, cell division, maintenance of redox homeostasis and biotic and abiotic stress responses. Being sedentary life forms, plants possess several regulatory modules that increase their performance in varying environments by facilitating activation of several signaling cascades upon perception of developmental and stress signals. Of the various regulatory modules, those involving MYB transcription factors are one of the extensive groups involved in regulating the phenylpropanoid metabolic enzymes in addition to other genes. R2R3 MYB transcription factors are a class of plant-specific transcription factors that regulate the expression of structural genes involved in anthocyanin, flavonoid and monolignol biosynthesis which are indispensable to several developmental pathways and stress responses. The aim of this review is to present the regulation of the phenylpropanoid pathway by MYB transcription factors via Phospholipase D/phosphatidic acid signaling, downstream activation of the structural genes, leading to developmental and/or stress responses. Specific MYB transcription factors inducing or repressing specific structural genes of anthocyanin, flavonoid and lignin biosynthetic pathways are discussed. Further the roles of MYB in activating biotic and abiotic stress responses are delineated. While several articles have reported the role of MYB's in stress responses, they are restricted to two or three specific MYB factors. This review is a consolidation of the diverse roles of different MYB transcription factors involved both in induction and repression of anthocyanin, flavonoid, and lignin biosynthesis.

The combination of R2R3-MYB gene AmRosea1 and hairy root culture is a useful tool for rapidly induction and production of anthocyanins in Antirrhinum majus L

Anthocyanins are the largest group of water-soluble pigments and beneficial for human health. Although most plants roots have the potential to express natural biosynthesis pathways required to produce specialized metabolites such as anthocyanins, the anthocyanin synthesis is specifically silenced in roots. To explore the molecular mechanism of absence and production ability of anthocyanin in the roots, investigated the effect of a bHLH gene AmDelila, and an R2R3-MYB gene AmRosea1, which are the master regulators of anthocyanin biosynthesis in Antirrhinum majus flowers, by expressing these genes in transformed hairy roots of A. majus. Co-ectopic expression of both AmDelila and AmRosea1 significantly upregulated the expression of the key target structural genes in the anthocyanin biosynthesis pathway. Furthermore, this resulted in strongly enhanced anthocyanin accumulation in transformed hairy roots. Ectopic expression of AmDelila alone did not gives rise to any significant anthocyanin accumulation, however, ectopic expression of AmRosea1 alone clearly upregulated expression of the main structural genes as well as greatly promoted anthocyanin accumulation in transformed hairy roots, where the contents reached 0.773–2.064 mg/g fresh weight. These results suggest that AmRosea1 plays a key role in the regulatory network in controlling the initiation of anthocyanin biosynthesis in roots, and the combination of AmRosea1 and hairy root culture is a powerful tool to study and production of anthocyanins in the roots of A. majus.

Fungal Pathogen Emergence: Investigations with an Ustilagomaydis × Sporisorium reilianum Hybrid.

The emergence of new fungal pathogens threatens sustainable crop production worldwide. One mechanism by which new pathogens may arise is hybridization. To investigate hybridization, the related smut fungi, Ustilago maydis and Sporisorium reilianum, were selected because they both infect Zea mays, can hybridize, and tools are available for their analysis. The hybrid dikaryons of these fungi grew as filaments on plates but their colonization and virulence in Z. mays were reduced compared to the parental dikaryons. The anthocyanin induction caused by the hybrid dikaryon infections was distinct, suggesting its interaction with the host was different from that of the parental dikaryons. Selected virulence genes previously characterized in U. maydis and their predicted S. reilianum orthologs had altered transcript levels during hybrid infection of Z. mays. The downregulated U. maydis effectors, tin2, pit2, and cce1, and transcription factors, rbf1, hdp2, and nlt1, were constitutively expressed in the hybrid. Little impact was observed with increased effector expression; however, increased expression of rbf1 and hdp2, which regulate early pathogenic development by U. maydis, increased the hybrid’s capacity to induce symptoms including the rare induction of small leaf tumors. These results establish a base for investigating molecular aspects of smut fungal hybrid pathogen emergence.

Jasmonate induces biosynthesis of anthocyanin and proanthocyanidin in apple by mediating the JAZ1-TRB1-MYB9 complex.

Jasmonate (JA) induces the biosynthesis of anthocyanin and proanthocyanidin. MdMYB9 is essential for modulating the accumulation of both anthocyanin and proanthocyanidin in apple, but the molecular mechanism for induction of anthocyanin and proanthocyanidin biosynthesis by JA is unclear. In this study, we discovered an apple telomere-binding protein (MdTRB1) to be the interacting protein of MdMYB9. A series of biological assays showed that MdTRB1 acted as a positive modulator of anthocyanin and proanthocyanidin accumulation, and is dependent on MdMYB9. MdTRB1 interacted with MdMYB9 and enhanced the activation activity of MdMYB9 to its downstream genes. In addition, we found that the JA signaling repressor MdJAZ1 interacted with MdTRB1 and interfered with the interaction between MdTRB1 and MdMYB9, therefore negatively modulating MdTRB1-promoted biosynthesis of anthocyanin and proanthocyanidin. These results show that the JAZ1-TRB1-MYB9 module dynamically modulates JA-mediated accumulation of anthocyanin and proanthocyanidin. Taken together, our data further expand the functional study of TRB1 and provide insights for further studies of the modulation of anthocyanin and proanthocyanidin biosynthesis by JA.

Simultaneous induction of anthocyanin and peroxidase by sucrose in hypocotyls and roots of Chinese red radish seedlings

Anthocyanin and peroxidase (POD) are important active compounds in Chinese red radish (Raphanus sativus L.). The effects of exogenous sucrose, mixture of fructose and glucose (F/G 1:1), and mannose on anthocyanin accumulation and POD activity were investigated in hypocotyls and roots of red radish seedlings. Sucrose was most effective in inducing anthocyanin accumulation and POD activity in both organs, followed by F/G; mannose caused only a little increase of anthocyanin content and POD activity in hypocotyls, but a decrease in roots. The distribution of anthocyanin accumulation was different between hypocotyls and roots in the presence or absence of sucrose. Anthocyanin was clearly induced in root tips and cortex under exogenous sucrose. Accumulation of anthocyanin was closely correlated to the increase of endogenous sucrose content rather than glucose or fructose content. Sucrose significantly induced the expressions of late anthocyanin biosynthetic genes by up-regulating Raphanus sativus myeloblastosis 1 and Raphanus sativus transparent testa 8 in both organs. The POD activity significantly increased following the remarkable accumulation of anthocyanin in hypocotyls under exogenous sucrose, which may be partially required for anthocyanin oxidation. In roots, the high POD activity might lead to a low anthocyanin content by degrading anthocyanin and diverting the metabolic flux to lignin synthesis.

Blue and UV-B light synergistically induce anthocyanin accumulation by co-activating nitrate reductase gene expression in Anthocyanin fruit (Aft) tomato.

The tomato accession LA1996, which carries a dominant allele of anthocyanin fruit (Aft) locus, accumulates anthocyanins in the epidermis of fruits when exposed to sunlight. The involvement of blue, UV-A, UV-B and a combination of these wavelengths on anthocyanin accumulation and the molecular mechanism of their regulation was investigated in LA1996. The most effective treatment for inducing anthocyanin biosynthesis in Aft fruits was co-irradiation with blue and UV-B (blue+UV-B) light. Finding the correlated genes is an important approach towards understanding their molecular mechanisms. In the present study, the nitrate reductase (NR) gene SlNIA was isolated using RNA-seq profiling of Aft fruits given different light treatments. The functions of NR-mediated anthocyanin induction by blue+UV-B were confirmed using a series of chemical treatments, followed by assessment of NR activity and nitric oxide (NO) detection. The expression of NR was highly induced by blue+UV-B, and this specificity was also confirmed with the enzyme activity of NR and the NO concentration. The NR inhibitors, which reduce NO generation, the expression levels of anthocyanin related genes and decreased anthocyanin accumulation in LA1996. Our results suggest that NR plays a key role in blue+UV-B-mediated anthocyanin accumulation in LA1996 fruits.

In vitro Anthocyanin Induction and Metabolite Analysis in Malus spectabilis Leaves Under Low Nitrogen Conditions

Absract Anthocyanins are the most widely produced secondary metabolites in plants, and they play an important role in plant growth and reproduction. The nitrogen source is an important factor affecting anthocyanin production, but the nitrogen concentrations on metabolism and the underlying genetic basis remain unclear. In this study, in vitro anthocyanin induction was conducted on Malus spectabilis. The leaf explants were cultivated in media containing different nitrogen concentrations. The results suggested that when the nitrogen contents decreased in limit, the color of leaf explants turned from green to red, and increased anthocyanin accumulation led to a change in phenotype. Furthermore, the content of other flavonoids, such as dihydroquercetin, epicatechin, and catechin, increased under low nitrogen conditions. The transcription levels of the general flavonoid pathway genes, from phenylalanine ammonia lyase (PAL) to anthocyanidin synthase (ANS), were associated with the concentration of corresponding flavonoid compounds and phenotype changes. In particular, the expression level of ANS increased substantially under a low nitrogen treatment, which was significantly and positively correlated with the anthocyanin levels (R2 = 0.72, P

Anthocyanin Induction by Drought Stress in the Calyx of Roselle Cultivars.

Abiotic factors can alter the chemical profile of crops and the number of compounds they contain. In this study, the anthocyanin and anthocyanidin contents, determined by ultra-performance liquid chromatography (UPLC-MS/MS), and the colour attributes of the calyces of three cultivars of Hibiscus sabdariffa subjected to three water stress regimes during the stage of physiological maturity were investigated. The total anthocyanin content in calyx increased relative to the control content under a 65% moisture irrigation regime. Among the cultivars, UAN16-2 showed the greatest increases in the contents of cyanidin, delphinidin 3-O-glucoside, cyanidin 3-O-glucoside, and cyanidin 3-O-sambubioside. The content of cyanidin 3-O-sambubioside showed the greatest increase, increasing by 55% relative to the control level. The contents of these compounds are correlated with colour attributes such as luminosity. Water stress under the 33% moisture condition during plant development led to decreased anthocyanin contents in all of the roselle cultivars.

PbMYB120 Negatively Regulates Anthocyanin Accumulation in Pear.

Subgroup 4 R2R3 MYBs play vital roles in the regulation of anthocyanin biosynthesis. However, there is limited knowledge regarding the functions of MYB repressors in pear (Pyrus × bretschneideri). Here, PbMYB120 was identified as a potential regulator of anthocyanin biosynthesis. A phylogenetic analysis revealed that PbMYB120 was clustered into the FaMYB1-like clade of the subgroup 4 R2R3 MYBs. PbMYB120 was expressed higher in red peels than in green peels in five pear cultivars. PbMYB120 expression was positively correlated with anthocyanin accumulation. However, the transient overexpression of PbMYB120 led to the inhibition of anthocyanin accumulation and PbUFGT1 expression. Promoter binding and activation assays indicated that PbMYB120 binds to the promoter of PbUFGT1 and represses the promoter’s activity. Thus, the inhibition of anthocyanin accumulation by PbMYB120 may be correlated with the repression of PbUFGT1. Furthermore, during anthocyanin induction, the expression levels of anthocyanin activators and PbMYB120 were upregulated. This study demonstrated that PbMYB120 was highly expressed in pear tissues having higher anthocyanin accumulations but acted as a repressor in the regulation of anthocyanin accumulation. PbMYB120 may work coordinately with anthocyanin activators and serve as a balancer of anthocyanin accumulation.

Genome-wide Association Analysis of Red Flesh Character Based on Resequencing Approach in Peach

Anthocyanins are important molecules that are responsible for fruit color formation and are also beneficial to human health. To date, numerous structural and regulatory genes associated with anthocyanin biosynthesis in peach (Prunus persica) have been reported based on linkage analysis. In this study, we sought to identify further genes associated with anthocyanin content in peach by conducting a genome-wide association analysis of 129 peach accessions to detect markers associated with the trait. Significant association signals were detected when anthocyanin content was considered a qualitative character but not when it was considered a quantitative trait. We detected an association region located between 11.7 and 13.1 Mb in chromosome 1, a region in which only 133 of 146 genes have previously been functionally annotated. Gene ontology annotation of the genes in this region showed that membrane-associated genes (including one gene encoding a chloride channel protein and 17 sugar transport/carrier-associated genes) were significantly enriched, and we focused on these in subsequent analyses. Based on in vitro induction of anthocyanins in fruit flesh using different exogenously applied sugars and subsequent culture, we found that the expression level of 3 of the 18 membrane-associated genes, Prupe.1G156300, Prupe.1G156900, and Prupe.1G157000, increased during induction treatment. Furthermore, during the fruit development period of a white-fleshed and a red-fleshed peach cultivar, the expression of one gene encoding a transmembrane sugar transport protein was observed to be positively correlated with anthocyanin biosynthesis. These results will facilitate understanding of the molecular mechanism of anthocyanin biosynthesis in peach.

Validation of reference genes for gene expression analysis of response to anthocyanin induction in cell cultures of Vitis davidii (Rom. Caill.) Foëx

Real-time quantitative polymerase chain reaction (RT-qPCR) is an effective method for detecting changes of gene expression in plant cell metabolic regulation. A set of 15 reference gene candidates were selected for the present study of anthocyanin biosynthesis regulation, and stability. The suitability of their expression was evaluated in eight different experimental treatments in spine grape (Vitis davidii [Rom. Caill.] Foex.) cell cultures. The results indicated that SAND family protein (SAND) and V-type proton ATPase subunit G (VAG) were the most stable reference genes for culture duration, tubulin alpha-3/alpha-5 chain (α-tubulin) and tubulin beta-1 chain (β-tubulin) for illumination conditions, ubiquitin-conjugating enzyme E2-17 kDa (UBQ) and VAG for UVB treatment, VAG and 60S ribosomal protein L18-2 (60SRP) for temperature treatment, AP47, clathrin adaptor complex subunit mu (AP-2) and 60SRP for cinnamic acid treatment, α-tubulin and UBQ for chitosan treatment, actin and alcohol dehydrogenase 2 (ADH2) for kinetin treatment, and β-tubulin and elongation factor 1-α (EF1-α) for cell line. Finally, the reliability of the selected reference genes was confirmed by investigating the expression profiles of the target gene dihydroflavonol 4-reductase (DFR) in spine grape cell cultures. The results of the present study offer the most robust platform for the most precise and broad application of RT-qPCR to investigate gene expression associated with anthocyanin biosynthesis in spine grape cell cultures.

Mitogen-activated protein kinase kinase 6 negatively regulates anthocyanin induction in Arabidopsis

ABSTRACTArabidopsis mitogen-activated protein (MAP) kinase kinase 6 (MKK6) has previously been shown to play important roles in plant immunity and cytokinesis. Here we report that it is also involved in the negative regulation of anthocyanin biosynthesis in Arabidopsis. Elevated anthocyanin levels are observed in mkk6 knock out mutant plants. RNA-sequencing analysis revealed that the expression level of MYB75 (Myb transcription factor 75), which encodes a key positive regulator of anthocyanin biosynthesis, is up-regulated in mkk6 mutant plants, suggesting that increased MYB75 expression contributes to the elevated anthocyanin levels. In addition, suppression of high sucrose-induced anthocyanin production by pathogen associated molecular pattern-triggered immunity is also dependent on MKK6, further supporting that MKK6 is a key negative regulator of anthocyanin biosynthesis in Arabidopsis.

Kinetics and modeling of cell growth for potential anthocyanin induction in cultures of Taraxacum officinale G.H. Weber ex Wiggers (Dandelion) in vitro

Background: Taraxacum officinale G.H. Weber ex Wiggers is a wild plant used in folk medicine to treat several diseases owing to bioactive secondary metabolites present in its tissue. The accumulation of such molecules in plant cells can occur as a response against abiotic stress, but these metabolites are often deposited in low concentrations. For this reason, the use of a biotechnological approach to improve the yields of technologically interesting bioactive compounds such as anthocyanins is a compelling option. This work focuses on investigating the potential of in vitro T. officinale cultures as an anthocyanin source. Results: To demonstrate the suitability of anthocyanin induction and accumulation in calluses under specific conditions, anthocyanin was induced in the T. officinale callus. A specific medium of 5.5% sucrose supplemented with 6-benzylaminopurine /1-naphthaleneacetic acid in a 10:1 ratio was used to produce an anthocyanin yield of 1.23 mg g-1 fw. An in vitro dandelion callus line was established from this experiment. Five mathematical models were then used to objectively and predictably explain the growth of anthocyanin-induced calluses from T. officinale. Of these models, the Richards model offered the most suitable representation of anthocyanin callus growth in a solid medium and permitted the calculation of the corresponding kinetic parameters. Conclusions: The findings demonstrate the potential of an in vitro anthocyanin-induced callus line from T. officinale as an industrial anthocyanin source.

Effect of Salicylic Acid on the Gene Transcript and Protein Accumulation of Flavonoid Biosynthesis-related Enzymes in Vitis vinifera Cell Suspension Cultures

Salicylic acid (SA) as a plant signal molecule plays an important regulatory role in stimulating the accumulation of plants’ defensive compounds. Numerous studies have shown its regulating effects on the biosynthesis of flavonoids. However, the controlling mechanism needs to be made clear further. Here, Vitis vinifera L. ‘Cabernet Sauvignon’ cell suspension cultures were treated with SA and its synthesis inhibitor paclobutrazol (Pac) to investigate their effects on flavonoid biosynthesis. The accumulation of gene transcripts and proteins of flavonoid biosynthesis pathway enzymes, including chalcone synthase (VvCHS), chalcone isomerase (VvCHI), dihydroflavonol 4-reductase (VvDFR), and anthocyanidin synthase (VvANS), were detected using real-time polymerase chain reaction (RT-PCR), quantitative polymerase chain reaction (qPCR), and western-blotting techniques. The results showed that treatment with exogenous SA at the proper concentration enhanced the production of flavonoids such as anthocyanins and proanthocyanidins (PAs) inside the suspension-cultured cells. The induction of anthocyanins and PAs was found to be time course-dependent. The mRNA and protein accumulation of VvCHS, VvCHI, VvDFR, and VvANS in the treatment system were enhanced too, and the changes were observed concomitantly. Treatment of Pac inhibited the induction of the accumulation of gene transcripts and proteins in accordance with the decreased accumulation of flavonoids. These results suggest that exogenous SA could induce both transcript and protein accumulation of flavonoid biosynthesis-related enzymes and in turn enhance the accumulation of flavonoid compounds such as anthocyanins and PAs in suspension-cultured grape cells.

Quantification of light screening by anthocyanins in leaves of Berberis thunbergii.

Up to 40% of incident light was screened in red Berberis leaves in vivo by anthocyanins, resulting also in up to 40% reduction of light-limited photosynthesis. The biological function of anthocyanins in leaves has been strongly discussed, but the hypothesis of a screening function is favored by most authors. For an evaluation of the function as photoprotective pigments, a quantification of their screening of the mesophyll is important. Here, chlorophyll fluorescence excitation of leaves of a red and a green variety of Berberis thunbergii was used to estimate the extent of screening by anthocyanins at 545nm and over the whole photosynthetically active wavelength range. Growth at high light (430µmolm-2s-1) resulted in 90% screening at 545nm corresponding to 40-50% screening over the whole wavelength range, depending on the light source. The concomitant reduction of photosynthetic quantum yield was of the same size as the calculated reduction of light reaching the chloroplasts. The induction of anthocyanins in the red variety also enhanced the epoxidation state of the violaxanthin cycle under growth conditions, indicating that red leaves were suffering less from excessive irradiance. Pool sizes of violaxanthin cycle carotenoids indicated a shade acclimation of the light harvesting complexes in red leaves. The observed reduction of internal light in anthocyanic leaves has by necessity a photoprotective effect.

Foliar-applied ethephon enhances the content of anthocyanin of black carrot roots (Daucus carota ssp. sativus var. atrorubens Alef.)

BackgroundBlack carrots (Daucus carota ssp. sativus var. atrorubens Alef.) constitute a valuable source of anthocyanins, which are used as natural red, blue and purple food colourants. Anthocyanins and phenolic compounds are specialised metabolites, accumulation of which often requires elicitors, which act as molecular signals in plant stress responses. In the present study, ethephon, an ethylene-generating compound was explored as enhancer of anthocyanin and phenolic contents during growth of ‘Deep Purple’ black carrots. The effects of ethephon on several parameters were investigated, and the expression of biosynthetic anthocyanin genes was studied during growth and anthocyanin accumulation.ResultsRoots of ethephon-treated carrot plants exhibited an increase in anthocyanin content of approximately 25%, with values ranging from 2.25 to 3.10 mg g−1 fresh weight, compared with values ranging from 1.50 to 1.90 mg g−1 fresh weight in untreated roots. The most rapid accumulation rate for anthocyanins, phenolic compounds, soluble solids and dry matter was observed between 10 and 13 weeks after sowing in both untreated and ethephon-treated carrots. The differences in anthocyanin contents between untreated and treated carrots increased for several weeks after the ethephon treatment was terminated. Five cyanidin-based anthocyanin forms were identified, with variable relative abundance values detected during root growth. Overall, the expression of the anthocyanin biosynthetic genes analysed (PAL1, PAL3, F3H1, DFR1, LDOX2) increased in response to ethephon treatment, as did the expression of the MYB1 transcription factor, which is associated with activation of the phenylpropanoid pathway under stress conditions. In addition, a correlation was proposed between ethylene and sugar contents and the induction of anthocyanin synthesis.ConclusionsThis study presents a novel method for enhancing anthocyanin content in black carrots. This finding is of economic importance as increased pigment concentration per unit of biomass implies improved profitability parameters in food colour production. We provide new insight into the accumulation patterns of the different cyanidin-based anthocyanins and phenolic compounds during root growth. Moreover, we show that enhanced anthocyanin content in ethephon-treated carrots is accompanied by increased expression of anthocyanin biosynthetic genes.

Induction of anthocyanin in the inner epidermis of red onion leaves by environmental stimuli and transient expression of transcription factors.

Novel imaging approaches have allowed measurements of the anthocyanin induction in onion epidermal cells that can be induced through water stress or transient expression of exogenous transcription factors. Environmental and genetic mechanisms that allow the normally colourless inner epidermal cells of red onion (Allium cepa) bulbs to accumulate anthocyanin were quantified by both absorbance ratios and fluorescence. We observed that water-stressing excised leaf segments induced anthocyanin formation, and fluorescence indicated that this anthocyanin was spectrally similar to the anthocyanin in the outer epidermal cells. This environmental induction may require a signal emanating from the leaf mesophyll, as induction did not occur in detached epidermal peels. Exogenous transcription factors that successfully drive anthocyanin biosynthesis in other species were also tested through transient gene expression using particle bombardment. Although the petunia R2R3-MYB factor AN2 induced anthocyanin in both excised leaves and epidermal peels, several transcription factors including maize C1 and Lc inhibited normal anthocyanin development in excised leaves. This inhibition may be due to moderate levels of conservation between the exogenous transcription factors and endogenous Allium transcription factors. The over-expressed exogenous transcription factors cannot drive anthocyanin biosynthesis themselves, but bind to the endogenous transcription factors and prevent them from driving anthocyanin biosynthesis.

Control of anthocyanin pigmentation during flower development inCymbidiumorchid

The range of flower colours in Cymbidium hybrida orchid is extensive. All three main pigment groups have been detected, but our focus has been on the anthocyanins, which may be present in all sepals and petals, only in the labellum, or as a colour blush. Since anthocyanin pigments have an important influence on final flower colour, it is important to study how their biosynthesis is regulated. We report here the isolation of a MYB transcription factor (ChMYB1) that is shown to be an anthocyanin-related MYB and likely to be part of a regulatory complex controlling anthocyanin biosynthesis in Cymbidium flowers. There are at least two separate phases of anthocyanin development in Cymbidium flowers. One occurs during flower bud development, and the other occurs in open flowers after pollination. The relatively rapid induction of anthocyanin biosynthesis after anther cap removal was used to monitor expression of the MYB1 gene and the flavonoid biosynthetic gene dihydroflavonol 4-reductase (DFR). The involvement of ethylene in this anthocyanin induction was examined by applying the ethylene action inhibitor, 1-methyl-cyclopropene (1-MCP), and by studying the expression of ethylene biosynthesis genes. Expression of the MYB1 gene was first detected 12 h after pollinia removal, and it peaked after 24 h, while expression of the DFR gene was first detected at 24 h after pollinia removal and it peaked after 48 h. 1-MCP treatment abolished completely both anthocyanin accumulation and the expression of the ChMYB1 and ChDFR genes. The results suggest that ChMYB1 regulates in Cymbidium hybrida flowers the pollination-induced anthocyanin production mediated by ethylene signalling.

The effect of sugars in relation to methyl jasmonate on anthocyanin formation in the roots of Kalanchoe blossfeldiana (Poelln.)

<p>This study investigated the effects of different sugars (sucrose, fructose, glucose) and sugar alcohols (mannitol, sorbitol) applied alone and in solution with methyl jasmonate (JA-Me) on the anthocyanin content in the roots of <em>Kalanchoe blossfeldiana</em>. None of the sugars used individually in the experiment affected anthocyanin accumulation in the roots of intact plants. The anthocyanin level was similar to that in the control. Sucrose at concentrations of 0.5% and 3.0%, and glucose at a concentration of 3.0% inhibited anthocyanin accumulation induced by JA-Me. Only fructose at a concentration of 3.0% stimulated anthocyanin accumulation induced by JA-Me. The sugar alcohols, mannitol at a concentration of 3.0% and sorbitol at 0.5% and 3.0%, inhibited anthocyanin accumulation in the roots of intact <em>K. blossfeldiana</em> plants induced by JA-Me. In excised roots, both sugars and JA-Me used individually did not affect the formation of anthocyanins. Also, the sugar alcohols (mannitol and sorbitol) applied simultaneously with JA-Me had no effect on the accumulation of anthocyanins. However, roots treated with sugars (sucrose, fructose, glucose) in solution with JA-Me promoted the induction of anthocyanins in the apical parts of the roots. </p><p>The results suggest that anthocyanin elicitation in the roots of <em>K. blossfeldiana</em> by methyl jasmonate may be dependent on the interaction of JA-Me with sugars transported from the stems (leaves) to the roots.</p>