Search

Poinsettia (Euphorbia pulcherrima, Willd. ex Klotzsch) originated in Mexico is an important ornamental tree in all over the world because its bract color can change from green to red under short-day conditions. In view of this, poinsettia not only has high ornamental value but also is an important model plant in studies on anthocyanin metabolism regulated by photoperiod. In this research, we compared the content of metabolic products in anthocyanin biosynthesis pathway and transcriptome sequencing data between green and red-turning bracts of poinsettia to clarify the mechanism of color change. The results of metabolic product analysis suggested that far downstream genes such as dihydroflavonol 4-reductase (DFR) gene in anthocyanin biosynthesis pathway could be inhibited in green bracts. A total of 91,917 uni-transcripts were identified through transcriptome sequencing. Seventy-two uni-transcripts were assigned to flavonoid biosynthesis pathways. Through a correlation analysis of gene expression profiles and color compound contents, DFR was taken into account as a candidate gene promoting anthocyanin accumulation in poinsettia bracts under short-day conditions. Transgenic research showed that overexpression of poinsettia DFR significantly increased the anthocyanin content in Arabidopsis (Arabidopsis thaliana). Based on these results, this research identified DFR as a promoter of anthocyanin accumulation in poinsettia bracts under short-day conditions. Moreover, the results of this research will shed light on elucidation of anthocyanin biosynthesis mechanism of plants and provide candidate genes for genetic improvement on poinsettia.

To fully elucidate molecular mechanisms of flavonoid biosynthesis in Chinese bayberry, transcriptomes of two genotypes with different colours, white cultivar (Shuijing, SJ) and red cultivar (Biqi, BQ), were compared. During fruit development, ‘BQ’ exhibited substantial increase of total anthocyanins content together with dramatic decrease of total soluble proanthocyanidins (PAs) content, while ‘SJ’ displayed decrease of total soluble PAs levels but failed to accumulate anthocyanin. Based on the sequencing results, 124,265 unigenes were generated with an average length of 708 bp. All genes involved in anthocyanin biosynthesis and glycosylation were identified and their expression patterns were in accordance with total anthocyanin accumulation in developing fruits of ‘BQ’ and ‘SJ’. Expression levels of leucoanthocyanidin reductase (LAR) and anthocyanidin reductase (ANR) were down-regulated in ‘SJ’ in agreement with the decrease in PAs, while an opposite trend was observed in ‘BQ’. The higher expression levels of LAR and ANR in ‘BQ’ may be an important reason for the higher levels of total soluble PAs as compared to ‘SJ’. Phylogenetic analysis showed that seven MYBs could be identified as putative homologues of PA-specific regulator and exhibited considerable genotypic and temporal specificity of expression. In addition, three WD40 genes in Chinese bayberry clustered with the WD40s related to flavonoid biosynthesis in other species. Finally, RNA-Seq data was validated by using qRT-PCR analysis with a high correlation, suggesting that the RNA-Seq data here are credible. These results provide new insights into the regulation of the complex branching pathway leading to various flavonoid compounds biosynthesis in bayberries.

In order to investigate the synergistic effect of abscisic acid and ethylene on tomato color development during ripening, mature green tomato fruit were harvested and treated with abscisic acid (ABA), 1-methylcyclopropene (1-MCP), alone or in combination, and dihydroguaiaretic acid (NDGA), and then were stored at 20 °C and 90% RH for fourteen days. Endogenous ethylene production, color development and the expression profiles of major related genes in treated fruits were examined. Furthermore, 2000 bp sequences upstream of major related genes were analyzed. Results indicated that ABA significantly up-regulated the expression levels of major genes related to carotenoids and flavonoids biosynthesis (ranging from 2.08 to 35 folds) and initiated the accumulation of carotenoids, phenolics and flavonoids by 2 or 4 days earlier than that in control. However, results demonstrated that the exogenous ABA could not significantly affect tomato color development without ethylene. The outcome of gene promoter analysis revealed that, besides single existence of ABRE or ERE motifs, 10 of 23 genes involved in carotenoids biosynthetic pathway, and 10 of 40 genes involved in flavonoid biosynthesis pathway possess both ABRE and ERE motifs in their 2000 bp upstream sequences, suggesting that ABA and ethylene may affect fruit color development via the collaborative regulation of these genes.

The rhizome is crucial for asexual propagation in plants. Green rhizome (termed as GR) and yellow rhizome (termed as YR) are the rhizomes of two Cymbidium tortisepalum var. longibracteatum cultivars with colour differences. In this study, we carried out integrated transcriptomic and metabolomic profiling to explore the pathways and key genes between them. The transcriptome assembled 134,527 unigenes and 508 unigenes (244 upregulated and 264 downregulated) with differential expression patterns. Metabolomic analysis identified 420 metabolites, and 115 were differentially accumulated metabolites, including 37 upregulated and 78 downregulated metabolites. Integration of transcriptome profiling and metabolite analysis revealed "phenylpropanoid biosynthesis" and "flavonoid biosynthesis" were significantly enriched. One R2R3 type v-myb avian myeloblastosis viral oncogene homologue (R2R3-MYB) transcription factor (c1121_g1), two basic helix-loop-helix (bHLH) transcription factors (c59082_g2 and c103838_g1), and five flavonoid biosynthesis related unigenes (c34902_g1, c82361_g1, c22242_g1, c39937_g1, c47509_g1) were highly expressed in YR, which is consistent with the flavonoid content. These findings shed light on the regulation of flavonoid biosynthesis and will contribute to the breeding of new cultivars in orchids.

Water availability is a crucial factor affecting fruit quality and productivity. A period of mild drought stress can increase fruit sweetness and improve fruit quality. However, the mechanism underlying the transcriptional regulation in Chinese jujube under water deficit conditions remains relatively uncharacterized. In this study, we analyzed the protein and sugar contents, the average weight, and transcript expression (RNA sequencing) of jujube fruit at different ripening stages (i.e., white mature and half-red fruit) under mild and severe water deficit conditions. The sucrose and protein contents increased significantly under water deficit conditions. The increase in water deficit stress from mild to severe did not significantly alter the sugar accumulation, but it decreased the average fruit weight. The sugar- and amino acid-related pathways, flavonoid biosynthesis, xyloglucan metabolism, and phenylpropanoid biosynthesis were affected by water deficit stress. Gene co-expression analyses identified many ABA- and ethylene-related genes with expression levels modulated by water deficit conditions, especially in the half-red stage. Additionally, we identified the key genes affecting fruit sugars, pigments, cell wall polysaccharides, and phenylpropanoids, which influence fruit quality. Notably, genes related to sugar transporters rather than sugar metabolism contributed to the sucrose accumulation. Flavonoid synthesis-related gene expression contributed to the earlier coloration of the stressed fruit than of the control fruit. Severe water deficit stress up-regulated the expression of pectinesterase and endotransglucosylase/hydrolase genes, which accelerated fruit ripening and softening. Regarding the phenylpropanoid biosynthesis pathway, the exposure to mild water deficit stress promoted the synthesis of secondary metabolites useful to humans (e.g., coniferin and syringin), whereas the severe water deficit treatment increased lignin accumulation. Considered together, these findings revealed the transcriptional regulatory mechanism that improved jujube fruit quality under mild drought conditions. Furthermore, the results of this study may be useful for optimizing the irrigation during jujube cultivation.

The efficacy of cinnamic acid (CA) as an antibrowning agent was evaluated in fresh-cut taro. Different concentrations (0.1 g L−1, 0.2 g L−1 and 0.4 g L−1) of CA treatments reduced the browning index and a* and b* values but maintained L* values, suggesting that CA treatments prevented the browning development of fresh-cut taro during storage. Among the concentrations used, 0.1 g L−1 CA was sufficient to reduce browning. CA treatment (0.1 g L−1) reduced the total flavonoid content and the activity and gene expression of four main enzymes (PAL, C4H, 4CL and CHS) in the flavonoid biosynthesis pathway, suggesting that CA treatment reduced taro browning by suppressing the de novo biosynthesis of flavonoid compounds. Furthermore, CA treatment significantly reduced the lignin content, activity and gene expression of cinnamyl-alcohol dehydrogenase and slightly reduced the firmness of taro slices. Moreover, CA treatment showed strong inhibition of PPO activity in vivo and in vitro, suggesting that CA reduced phenolic oxidation by inhibiting PPO activity. CA-treated taro showed significantly reduced hydrogen peroxide content but enhanced activity and gene expression of catalase and peroxidase. In addition, CA had strong radical scavenging activity, suggesting that the application of CA to fresh-cut taro enhanced antioxidant activity. Overall, CA treatment reduced the surface browning of fresh-cut taro by suppressing the activity of browning-related enzymes and by improving antioxidant activity. The results presented in this study indicate that CA is an effective natural antibrowning agent for fresh-cut taro.

It is well-known that abscisic acid (ABA) inhibits seed germination, but the mechanism is still unclear. In this study, after removing the seed coats, the seeds treated with 1 ppm ABA to inhibit embryo germination. A total of 715 compounds that were involved in 271 metabolic pathways were identified from a broadly targeted metabolome. Of these compounds, the number of flavonoids is most and accounting for 21%. Moreover, compared to the control embryos, over 80% of the differentially accumulated compounds (DACs) were down-regulated in the ABA-treated embryos, while only 46 compounds were up-regulated. These differentially accumulated compounds were involved in 26 metabolic pathways. Transcriptome analysis showed that 6348 genes were differentially expressed between ABA-treated and control embryos. These differentially expressed genes (DEGs) were enriched into 28 metabolic pathways including photosynthesis. Interestingly, both DEG and DAC analyses had identified the 10 common metabolic pathways, including oxidative phosphorylation, phenylpropanoid biosynthesis, flavonoid biosynthesis, pyrimidine metabolism, ascorbate and aldarate metabolism, galactose metabolism, glycolysis/gluconeogenesis, carbon metabolism, amino sugar and nucleotide sugar metabolism, and valine, leucine and isoleucine degradation. Taken together, ABA represses the expression of the genes involved in photosynthesis and those 10 metabolic pathways to suppress the secondary metabolism of the embryos, resulting in the inhibition of embryo germination.

Zanthoxylum armatum is an important economic tree for the food and pharmaceutical industries, due to its the special numbing taste. Despite having highly volatile aromatic compounds, the cultivars of Z. armatum are underexplored for genetics and molecular breeding programs. In this study, we integrated the fruit development and maturation process across eight samples (Fr1 to Fr8) in Z. armatum. From the Fr1 to Fr4 stage, the fruit grew rapidly to a certain size, however, in subsequent stages (Fr5 to Fr8) the fruit size did not increase but inclusions began to accumulate within the oil vacuole. Additionally, the significantly differentially expressed genes in the fruit compared with other organs (root, stem, leaves, and bud) were screened and enriched in 17 KEGG pathways, including 28 genes for terpenoids, 5 genes for alkaloids and 7 genes for flavonoid biosynthesis processes. Furthermore, some bioinformatic analyses were performed to obtain more information about these genes. Moreover, the RT-qPCR results of all vital genes selected in present study showed that the Fr4 stage was the core phase for the biosynthesis of numbing taste compounds in Z. armatum. To the best of our knowledge, this study is the first comprehensive analysis to identify the key genes associated with terpenoid, alkaloid and flavonoid biosynthesis processes in the fruit of Z. armatum. Our results will provide an insight into explore the genetic mechanism of numbing taste in Zanthoxylum, which will be helpful for identifying and breeding some high-quality varieties.

High temperature poses a major threat to sustainable development of the lettuce industry. Investigation of the mechanisms that regulate heat stress responses has great significance. Four lettuce accessions-two thermotolerant and two thermosensitive cultivars-were selected for comparative analysis. Subsequently, the metabolic changes in lettuce in response to heat treatment were investigated using untargeted metabolomic analysis. Several discriminatory metabolites were identified, including three amino acids, one carbohydrate, eight phenolic compounds, one terpene, one alcohol and one lignin. Transcriptomics analysis was performed in parallel using the same four lettuce accessions. The integrated analysis suggested that a large number of metabolites and genes detected with measurable changes during the heat response are involved in flavonoid biosynthesis. Additionally, 25 of the 31 transcription factors identified, including MYBs, WRKYs, NACs, bHLHs, MADSs, AP2/ERFs and bZIP, were also upregulated. Thus, this study provides a comprehensive understanding of the complex molecular mechanisms underlying the thermal stress responses of lettuce.

The formation of rough-skinned fruits is one of the major factors that adversely affect the Korla pear (Pyrus sinkiangensis Yu) fruit quality. However, little is known about the underlying mechanism of pericarp roughening. The aim of this study was to determine the metabolic pathways and biological processes involved in the formation of rough-skinned fruits using both the pericarp and pulp of normal and rough-skinned fruits. Morphological and physiological observations showed that stone cell, cellulose, hemicellulose, lignin and polysaccharide contents in both the pericarp and pulp of rough-skinned fruits were significantly higher than normal fruits. However, flavor substances like soluble sugar, fructose, glucose, and sucrose were abundant in the pulp of normal fruits. In addition, the total phenol, flavone and isoflavone contents were much higher in the pericarp of rough-skinned fruits than in that of normal fruits, while anthocyanin was abundant in the pericarp of normal fruits. Accordingly, in our metabolomic and transcriptomic analysis, the differentially accumulated metabolites (DAMs) and differentially expressed genes (DEGs) involved in flavone and flavonol biosynthesis, flavonoid biosynthesis, and phenylalanine metabolism pathways were further investigated. Moreover, we identified 33 DAMs and 84 DEGs that were enriched in the aforementioned pathways. Compared with normal fruits, these DAMs and DEGs were significantly upregulated in both the pericarp and pulp of rough-skinned fruits. Correlation analysis indicates that these identified genes encode enzymes that are responsible for the biosynthesis of DAMs identified in this study. Significant enrichment of these pathways in both the pericarp and pulp of rough-skinned fruits is probably responsible for pericarp roughening and lack of coloring in rough-skinned fruits.

Litchi is a subtropical fruit crop indigenous to South China. The pericarp of the variety Feizixiao does not display the overall bright red hue at harvest, i.e. “stay-green” phenomenon. This phenomenon could be solved by Mg foliar nutrient sprays. This study will attempt to discover the molecular mechanisms in litchi pericarp under Mg treatment by sequencing and de novo assembling the transcriptome. We assembled 50809 unigenes with an average length of 735.47 bp; approximately 55.11% (28005) of unigenes could be annotated using the NCBI (National Center of Biotechnology Information) non-redundant (nr) database. Five DGE libraries have been generated from litchi pericarp, and approximately 20 million filtered reads per library were generated. A total of 1226 unigenes were found to be differently expressed in the pair-wise comparisons between any two periods of Mg-treated, and genes encoding key enzymes involved in flavonoid biosynthesis, anthocyanin biosynthesis, ABA signal pathway were identified.

Plants are known to utilize electrical signals under several physiological conditions and electrical stimulation from the outside induces physiological changes in plants. In this study, to improve grape berry composition in field-grown grapevines, electrical stimulation of grapevine using solar panels was undertaken as an abiotic stress generator in 2015 and 2016 growing seasons. Electrical stimulation had a notable effect on grapevine growth and development as well as photosynthetic performance. Berry weight and tartaric acid and total phenolic contents in berries of grapevines exposed to electrical stimulation were similar among the grapevines tested. Brix in berries of grapevines exposed to electrical stimulation and electrode-treated grapevines was higher than that in control grapevines in both years. Electrical stimulation increased anthocyanin and resveratrol contents in berries of grapevines in both years relative to those of control grapevines and electrode-treated grapevines. The alteration of Brix and anthocyanin and resveratrol contents in berries was supported by the results of microarray analysis demonstrating the transcriptional upregulation of genes related to sucrose metabolism, phenylpropanoid biosynthesis, flavonoid biosynthesis, stilbenoid biosynthesis, and anthocyanin biosynthesis in grape cells exposed to electrical stimulation. Taken together, the results suggested that electrical stimulation of grapevine enhanced anthocyanin and resveratrol biosynthesis by activating their biosynthetic pathways.

Dopamine (DA) acts as a mediator in numerous plant physiological processes. In order to provide a basis for apple fruit quality improvements, we applied dopamine to apple trees via spraying (SDA) and watering (WDA). Five-year-old Changfu 2 (Malus domestica Borkh. cv. Naganofuji No.2) apple trees were treated with SDA or WDA in 0, 50, 100 and 200 μM. Results demonstrate that fruit fructose, sucrose and anthocyanin content, and ethylene production significantly increased for SDA100 and WDA100. Furthermore, the significant upregulation in WDA100 compared to WDA0 was observed for sugar transporter and flavonoid biosynthesis genes. Differential metabolite profiling analysis revealed the ability of flavonoids to distinguish between WDA0 and WDA100. Overexpression of the apple tyrosine decarboxylase gene MdTyDC in apple calli improved the dopamine and soluble content. This study demonstrates the role of dopamine as a regulator of the flavonoids and soluble sugar metabolism in improving apple fruit quality.

Recent studies have suggested that sound waves regulate the growth, phytochemical contents, and stress responses of plants. Here, we investigated the effect of different frequencies of sound waves (0.25, 0.8, 1 and 1.5 kHz) on the flavonoid contents and antioxidative properties of 1–6 day treated sprouts, including red radish (Raphanus sativus), lettuce (Lactuca sativa), and Chinese cabbage (Brassica rapa subsp. pekinensis). These sprouts were treated with each sound wave for 2 h per day for either consecutive (long term [LT]) or three alternating (1st, 3rd, and 5th) days (short term [ST]). The flavonoid contents of the sprouts were found to vary according to the sound frequency, exposure time, species, and growth conditions. A 25–88% increase in flavonoid content could be induced in the sprouts under specific conditions. Quantitative RT-PCR (qPCR) based analysis showed that the expression patterns of the flavonoid biosynthesis-related genes were correlated with the flavonoid contents observed in each treatment suggesting that sound waves regulate the flavonoid biosynthesis pathway. In addition, DPPH and FRAP assays indicated that the antioxidative effects of the sprouts were significantly higher under certain sound wave treatments. Furthermore, the flavonoid accumulation was positively correlated with the antioxidative properties of the sprouts. Therefore, sound waves with a particular frequency could be used to improve the phytochemical contents of crops for functional products.

Tea ( Camellia sinensis (L.) O. Kuntze) is a commercially important crop valued for its secondary metabolites. Different cultivation methods affect tea quality by altering the biosynthesis of flavonoids. Shade can effectively improve the quality of tea beverages by causing reduction of the concentration of flavonoids, the main compounds that contribute to astringency, in the leaves. The aim of this study was to analyze the influence of shade on flavonoid biosynthesis in relation to expression of the flavonoid pathway genes in tea leaves. Our data revealed that shade had notable effects on both flavonoid (including catechins, O -glycosylated flavonols and proanthocyanins (PAs)) and lignin biosynthesis, but had no significant effect on anthocyanin accumulation. Among all the detected compounds, the concentration of PAs and O -glycosylated flavonols in shaded leaves changed more than other compounds, decreasing 53.37% and 43.26%, respectively, compared to the sunlight-exposed leaves. Expression of phenylalanine ammonialyase ( PAL ), flavanone 3-hydroxylase ( F3H ), flavonoid 3′-hydroxylase ( F3 ′ H ), dihydroflavonol reductase ( DFR ) and anthocyanidin reductase1 ( ANR1 ) was notably correlated with the concentration of PAs in leaves, and expression of chalcone synthase ( CHS ) and flavonoid 3′,5′-hydroxylase ( F3 ′ 5 ′ H ) was remarkably correlated with the concentration of O -glycosylated flavonols. It is suggested that polymerization of catechins and glycosylation of flavonols might be key pathways of flavonoid metabolism in tea leaves affected by shade treatment. Regarding phenolic acids, a marked increase in concentration in shaded leaves and negative correlation with lignin accumulation suggests that phenolic acids might compete for the same substrate with lignins and flavonoids in tea leaves under different illumination conditions. Further investigations are required to understand the relationship between phenolic acids and other flavonoid compounds in tea plants.

The cotyledon stage is a crucial developmental stage during longan embryo development. Two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption ionization-time of flight-tandem mass spectrometry (MALDI-TOF/TOF-MS) were conducted to separate and identify proteins expressed in the longan cotyledon embryos at different development stages. A total of 28 proteins that exhibited regulated expression were successfully identified with a protein identification success rate of 72.2%. The 28 proteins were assigned to six functional classes based on their putative biological functions: energy and metabolism (21%), secondary metabolism (18%), protein metabolism (21%), cell division (11%), antioxidation (4%), nucleic acid metabolism (4%), hormonal regulation (4%) and unknown proteins (18%). Interestingly, three enzymes involved in flavonoid biosynthesis, whose expression in embryos had not been observed previously were clearly up-regulated during the cotyledon stage of embryo development in longan. Identification and analysis of the 28 proteins would shed new lights on further understanding of the biochemical and physiological processes of the embryo development at cotyledon stage in longan.

Chalcone synthase (CHS) and chalcone isomerase (CHI) are two key genes involved in flavonoid biosynthesis. They were both cloned from Guoqing No. 4 satsuma mandarin (Citrus unshiu Marcow), and their relative expression and accumulation of corresponding flavonoid components during fruit maturation were investigated by real-time PCR and HPLC techniques, respectively. During fruit maturation, expression of CHS and CHI genes declined gradually in peels, as well as the concentrations of total flavonoids, trans-chalcone, narirutin and hesperidin; in pulps, however, expression of both genes showed an approximately uptrend, and the concentrations of total flavonoids and those three components were detected in a lower level without significant changes among different developmental periods (P

The forward and reverse suppression subtractive cDNA libraries were constructed in petals of Eustoma grandiflorum at bud stage (stage 1) and anthesis (stage 7). Approximately 1000 clones were isolated from stage 1- (S1) and stage 7-specific (S7) libraries. The clones were sequenced and assembled, which yielded 98 contigs and 444 singletons. BLAST search was conducted on these assembled sequences. Generally, probes isolated from the S7 library exhibited higher expression at stage 7 by microarray analysis, as did those of the S1 library at stage 1. A clone set from the S7 library contained genes from later steps of anthocyanin biosynthesis pathway, terpene synthases, GAST (gibberellic acid-stimulated) family proteins, xyloglucan endotransglucosylase/hydrolase, glycosidases, and stress- and senescence-related proteins. In contrast, the S1 library contained genes associated with flavonol biosynthesis, phenylpropanoid metabolism, terpenoid metabolism, and floral organ development. Gene expression profiling for flavonoid biosynthesis was in accordance with preferential accumulation of flavonols at bud stages and anthocyanins at anthesis.

As a tool for breeding new floral colors into azalea, we obtained basic gene information for flavonoid synthesis in floral tissues of azalea ( Rhododendron × pulchrum Sweet cv. Oomurasaki). The partial- or full-length cDNA sequences of eight structural genes involved in the flavonoid biosynthetic pathway were isolated: chalcone synthase (CHS), chalcone isomerase (CHI), flavonone-3-hydroxylase (F3H), flavonoid-3′hydroxylase (F3′H), flavonoid-3′,5′-hydroxylase (F3′5′H), dihydroflavonol reductase (DFR), anthocyanidin synthase (ANS), and flavonol synthase (FLS). These genes were isolated from petals of R. × pulchrum by PCR using degenerate and gene-specific primers and their expression levels were analyzed. Deduced amino acid sequences of obtained genes showed 76–80% identities with the corresponding flavonoid biosynthetic pathway sequences from other dicotyledonous species. Expression of these eight genes during azalea flower development was investigated. A real-time PCR analysis showed that transcripts of CHS , F3H and ANS genes decreased as flowering progressed, and those of CHI , DFR , F3 ′ H , and FLS genes transiently increased at the stage of pigmentation initiation. In addition, maximum expression of the F3 ′ 5 ′ H gene was expressed concomitant with anthocyanin synthesis. Spatial expression showed that the CHS , DFR , and FLS genes are more abundant in other floral organs or leaves than petals. The levels of CHI , F3H , ANS , and F3 ′ H gene transcripts were highest in leaf tissue compared with floral organs. The highest level of F3 ′ 5 ′ H expression was in the petal at stage 3. These results indicated that F3 ′ 5 ′ H gene is strongly correlated to pigmentation in azalea petals, but expression of other genes are unclear for anthocyanin synthesis.

The effect of ethephon (2-chloroethyl phosphonic acid) and a seniphos-like substance (SLS) (a mixture of 310 g/l P 2 O 5 , 56 g/l CaO and 30 g/l N: 1% NO 3 and 2% NH 3 ) on the coloring of skin of ‘Fuji’ apple were studied. Both treatments applied 4 weeks before commercial harvest, caused an enhancement of red peel color and an increase in concentration of flavonoid compounds. Anthocyanin, proanthocyanidins and flavonols showed different accumulation pattern with different treatments during fruit maturation, but eventually became similar concentrations at harvest. ACC (1-aminocyclopropane-1-carboxylic acid) oxidase activity and internal ethylene concentration were greatly increased by the ethephon treatment but slightly by SLS treatment. The ethephon treatment increased greatly the chalcone isomerase (CHI) activity, and moderately phenylalanine-ammonia lyase (PAL) activity, but showed no effect on UDP-3- O -galactosyltransferase (UFGalT), all of which are involved in flavonoid biosynthesis. On the other hand, the SLS increased PAL and UFGalT activities greatly and CHI activity moderately.

Analysis of flavonoid composition and gene expression of enzymes involved in anthocyanin synthesis in flowers of four acyanic and one cyanic cultivar of Sim carnation showed that the acyanic flower cultivars are divided into three types. The first includes two normal white cultivars, ‘U Conn Sim’ and ‘White Sim’; the second includes a nearly pure white cultivar, ‘Kaly’; and the third includes a nearly pure white cultivar, ‘White Mind’. ‘U Conn Sim’ and ‘White Sim’ accumulated flavonol glycosides and lacked anthocyanins. The transcription of the several genes of enzymes involved in flavonoid biosynthesis were reduced at a later flowering stage than the cyanic cultivar, especially the genes encoding dihydroflavonol 4-reductase and anthocyanidin synthase. ‘Kaly’ accumulated flavanone glycosides and a small amount of flavonol and flavone glycosides by blocking the transcription of the gene encoding flavanone 3-hydroxylase, in addition to the transcriptional reduction of the genes for flavonoid biosynthesis at a later flowering stage. Although ‘White Mind’ contains little flavonoid, the position of the block on flavonoid biosynthesis in ‘White Mind’ is not known.

Measurement of flower colors with a color analyzer showed significant differences among 13 white carnation (Dianthus caryophyllus L.) cultivars. Petals of three cultivars, `White Mind', `Kaly' and `White Barbara', were nearly pure white, compared with the other 10 cultivars. Analysis of pigment composition by two-dimensional thin-layer chromatography classified 13 white cultivars into three types. The nearly pure-white cultivar, `White Mind' lacked flavonoid compounds in the petals. `Kaly' and `White Barbara' accumulated a large amount of naringenin derivatives. The other normal white cultivars contained kaempferol derivatives as the major flavonoid. We concluded that `White Mind', `Kaly' and `White Barbara' were nearly pure white because they lack flavonols, such as kaempferol derivatives. Our results suggest that in `White Mind', the flavonoid biosynthesis pathway is blocked before chalcone synthesis, whereas in `Kaly' and `White Barbara' it is blocked at the flavanone-3-hydroxylase step.