Role of aluminum in red-to-blue color changes in <Emphasis Type="Italic">Hydrangea macrophylla</Emphasis> sepals

Red, purple, and blue sepals on selected cultivars of Hydrangea macrophylla were analyzed for their aluminum content. This content was determined to be a function of the sepal color with red sepals possessing 0–10 μg Al/g fresh sepal, purple sepals having 10–40 μg Al/g fresh sepal, and blue sepals containing greater than 40 μg Al/g fresh sepal. Accordingly, the threshold aluminum content needed to change H. macrophylla sepals from red to blue was about 40 μg Al/g fresh sepal. Higher aluminum concentrations were incorporated into the sepals, but this additional aluminum did not affect the intensity or hue of the blue color. These observations agreed with a chemical model proposing that the concentration of the blue Al³⁺-anthocyanin complex reached a maximum when a sufficient excess of aluminum was present. In addition, the visible absorbance spectra of harvested red, purple, and blue sepals were duplicated by Al³⁺ and anthocyanin (delphinidin-3-glucoside) mixtures in this model chemical system.     

Accumulation of Anthocyanins and Flavones during Bud and Flower Development in Campanula isophylla Moretti

In the blue flowers of Italian bellflower (Campanula isophyllaMoretti), the formation of anthocyanins progresses from simpleunacylated anthocyanins, delphinidin 3–glucoside and bisdeacylplatyconin,through a series of progressively-acylated and glycosylatedcompounds, including diacylated violdelphin and monodeacylcampanin,to the triacylated campanin. In this study, anthocyanin andflavone contents were very low in buds until a few days beforeanthesis, after which they increased rapidly. Bisdeacylplatyconinand luteolin 7-O -glucoside peaked 2 d before anthesis. Themore complicated luteolin glucosides peaked 2 d after anthesis,slightly preceding monodeacylcampanin and campanin. Total anthocyanincontent peaked approx. 5 d after anthesis followed by a slowdecline. The highest total flavone content was reached at anthesis,after which it remained almost constant, but with some changesin the proportion of individual compounds. In the investigationtwo phenotypes were used, types B and C. Acylation of monodeacylcampaninto campanin is blocked in type B, but not in type C plants.Conversion of bisdeacylplatyconin into acylated anthocyaninswas shown to be slower in type C than in type B plants. Campanula isophylla ; Campanulaceae; Italian bellflower; anthocyanin; flavone; biosynthesis; flower development     

p-Hydroxybenzoyl-Glucose Is a Zwitter Donor for the Biosynthesis of 7-Polyacylated Anthocyanin in Delphinium

The blue color of delphinium (Delphinium grandiflorum) flowers is produced by two 7-polyacylated anthocyanins, violdelphin and cyanodelphin. Violdelphin is derived from the chromophore delphinidin that has been modified at the 7-position by Glc and p-hydroxybenzoic acid (pHBA) molecules. Modification of violdelphin by linear conjugation of Glc and pHBA molecules to a Glc moiety at the 7-position produces cyanodelphin. We recently showed that anthocyanin 7-O-glucosylation in delphinium is catalyzed by the acyl-Glc–dependent anthocyanin glucosyltransferase (AAGT). Here, we sought to answer the question of which enzyme activities are necessary for catalyzing the transfer of Glc and pHBA moieties to 7-glucosylated anthocyanin. We found that these transfers were catalyzed by enzymes that use p-hydroxybenzoyl-Glc (pHBG) as a bifunctional acyl and glucosyl donor. In addition, we determined that violdelphin is synthesized via step-by-step enzymatic reactions catalyzed by two enzymes that use pHBG as an acyl or glucosyl donor. We also isolated a cDNA encoding a protein that has the potential for p-hydroxybenzoylation activity and two AAGT cDNAs that encode a protein capable of adding Glc to delphinidin 3-O-rutinoside-7-O-(6-O-[p-hydroxybenzoyl]-glucoside) to form violdelphin.     

Analysis of flavonoids in flower petals of soybean near-isogenic lines for flower and pubescence color genes

W1, W3, W4, and Wm genes control flower color, whereas T and Td genes control pubescence color in soybean. W1, W3, Wm, and T are presumed to encode flavonoid 3'5'-hydroxylase (EC 1.14.13.88), dihydroflavonol 4-reductase (EC 1.1.1.219), flavonol synthase (EC 1.14.11.23), and flavonoid 3'-hydroxylase (EC 1.14.13.21), respectively. The objective of this study was to determine the structure of the primary anthocyanin, flavonol, and dihydroflavonol in flower petals. Primary component of anthocyanin in purple flower cultivars Clark (W1W1 w3w3 W4W4 WmWm TT TdTd) and Harosoy (W1W1 w3w3 W4W4 WmWm tt TdTd) was malvidin 3,5-di-O-glucoside with delphinidin 3,5-di-O-glucoside as a minor compound. Primary flavonol and dihydroflavonol were kaempferol 3-O-gentiobioside and aromadendrin 3-O-glucoside, respectively. Quantitative analysis of near-isogenic lines (NILs) for flower or pubescence color genes, Clark-w1 (white flower), Clark-w4 (near-white flower), Clark-W3w4 (dilute purple flower), Clark-t (gray pubescence), Clark-td (near-gray pubescence), Harosoy-wm (magenta flower), and Harosoy-T (tawny pubescence) was carried out. No anthocyanins were detected in Clark-w1 and Clark-w4, whereas a trace amount was detected in Clark-W3w4. Amount of flavonols and dihydroflavonol in NILs with w1 or w4 were largely similar to the NILs with purple flower suggesting that W1 and W4 affect only anthocyanin biosynthesis. Amount of flavonol glycosides was substantially reduced and dihydroflavonol was increased in Harosoy-wm suggesting that Wm is responsible for the production of flavonol from dihydroflavonol. The recessive wm allele reduces flavonol amount and inhibits co-pigmentation between anthocyanins and flavonols resulting in less bluer (magenta) flower color. Pubescence color genes, T or Td, had no apparent effect on flavonoid biosynthesis in flower petals.     

Engineering of the rose flavonoid biosynthetic pathway successfully generated blue-hued flowers accumulating delphinidin

Flower color is mainly determined by anthocyanins. Rosa hybrida lacks violet to blue flower varieties due to the absence of delphinidin-based anthocyanins, usually the major constituents of violet and blue flowers, because roses do not possess flavonoid 3',5'-hydoxylase (F3'5'H), a key enzyme for delphinidin biosynthesis. Other factors such as the presence of co-pigments and the vacuolar pH also affect flower color. We analyzed the flavonoid composition of hundreds of rose cultivars and measured the pH of their petal juice in order to select hosts of genetic transformation that would be suitable for the exclusive accumulation of delphinidin and the resulting color change toward blue. Expression of the viola F3'5'H gene in some of the selected cultivars resulted in the accumulation of a high percentage of delphinidin (up to 95%) and a novel bluish flower color. For more exclusive and dominant accumulation of delphinidin irrespective of the hosts, we down-regulated the endogenous dihydroflavonol 4-reductase (DFR) gene and overexpressed the Irisxhollandica DFR gene in addition to the viola F3'5'H gene in a rose cultivar. The resultant roses exclusively accumulated delphinidin in the petals, and the flowers had blue hues not achieved by hybridization breeding. Moreover, the ability for exclusive accumulation of delphinidin was inherited by the next generations.     

Genetic engineering of the anthocyanin biosynthetic pathway with flavonoid-3′,5′-hydroxylase: specific switching of the pathway in petunia

Flavonoid-3',5'-hydroxylase (F3'5'H) is the key enzyme in the synthesis of 3',5'-hydroxylated anthocyanins, which are generally required for the expression of blue or purple flower color. It has been predicted that the introduction of this enzyme into a plant species that lacks it would enable the production of blue or purple flowers by altering the anthocyanin composition. We present here the results of the genetic engineering of petunia flower color, pigmentation patterns and anthocyanin composition with sense or antisense constructs of the F3'5'H gene under the control of the CaMV 35S promoter. When sense constructs were introduced into pink flower varieties that are deficient in the enzyme, transgenic plants showed flower color changes from pink to magenta along with changes in anthocyanin composition. Some transgenic plants showed novel pigmentation patterns, e.g. a star-shaped pattern. When sense constructs were introduced into blue flower petunia varieties, the flower color of the transgenic plants changed from deep blue to pale blue or even pale pink. Pigment composition analysis of the transgenic plants suggested that the F3'5'H transgene not only created or inhibited the biosynthetic pathway to 3',5'-hydroxylated anthocyanins but switched the pathway to 3',5'-hydroxylated or 3'-hydroxylated anthocyanins.     

Changes in Amide-Linked and Ester Indole-3-Acetic Acid in Cotton Fruiting Forms during Their Development

The concentration of free indoleacetic acid (IAA) is high in cotton (Gossypium hirsutum L.) fruiting forms before anthesis, but is low at and for a few days after anthesis. Amide-linked and ester IAA were measured in fruiting forms at 9, 6, and 3 days before anthesis; at anthesis; and at 2, 4, 7, and 9 days after anthesis to determine if free IAA decreased because it was converted to a conjugated form. That did not appear to be the case. While the major decrease in free IAA occurred during the 6 days before anthesis, ester IAA increased only a small amount and amide-linked IAA decreased even more than free IAA. During the 6 days before anthesis free IAA decreased from 0.62 to 0.12 micrograms per gram and amide-linked IAA decreased from 19.14 to 1.16 micrograms per gram dry weight. No evidence was found that a large amount of amide-linked IAA was converted to an insoluble form; flowers contained less than 1 microgram per gram of insoluble IAA. The free and amide-linked IAA must have been converted to other forms, perhaps by oxidation. Soluble amide-linked IAA remained low after anthesis. No ester IAA was detected 6 days before anthesis and only 0.08 microgram per gram dry weight was measured at anthesis. The concentration of ester IAA increased thereafter to 4.43 micrograms per gram at 9 days after anthesis. Therefore, amide-linked IAA was the major form of IAA in flower buds and ester IAA was the major form in young fruits (bolls). Minimum concentrations of free and total IAA occurred during the 4 days after anthesis, a stage when cotton fruiting forms are most likely to abscise. The large decreases in free and amide-linked IAA during the 6 days before anthesis may indicate a rapid turnover of IAA in flower buds. But, the decrease in free IAA was not accompanied by a comparable increase in ester or amide-linked IAA.     

Relationship between the composition of flavonoids and flower colors variation in tropical water lily (Nymphaea) cultivars

Water lily, the member of the Nymphaeaceae family, is the symbol of Buddhism and Brahmanism in India. Despite its limited researches on flower color variations and formation mechanism, water lily has background of blue flowers and displays an exceptionally wide diversity of flower colors from purple, red, blue to yellow, in nature. In this study, 34 flavonoids were identified among 35 tropical cultivars by high-performance liquid chromatography (HPLC) with photodiode array detection (DAD) and electrospray ionization mass spectrometry (ESI-MS). Among them, four anthocyanins: delphinidin 3-O-rhamnosyl-5-O-galactoside (Dp3Rh5Ga), delphinidin 3-O-(2"-O-galloyl-6"-O-oxalyl-rhamnoside) (Dp3galloyl-oxalylRh), delphinidin 3-O-(6"-O-acetyl-β-glucopyranoside) (Dp3acetylG) and cyanidin 3- O-(2"-O-galloyl-galactopyranoside)-5-O-rhamnoside (Cy3galloylGa5Rh), one chalcone: chalcononaringenin 2'-O-galactoside (Chal2'Ga) and twelve flavonols: myricetin 7-O-rhamnosyl-(1 → 2)-rhamnoside (My7RhRh), quercetin 7-O-galactosyl-(1 → 2)-rhamnoside (Qu7GaRh), quercetin 7-O-galactoside (Qu7Ga), kaempferol 7-O-galactosyl-(1 → 2)-rhamnoside (Km7GaRh), myricetin 3-O-galactoside (My3Ga), kaempferol 7-O-galloylgalactosyl-(1 → 2)-rhamnoside (Km7galloylGaRh), myricetin 3-O-galloylrhamnoside (My3galloylRh), kaempferol 3-O-galactoside (Km3Ga), isorhamnetin 7-O-galactoside (Is7Ga), isorhamnetin 7-O-xyloside (Is7Xy), kaempferol 3-O-(3"-acetylrhamnoside) (Km3-3"acetylRh) and quercetin 3-O-acetylgalactoside (Qu3acetylGa) were identified in the petals of tropic water lily for the first time. Meanwhile a multivariate analysis was used to explore the relationship between pigments and flower color. By comparing, the cultivars which were detected delphinidin 3-galactoside (Dp3Ga) presented amaranth, and detected delphinidin 3'-galactoside (Dp3'Ga) presented blue. However, the derivatives of delphinidin and cyanidin were more complicated in red group. No anthocyanins were detected within white and yellow group. At the same time a possible flavonoid biosynthesis pathway of tropical water lily was presumed putatively. These studies will help to elucidate the evolution mechanism on the formation of flower colors and provide theoretical basis for outcross breeding and developing health care products from this plant.     

Agroinfiltration: a rapid and reliable method to select suitable rose cultivars for blue flower production

Rose cultivars with blue flower color are among the most attractive breeding targets in floriculture. However, they are difficult to produce due to the low efficiency of transformation systems, interactive effects of hosts and vectors, and lengthy processes. In this study, agroinfiltration-mediated transient expression was investigated as a tool to assess the function of flower color genes and to determine appropriate host cultivars for stable transformation in Rosa hybrida. To induce delphinidin accumulation and consequently to produce blue hue, the petals of 30 rose cultivars were infiltrated with three different expression vectors namely pBIH-35S-CcF3′5′H, pBIH-35S-Del2 and pBIH-35S-Del8, harbouring different sets of flower color genes. The results obtained showed that the ectopic expression of the genes was only detected in three cultivars with dark pink petals (i.e. ‘Purple power’, ‘High & Mora’ and ‘Marina’) after 6–8 days. The high performance liquid chromatography analyses confirmed delphinidin accumulation in the infiltrated petals caused by transient expression of CcF3′5′H gene. Moreover, there were significant differences in the amounts of delphinidin among the three cultivars infiltrated with the three different expression vectors. More specifically, the highest delphinidin content was detected in the cultivar ‘Purple power’ (4.67 µg g^?1 FW), infiltrated with the pBIH-35S-Del2 vector. The expression of CcF3′5′H gene in the infiltrated petals was also confirmed by real time PCR. In conclusion and based on the findings of the present study, the agroinfiltration could be regarded as a reliable method to identify suitable rose cultivars in blue rose flower production programs.     

紫茉莉开花过程中花色和花色素的变化规律

紫茉莉是我国广泛分布的庭院花卉之一,具有丰富的花色。但不同花色紫茉莉在开花过程中的花色变化规律及其呈色机制还不清楚。以紫红色、黄色和白色紫茉莉为研究对象,分别通过色差仪测定法和紫外-可见分光光度法测定了不同开花时期不同花色紫茉莉花色表型及各类色素含量,探讨了其花色和色素变化规律,揭示其呈色机制。结果表明,从花蕾期到盛开期,紫红色紫茉莉花冠由淡绿色转变为紫红色,明度L^*值和色相b^*值减小,而色相a^*值、色度C^*值和色度角h值增大,叶绿素含量逐渐下降,类胡萝卜素、花色素苷和总黄酮含量逐渐升高;黄色紫茉莉花冠由淡绿色转变为黄色,盛开期具有最高的色度C^*值、色相a^*值和b^*值,整个开花过程具有较稳定的叶绿素和总黄酮含量,同时具有较高的类胡萝卜素含量;白色紫茉莉花冠由淡绿色转变为白色,过渡期具有最高的明度L^*值、色度C^*值、色相a^*值和b^*值,整个开花过程花色素苷和总黄酮含量较低,但随着开花进程逐渐升高,而类胡萝卜素含量稳定,过渡期总叶绿素含量显著低于其他2个时期。可见,不同花色紫茉莉开花过程中花色变化规律存在差异,而其差异性与其相应的色素成分变化密切相关。     

Anthocyanins and anthocyanidins in the flowers of Aconitum (Ranunculaceae)

The presence of anthocyanidins and anthocyanins were analyzed in flowers of 30 taxa of Aconitum. Delphinidin was detected as a major anthocyanidin from the hydrolysate of 29 taxa with violet and violet-blue flowers. Pelargonidin was identified as a major anthocyanidin in one taxon with white flowers (partially pale reddish purple; White group N155C by R.H.S. Colour Chart). This is the first reported detection of pelargonidin as a major anthocyanidin from Aconitum flowers. Pelargonidin was also found in ten taxa as a minor anthocyanidin, whereas cyanidin was detected from the flowers of all 30 taxa as a minor anthocyanidin.Two anthocyanins polyacylated by p-hydroxybenzoic acids, violdelphin and monodeacylcampanin were identified from 29 taxa with violet and violet-blue flowers as major anthocyanins. This is the first reported isolation of monodeacylcampanin from Aconitum flowers. The structures of these two anthocyanins were elucidated on the basis of Nuclear Magnetic Resonance (NMR) and Mass Spectrometry (MS).     

A vacuolar iron transporter in tulip, TgVit1, is responsible for blue coloration in petal cells through iron accumulation

Blue color in flowers is due mainly to anthocyanins, and a considerable part of blue coloration can be attributed to metal-complexed anthocyanins. However, the mechanism of metal ion transport into vacuoles and subsequent flower color development has yet to be fully explored. Previously, we studied the mechanism of blue color development specifically at the bottom of the inner perianth in purple tulip petals of Tulipa gesneriana cv. Murasakizuisho. We found that differences in iron content were associated with the development of blue- and purple-colored cells. Here, we identify a vacuolar iron transporter in T. gesneriana ( TgVit1 ), and characterize the localization and function of this transporter protein in tulip petals. The amino acid sequence of TgVit1 is 85% similar that of the Arabidopsis thaliana vacuolar iron transporter AtVIT1, and also showed similarity to the AtVIT1 homolog in yeast, Ca²⁺-sensitive cross-complementer 1 (CCC1). The gene TgVit1 was expressed exclusively in blue-colored epidermal cells, and protein levels increased with increasing mRNA expression and blue coloration. Transient expression experiments revealed that TgVit1 localizes to the vacuolar membrane, and is responsible for the development of the blue color in purple cells. Expression of TgVit1 in yeast rescued the growth defect of ccc1 mutant cells in the presence of high concentrations of FeSO₄. Our results indicate that TgVit1 plays an essential role in blue coloration as a vacuolar iron transporter in tulip petals. These results suggest a new role for involvement of a vacuolar iron transporter in blue flower color development.     

Perianth bottom-specific blue color development in Tulip cv. Murasakizuisho requires ferric ions

The entire flower of Tulipa gesneriana cv. Murasakizuisho is purple, except the bottom, which is blue. To elucidate the mechanism of the different color development in the same petal, we prepared protoplasts from the purple and blue epidermal regions and measured the flavonoid composition by HPLC, the vacuolar pH by a proton-selective microelectrode, and element contents by the inductively coupled plasma (ICP) method. Chemical analyses revealed that the anthocyanin and flavonol compositions in both purple and blue colored protoplasts were the same; delphinidin 3-O-rutinoside (1) and major three flavonol glycosides, manghaslin (2), rutin (3) and mauritianin (4). The vacuolar pH values of the purple and blue protoplasts were 5.5 and 5.6, respectively, without any significant difference. However, the Fe(3+) content in the blue protoplast was approximately 9.5 mM, which was 25 times higher than that in the purple protoplasts. We could reproduce the purple solution by mixing 1 with two equimolar concentrations of flavonol with lambda(vismax) = 539 nm, which was identical to that of the purple protoplasts. Furthermore, addition of Fe(3+) to the mixture of 1-4 gave the blue solution with lambda(vismax) = 615 nm identical to that of the blue protoplasts. We have established that Fe(3+) is essential for blue color development in the tulip.     

基于花青素代谢培育蓝色花卉的研究进展

花色是植物吸引昆虫传播花粉的主要因素,对于植物在自然界的生存必不可少,也是观赏植物最重要的性状之一。在蓬勃发展的花卉产业中,色彩各异花卉的培育,可以弥补自然花色的匮乏,但是令人垂涎的蓝色花比较难培育。花色的多样性主要是由花青素及其衍生物的种类和含量等因素决定的,飞燕草色素的合成是形成蓝色花的关键因素,许多植物体内缺少合成飞燕草色素的结构基因。近年来,利用基因工程技术培育蓝色花的研究也时有报道。文中以常见的观赏植物为例,基于花青素代谢调控,从影响飞燕草色素合成的关键因素和不同分子改良途径培育蓝色花等几个方面对植物花朵呈色的机制进行了综述,并展示不同分子育种策略可能在其他领域的应用,为其他植物或经济作物的色泽改良如彩色棉蓝色纤维的培育等提供参考和技术支持。     

Dynamics of inositol phosphate pools (tris-, tetrakis- and pentakisphosphate) in relation to the rate of phytate synthesis during seed development in common bean (Phaseolus vulgaris)

Four cultivars of Phaseolus vulgaris were grown in a greenhouse and each flower was Labeled with date of anthesis. Seeds were collected at six different stages of development and inositol phosphates (InsPs) were analyzed by ion-pair reversed-phase HPLC. Phytate accumulation was similar in all cultivars, and the specific rate of phytate synthesis (Rs) peaked at about 22 days after flowering (DAF). Variations in the concentrations of the InsP3 and InsP4 pools matched changes in Rs in cultivars Una and Aru?. These results suggest mass-action effects. Thus, the rates of conversion of InsP3 to InsP5 appeared to be at least partly dependent on substrate concentration. Proportional increases in size of all InsP pools up to 21 DAF are also consistent with Little regulation in this part of the pathway. However, this did not appear to be the case in cv. Diamante Negro or with the conversion of InsP5 to InsP6 in all cultivars, where concentrations of the InsP precursor pools peaked earlier or even dropped as Rs peaked, suggesting activation of enzyme activity. Therefore, the evidence is consistent with a control point regulating this metabolic route upstream of InsP3 and possibly in the conversion of InsP5 to InsP6.     

Determination of anthocyanins and exploration of relationship between their composition and petal coloration in crape myrtle (Lagerstroemia hybrid)

Petal coloration and pigment components in 12 American crape myrtle cultivars (Lagerstroemla indica x Lagerstroemla fauriei) and five Chinese crape myrtle cultivars (L. indica hybrids) were studied. Color was measured by ClEL'a'b" scale and anthocyanin composition of crape myrtle was determined using high-performance liquid chromatography coupled to photodiode array detection and electrospray ionization mass spectrometry. The presence of the previously reported delphinidin 3-O-glucoside, petunidin 3-O-glucoside and malvidin 3-O-glucoside were confirmed. Cyanidin 3-O-glucoside was identified in crape myrtle for the first time. We explored the relationship between petal color and anthocyanin contents by multiple linear regression analyses. The results indicated that total flavones and flavonols were important variables and contributed to blue-enhancing in crape myrtle. Based on anthocyanins and co-pigments analysis, flower color breeding in crape myrtle towards true-red and blue were discussed.     

菊花不同花色品种中花青素苷代谢分析

应用高效液相色谱和多级质谱联用技术(HPLC-ESI-MSⁿ), 分析菊花(Chrysanthemum × morifolium)白色、粉色、红色、紫色、红紫色和墨色6个色系共计82个品种中花青素苷合成过程的中间产物和最终产物, 发现从白色、粉色、红色、紫色、红紫色到墨色花青素苷含量快速增加, 分别为4.68、111.60、366.89、543.56、1 220.36和2 674.95 μg·g^–1, 不同色系间花青素苷的含量差异显著(P<0.01), 花青素苷含量越高花色越深; 墨色菊花品种中总类黄酮含量显著高于其它花色品种(P<0.01), 其它不同色系间总类黄酮含量差异不显著(P>0.05); 随着菊花花色变深, 从柚皮素分支到圣草酚的代谢流, 以及从圣草酚分支到矢车菊素苷的代谢流比例增加。花青素苷成分分析发现: 菊花中只含有矢车菊素苷类化合物。根据花青素苷代谢成分分析结果绘制了菊花中花青素苷代谢路径图, 即在菊花类黄酮代谢途径中只存在矢车菊素苷代谢分支途径;菊花不同色系在柚皮素和圣草酚2个关键代谢分支点上向不同方向代谢流的分配比例不同, 造成花青素苷产物含量不同,导致不同花色。以上研究结果为菊花花色改良的分子育种提供了理论依据。