Mechanism of dusky reddish-brown "kaki" color development of Japanese morning glory,Ipomoea nil cv. Danjuro

The mechanism of dusky reddish-brown "kaki" color development of morning glory, Ipomoea nil cv. Danjuro, was studied. Three major known anthocyanins were isolated as glucosylated pelargonidin derivatives. Measurement of the vacuolar pH with proton-selective microelectrodes revealed the vacuolar pH of the colored cell of open flowers to be 6.8, while that of buds was 5.8. Mixing of the three anthocyanins according to the composition ratio in petals at pH 6.8 allowed the identical color to that of petals to be reproduced. The typical "kaki" color development was mostly caused by 5-OH free acylated anthocyanins, which have two lambdamax around 435 and 535 nm in the visible region.     

The involvement of tonoplast proton pumps and Na+(K+)/H+ exchangers in the change of petal color during flower opening of Morning Glory, Ipomoea tricolor cv. Heavenly Blue

The petal color of morning glory, Ipomoea tricolor cv. Heavenly Blue, changes from purplish red to blue during flower opening. This color change is caused by an unusual increase in vacuolar pH from 6.6 to 7.7 in the colored adaxial and abaxial cells. To clarify the mechanism underlying the alkalization of epidermal vacuoles in the open petals, we focused on vacuolar H+-ATPase (V-ATPase), H+-pyrophosphatase (V-PPase) and an isoform of Na+/H+ exchanger (NHX1). We isolated red and blue protoplasts from the petals in bud and fully open flower, respectively, and purified vacuolar membranes. The membranes contained V-ATPase, V-PPase and NHX1, which were immunochemically detected, with relatively high transport activity. NHX1 could be detected only in the vacuolar membranes prepared from flower petals and its protein level was the highest in the colored petal epidermis of the open flower. These results suggest that the increase of vacuolar pH in the petals during flower opening is due to active transport of Na+ and/or K+ from the cytosol into vacuoles through a sodium- or potassium-driven Na+(K+)/H+ exchanger NXH1 and that V-PPase and V-ATPase may prevent the over-alkalization. This systematic ion transport maintains the weakly alkaline vacuolar pH, producing the sky-blue petals.     

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.     

Structure of anthocyanin from the blue petals of Phacelia campanularia and its blue flower color development

The dicaffeoyl anthocyanin, phacelianin, was isolated from blue petals of Phacelia campanularia. Its structure was determined to be 3-O-(6-O-(4'-O-(6-O-(4'-O-beta-d-glucopyranosyl-(E)-caffeoyl)-beta-d-glucopyranosyl)-(E)-caffeoyl)-beta-d-glucopyranosyl)-5-O-(6-O-malonyl-beta-d-glucopyranosyl)delphinidin. The CD of the blue petals of the phacelia showed a strong negative Cotton effect and that of the suspension of the colored protoplasts was the same, indicating that the chromophores of phacelianin may stack intermolecularly in an anti-clockwise stacking manner in the blue-colored vacuoles. In a weakly acidic aqueous solution, phacelianin displayed the same blue color and negative Cotton effect in CD as those of the petals. However, blue-black colored precipitates gradually formed without metal ions. A very small amount of Al(3+) or Fe(3+) may be required to stabilize the blue solution. Phacelianin may take both an inter- and intramolecular stacking form and shows the blue petal color by molecular association and the co-existence of a small amount of metal ions. We also isolated a major anthocyanin from the blue petals of Evolvulus pilosus and revised the structure identical to phacelianin.     

Sepal color variation of Hydrangea macrophylla and vacuolar pH measured with a proton-selective microelectrode

Sepal color of hydrangea varies with the environmental conditions. Although chemical and biological studies on this color variation have a long history, little correct knowledge has been generated about color development. All colored sepals contain the same anthocyanin, delphinidin 3-glucoside. Thus, there must be some other system for developing the wide variety of colors. In hydrangea sepals the cells of the epidermis are colorless and only the second layer of cells contain pigment. We prepared protoplasts without any color change during enzyme treatment of sepals and measured the vacuolar pH of each of the colored cells. We could correlate the color of a single hydrangea cell with its vacuolar pH using a combination of micro-spectrophotometry and a proton-selective microelectrode. Values for the vacuolar pH of blue (lambda vismax: 589 nm) and red cells (lambda vismax: 537 nm) were 4.1 and 3.3, respectively, the vacuolar pH of blue cells being significantly higher.     

Specific expression of the vacuolar iron transporter, TgVit, causes iron accumulation in blue-colored inner bottom segments of various tulip petals

Several flowers of Tulipa gesneriana exhibit a blue color in the bottom segments of the inner perianth. We have previously reported the inner-bottom tissue-specific iron accumulation and expression of the vacuolar iron transporter, TgVit1, in tulip cv. Murasakizuisho. To clarify whether the TgVit1-dependent iron accumulation and blue-color development in tulip petals are universal, we analyzed anthocyanin, its co-pigment components, iron contents and the expression of TgVit1 mRNA in 13 cultivars which show a blue color in the bottom segments of the inner perianth accompanying yellow- and white-colored inner-bottom petals. All of the blue bottom segments contained the same anthocyanin component, delphinidin 3-rutinoside. The flavonol composition varied with cultivar and tissue part. The major flavonol in the bottom segments of the inner perianth was rutin. The iron content in the upper part was less than that in the bottom segments of the inner perianth. The iron content in the yellow and white petals was higher in the bottom segment of the inner perianth than in the upper tissues. TgVit1 mRNA expression was apparent in all of the bottom tissues of the inner perianth. The result of a reproduction experiment by mixing the constituents suggests that the blue coloration in tulip petals is generally caused by iron complexation to delphinidin 3-rutinoside and that the iron complex is solubilized and stabilized by flavonol glycosides. TgVit1-dependent iron accumulation in the bottom segments of the inner perianth might be controlled by an unknown system that differentiated the upper parts and bottom segments of the inner perianth.     

5种野牡丹属植物花色素成分及影响花色呈色因子分析

为明确野牡丹属(Melastoma L.)植物花瓣的色素成分和呈色机理,为花色育种提供参考。以野牡丹(M.candidum)、白花野牡丹(M.candidum f.albiflorum)、印度野牡丹(M.malabathiricum)、白花印度野牡丹(M. malabathricumvar.alba)、毛稔(M.sanguinrum)5种野牡丹属植物材料,采用目测法、RHSCC比色法和色差仪测定花瓣表型,应用化学显色法、紫外分光光度法对花色素成分及含量进行初步分析与测定,通过徒手切片组织切片法观察花瓣表皮细胞的显微结构和分布特点,测定花瓣pH值、可溶性糖及可溶性蛋白含量等生理指标分析对花色的影响。结果显示,野牡丹属植物花瓣不含叶绿素和类胡萝卜素,紫罗兰色系主要含花青素苷和黄酮类化合物,白色系主要含黄酮类化合物。野牡丹和毛稔花色素分布于上、下表皮,印度野牡丹花色素分布于上、下表皮和栅栏组织,白花野牡丹和白花印度野牡丹花瓣没有发现色素积累;紫罗兰色系野牡丹上表皮细胞呈圆锥形突起,白色系野牡丹上表皮细胞呈不规则的扁平状,它们下表皮细胞全呈不规则的扁平状。野牡丹属植物花色明度L*随花瓣颜色变深而降低,明度L*与红度a*呈极显著负相关、与蓝度b*呈极显著的正相关。花瓣中花青素苷含量与其明度L*和蓝度b*呈显著负相关,pH值与花瓣红度a*呈现显著的负相关。研究表明,野牡丹属植物花色主要由花青素苷决定,花青素苷含量、色素分布、上表皮细胞形状等是引起花色呈现多样的主要因子。     

Flavonoid composition related to petal color in different lines of Clitoria ternatea

Flavonoids in the petals of several C. ternatea lines with different petal colors were investigated with LC/MS/MS. Delphinidin 3-O-(2"-O-alpha-rhamnosyl-6"-O-malonyl)-beta-glucoside was newly isolated from the petals of a mauve line (wm) together with three known anthocyanins. They were identified structurally using UV, MS, and NMR spectroscopy. Although ternatins, a group of 15 (poly)acylated delphinidin glucosides, were identified in all the blue petal lines (WB, BM-1, 'Double Blue' and 'Albiflora'), WM accumulated delphinidin 3-O-(6"-O-malonyl)-beta-glucoside instead. The white petal line (WW) did not contain anthocyanins. Quantitative data showed that the total anthocyanin contents in WB and 'Double Blue' were ca. 8- and 10-fold higher than that in BM-1, a bud mutant of 'Double Blue', respectively. The total anthocyanin content in 'Albiflora' was less than 2 x 10(-3) times those in WB or 'Double Blue'. While all the lines contained the same set of 15 flavonol glycosides in similar relative ratios, the relative ratio of myricetin glycosides in ww and 'Albiflora' was ca. 30-70 times greater than those in the other lines. The change in flower color from blue to mauve was not due to a change in the structure of an anthocyanidin from delphinidin, but to the lack of (polyacylated) glucosyl group substitutions at both the 3'- and 5'-positions of ternatins. This implies that glucosylation at the 3'- and 5'-positions of anthocyanin is a critical step in producing blue petals in C. ternatea.     

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.     

丽格海棠花青素苷成分及分布对花色的影响

以红色、红心白边、粉红、玫红、黄色、黄心红边、浅粉和白色8种花色丽的格海棠花瓣为试验材料,采用目视测色法、RHSCC比色法和色差仪测定花瓣表型,通过组织切片法观察花瓣色素细胞的显微结构和分布特点,采用双光束紫外-可见光分光光度计和高效液相色谱-电喷雾离子化-质谱连用技术(HPLC-ESI-MS)测定分析花瓣中花青素苷的成分和含量,为探讨丽格海棠花色的呈色机理和花色育种提供参考。结果显示:(1)丽格海棠的明度L*随花瓣颜色变深而降低,红度a*则表现出相反趋势,红度(a*)和彩度(C*)值与明度(L*)呈显著负相关关系,且a*和C*是影响L*的主要因素。(2)红花品种花瓣色素主要分布于上表皮细胞和海绵组织中;红白花品种花瓣色素主要分布于上下表皮中,且下表皮积累量更多;粉色花和玫红花品种花瓣色素主要分布于上下表皮细胞;黄红花和粉白色花品种花瓣上表皮中含有少量色素,而黄花和白花品种花瓣几乎没有色素积累。各花色丽格海棠花瓣上表皮细胞均为圆锥形,且红花和红白花品种锥形化程度最高,它们花瓣下表皮细胞均呈扁平的长方形。(3)8个丽格海棠品种花瓣中共检测出15种花青素苷,其中10种为芍药素苷,3种为矢车菊素苷,1种为锦葵素苷,1种为飞燕草素苷,酰化花青素苷占多数;红花品种花瓣中总花青素苷含量最高,玫红花品种次之,黄花和白花品种中未检出;除粉红花品种外,其余含花青素苷的品种中芍药素苷含量最高,均占总花青素苷含量的50%以上,是花瓣的主要呈色物质。(4)丽格海棠花瓣中总花青素苷含量与其红度(a*)、彩度(C*)值呈正相关关系、与其L*值呈负相关关系。研究表明,花青素苷的积累有利于丽格海棠花瓣红色化,并影响其花瓣彩度(C*)及明度(L*);色素分布细胞数量和上表皮细胞锥形化明显影响花瓣呈色,且花瓣主要的呈色物质为芍药素苷,酰基化修饰可能影响其明度。     

矮牵牛新种质的花色表型及花色素分析

以27个上海交通大学自育矮牵牛新种质为研究材料,对花色这一重要观赏性状及其花色素进行了系统研究。用RHSCC比色和色差仪测色方法描述了矮牵牛的花色表型,通过特征显色反应初步判断了矮牵牛的花色素类型,以标准曲线法和pH示差法等方法测定了矮牵牛3类花色素的含量。研究表明：这27个矮牵牛种质的花色可归于5个色系,以紫红色和红色为主;矮牵牛花色在CIELab表色系统中分布较广,而且不同色系花色参数的区分度较大。矮牵牛花瓣中含有类黄酮和花色苷,不含或含少量类胡萝卜素。13个被测种质的花瓣类黄酮含量在2.5～12.2 mg·/g–1 ·FW之间,花色苷含量在0.08～3.88 mg·g–1 FWmg/g·FW之间,而类胡萝卜素在矮牵牛花瓣中含量很低,远远低于类黄酮含量,在7个被测种质中,最高仅为0.216 mg·g–1 FWmg/g·FW,最低为0.004 mg·g–1 FWmg/g·FW。以上结果显示,5个色系矮牵牛所含花色素种类不尽相同,含量也有明显差异,其中紫红色系和红色系花瓣大多不含或含极少量类胡萝卜素,黄色系、白色系和紫色系花瓣的类黄酮含量较高,紫色系和紫红色系花瓣花色苷含量较高。     

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.     

The blue anthocyanin pigments from the blue flowers of Heliophila coronopifolia L. (Brassicaceae)

Six acylated delphinidin glycosides (pigments 1-6) and one acylated kaempferol glycoside (pigment 9) were isolated from the blue flowers of cape stock (Heliophila coronopifolia) in Brassicaceae along with two known acylated cyanidin glycosides (pigments 7 and 8). Pigments 1-8, based on 3-sambubioside-5-glucosides of delphinidin and cyanidin, were acylated with hydroxycinnamic acids at 3-glycosyl residues of anthocyanidins. Using spectroscopic and chemical methods, the structures of pigments 1, 2, 5, and 6 were determined to be: delphinidin 3-O-[2-O-(β-xylopyranosyl)-6-O-(acyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which acyl moieties were, respectively, cis-p-coumaric acid for pigment 1, trans-caffeic acid for pigment 2, trans-p-coumaric acid for pigment 5 (a main pigment) and trans-ferulic acid for pigment 6, respectively. Moreover, the structure of pigments 3 and 4 were elucidated, respectively, as a demalonyl pigment 5 and a demalonyl pigment 6. Two known anthocyanins (pigments 7 and 8) were identified to be cyanidin 3-(6-p-coumaroyl-sambubioside)-5-(6-malonyl-glucoside) for pigment 7 and cyanidin 3-(6-feruloyl-sambubioside)-5-(6-malonyl-glucoside) for pigment 8 as minor anthocyanin pigments. A flavonol pigment (pigment 9) was isolated from its flowers and determined to be kaempferol 3-O-[6-O-(trans-feruloyl)-β-glucopyranoside]-7-O-cellobioside-4′-O-glucopyranoside as the main flavonol pigment.On the visible absorption spectral curve of the fresh blue petals of this plant and its petal pressed juice in the pH 5.0 buffer solution, three characteristic absorption maxima were observed at 546, 583 and 635 nm. However, the absorption curve of pigment 5 (a main anthocyanin in its flower) exhibited only one maximum at 569 nm in the pH 5.0 buffer solution, and violet color. The color of pigment 5 was observed to be very unstable in the pH 5.0 solution and soon decayed. In the pH 5.0 solution, the violet color of pigment 5 was restored as pure blue color by addition of pigment 9 (a main flavonol in this flower) like its fresh flower, and its blue solution exhibited the same three maxima at 546, 583 and 635 nm. On the other hand, the violet color of pigment 5 in the pH 5.0 buffer solution was not restored as pure blue color by addition of deacyl pigment 9 or rutin (a typical flower copigment). It is particularly interesting that, a blue anthocyanin-flavonol complex was extracted from the blue flowers of this plant with H₂O or 5% HOAc solution as a dark blue powder. This complex exhibited the same absorption maxima at 546, 583 and 635 nm in the pH 5.0 buffer solution. Analysis of FAB mass measurement established that this blue anthocyanin-flavonol complex was composed of one molecule each of pigment 5 and pigment 9, exhibiting a molecular ion [M+1] ⁺ at 2102 m/z (C₉₃H₁₀₅O₅₅ calc. 2101.542). However, this blue complex is extremely unstable in acid solution. It really dissociates into pigment 5 and pigment 9.     

A rationale for the shift in colour towards blue in transgenic carnation flowers expressing the flavonoid 3',5'-hydroxylase gene

Recently marketed genetically modified violet carnations cv. Moondust and Moonshadow (Dianthus caryophyllus) produce a delphinidin type anthocyanin that native carnations cannot produce and this was achieved by heterologous flavonoid 3',5'-hydroxylase gene expression. Since wild type carnations lack a flavonoid 3',5'-hydroxylase gene, they cannot produce delphinidin, and instead accumulate pelargonidin or cyanidin type anthocyanins, such as pelargonidin or cyanidin 3,5-diglucoside-6"-O-4, 6"'-O-1-cyclic-malyl diester. On the other hand, the anthocyanins in the transgenic flowers were revealed to be delphinidin 3,5-diglucoside-6"-O-4, 6"'-O-1-cyclic-malyl diester (main pigment), delphinidin 3,5-diglucoside-6"-malyl ester, and delphinidin 3,5-diglucoside-6",6"'- dimalyl ester. These are delphinidin derivatives analogous to the natural carnation anthocyanins. This observation indicates that carnation anthocyanin biosynthetic enzymes are versatile enough to modify delphinidin. Additionally, the petals contained flavonol and flavone glycosides. Three of them were identified by spectroscopic methods to be kaempferol 3-(6"'-rhamnosyl-2"'-glucosyl-glucoside), kaempferol 3-(6"'-rhamnosyl-2"'-(6-malyl-glucosyl)-glucoside), and apigenin 6-C-glucosyl-7-O-glucoside-6"'-malyl ester. Among these flavonoids, the apigenin derivative exhibited the strongest co-pigment effect. When two equivalents of the apigenin derivative were added to 1 mM of the main pigment (delphinidin 3,5-diglucoside-6"-O-4,6"'-O-1-cyclic-malyl diester) dissolved in pH 5.0 buffer solution, the lambda(max) shifted to a wavelength 28 nm longer. The vacuolar pH of the Moonshadow flower was estimated to be around 5.5 by measuring the pH of petal. We conclude that the following reasons account for the bluish hue of the transgenic carnation flowers: (1). accumulation of the delphinidin type anthocyanins as a result of flavonoid 3',5'-hydroxylase gene expression, (2). the presence of the flavone derivative strong co-pigment, and (3). an estimated relatively high vacuolar pH of 5.5.     

观赏植物蓝色花形成的机制

在观赏植物中,蓝色系的花卉属于较为罕见的种类,也是花卉育种一直以来的目标。本文对蓝色花卉的花青素代谢途径,影响蓝色花卉形成的核心色素种类,花青素转运方式,花青素在液泡中的积累,花青素的共价修饰,分子间辅色作用,金属离子和液泡pH等影响因素进行系统地介绍和讨论,以期为培育新的蓝色花卉提供参考。     

Development of Anthocyanin Pigmentation in Flowers of Lathyrus odoratus

A quantitative study has been made of developmental changesin the anthocyanins and a flavonol glycoside in the red/bluebicoloured flowers of Lathyrus odoratus L. Anthocyanin formationoccurs during the period of most rapid growth of the petals.At maturity about four times as much anthocyanin is presentin the standard petal as in the pair of wing petals, which aretogether comparable in fresh weight to the standard. The patternof development of flavonol glycoside is quite different; someare formed well before anthocyanin formation occurs and at maturityabout six times as much flavonol glycoside is present in thewings as in the standard per unit amount of anthocyanin. Somefurther evidence is thus provide that the flavonol glycosidemay be acting as a co-pigment which modifies the wing petalcolour to blue.     

Anthocyanic vacuolar inclusions--their nature and significance in flower colouration

The petals of a number of flowers are shown to contain similar intensely coloured intravacuolar bodies referred to herein as anthocyanic vacuolar inclusions (AVIs). The AVIs in a blue-grey carnation and in purple lisianthus have been studied in detail. AVIs occur predominantly in the adaxial epidermal cells and their presence is shown to have a major influence on flower colour by enhancing both intensity and blueness. The latter effect is especially dramatic in the carnation where the normally pink pelargonidin pigments produce a blue-grey colouration. In lisianthus, the presence of large AVIs produces marked colour intensification in the inner zone of the petal by concentrating anthocyanins above levels that would be possible in vacuolar solution. Electron microscopy studies on lisianthus epidermal tissue failed to detect a membrane boundary in AVI bodies. AVIs isolated from lisianthus cells are shown to have a protein matrix. Bound to this matrix are four cyanidin and delphinidin acylated 3,5-diglycosides (three, new to lisianthus), which are relatively minor anthocyanins in whole petal extracts where acylated delphinidin triglycosides predominate. Flavonol glycosides were not bound. A high level of anthocyanin structural specificity in this association is thus implied. The specificity and effectiveness of this anthocyanin "trapping" is confirmed by the presence in the surrounding vacuolar solution of only delphinidin triglycosides, accompanied by the full range of flavonol glycosides. "Trapped" anthocyanins are shown to differ from solution anthocyanins only in that they lack a terminal rhamnose on the 3-linked galactose. The results of this study define for the first time the substantial effect AVIs have on flower colour, and provide insights into their nature and their specificity as vacuolar anthocyanin traps.     

Genes encoding the vacuolar Na+/H+ exchanger and flower coloration

Vacuolar pH plays an important role in flower coloration: an increase in the vacuolar pH causes blueing of flower color. In the Japanese morning glory (Ipomoea nil or Pharbitis nil), a shift from reddish-purple buds to blue open flowers correlates with an increase in the vacuolar pH. We describe details of the characterization of a mutant that carries a recessive mutation in the Purple (Pr) gene encoding a vacuolar Na+/H+ exchanger termed InNHX1. The genome of I. nil carries one copy of the Pr (or InNHX1) gene and its pseudogene, and it showed functional complementation to the yeast nhx1 mutation. The mutant of I. nil, called purple (pr), showed a partial increase in the vacuolar pH during flower-opening and its reddish-purple buds change into purple open flowers. The vacuolar pH in the purple open flowers of the mutant was significantly lower than that in the blue open flowers. The InNHX1 gene is most abundantly expressed in the petals at around 12 h before flower-opening, accompanying the increase in the vacuolar pH for the blue flower coloration. No such massive expression was observed in the petunia flowers. Since the NHX1 genes that promote the transport of Na+ into the vacuoles have been regarded to be involved in salt tolerance by accumulating Na+ in the vacuoles, we can add a new biological role for blue flower coloration in the Japanese morning glory by the vacuolar alkalization.     

Components of protocyanin, a blue pigment from the blue flowers of Centaurea cyanus

The components involved in the formation of protocyanin, a stable blue complex pigment from the blue cornflower, Centaurea cyanus, were investigated. Reconstruction experiments using highly purified anthocyanin [centaurocyanin, cyanidin 3-O-(6-O-succinylglucoside)-5-O-glucoside], flavone glycoside [apigenin 7-O-glucuronide-4'-O-(6-O-malonylglucoside)] and metals, Fe and Mg, showed the presence of another factor essential for the formation of protocyanin. The unknown factor was revealed to be Ca. Reconstructed protocyanin using anthocyanin, flavone, Fe, Mg, and Ca was identical with protocyanin from nature in UV-Vis and CD spectra, and was isolated as crystals for the first time. In addition, substitution of the metal components in protocyanin with other metals was also examined.