Effects of Varying Light Intensities and Temperature Treatments Applied to Whole Plants, or Locally to Leaves or Flower Buds, on Growth and Pigmentation of 'Baccara' Roses

Varying light intensity and temperature treatments were applied to whole plants, or to the leaves, or to the flower buds of ‘Baccara’ roses. The effect of these treatments on flower dimensions and pigmentation of the petals was examined. Cooling only the leaves had no effect; cooling only the buds enhanced both bud weight and pigmentation, but the effect was less marked than when the whole plant was cooled. Reducing plant temperature by misting with desalinated water enhanced both pigmentation and flower size. Darkening of only the leaves, or their removal, resulted in an inhibition of the pigmentation and also in a decrease in bud weight. Darkening of only the flower bud did not affect either pigmentation or bud weight, but caused bud elongation. It is suggested that light intensity and temperature affect flower growth and pigmentation via their effects on the availability of sugars in the flower bud.     

Growth retardation of woody species by three growth regulators

Flower-bud blasting in Iris occurs in the winter when low light intensities and short days prevail. After introduction of ¹⁴CO₂ to one leaf the transport of assimilates was studied under controlled culture conditions in a control light treatment and in a treatment of 7 days darkness followed by standard light conditions. Little assimilate transport was found in the direction of the bud in dark-treated plants. However, zeatin injection into the flower buds of the plants subjected to the dark treatment clearly promoted assimilate transport ot these buds. Abscisic acid levels, determined by gas chromatography, were found to increase in the buds of dark-treated plants. Zeatin injection into the flower bud resulted in a suppression of the abscisic acid level. The latter treatment also resulted in higher percentage of flowering. Removal of flower parts was found to inhibit peduncle elongation. The peduncle elongation of complete flowers started in a well defined period, and the fresh weight of buds was found to increase mainly in the last part of that period. Assimilate transport under low light intensities in relation to abscisic acid and supposed gibberellin is discussed.     

Arctic mustard flower color polymorphism controlled by petal-specific downregulation at the threshold of the anthocyanin biosynthetic pathway

Intra- and interspecific variation in flower color is a hallmark of angiosperm diversity. The evolutionary forces underlying the variety of flower colors can be nearly as diverse as the colors themselves. In addition to pollinator preferences, non-pollinator agents of selection can have a major influence on the evolution of flower color polymorphisms, especially when the pigments in question are also expressed in vegetative tissues. In such cases, identifying the target(s) of selection starts with determining the biochemical and molecular basis for the flower color variation and examining any pleiotropic effects manifested in vegetative tissues. Herein, we describe a widespread purple-white flower color polymorphism in the mustard Parrya nudicaulis spanning Alaska. The frequency of white-flowered individuals increases with increasing growing-season temperature, consistent with the role of anthocyanin pigments in stress tolerance. White petals fail to produce the stress responsive flavonoid intermediates in the anthocyanin biosynthetic pathway (ABP), suggesting an early pathway blockage. Petal cDNA sequences did not reveal blockages in any of the eight enzyme-coding genes in white-flowered individuals, nor any color differentiating SNPs. A qRT-PCR analysis of white petals identified a 24-fold reduction in chalcone synthase (CHS) at the threshold of the ABP, but no change in CHS expression in leaves and sepals. This arctic species has avoided the deleterious effects associated with the loss of flavonoid intermediates in vegetative tissues by decoupling CHS expression in petals and leaves, yet the correlation of flower color and climate suggests that the loss of flavonoids in the petals alone may affect the tolerance of white-flowered individuals to colder environments.     

植物花色形成及其调控机理

综述了植物花色的表现、起源与进化、功能及其调控机制。植物花色主要表现为单色、变色和杂色,是长期进化的结果,主要功能是指示传粉者和保护花器官。花色素主要包括类黄酮、类胡萝卜素和生物碱。花色素的存在及其变化是植物花色表现的化学机制,色素在花瓣中的空间分布及其对光的作用是花色表现的解剖学和光学机制,细胞液pH值、花发育阶段和植物激素是花色表现的植物生理学机制。传粉者、真菌侵染、机械损伤、园艺措施、光、温度、水分、矿质营养和糖等是影响花色的外部因素。花瓣彩斑主要由基因突变或病毒入侵而形成。     

U.v.-induced blackening of rose petals

Blackening of petals is common in roses cv. Mercedes during the winter in unheated greenhouses clad with polyethylene films which are transparent to solar radiation of 300 nm wavelength and longer. Petal blackening was prevented when the rose plants were kept at 18°C or a higher temperature. Blackening was also prevented when the flower buds were covered with aluminum foil from dawn to dusk, or when flower buds were covered with polyethylene or PVC films, opaque to solar radiation in a u.v. range shorter than 350 nm even when they were exposed to outdoor conditions with minimum temperatures as low as 5°C. Blackening was not prevented when the flower buds were covered with aluminum foil only during the night, or when covered with polyethylene film transparent to u.v. radiation. Measurements of the spectral transmission of the various plastic materials showed that PVC film and the IR/VR-type of polyethylene were opaque to u.v. radiation. High levels of u.v. transmission were measured in the IR-type polyethylene and low levels of u.v. transmission were present under horticultural glass. The involvement of u.v.-B radiation in the phenomenon of rose petal blackening and its interaction with low temperature is discussed.     

Cell distribution and surface morphology in petals, androecia and styles of Commelinaceae

Cell distribution and surface morphology in petals, androecia and styles of Commelinaceae. Epidermal cell shape, distribution, surface topography and cuticular morphology in petals, androecia and styles of 10 species in the Commelinaceae are described. Petals of all species possess a basal area of elongated, straight-sided cells and an area of cells with sinuous, anticlinal walls. The degree of convolution of anticlinal wall and the length of cells varies between genera. The surface of cells in Aneilema, Commelina and Cyanotis are micropapillate. In all other genera they are low-domed. Cuticular surfaces of the three genera are smooth, while in the remainder heavily striated. The cells of stamens, staminodes, staminal hairs, and styles are variably elongated and straight-sided, their surfaces convex and cuticle striated. The degree of striation is less pronounced at the base of each organ but becomes more densely arrayed towards the apex. Petal pigments are located in upper epidermal cells in Tradescantia and Thyrsanthemum , in upper and lower epidermises in Dichorisandra and Commelina , and in both epidermises, and mesophyll of Aneilema. In most species pigmentation of androecium and style is similar to petals though often fainter at base and apex. Flavonols in the pigments give rise to spectral polmorphisms visible in longwave UV light. Epidermal adaptations for light capture in petals is compared to that in leaf structure.     

Fructan Hydrolysis Drives Petal Expansion in the Ephemeral Daylily Flower

Dry weight, water content, soluble carbohydrate content, and carbohydrate composition of daylily (Hemerocallis hybrid cv Cradle Song) flower petals were monitored in the 3 d leading up to full opening and in the first day of senescence. Timing of events was related to the time (hour 0) when flower expansion was 60% complete. Petal dry weight increased linearly from hour -62 (tight bud) to hour 10 (fully developed flower), then fell rapidly to hour 34 as senescence advanced. Increase in water content was proportional to dry weight increase from hour -62 to hour -14, but was more rapid as the bud cracked and the flower opened, giving an increase in fresh weight/dry weight ratio. Soluble carbohydrate was 50% of petal dry weight up to hour 10, then decreased during senescence to reach 4% by hour 34. Up until hour -14, fructan accounted for 80% of the soluble carbohydrate in the petals, whereas hexose accounted for only 2%. Fructan hydrolysis started just prior to bud crack at hour -14, reaching completion by hour 10 when no detectable fructan remained, and fructose plus glucose accounted for more than 80% of the total soluble carbohydrate. The proportion of sucrose remained constant throughout development. Osmolality of petal cell sap increased significantly during fructan hydrolysis, from 0.300 to 0.340 osmolal. Cycloheximide applied to excised buds between hour -38 and hour -14 halted both fructan hydrolysis and flower expansion. The findings suggest that onset of fructan hydrolysis, with the concomitant large increase in osmoticum, is an important event driving flower expansion in daylily.     

ANTHOCYANIN SYNTHESIS IN SALPIGLOSSIS SINUATA

Measurements were made of the growth and pigment content of developing flower buds of Salpiglossis sinuata. From the time the buds were approximately 10 mm long they grew in length exponentially until they reached their final length. The logarithm of bud length increased linearly with time and served as a convenient morphological index on which to relate the progress of anthocyanin synthesis. Buds shorter than about 42 mm had no anthocyanin, but when buds reached this length, anthocyanin production was initiated and proceeded rapidly. The maximum relative pigment concentration (pigment/mg fresh weight) was attained by the buds about 17 hr after the initiation of pigment synthesis. In the mahogany-colored variety used in these studies, two anthocyanidins were found and identified as cyanidin and delphinidin. Buds excised from the plants could be cultured in vitro. Buds started in culture at a length of 30–35 mm when they contained no anthocyanins developed pigment during their growth. The amount of pigment formed increased with increasing light intensity, while only small amounts of pigment could be formed in buds cultured in darkness. The anthocyanidins of these cultured buds were the same as those of the intact flowers, but the ratio of delphinidin to cyanidin decreased with decreasing light intensity. Brief daily irradiation of dark-grown buds with red, far-red or blue light did not increase pigment synthesis nor change the anthocyanidin ratio. If buds were placed in culture at 20–25 mm and grown in darkness, they developed a third anthocyanidin, identified as malvidin, which was not present in intact flowers, light-grown buds or 30–35-mm buds cultured in darkness.     

Petal Abscission in Rose Flowers: Effects of Water Potential, Light Intensity and Light Quality

Petal abscission was studied in roses (Rosa hybrida L.), cvs.Korflapei (trade name Frisco), Sweet Promise (Sonia) and CaraMia (trade name as officially registered cultivar name). Unlikeflowers on plants in greenhouses, cut flowers placed in waterin the greenhouse produced visible symptoms of water stress,depending on the weather during the experiment and on the cultivar.Cut Frisco roses showed no visible signs of water stress andthe time to petal abscission was as in uncut flowers. In Soniaroses the symptoms of water stress varied from mild to severe,and the number of flowers in which the petals abscised variedfrom 100% (mild stress) to 0% (severe stress). An antimicrobialcompound in the vase water of Sonia roses, or removal of theleaves, alleviated the symptoms of water stress and increasedthe number of stems in which the petals abscised. Cut Cara Miaroses showed severe symptoms of water stress in all experimentsand petal abscission was found in only a few flowers, even whenthe stems were placed at 20 °C and low photon flux (15 µmolm^-2s^-1). Abscission in Sonia and Cara Mia roses was low or absentwhen the water potential of the leaves reached values below-2.0 MPa within the first 5 d of the experiment; such low valueswere not reached in Frisco roses. Addition of sucrose to the vase solution, together with an effectiveantimicrobial compound, had no effect on the time to petal abscission,at any light intensity. Placing flowers in far-red light alsohad no effect on abscission, compared with flowers placed inred light or white light of the same photon fluence. It is concluded that petal abscission in the rose cultivarsstudied is not affected by their water status unless the plantsreach a low water potential (about -2 MPa) early on during vaselife. Petal abscission is not inhibited by low light intensitynor affected by the Pr/Pfr ratio. Abscission; light intensity; petals; phytochrome; Rosa hybrida L.; rose; sugars; water potential     

The effect of growth regulators on the growth and pigmentation of "Baccara" rose flowers

"Baccara" rose buds were treated with various growth regulatorsduring late stages of bud development. The effect of these substanceson growth and pigmentation were determined. Growth regulatorswere applied by spray or injection or as a lanolin paste, alsoin the nutrient media on which petals were cultured in vitro.Injection of GA into the base of the receptacle caused elongationof the bud whereas IAA, K, ABA, AMO-1618, CCC, and SADH hadlittle or no effect. CCC and MeCl-F did not reduce the elongationcaused by GA. GA treatments also enhanced flower weight andpetal pigmentation and MeCl-F decreased the gibberellin effecton pigmentation. GA treatments of intact flowers and excisedpetals cultured in vitro, were only effective at low temperatures. Gibberellin treatments increased the size of petals, the receptacleand the pedicel only if applied directly to the receptacle.Treatments at lower positions on the flowering shoot eitherhad no effect at all, or caused elongation of only the receptacle. Endogenous gibberellin levels are higher in the receptacle thanin petals or in the pedicel. Injection of GA into the receptaclesignificantly increased gibberellin activity in all flower partswhereas injection into the flowering-shoot base increased gibberellinactivity only in the receptacle. The possibility is discussed that GA, which is exogenously supplieddirectly to the receptacle, enhances flower dimensions and pigmentationby drawing photosynthates to the flower as a consequence ofintensification of the sink. (Received August 17, 1973; )     

Contribution of sepals and gibberellin treatments to growth and development of rose (Rosa hybrida) flowers

The fresh weight of sepals during the development of the rose flowerbuds from 4 mm to 22 mm in diameter increased fromabout 30 mg to ca. 350 mg. However, due to a morerapid gain in the total fresh weight of the flower, the sepal fresh weight as aproportion of the total weight of the buds decreased from about 55% to only 8%at the end of the measurement period. The net photosynthesis of sepals,measuredclose to the flower harvest, was approximately 60% of that in the youngest,uppermost leaves whereas no photosynthesis occured in the petals. Theconcentration of sucrose in petals of almost fully developed, desepalledflowerswas 15% lower in comparison with the control flowers with intact sepals. On theother hand, the concentration of sucrose in petals of control and desepalledflowers that were kept for 10 days in complete darkness was equal, reachingabout 50% of the concentration in petals of flowers grown in the light.Periodicmeasurements of reducing sugars in the petals did not show differences in theirconcentration between the control and desepalled flowers during the first 8daysafter sepal removal. After an additional four days the concentration ofreducingsugars in petals of the desepalled flowers was only 50% in comparison to thatinpetals of control flowers. Excising the sepals reduced fresh and dry weights,aswell as the length of buds and the peduncles, indicating that sepals may be asource of gibberellins during flower development. Treatment with50mg GA₃ in lanolin paste, completely restored thelength of the peduncles, but only partially restored the other measuredparameters of the flowers. Formation of 'star-shape' abnormality indesepalled flowers, which is a common phenomenon in rose flowers exposed toexternal ethylene was completelly prevented by applying GA₃ afterthesepals were excisied. This supported the previously suggested hypothesis aboutthe flinction of gibberellins in reducing the sensitivity of rose flower organsto ethylene.     

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。     

Onset of Phloem Export from Senescent Petals of Daylily

During senescence, petals of attached daylily (Hemerocallis hybrid cv Cradle Song) flowers lost 95% sugar and 65% dry weight over the first 24 h, with 30% of dry weight loss coming from nonsugar components. Detaching flowers did not delay senescence, but halted loss of carbohydrate and amino acid, suggesting that loss in the intact state was due to phloem export. Petal autolysis occurred mainly in the interveinal parenchyma, causing vascular strands to begin separating from the petal mass. Such vascular strands still stained with tetrazolium and accumulated sucrose, indicating a retained viability. Their sucrose accumulation rates were high in comparison with those of other plant tissues, and the accumulated product was mainly sucrose. Sucrose synthesis took place in the senescent petal, and sucrose was the principal sugar in phloem exudate, whereas hydroxyproline and glutamine were the main transport amino acids. [14C]Sucrose applied to attached senescent flowers was rapidly translocated to other parts of the plant, particularly developing flower buds. Thus, onset of phloem export allowed most of the soluble carbohydrate and amino acid in the senescing flower to be retrieved by the plant. Additional salvaged material came from proteins and possibly from structural carbohydrate. Over a 12-h period, the flower switched from acting as a strong carbohydrate sink during expansion to become a strong source during senescence. This rapid reversal offers potential for phloem transport studies.     

Patterns of flower morphology and structural changes during interconversion between chasmogamous and cleistogamous flowers in Viola philippica

Aims Viola philippica is a species with a typical chasmogamous-cleistogamous (CH-CL) mixed breeding system. It provides a flower model system to investigate floral organs development under different photoperiods. Morphological changes of intermediate cleistogamous (inCL) flowers have been observed, the trends in variation of changes from CH flowers to CL flowers or from CL flowers to CH flowers have been analyzed, the localized effects of poorly developed stamens and petals in CL and inCL flowers have been identified. This research provided morphology and structural changes with implication for the evolutionary significance of the dimorphic flower formation for further study in dimorphic flower development.Methods We used methods of anatomy and structural analysis to observe the morphological structures of flowers under different photoperiods.Important findings Photoperiod played an important role in the development of CH and CL flowers in V. philippica. Under short-day light and intermediate-day light, both CH and inCL flowers developed simultaneously. Most of the floral buds were CH flowers under a photoperiod of short-day light, but most of the floral buds were inCL flowers under mid-day light. Complete CL flowers formed under long-day lights. However, there were a series of transitional types in the number and morphology of stamens and petals among inCL flowers, including five stamens with three petals related to CH flowers and two stamens with one petal related to CL flowers. The former type was dominant under short-day light conditions, and the latter type was dominant under mid-day light. Further more, there were localized effects in stamen and petal development for CL and inCL flowers. The development of ventral lower petal (corresponding to the lower petal with spur of CH flower) and the adjacent two stamens in inCL flowers were best, and the back petal was similar to that of CL flowers, an organ primordium structure. The adjacent stamens with the back petals tended to be poorly developed. In extreme cases, these stamens in inCL flowers had no pollen sac, only a membranous appendage or even a primordium structure. When the plants with CL or CH flowers were placed under short-day light or long-day light, the newly induced flowers all showed a series of inCL flower types, finally the CL flowers transformed into CH flowers, and the CH flowers transformed into CL flowers. This result indicates the gradual effects of different photoperiods on dimorphic flowers development of V. philippica. A long photoperiod could inhibit the development of partial stamens and petals, and a short photoperiod could prevent the suppression of long-day light and promote the development of stamens and petals.     

Biosynthesis of sorbic acid in aphids: An investigation into symbiont involvement and potential relationship with aphid pigments

Studies were undertaken to determine the role of symbionts and UV exposure in biosynthesis of the aphid-specific polyketides, sorbic acid and quinone pigments. Injection of adult potato aphids, Macrosiphum euphorbiae (Thomas), with the antibiotic rifampicin did not alter the level of sorbic or myristic acid in triglycerides of resultant progeny; pigmentation was also unaffected. However, antibiotic injection did produce marked physiological effects; progeny from injected aphids were smaller, slower to mature, and not fecund. Light microscopy confirmed that only 8% of rifampicin-treated aphids contained mycetocytes; thus, symbiont involvement in the production of this unusual UV-quenching short chain fatty acid is not supported. Following multigenerational exposure to long wavelength UV light, no substantial changes in sorbic acid content were detected in the potato aphid or the oleander aphid, Aphis nerii Fonscolombe. Pigments from UV-exposed oleander aphids had a peak absorbance at 390 nm, 70 nm lower than unexposed aphids. This suggests a photo-protective role for the pigments of the sunlight-inhabiting A. nerii; by contrast, no changes were observed in pigments of M. euphorbiae which usually feeds in the shade. Injection of adult potato aphids with sodium [1-¹⁴C]-acetate rapidly labeled both sorbic acid and pigments, particularly among the latter a yellow pigment which co-chromatographed with the dominant C15 yellow pigment of the oleander aphid. These data support the hypothesis that aphid C30 pigments are built up by coupling of “monomeric type” C15 pigments. Although aphid and not symbiont enzymes appear to synthesize these acetogenins, a possible biosynthetic link between sorbic acid and aphid pigments requires further clarification. © 1994 Wiley-Liss, Inc.     

Patterns of flower morphology and structural changes during interconversion between chasmogamous and cleistogamous flowers in Viola philippica北大核心CSCD

Aims: Viola philippica is a species with a typical chasmogamous-cleistogamous (CH-CL) mixed breeding system. It provides a flower model system to investigate floral organs development under different photoperiods. Morphological changes of intermediate cleistogamous (inCL) flowers have been observed, the trends in variation of changes from CH flowers to CL flowers or from CL flowers to CH flowers have been analyzed, the localized effects of poorly developed stamens and petals in CL and inCL flowers have been identified. This research provided morphology and structural changes with implication for the evolutionary significance of the dimorphic flower formation for further study in dimorphic flower development. Methods: We used methods of anatomy and structural analysis to observe the morphological structures of flowers under different photoperiods. Important findings: Photoperiod played an important role in the development of CH and CL flowers in V. philippica. Under short-day light and intermediate-day light, both CH and inCL flowers developed simultaneously. Most of the floral buds were CH flowers under a photoperiod of short-day light, but most of the floral buds were inCL flowers under mid-day light. Complete CL flowers formed under long-day lights. However, there were a series of transitional types in the number and morphology of stamens and petals among inCL flowers, including five stamens with three petals related to CH flowers and two stamens with one petal related to CL flowers. The former type was dominant under short-day light conditions, and the latter type was dominant under mid-day light. Further more, there were localized effects in stamen and petal development for CL and inCL flowers. The development of ventral lower petal (corresponding to the lower petal with spur of CH flower) and the adjacent two stamens in inCL flowers were best, and the back petal was similar to that of CL flowers, an organ primordium structure. The adjacent stamens with the back petals tended to be poorly developed. In extreme cases, these stamens in inCL flowers had no pollen sac, only a membranous appendage or even a primordium structure. When the plants with CL or CH flowers were placed under short-day light or long-day light, the newly induced flowers all showed a series of inCL flower types, finally the CL flowers transformed into CH flowers, and the CH flowers transformed into CL flowers. This result indicates the gradual effects of different photoperiods on dimorphic flowers development of V. philippica. A long photoperiod could inhibit the development of partial stamens and petals, and a short photoperiod could prevent the suppression of long-day light and promote the development of stamens and petals.     

环境因子调控植物花青素苷合成及呈色的机理

花青素苷（anthocyanin）是决定被子植物花、果实和种皮等颜色的重要色素之一。花青素苷的合成与积累过程往往与植物发育过程密切相关,由内外因子共同控制。环境因子通过诱导植物体内花青素苷合成途径相关基因的表达来调控花青素苷的呈色反应。该文追踪了国内外相关研究,认为光是影响花青素苷呈色的主要环境因子之一,光质和光强均能在一定程度上影响花青素苷的合成,其中光质起着更为关键的作用;低温能诱导花青素苷的积累,高温则会加速花青素苷的降解;不同的糖类物质均能影响花青素苷的合成,大部分结构基因和调节基因的表达均受糖调控。关于花发育与花青素苷呈色的关系、观赏植物花色对环境因子的响应以及花青素苷抵御逆境的机理尚待深入研究。因此,综合考察花发育与植物花青素苷合成及其呈色之间的关系,特别是光周期对花发育的影响导致花青素苷合成及呈色的机理是花色研究的一个重要课题。利用环境因子调控花色将会极大地提高花卉的观赏价值。     

环境因子调控植物花青素苷合成及呈色的机理

花青素苷(anthocyanin)是决定被子植物花、果实和种皮等颜色的重要色素之一。花青素苷的合成与积累过程往往与植物发育过程密切相关, 由内外因子共同控制。环境因子通过诱导植物体内花青素苷合成途径相关基因的表达来调控花青素苷的呈色反应。该文追踪了国内外相关研究, 认为光是影响花青素苷呈色的主要环境因子之一, 光质和光强均能在一定程度上影响花青素苷的合成, 其中光质起着更为关键的作用; 低温能诱导花青素苷的积累, 高温则会加速花青素苷的降解;不同的糖类物质均能影响花青素苷的合成, 大部分结构基因和调节基因的表达均受糖调控。关于花发育与花青素苷呈色的关系、观赏植物花色对环境因子的响应以及花青素苷抵御逆境的机理尚待深入研究。因此, 综合考察花发育与植物花青素苷合成及其呈色之间的关系, 特别是光周期对花发育的影响导致花青素苷合成及呈色的机理是花色研究的一个重要课题。利用环境因子调控花色将会极大地提高花卉的观赏价值。     

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.     

Flowering response of Lemna perpusilla 6746 to a single dark period

Lemna perpusilla 6746 is induced to flower by a single longdark period, but the floral buds once formed disappear afterseveral days under 5000 lux/25?C. Such regression of floralbuds is prevented by lowering the light intensity or temperature,but if the light intensity and/or temperature are lowered beyondcritical levels, new floral buds form. If the cultures are subjectedto 100 lux/20?C, neither regression nor new formation of floralbuds occurs. Under such conditions, the number of floral frondsreaches maximum about 6 days after the inductive dark periodand reamins unchanged for at least 10 days, while the percentageof floral fronds rapidly decreases thereafter, owing to thedilution by newly developed vegetative fronds. When the cultures are subjected to various lengths of a singledark period (25?C) followed by 100 lux/20?C, flowering responsesrepresented by the number of floral fronds per flask show rhythmicfluctuation with a cycle length of about 24 hr. Similar rhythmicresponse is observed when a brief light interruption is givenat different times during a single long dark period. (Received December 2, 1974; )