Influence of ethanol on ethylene biosynthesis and flower senescence of cut carnation

Ethanol in the holding-solution inhibited climacteric ethylene (C₂H₄) biosynthesis and decreased the respiration rate 60% during a 7-day period in cut carnation flowers. Conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to C₂H₄ was inhibited by adding ethanol to the holding-solution. Simultaneously, ACC-induced senescence in carnation flowers was inhibited by ethanol. Ethanol was the most effective alcohol in delaying carnation flower senescence of the tested series methanol, ethanol, propanol, tert-butanol and n-butanol. Ovary development was also inhibited in carnation flowers by ethanol. The senescence of Easter lily flowers (Lilium longiflorum) and tulip flowers (Tulipa gesneriana) was not delayed by ethanol.     

Azalea indica flower colour as related to the parameters pH,anthocyanins and flavonol co-pigments

The influence of epidermal tissue pH on flower colour was studied in 104 cultivars of Azalea indica (Rhododendron simsii Planch.). Based on H.C.C. visual colour number, cultivars were classified in 4 colour groups: purple; carmine red; red; white.A method for pH determination using microvolumes (30 μl) on a microelectrode has been perfected. Within each colour group, flower colour was determined within a mean pH environment of 3.04 ± 0.06. Epidermal pH was approximately 0.3 units lower than the pH of the expressed sap of entire petals. Purple colours occurred with co-pigmented malvidin or delphinidin glycosides. Carmine red and red colours were produced by the same cyanidin glycosides that in the case of carmine red were co-pigmented with flavonol glycosides. The lower the content of anthocyanins (cyanidin glycosides) and the higher that of flavonols, the bluer the red (higher H.C.C. number; bathochromic shift of about 20 nm). A carmine red flower colour (± 58 B) may also occur when delphinidin glycosides occur in the absence of flavonol glycosides (pH < 4).Prospects for obtaining a blue flower colour are, because of low epidermal pH, very small.     

Effects of high temperature on flower colour and anthocyanin content in pink flower genotypes of greenhouse chrysanthemum (Chrysanthemum morifolium Ramat.)

Summary

The relationship between the intensity of flower colour and changes in the content of the main anthocyanins under various controlled temperatures was examined in order to clarify the effects of high temperature on flower colouration in six pink flower genotypes of greenhouse chrysanthemum (Chrysanthemum morifolium Ramat.). Poor colouration of flowers was observed at 30°C in all genotypes except ‘Chatoo’. This genotype showed little difference in flower colour between different temperature treatments. The degree of change in flower colour differed depending on the genotype, whereas no clear differences in flower colouring were observed between Summer – Autumn flowering and Autumn-flowering genotypes. All genotypes showed lower contents of the two anthocyanins tested [cyanidin 3-O-(6’’-O-monomalonyl- -glucopyranoside) and cyanidin 3-O-(3’’,6’’-O-dimalonyl- -glucopyranoside)] at higher temperatures. Therefore, flower colour changes were attributable to changes in these two main anthocyanins. Differences in colouration between genotypes and temperature conditions were also detectable in values that were measured using a colorimeter. Changed parameters that were visually verifiable were the a* value, representing the degree of red colour, and the C* value, representing chroma. For ‘Sei-Monako’, which showed visually greater differences between temperature treatments, the a* and C* values were low under high temperature conditions. On the other hand, in ‘Chatoo’, the differences detected by eye and those in a* and C* values between temperature treatments were small. In addition, the present results indicate that mean temperature is more important than either day or night temperature in determining the degree of flower colouration.     

The susceptibility of pepper (Capsicum annuum) to heat induced flower abscission: Possible involvement of ethylene

SUMMARY

Heat stress causes abscission of flowers in pepper plants and thus reduces yield. In the present study, we investigated the involvement of ethylene in heat-stress related flower abscission, by comparing the response of flowers of bell pepper, cv. Maor, known to be sensitive to flower abscission, and flowers of paprika, cv. Lehava, a resistant cultivar of Capsicum annuum. Their differing susceptibilities to high temperatures depend on light. Under high-temperature, high-light conditions, bell pepper was less susceptible than paprika, but, under high-temperature low-light, bell pepper was more susceptible. At high temperatures, flower explant abscission was much higher with bell pepper than paprika. Ethylene production (EP) by bell pepper explants reached a maximum at 34°C and decreased at higher temperatures (42 and 48 C), while in paprika EP rates were lower and reached the maximum at 42°C. Explants of bell pepper flowers were more susceptible to exogenous ethephon than paprika flowers. The sensitivity of a collection of pepper cul-tivars to heat induced flower abscission was more closely correlated with their flower sensitivity to ethephon than with the flower EP rate. We suggest that the differential susceptibility of bell pepper and paprika to heat stress is a result of both different ethylene production by their flowers and their differing sensitivities to ethylene produced under high-temperature stress. However, the sensitivity of the flower to ethylene may be more important in inducing their abscission.     

Characterisation of respiration,ethylene production,and carbohydrate contents during flower opening in Epidendrum ibaguense

Summary

The opening of flowers in Epidendrum ibaguense is characterised by continuous drops in respiration, ethylene production, and 1-aminocyclopropone-1-carboxylate (ACC) oxidase activity from the bud stage to fully open. Later, an increase in ethylene production and ACC oxidase activity occurred, suggesting autocatalytic production of ethylene, beginning at an early stage of senescence. Regardless of developmental stage, the main non-structural carbohydrates in flowers were non-reducing sugars [23.7% (w/w) fresh weight (FW)]. Starch accounted for 3.1% (w/w) FW and reducing sugars for 0.7% (w/w) FW. No depletion in the level of any carbohydrate was observed throughout senescence. At the beginning of floral senescence, a sharp increase occurred in the activities of acid and alkaline invertases, suggesting a role for both enzymes in the cleavage of sucrose. However, no major changes in sucrose synthase activity were found during flower development.     

Newly developed SSR markers reveal genetic diversity and geographical clustering in Paeonia suffruticosa based on flower colour

Tree peony (Paeonia suffruticosa Andr.), considered by many to be the national flower of China, is famous for its ornamental, medicinal and culinary attributes. In this study, a total of 8,663 Simple Sequence Repeats (SSRs) were detected by means of a microsatellite search of unigene sequences identified from the de novo assembly of sequence data from different genotypes of tree peony from the Zhongyuan group. Among 100 randomly selected SSR markers, 25 were successfully amplified and showed polymorphism in 31 tree peony accessions. The number of polymorphic alleles ranged from 3 to 11 for each locus and the polymorphism information content value (PIC) ranged from 0.58 to 0.85, with a mean of 0.73, indicating a high level of discriminative capability. To analyse the genetic diversity, a phylogenetic tree was constructed, which demonstrated that tree peonies of similar flower colour were clustered together. The large number of tree peony SSR markers identified in this study will be valuable in studies in genetic diversity and linkage map construction, in gene localisation and cloning and in molecular-marker-assisted breeding in tree peony.     

南瓜果肉可溶性固形物含量与叶、花、果肉色泽的相关性分析

以14种不同品种的南瓜为材料,在果实成熟期采用CR-3型色差仪测量其叶片、花朵、果肉的Lab值,同时采用PAL-1型测糖仪测量果肉中可溶性固形物含量,并对叶、花、果肉的Lab值与果肉中可溶性固形物含量进行了相关性分析。结果表明,南瓜叶、花、果肉色泽的Lab值的变异系数有差异,果肉中红色成分变异系数最大,达27.43%;果肉中可溶性固形物含量与叶片的亮度呈极显著正相关(r=0.632),与果肉中红色成分呈显著正相关(r=0.412)。这为南瓜品质育种田间筛选可溶性固形物含量高的试验材料提供了便捷的方法。     

The role of flower and leaves in cut flower water uptake

Removal of the cut rose flower of ‘Forever Yours’ decreased water uptake by 20.4%, leaf removal 78.5%, and both flower and leaf removal 95.2%. Cut carnation ‘White Sim’ water uptake declined 27.1, 37,3 and 59.6% after flower, leaf, or both were removed, respectively. A high rate of water uptake (40.4%) continued after both carnation flower and leaf removal.     

Video evaluation of ethylene sensitivity after anthesis in carnation (Dianthus caryophyllus L.) flowers

Differences in ethylene sensitivity among carnation (Dianthus caryophyllus L.) cultivars were evaluated using a time-lapse video recording system. Measurement of time to petal inrolling of ‘White Sim’, ‘Nora’, ‘Chinera’, and line 64-54 flowers subjected to a range of 1–20 μl l⁻¹ ethylene showed that 10 μl l⁻¹ was the optimum concentration for sensitivity evaluation with our video system. With this system we found clear differences in ethylene sensitivity among 10 cultivars and one line. ‘Candy’, ‘Pallas’, ‘Chinera’, and line 64-54 had lower ethylene sensitivities than the other seven cultivars. Line 64-54 had the longest ethylene response time (20.6 h to start of petal inrolling). Video monitoring is a simple and accurate way of evaluating ethylene sensitivity. We have also used the system to study changes in the ethylene sensitivity of carnation flowers after anthesis. We were able to detect a shift in responsiveness to ethylene that was impossible to detect by previous methods. In the Sim-type carnation cultivars tested (‘White Sim’, ‘Scania’, ‘U Conn Sim’, and ‘Nora’), ethylene sensitivity after anthesis decreased significantly with age in both early-cut and late-cut flowers. These results clearly showed that decline of ethylene sensitivity is caused by the increasing physiological age of flowers. Ethylene sensitivity after anthesis decreased with age in normal Sim-type carnations in the same way as in long-vase-life variants such as ‘Sandrosa’.     

Influence of flower bud density,flower bud drop and fruit set on apricot productivity

Flower bud density, flower bud drop and fruit set were studied for nine apricot cultivars in order to understand the influence of these variables on apricot biology and productivity. Cultivars in southern Spain were chosen as representatives of different flowering times and productivity. Results indicate differences among cultivars in the studied parameters. Low flower bud production, high flower bud drop and low fruit set were often recorded in mid- to late flowering cultivars. These traits subsequently led to poor yields. Early blooming varieties, which are frequently good producers, generally showed the highest flower bud density, medium flower bud drop and high percentage of fruit set. The influence of the cultivar was more determinant than the seasonal effect on fruit yield. This information should be useful to breeders for choosing the best parents for productivity.     

Effects of shading on growth rate,flower initiation and flower development of Begonia x semperflorens-cultorum

Seedlings of Begonia x semperflorens-cultorum Hort. ‘Scarletta’ were grown under 0,45, or 57% of ambient light in a glass greenhouse. Shoot dry weight, lateral shoot leaf area, total leaf area, and node number decreased under increasing shade over time. Histological examination of shoot apices indicated that floral initiation occurred two to three weeks later in plants under 57% shade than those under ambient light or 45% shade. Plants under ambient light reached visible bud about five weeks before those under 57% shade and the time of floral development from visible bud to anthesis was also shorter for plants in ambient light compared with those grown under 45 and 57% shade. Staminate flower numbers on the first inflorescence increased under 45% shade compared with ambient light and 57% shade while pistillate flower numbers were unchanged.     

Abscisic acid content of Citrus flavedo in relation to colour development

Summary

The relationship between endogenous abscisic acid concentrations and the development of colour was examined in six cultivars of Citrus sinensis. Abscisic acid content increased throughout the course of colour development and reached a maximum at time of colour break. Late-maturing cultivars accumulated substantially more abscisic acid and development of colour occurred visibly later than in ‘Navel’ selections. A decline in abscisic acid concentration occurred concomitantly with full expression of colour. Analysis of the pigment composition of flavedo from Citrus sinensis cv. Midknight revealed that development of orange colour was associated with a decline in levels of β,β-carotenoids, an increase in violaxanthin monoesters and formation of xanthophyll acyl esters.     

Growth and abortion of flower buds in gynoecious cucumber plants in relation to temperature

The growth of flower buds in a gynoecious cucumber cultivar was studied at 15, 21 and 27°C. Competition between buds in the same node was measured as the ratio of the growth rates of individual buds. This competition was stronger at 21 and 27 than at 15°C. At 15°C, at least 3 buds were about equally strong; at 21°C, 2 buds developed fast and suppressed the other buds; at 27°C, the first bud which developed suppressed all other buds. When plants were transferred from one temperature to another, the growth-rate ratio between buds in older nodes was maintained. In nodes formed in the new temperature regime, the growth-rate ratio was determined by the new temperature.     

Effects of exposing freesia corms to ethylene or to smoke on dormancy-breaking and flowering

Ethylene (C₂H₄), applied at an early stage of the high-temperature treatment for dormancy breaking, promoted sprouting. Five μl l^?1 of C₂H₄, applied during 2 days, replaced 2 weeks of high temperatures. The promotive effect of C₂H₄ diminished with increasing exposure period and no difference was found between the effects of 5 and 50 μl l^?1. The promotive effect of exposing corms to smoke was slightly lower than that of C₂H₄. Neither had an adverse effect on flowering and both resulted in shorter leaf length and rigid growth, which could be useful for solving the problems of leafiness during winter.     

Petunia cultivar sensitivity to ozone and sulphur dioxide

Ozone (O₃) and sulphur dioxide (SO₂) are widespread pollutants in many of the areas in which petunias are grown as bedding-plants. Controlled environment experiments were conducted to evaluate the sensitivity of ‘Capri’, ‘White Magic’ and ‘White Cascade’ to separate or combined O₃ and SO₂ at 2 growth stages. Relative cultivar sensitivity was the same for O₃, SO₂ or O₃ + SO₂, with ‘Capri’ leaves least injured and ‘White Cascade’ leaves most injured. Visible injury symptoms were similar in all cultivars. Leaves of intermediate age were most sensitive, but early vegetative plants were more sensitive to O₃ than plants in immediate prefloral stage. Severity of leaf injury was generally greater from the combined gases than from the single gases, and the combination treatment at the early vegetative stage significantly reduced plant growth and flower weight 4 weeks later.     

Sensitivity of Geraldton waxflower to ethylene-induced flower abscission is reduced at low temperature

Summary

Exposure to ethylene gas elicits flower abscission from cut stems of Geraldton waxflower (Chamelaucium uncinatum Schauer). Ethylene response rates in plants are mediated by temperature. At 20°C, flower abscission from waxflower ‘Purple Pride’ occurred upon 12 h exposure to 1 µ11^–1 ethylene. This ethylene treatment did not cause flower abscission at either 10 or 2°C. Moreover, flowers held at 2°C were insensitive to 48 h exposure to 1, 10 and 100 µ11^–1 ethylene. However, increasing the duration of treatment with 1 µ11^–1 ethylene at 10 and 2°C to 48 and 144 h, respectively, induced flower abscission. When flowers were held at 20°C in air without exogenous ethylene following continuous exposure to 1 µ11^–1 ethylene at 2°C, the duration required to elicit flower abscission was reduced from 144 to 72 h. Collectively, these responses show that maintaining harvested waxflower at low temperature (e.g. 2°C) is an effective means to minimise ethylene-mediated flower abscission.     

The influence of fruiting on the bud sprouting and flower induction responses to chilling in Citrus

Summary

The effect of chilling temperatures on bud sprouting and flower formation was compared on fruiting and non-fruiting ‘Owari’ satsuma mandarin (Citrus unshiu Marc) trees. On non-fruiting trees, bud dormancy was weak, and a significant proportion of buds were able to sprout at high temperatures without being chilled. Separate effects of low temperatures on bud sprouting and flower induction were demonstrated. On fruiting trees these two effects of low temperatures were also demonstrated on summer-flush buds, but not on older (spring-flush) buds. The spring-flush buds from fruiting trees scarcely sprouted without being chilled. These buds required a longer chilling period for dormancy release than for flower induction, and it was not possible to separate the effect of low temperature on flower induction from the effect on dormancy release. The presence of fruit reduced flower formation by reducing bud sprouting. Furthermore, fruit had a direct inhibitive effect on vernalization which resulted in increased formation of vegetative shoots. The effect of fruit and low temperature on flowering was unrelated to carbohydrate accumulation in the leaves or the roots.     

Delay in ripening of picked olives due to ethylene treatments

Picked olive fruit, cv Manzanillo, in both green and half-black stages, was exposed for 1 to 2 weeks to 1–1 000 μl/l of ethylene, or dipped in ethephon at concentrations from 100 to 5 000 mg/l. All treatments inhibited anthocyanin accumulation and retarded softening of the pericarp; similar results were obtained when picked olives were exposed to a CO₂-rich atmosphere. The ethylene treatments also resulted in a faster chlorophyll disappearance.These findings are discussed in relation to the role of ethylene in fruit ripening.     

Anatomy of flower differentiation and abortion,in relation to the growth and development of hybrid tea-rose seedlings

From germination until anthesis or flower bud abortion, seedlings from ‘Sonia’ × ‘Hadley’ were grown in both a greenhouse (full daylight, 20° C) and a growth room (8 Wm^?2, 8 h, 20°C) of the IVT-phytotron. Plastochron was an external indication of the stage of flower differentiation. Flower differentiation in flowering and aborting seedlings ran parallel up to petal-segregation. Flower differentiation in aborting seedlings did not proceed beyond stamen formation. Early abortion, which also caused absence of the upper leaf, occurred without, later abortion with, an abscission zone in the flowerstalk.     

Genetics of bulb colour variation and flavonoids in onion

Onion (Allium cepa L.) is one of the most important vegetable crops due to its diverse culinary and health promoting properties. It is a rich source of dietary phytochemicals such as flavonoids and other antioxidants which enhance the medicinal importance of onion. Onion bulb colour is one of the important quality characters actively targeted in breeding programmes. Onion bulbs with red, white, yellow, golden, pink, chartreuse, etc. colour are available and this variation is due to the mutations in structural and regulatory genes of the flavonoid biosynthesis pathway. The genetics of bulb colour variation is very complex and involves multiple genes and their interactions. Further, these flavonoid compounds and their derivatives play diverse roles in plant development and stress tolerance in plants. Here, we review the biosynthesis of flavonoids, genetics and multiple alleles of genes for onion bulb colour, metabolic engineering, flavonoid in biotic and abiotic stress response and effect of cultural and storage practices on onion flavonoids.