Plant pigments

This study had investigated on the possibility of blood
leaf( Iresine herbstii) as a soil pH indicator. An aqueous solution
was prepared and settled to remove impurities.  The pH is 4.6.
The solution was tested in a 0-14 pH solutions to check on the
color changes in the scale. The soil  pH was tested using pH
paper and pH meter. The soil pH was also tested using the  blood
leaf extract and the tests showed the same result.  In conclusion, 
the aqueous extract of blood leaf can be used as  soil pH
indicator. This can benefit gardeners and flower growers because
they can use it as fresh extract or can be kept even for many
weeks in closed container.

Colour patterns of flowers are vital commercial characteristics that influence floricultural plants and industries around the globe because of the multiple colour pigmentation produced by flowering plants. Flower colour patterns comprising different sets of colour can be found in many plant species and their cultivars. The varieties of an ornamental cultivated flowering plant like Clivia have also improved significantly in the floricultural industry worldwide. Clivias were recently subjected to a notable deal of retail market among conventional breeders to enhance varieties of variable flower colour traits, thus allowing the idea to understand and explore the origin and development new plant varieties. However, these ideas will be more credible if innovative studies are done on flower modification of pigments. Nonetheless, the review was focused on Clivia biology, flavonoid pigments, and factors affecting anthocyanins accumulation and colour in flowers, anthocyanin biosynthetic structural genes and CHS and ANS gene expression in flowering plants. In addition, the review concentrated on known important species of clivia, specifically on Clivia miniata, and the general studies of flavonoid biosynthetic genes from other plants in regards to flower pigmentation.

Flowers of the annual corn poppy (Papaver rhoeas L.) often exhibit two-coloured petals, which appear red with a black region on their base. In several cases, a white stripe between the red and the black region exists, especially on the adaxial surface. The white stripe of the petals possesses a pink and a grey hue on its margins to the red and the black region of the petal, respectively. Floral pigments localized in the vacuolar sap of epidermal cells are responsible for the petals’ colouration. Thus, isolated epidermises might be red, colourless and purple depending on whether they originate from the red, white or black petal region. The graduated transition from either the black or the red region to the white region is achieved by a gradient variation in pigment concentrations and/or the co-existence of both coloured and colourless epidermal cells, on the two sides of the petals. When the white stripe is absent, the transition from red to purple epidermal cells is achieved without the interference of intermediate-coloured cells. The role of this chromatic pattern is discussed.

The aim of this thesis is to study the colour, the pigments and the optical properties of the two-coloured petals of corn poppy (Papaver rhoeas L.) flowers. The corn poppy was chosen to be studied because of the coexistence of a discrete red and a discrete black region on their petals, and its common presence in the Mediterranean ecosystems. The red and the black regions are studied comparatively. The study of the colouration intended to incorporate both the chemical (pigmentary) and the structural components of plant colour. The methods used include the morphological description of petals, the UV-Vis spectroscopy of petal extracts for the qualitative and quantitative analysis of major plant pigment pigments groups (anthocyanins, flavons and flavonols, chlorophylls & carotenoids), the UV-Vis-NIR spectroscopy of intact petals with the aid of an integrating sphere, the study of petal micromorphology via SEM microscopy and the EDX-SEM element analysis of the tissue samples. Fully expanded corn poppy flowers were collected throughout the entire flowering season from Athens (Greece) and used for the experiments as fresh material, dried and powdered or prepared from SEM microscopy. Petals from different flowers vary in size, shape and colouration pattern, some of which bear a thin white stripe on the adaxial surface between the red and black petal regions. Acidified methanol petal extract absorption spectra of the red and the black region differ, implying differences in their pigment content. The red region spectrum shows a sharp maximum in a shorter wavelength to the black region spectrum maximum, which is also much broader and less sharp. Moreover, the red region spectrum drops in the red region, whereas the black region is gradually reduced. Pigment quantification validated that anthocyanins are the main pigments of the petals. Unlike expected, anthocyanin concentration was much higher in the black region than in the red region. Additionally, anthocyanin concentration is heavily reduced in the red region –but not in the black region- at the end of the flowering season. These measurements conclude that although anthocyanins are the main pigments in both regions, they considerably differ in their pigment content. The black colour is not the result of high anthocyanin concentration but of the inclusion of a high variety of anthocyanins that cover almost all the range of the visible spectrum. The sharp absorption maximum from the red area explains the high saturation of the red colour corn poppy flowers. Pure methanol and ethanol extracts imply the presence of flavones in the black region and flavonols in the red region, which may act as co-pigments to anthocyanins. Flavone and flavonol (‘total flavonoid’) quantification showed the same seasonal variation pattern as the anthocyanins during the flowering season, both for the red and the black region. The quantification showed that the flavones and flavonols concentration is much lower than the anthocyanin concentration, questioning their potential role as co-pigments. Chlorophylls and carotenoids were not identified. Absorbance spectra of intact petals reveal important differences in contrast to absorption spectra of extracted pigments. Both the black and the red regions show very high and steady absorbance (>90%) from 250 nm to 570 nm (red region) or 620 nm (black region). Absorbance spectra of the adaxial and the abaxial surface do not show important differences. The big differences from the absorption spectra of extracted pigments imply the high participation of structural elements in the flower colour. More specifically, high absorbance above 700 nm in the black region may reveal the extended presence of scattering petals in petals. Light scattering structures might include the extended petal intercellular spaces. SEM microscopy of petal surfaces showed the presence of fine cuticle micro-structures which may be more or less irregular, which consists, in some areas, of the presence of two different cuticle nano-ridges with different orientations one on top of the other. The red petal region shows more intense cuticle microstructures. The ridges were not extended enough to be considered responsible of purely structural colour. EDX analysis revealed some differences between the two regions, but the reliability of these results is questionable. Molybdenum was detected only in the black area, sulfur only in the red area, potassium concentrations were much higher in the black area.

Heavy metals affect growth, morphology and metabolism of plants in several ways. To reveal relationship between metal toxicity, oxidative stress and detoxification responses, the effects of four different heavy metals (Cd, Co, Pb and Ag) on Aeluropus littoralis was determined. So, one-month-old plantlets were treated with different concentrations (50 μM and 100 μM) of heavy metals for one week and the contents of photosynthetic pigments, phenolic compounds, proline, soluble proteins and the activities of enzymatic antioxidants (superoxide dismutase, guiacol peroxidase and catalase) as marker for oxidative stress were investigated. Survey results indicated that the amount of non-enzymatic antioxidant compounds (phenol and proline) significantly were increased in all treatments but a significant decrease was observed in photosynthetic pigments in the most treatments. Also, the accumulation of soluble proteins and increase in superoxide dismutase activity of which are respectively reco...

In order to investigate the impact of drought stress, a trail was carried out in a factorial experiment in the base of randomized complete design on traits such as pigments and photosynthesis in five Eucalyptus species (E. globulus, E. largiflorens, E .robusta, E. sideroxylon, E. tereticornis). Drought treatments contained polyethylene glycol solution with five levels (0, -1, -3, -6, -12 bar). In this investigation characteristics such as: chlorophyll and carotenoids, photosynthesis rate, leaf water potential and stomata number were studied. Most of the traits were significantly decreased under water stress condition. The highest amount of chlorophyll, carotenoids, photosynthesis and leaf water potential were related to control plants of different species. Results showed that these traits caused lower reduce under drought stress condition in E. largiflorens. Whereas these traits have positive correlation with resistance to drought, consequently E. largiflorens were most resistance species to drought stress. E. sideroxylon and E. tereticornis with high reduce in traits were sensitive species to drought under drought stress condition. E. globulus and E. robusta were relative high resistance species to drought stress.

The Lc petunia system, which displays enhanced, light-induced vegetative pigmentation, was used to investigate how high light affects anthocyanin biosynthesis, and to assess the effects of anthocyanin pigmentation upon photosynthesis. Lc petunia plants displayed intense purple anthocyanin pigmentation throughout the leaves and stems when grown under high-light conditions, yet remain acyanic when grown under shade conditions. The coloured phenotypes matched with an accumulation of anthocyanins and flavonols, as well as the activation of the early and late flavonoid biosynthetic genes required for flavonol and anthocyanin production. Pigmentation in Lc petunia only occurred under conditions which normally induce a modest amount of anthocyanin to accumulate in wild-type Mitchell petunia [Petunia axillaris×(Petunia axillaris×Petunia hybrida cv. ‘Rose of Heaven’)]. Anthocyanin pigmentation in Lc petunia leaves appears to screen underlying photosynthetic tissues, increasing light saturation and light compensation points, without reducing the maximal photosynthetic assimilation rate (Amax). In the Lc petunia system, where the bHLH factor Leaf colour is constitutively expressed, expression of the bHLH (Lc) and WD40 (An11) components of the anthocyanin regulatory system were not limited, suggesting that the high-light-induced anthocyanin pigmentation is regulated by endogenous MYB transcription factors.

Photoprotection of the chloroplast is an important component of abiotic stress resistance in plants. Carotenoids have a central role in photoprotection. We review here the recent evidence, derived mainly from in vitro reconstitution of recombinant Lhc proteins with different carotenoids and from carotenoid biosynthesis mutants, for the existence of different mechanisms of photoprotection and regulation based on xanthophyll binding to Lhc proteins into multiple sites and the exchange of chromophores between different Lhc proteins during exposure of plants to high light stress and the operation of the xanthophyll cycle. The use of recombinant Lhc proteins has revealed up to four binding sites in members of Lhc families with distinct selectivity for xanthophyll species which are here hypothesised to have different functions. Site L1 is selective for lutein and is here proposed to be essential for catalysing the protection from singlet oxygen by quenching chlorophyll triplets. Site L2 a...

Partial table of contents: Carbon Balance of Stressed Plants: A Conceptual Model for Integrating Research Results (J. Amthor & K. McCree). Transport/Harvest Index: Photosynthate Partitioning in Stressed Plants (T. Setter). Physiochemical Basis for Free Radical Formation in Cells: Production and Defenses (G. Winston). Effects of Abiotic Stresses on Plant Hormone Systems (P. Morgan). Superoxide Dismutases in Aerobic Organisms (H. Hassan & J. Scandalios). Glutathione (I. Smith, et al.). Stomatal Behavior in Water Stressed Plants (T. Mansfield & C. Atkinson). Adaptations to Low Temperatures (J.-E. H?llgren & G. ?quist). Heat Shock Protein Function and Expression in Plants (E. Vierling). Heavy Metal Stress and the Phytochelatin Response (J. Steffens). Index.

This study had investigated on the possibility of blood leaf(Iresine herbstii) as a soil pH indicator. An aqueous solution was prepared and settled to remove impurities. The pH is 4.6. The solution was tested in a 0-14 pH solutions to check on the color changes in the scale. The soil pH was tested using pH paper and pH meter. The soil pH was also tested using the blood leaf extract and the tests showed the same result. In conclusion, the aqueous extract of blood leaf can be used as soil pH indicator. This can benefit gardeners and flower growers because they can use it as fresh extract or can be kept even for many weeks in closed container.

In this study, we investigated the role of acetylsalicylic acid pretreatment (0, 1 and 10 µM) in inducing salt and osmotic tolerance in a wild species of potato (Solanum bulbocastanum). To determine whether the major influence of salinity is caused by the osmotic component or by salinity induced specific ion toxicity, we compared the effects of iso-osmstic concentrations of polyethylene glycol 6000 (15%) and NaCl (80 mM NaCl) on the physiological responses of this species explants grown in the liquid Morashige and Skoog medium. Both salt and drought reduced shoot growth parameters, photosynthetic pigments and increased lipid peroxidation, electrolyte leakage, HO level and lipoxygenase activity and the effect of NaCl was more severe than 2 2 polyethylene glycol. Salinity increased Na content and decreased K and K /Na ratio. Under salt and osmotic + + + + stress, the activity of superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase, catalase and glutathione reductase enzymes...

Flowers of the annual corn poppy (Papaver rhoeas L.) often exhibit two-coloured petals, which appear red with a black region on their base. In several cases, a white stripe between the red and the black region exists, especially on the adaxial surface. The white stripe of the petals possesses a pink and a grey hue on its margins to the red and the black region of the petal, respectively. Floral pigments localized in the vacuolar sap of epidermal cells are responsible for the petals’ colouration. Thus, isolated epidermises might be red, colourless and purple depending on whether they originate from the red, white or black petal region. The graduated transition from either the black or the red region to the white region is achieved by a gradient variation in pigment concentrations and/or the co-existence of both coloured and colourless epidermal cells, on the two sides of the petals. When the white stripe is absent, the transition from red to purple epidermal cells is achieved without the interference of intermediate-coloured cells. The role of this chromatic pattern is discussed.

In this study, we investigated the role of acetylsalicylic acid pretreatment (0, 1 and 10 µM) in inducing salt and osmotic tolerance in a wild species of potato (Solanum bulbocastanum). To determine whether the major influence of salinity is caused by the osmotic component or by salinity induced specific ion toxicity, we compared the effects of iso-osmstic concentrations of polyethylene glycol 6000 (15%) and NaCl (80 mM NaCl) on the physiological responses of this species explants grown in the liquid Morashige and Skoog medium. Both salt and drought reduced shoot growth parameters, photosynthetic pigments and increased lipid peroxidation, electrolyte leakage, H O level and lipoxygenase activity and the effect of NaCl was more severe than 22 polyethylene glycol. Salinity increased Na content and decreased K and K /Na ratio. Under salt and osmotic + + + + stress, the activity of superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase, catalase and glutathione reductase enzymes...