Monochromatic red light during plant growth decreases the size and improves the functionality of stomata in chrysanthemum.

Light emitting diodes (LEDs) now enable precise light quality control. Prior to commercialisation however, the plant response to the resultant light quality regime ought to be addressed. The response was examined here in chrysanthemum by evaluating growth, chlorophyll fluorescence (before and following water deficit), as well as stomatal anatomy (density, size, pore dimensions and aperture heterogeneity) and closing ability. Plants were grown under blue (B), red (R), a mixture of R (70%) and B (RB), or white (W; 41% B, 39% intermediate spectrum, 20% R) light LEDs. Although R light promoted growth, it also caused leaf deformation (epinasty) and disturbed the photosynthetic electron transport system. The largest stomatal size was noted following growth under B light, whereas the smallest under R light. The largest stomatal density was observed under W light. Monochromatic R light stimulated both the rate and the degree of stomatal closure in response to desiccation compared with the other light regimes. We conclude that stomatal size is mainly controlled by the B spectrum, whereas a broader spectral range is important for determining stomatal density. Monochromatic R light enhanced stomatal ability to regulate water loss upon desiccation.

Blue Light Improves Vase Life of Carnation Cut Flowers Through Its Effect on the Antioxidant Defense System.

Improving marketability and extension of vase life of cut flowers has practical significance for the development of the cut flower industry. Although considerable efforts have been made over many years to improve the vase life of cut flowers through controlling the immediate environment and through post-harvest use of floral preservatives, the impact of lighting environment on vase life has been largely overlooked. In the current study, the effect of three LED light spectra [white (400-730 nm), blue (peak at 460 nm), and red (peak at 660 nm)] at 150 µmol m-2 s-1 on vase life and on physiological and biochemical characteristics of carnation cut flowers was investigated. Exposure to blue light (BL) considerably delayed senescence and improved vase life over that of flowers exposed to red light (RL) and white light (WL). H2O2 and malondialdehyde (MDA) contents in petals gradually increased during vase life; the increase was lowest in BL-exposed flowers. As a consequence, BL-exposed flowers maintained a higher membrane stability index (MSI) compared to RL- and WL-exposed flowers. A higher activity of antioxidant enzymes [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)] was detected in petals of BL-exposed flowers, compared to their activities in RL- and WL-exposed flowers. In BL-exposed flowers, the decline in petal carotenoid contents was delayed in comparison to RL- and WL-exposed flowers. Maximum quantum efficiency of photosystem II (Fv/Fm) and a higher percentage of open stomata were observed in leaves of BL-exposed flowers. Sucrose and glucose contents accumulated in petals during vase life; sugar concentrations were higher in BL-exposed flowers than in RL- and WL-exposed flowers. It is concluded that BL exposure improves the vase life of carnation cut flowers through its effect on the antioxidant defense system in petals and on photosynthetic performance in the leaves.

Blue light postpones senescence of carnation flowers through regulation of ethylene and abscisic acid pathway-related genes.

Endogenous signals in response to exogenous factors determine the senescence of flowers. Interactions among phytohormones especially abscisic acid (ABA) and ethylene are the major determinant of the senescence. In the present study, complex expression patterns of the genes related to ABA and ethylene as endogenous signals were investigated on cut carnations (Dianthus caryophyllus L.) that were exposed to different light spectra. Expression of ethylene biosynthetic (DcACS and DcACO), and signaling (DcETR and DcEin2) genes and also genes involved in ABA biosynthesis (DcZEP1 and DcNCED1), transport (DcABCG25 and DcABCG40) and catabolism (DcCYP707A1) were evaluated in petals of carnations exposed to three light spectra [white, blue and red]. Lowest relative membrane permeability (RMP) was detected in flowers that exposed to Blue light (BLFs), as a consequence, the longest vase life was found in BLFs. The Red and White lights markedly accelerated flower senescence and increased expression of DcACS and DcACO on day 6 and 10 of vase life assessment respectively; while Blue light inhibited the expression of ethylene biosynthetic genes. Expression of the genes involved in the production and transport of ABA and in signal transduction of ethylene was elevated during vase life of flowers irrespective of exposure to different light spectra. In conclusion, Blue light can be an effective environmental factor to extend the vase life of carnation flowers by delaying the petal senescence through down-regulation of ethylene biosynthetic genes and up-regulation of ABA biosynthetic genes.

Effects of growth under different light spectra on the subsequent high light tolerance in rose plants.

Photosynthesis is defined as a light-dependent process; however, it is negatively influenced by high light (HL) intensities. To investigate whether the memory of growth under monochromatic or combinational lights can influence plant responses to HL, rose plants were grown under different light spectra [including red (R), blue (B), 70:30 % red:blue (RB) and white (W)] and were exposed to HL (1500 µmol m-2 s-1) for 12 h. Polyphasic chlorophyll a fluorescence (OJIP) transients revealed that although monochromatic R- and B-grown plants performed well under control conditions, the functionality of their electron transport system was more sensitive to HL than that of the RB- and W-grown plants. Before exposure to HL, the highest anthocyanin concentration was observed in R- and B-grown plants, while exposure to HL reduced anthocyanin concentration in both R- and B-grown plants. Ascorbate peroxidase and catalase activities decreased, while superoxide dismutase activity was increased after exposure to HL. This caused an increase in H2O2 concentration and malondialdehyde content following HL exposure. Soluble carbohydrates were decreased by exposure to HL, and this decrease was more emphasized in R- and B-grown plants. In conclusion, growing plants under monochromatic light reduced the plants ability to cope with HL stress.

Molecular and physiological responses of Iranian Perennial ryegrass as affected by Trinexapac ethyl, Paclobutrazol and Abscisic acid under drought stress.

Drought stress is the major limiting factor which affects turfgrass management in area with restricted rainfall or irrigation water supply. Trinexapac ethyl (TE), Paclobutrazol (PAC) and Abscisic acid (ABA) are three plant growth regulators (PGRs) that are commonly used on turf species for increasing their tolerance to different environmental stresses such as drought. However, little is known about the impact of PGRs on stress tolerance of Iranian Perennial ryegrass (Lolium perenne). The present study was conducted to examine the visual and physiological changes of Iranian Perennial ryegrass in response to foliar application of TE, PAC, and ABA under drought stress conditions. According to the obtained results, application of all three PGRs considerably restored visual quality of drought exposed plants. TE treatment increased chlorophyll content, proline content and resulted in less malondialdehyde (MDA) in drought stressed Perennial ryegrass. Application of all PGRs enhanced the relative water content (RWC) and decreased the electrolyte leakage (EL) and Hydrogen peroxide contents (H2O2 content) of plants under drought stress, though the impact of TE was more pronounced. Throughout the experiment, TE- and ABA-treated plant showed greater soluble sugar (SSC) content as compared to the control. Antioxidant enzymes activities of drought exposed plants were considerably increased by PGRs application. Catalase (CAT) and Superoxide dismutase (SOD) activities were greater in TE-treated grasses followed by PAC-treated plants. Ascorbate peroxidase (APX) and peroxidase (POD) activities were significantly enhanced by TE and ABA application. The results of the present investigation suggest that application of TE, ABA and PAC enhances drought tolerance in Perennial ryegrass. TE, PAC and ABA were all effective in mitigating physiological damages resulting from drought stress, however the beneficial effects of TE were more pronounced. The result obtained of real time-PCR suggested that regulation of CAT, APX, POD and SOD genes expression at translational levels highly depended on the application of TE, PAC and ABA. Also, the results showed that deletion mutation in SOD and POD genes were not leading to enzyme inactivation.

Cognitive-analytical therapy for a patient with functional neurological symptom disorder-conversion disorder (psychogenic myopia): A case study.

Functional neurological symptom disorder commonly presents with symptoms and defects of sensory and motor functions. Therefore, it is often mistaken for a medical condition. It is well known that functional neurological symptom disorder more often caused by psychological factors. There are three main approaches namely analytical, cognitive and biological to manage conversion disorder. Any of such approaches can be applied through short-term treatment programs. In this case, study a 12-year-old boy with the diagnosed functional neurological symptom disorder (psychogenic myopia) was put under a cognitive-analytical treatment. The outcome of this treatment modality was proved successful.