The terpenoids constitute the largest class of natural products and many interesting products are extensively applied in the industrial sector as flavors, fragrances, spices and are also used in perfumery and cosmetics. Many terpenoids have biological activities and also used for medical purposes. In higher plants, the conventional acetate-mevalonic acid pathway operates mainly in the cytosol and mitochondria and synthesizes sterols, sesquiterpenes and ubiquinones mainly. In the plastid, the non-mevalonic acid pathway takes place and synthesizes hemi-, mono-, sesqui-, and diterpenes along with carotenoids and phytol tail of chlorophyll. In this review paper, recent developments in the biosynthesis of terpenoids, indepth description of terpene synthases and their phylogenetic analysis, regulation of terpene biosynthesis as well as updates of terpenes which have entered in the clinical studies are reviewed thoroughly.

https://link.springer.com/content/pdf/10.1007%2Fs13205-014-0220-2.pdf

Plant terpenes: defense responses, phylogenetic analysis, regulation and clinical applications

Plant growth regulator mediated consequences of secondary metabolites in medicinal plants.

Plants grow on soils that not only provide support for root anchorage but also act as a reservoir of water and nutrients important for plant growth and development. However, environmental factors, such as high salinity, hinder the uptake of nutrients and water from the soil and reduce the quality and productivity of plants. Under high salinity, plants attempt to maintain cellular homeostasis through the production of numerous stress-associated endogenous metabolites that can help mitigate the stress. Both primary and secondary metabolites can significantly contribute to survival and the maintenance of growth and development of plants on saline soils. Existing studies have suggested that seed/plant-priming with exogenous metabolites is a promising approach to increase crop tolerance to salt stress without manipulation of the genome. Recent advancements have also been made in genetic engineering of various metabolic genes involved in regulation of plant responses and protection of the cells during salinity, which have therefore resulted in many more basic and applied studies in both model and crop plants. In this review, we discuss the recent findings of metabolic reprogramming, exogenous treatments with metabolites and genetic engineering of metabolic genes for the improvement of plant salt tolerance.

https://www.mdpi.com/2073-4409/9/11/2492/pdf

Enhancing Salt Tolerance of Plants: From Metabolic Reprogramming to Exogenous Chemical Treatments and Molecular Approaches.

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.

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

Phyto-miRNAs-based regulation of metabolites biosynthesis in medicinal plants.

Light spectrum of growing environment is a determinant factor for plant growth and photosynthesis. Plants under different light spectra exhibit different growth and photosynthetic behaviors. To unravel the effects of light spectra on plant growth, photosynthetic pigments and electron transport chain reactions, purple and green basil varieties were grown under five different light spectra including white (W: 400–730 nm), blue (B: 400–500 nm), red (R: 600–700 nm) and two combinations of R and B lights (R50B50 and R70B30), with same PPFD (photosynthetic photon flux density). Almost all values for shoot and root growth traits were higher in purple variety and were improved by combinational R and B lights (especially under R70B30), while they were negatively influenced by B monochromatic light when compared to growth traits of W-grown plants. Highest concentration of photosynthetic pigments was detected in R70B30. Biophysical properties of photosynthetic electron transport chain showed higher florescence intensity at all steps of OJIP kinetics in plants grown under R light in both varieties. Oxygen evolving complex activity (Fv/Fo) and PSII maximum quantum efficiency (Fv/Fm) in R-grown plants were lower than plants grown under other light spectra. Values for parameters related to specific energy fluxes per reaction center (ABS/RC, TRo/RC, ETo/RC and DIo/RC) were increased under R light (especially for purple variety). Performance index was significantly decreased under R light in both varieties. In conclusion, light spectra other than RB combination, induced various limitations on pigmentations, efficiency of electron transport and growth of basil plants and the responses were cultivar specific.

/pdf/photosynthetic-and-growth-responses-of-green-and-purple-4816ltvbkw.pdf

Photosynthetic and growth responses of green and purple basil plants under different spectral compositions

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.

/pdf/blue-light-improves-vase-life-of-carnation-cut-flowers-3fomfc3jon.pdf

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

Light is the driving force for plant photosynthesis. Different attributes of light (e.g. intensity, spectrum and duration) can influence plant growth and development. We studied growth and photosystem II performance ofEnglish marigold cut flowers under red (635-665 nm) and white (420-700 nm) LEDs. Although growing plants under red light resulted in morphological deformation such as leaf epinasty, it led to an early flowering and improved growth compared with white light-grown plants. In plants that were grown under red light, flowers were emerged 45 days after germination. In the time of flowering, there were 30 leaves (sum of rosette and lateral leaves) on the red light-grown plants, while 20 leaves were observed on white light-grown plants without flowering on day 45. Fast induction of chlorophyll fluorescence showed that fluorescence intensities of O-J-I-P phases in a typical fluorescence transient exhibited after a 20 min dark-adapted leaves were increased in red light-grown plants. Maximum efficiency of photosystem II (Fv/Fm) and performance index per absorbed light were decreased by red light, while quantum yield of energy dissipation was increased by red light. Most of the energy absorbed by the photosystems in red light-grown plants was dissipated as heat. In conclusion, although red light improved growth and induced early flowering in Calendula officinalis, full light spectrum is required to prevent leaf deformation and electron transport disruption under monochromatic red light.

https://ijhst.ut.ac.ir/article_68069_2d8c151476cfcc302cf44ed83f980664.pdf

Mahboobeh Zare Mehrjerdi

Papers

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

Photosynthetic and growth responses of green and purple basil plants under different spectral compositions

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

Growth and Photosynthetic Performance of Calendula officinalis under Monochromatic Red Light

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