Lycopene beta cyclase

Federal government websites often end in. The site is secure. We also aimed to obtain more information about the endogenous carotenoid biosynthetic pathway and thus provide experimental support for carotenoid metabolic engineering in wheat.

Metrics details. Carotenoids are a group of C40 isoprenoid molecules that play diverse biological and ecological roles in plants. Genes encoding enzymes involved in carotenoid biosynthetic pathway have been cloned. However, regulation of genes involved in carotenoid biosynthetic pathway and accumulation of specific carotenoid in chromoplasts are not well understood. One of the approaches to understand regulation of carotenoid metabolism is to characterize the promoters of genes encoding proteins involved in carotenoid metabolism. To identify promoter region necessary for regulating developmental expression of the ShCYC-B gene, the full-length promoter and its three different 5' truncated fragments were cloned upstream to the initiation codon of GUS reporter cDNA in binary vectors. These four plant transformation vectors were separately transformed in to Agrobacterium.

Lycopene beta cyclase

Carotenoids are important isoprenoids produced in the plastids of photosynthetic organisms that play key roles in photoprotection and antioxidative processes. Xanthi resulted in increased levels of abscisic acid ABA and especially gibberellins GAs , resulting in increased plant yield. In order to understand this phenomenon prior to exporting this genetic strategy to crops, we generated tobacco Nicotiana tabacum cv. Transplastomic plants expressing DcLCYB1 at high levels showed a wild-type-like growth, even though their pigment content was increased and their leaf GA 1 content was reduced. Remarkably, drastic changes in phytohormone content also occurred in the RNAi lines. However, external application of phytohormones was not sufficient to rescue these phenotypes, suggesting that altered photosynthetic efficiency might be another important factor explaining their reduced biomass. These results show that LCYB expression influences plant biomass by different mechanisms and suggests thresholds for LCYB expression levels that might be beneficial or detrimental for plant growth. Carotenoids are carbon isoprenoids with polyene chains containing up to 15 conjugated double bonds Hirschberg, In plants, carotenoids have many important functions, such as chlorophyll protection from UV light, and multiple antioxidant activities, including the ability to scavenge reactive oxygen species ROS , such as singlet oxygen, and peroxyl radicals Krinsky, As membrane-bound compounds, they provide membrane stabilization Frank and Cogdell, , ; Demmig-Adams et al. Moreover, they are precursors of the apocarotenoid phytohormone abscisic acid ABA , which is involved in developmental processes and adaptive stress responses to environmental stimuli such as drought-induced stomatal closure in plants Nambara and Marion-Poll, ; Taylor et al. Overexpression of LCYB leads to increased tolerance to abiotic stresses e. This was shown under fully controlled constant and fluctuating light regimes and non-controlled climate conditions Moreno et al. However, unexpectedly, transgenic DcLCYB1 lines also showed increased transcript levels of key genes involved in several metabolic pathways related to isoprenoid metabolism, resulting in increased biosynthesis of ABA and especially of different gibberellins GAs; Fig.

Exhaustion of the chloroplast protein synthesis capacity by massive expression of a highly stable protein antibiotic. Published : 09 April

However, the roles and underlying mechanisms of the LCYB gene in plant responses to abiotic stresses are rarely known. This gene has not been used to improve carotenoid contents of sweetpotato, Ipomoea batatas L. Shangshu 19 plants. The genes involved in carotenoid and abscisic acid ABA biosynthesis pathways and abiotic stress responses were up-regulated in the transgenic plants. The ABA and proline contents and superoxide dismutase SOD activity were significantly increased, whereas malonaldehyde MDA and H 2 O 2 contents were significantly decreased in the transgenic plants under abiotic stresses.

Federal government websites often end in. The site is secure. The composition of carotenoids, along with anthocyanins and chlorophyll, accounts for the distinctive range of colour found in the Actinidia kiwifruit species. Lutein and beta-carotene are the most abundant carotenoids found during fruit development, with beta-carotene concentration increasing rapidly during fruit maturation and ripening. In addition, the accumulation of beta-carotene and lutein is influenced by the temperature at which harvested fruit are stored. Plants accumulate a huge variety of secondary metabolites. Carotenoids are one such group of compounds that are synthesized in the plastids, mainly the chloroplasts and chromoplasts, by enzymes that are nuclear-encoded Hirschberg, Carotenoids are 40 carbon isoprenoids that contain polyene chains containing conjugated double bonds.

Lycopene beta cyclase

Metrics details. We also aimed to obtain more information about the endogenous carotenoid biosynthetic pathway and thus provide experimental support for carotenoid metabolic engineering in wheat. The cyclization activity of the encoded protein was demonstrated by heterologous complementation analysis. In addition, changes in TaLCYB expression also affected the expression of several endogenous carotenogenic genes to varying degrees. Our attempt to silence it not only contributes to elucidating the mechanism of carotenoid accumulation in wheat but may also help in breeding wheat varieties with high provitamin A content through RNA interference RNAi to block specific carotenogenic genes in the wheat endosperm. Carotenoids are important natural isoprenoid pigments synthesized in plants that have essential roles in protecting against excess light energy and oxidative damage, and in light-harvesting [ 1 , 2 ]. Their provitamin A activity and antioxidant properties are their most attractive functions. In higher plants, although the main pathway of carotenoid biosynthesis has been studied extensively [ 6 - 8 ], the regulatory mechanisms of carotenoid biosynthesis are still not well known. Because of the special position of lycopene cyclization, researchers have focused on the function of LCYB and its relationship with carotenoid accumulation in plants [ 10 - 13 ]. Carotenoid biosynthetic pathway in wheat.

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Because of the special position of lycopene cyclization, researchers have focused on the function of LCYB and its relationship with carotenoid accumulation in plants [ 10 - 13 ]. Overexpression of phytoene synthase gene from Salicornia europaea alters response to reactive oxygen species under salt stress in transgenic Arabidopsis. Arun Sampathkumar. By contrast, yellow sectors of R1 leaves had only a very few chloroplasts, which were either not present close to the cell contour, unlike the wild type, or unstructured Supplementary Fig. Figure S5. In kiwifruit and papaya, the major carotenoid was controlled by the expression level of LCYB [ 12 , 13 ]. Transgenic strategies for the nutritional enhancement of plants. Plasmid was isolated from transformed Agrobacterium cultures and was back-transformed into E. Krause GH , Weis E. Journal of Experimental Botany 69 , — J Chromatogr A. Current Biology 27 , —

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There was no difference in the localization of GUS activity in fruits among full-length and truncated promoter constructs at various stages of fruit development. This reduction is in line with the reduced GA, chlorophyll, and carotenoid content. Advanced Search. Contrary to the expectation, the PSY1 over-expressing transgenic tomato fruit also had reduced lycopene content as compared to untransformed plants [ 27 ]. Carotenoid, chlorophyll, and GA biosynthesis pathways take place in the chloroplast and all share the same precursor, GGPP Bouvier et al. The Plant Cell 23 , — Nature Biotechnology 19 , — As membrane-bound compounds, they provide membrane stabilization Frank and Cogdell, , ; Demmig-Adams et al. Leaf tissue was frozen immediately in liquid nitrogen and ground to a fine powder. Transplastomic plants expressing DcLCYB1 at high levels showed a wild-type-like growth, even though their pigment content was increased and their leaf GA 1 content was reduced. Copy Download.