Phytoene synthase (Psy) and Phytoene desaturase (Pds) are the first two regulatory enzymes in the carotenoids biosynthetic pathway. The genes Psy and Pds are under transcriptional control in many photosynthetic organisms. In the present study, using quantitative real time- PCR (qRT-PCR), the effects of uncoated and gum-Arabic coated PbS nanoparticles (GA-coated PbS NPs) and light intensity on t...

In vitro studies of the influence of FMC 57020 on terpenoid biosynthesis have shown that this herbicide acts at an early stage. It affects the conversion of isopentenyl pyrophosphate to geranylgeranyl pyrophosphate catalyzed by isopentenyl pyrophosphate isomerase and prenyl transferase. An inhibition of the carotenogenic enzymes phytoene desaturase, ^-carotene desaturase, and lycopene cyclase c...

Assay systems have been developed in order to differentiate between the m odes o f action o f certain bleaching herbicides. These include inhibition o f chlorophyll or carotenoid biosynthesis, and initiation o f pigment degradation. Herbicidal com pounds with phytoene desaturase as their primary target site were investigated in a cell-free carotenogenic system from Aphanocapsa. In a comparative...

Carotenoids are isoprenyl pigments necessary for protection of the photosynthetic apparatus in a11 green plants. One of the intermediate steps in carotenoid biosynthesis is the conversion of phytoene to {-carotene via two dehydrogenation reactions catalyzed by the enzyme PDS. We have previously cloned cDNAs for this enzyme from soybean (Glycine max; Bartley et al., 1991) and tomato (Lycopersico...

Synthesis o f carotenoids is photoregulated in m any fungi including Neurospora crassa. In order to investigate the regulatory m echanism at the enzym e level, several carotenoid m utants o f Neurospora were used to determ ine the activities o f enzym es involved in the carotenoid b io­ synthetic pathway after growth under illum ination or in darkness. Light stim ulation o f caro­ tenoid form a...

The phytoene desaturase (PDS) encodes a crucial enzyme in the carotenoid biosynthesis pathway. Silencing or inhibiting PDS expression leads to appearance of mottled, chlorosis, albino leaves. In this study, CDS sequence EuPDS (Eucommia ulmoides Phytoene Desaturase) was first cloned and then silenced Nicotiana benthamiana. Result showed level leaves higher than that roots stems. N. benthamiana l...

This report gives an insight into the specific changes in the transcription of four key carotenogenic genes [encoding geranylgeranyl diphosphate synthase (crtE), phytoene desaturase (crtI), phytoene synthase lycopene cyclase (crtYB), and astaxanthin synthase (ast), respectively] in Xanthophyllomyces dendrorhous cultures, with regard to dissolved oxygen (DO) contents of 10%, 25%, and 40% air sat...

The endosperm of Golden Rice (Oryza sativa) is yellow due to the accumulation of beta-carotene (provitamin A) and xanthophylls. The product of the two carotenoid biosynthesis transgenes used in Golden Rice, phytoene synthase (PSY) and the bacterial carotene desaturase (CRTI), is lycopene, which has a red color. The absence of lycopene in Golden Rice shows that the pathway proceeds beyond the tr...

background and aims: virus-induced gene silencing (vigs) is a virus vector technology that exploits antiviral defense mechanism. by infecting plants with recombinant viruses containing host genes inserted in the viral genome, vigs achieves the rna silencing process. the purpose of this study was to investigate the possibility of tomato (lycopersicon esculentum mill.) and tobacco (nicotiana bent...

The herbicide norflurazon inhibits carotene biosynthesis in photosynthetic organisms by blocking the enzyme phytoene dehydrogenase (= phytoene desaturase). We have isolated norflurazon-resistant mutants of the cyanobacterium Synechococcus PCC7942. The herbicide-resistance gene from the mutant NFZ4 has been cloned by genetic complementation of the resistance trait in wild type cells. The experim...