| 1. |
- Czégény, Gyula, et al.
(author)
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Multiple roles for Vitamin B6in plant acclimation to UV-B
- 2019
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In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 9:1
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Journal article (peer-reviewed)abstract
- Direct and indirect roles of vitamin B6in leaf acclimation to supplementary UV-B radiation are shown in vitamin B6deficient Arabidopsis thalianamutant rsr4-1 and C24 wild type. Responses to 4 days of 3.9 kJ m-2d-1 biologically effective UV-B dose were compared in terms of leaf photochemistry, vitamer content, and antioxidant enzyme activities; complemented with a comprehensive study of vitamer ROS scavenging capacities. Under UV-B, rsr4-1 leaves lost more (34%) photochemical yield than C24 plants (24%). In the absence of UV-B, rsr4-1 leaves contained markedly less pyridoxal-5’-phosphate (PLP) than C24 ones, but levels increased up to the C24 contents in response to UV-B. Activities of class-III ascorbate and glutathione peroxidases increased in C24 leaves upon the UV-B treatment but not in the rsr4-1 mutant. SOD activities remained the same in C24 but decreased by more than 50% in rsr4-1 under UV-B. Although PLP was shown to be an excellent antioxidant in vitro, our results suggest that the UV-B protective role of B6 vitamers is realized indirectly, via supporting peroxidase defence rather than by direct ROS scavenging. We hypothesize that the two defence pathways are linked through the PLP-dependent biosynthesis of cystein and heme, affecting peroxidases.
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| 2. |
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| 3. |
- Qian, Minjie, 1987-, et al.
(author)
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UV regulates expression of phenylpropanoid biosynthesis genes in cucumber (Cucumis sativus L.) in an organ and spectrum dependent manner
- 2019
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In: Photochemical and Photobiological Sciences. - London, UK : Royal Society of Chemistry. - 1474-905X .- 1474-9092. ; 18:2, s. 424-433
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Journal article (peer-reviewed)abstract
- Expression of cucumber (Cucumis sativus) genes encoding the phenylpropanoid and flavonoid biosynthetic enzymes phenylalanine ammonia lyase (PAL), cinnamic acid 4-hydroxylase (C4H), and chalcone synthase (CHS), was studied under control light conditions (photosynthetically active radiation, PAR) in root, stem, and leaf. Furthermore, expression was quantified in leaves illuminated with PAR and supplemental ultraviolet-A (315-400nm) or ultraviolet-B (280-315 nm) radiation. The expression pattern of all twelve CsPAL, threeCsC4H, and three CsCHS genes was established. Among the genes regulated by UV two general expression patterns emerge. One pattern applies to genes primarily regulated by enriched UV-A illumination (pattern 1). Another (pattern 2) was found for the genes regulated by enriched UV-B. Three of the pattern 2 genes (CsPAL4, CsPAL10, CsCHS2) displayed a particular sub-pattern (pattern 2b) with transcription enriched by at least 30 fold. In contrast to the other genes studied, the promoters of the genes regulated according to pattern 2b contained a combination of a number of cis-acting regulatory elements (MREs, ACEs, and G-boxes) that may be of importance for the particularly high enhancement of expression under UV-B- containing light. The regulation of phenylpropanoid and flavonoid biosynthesis genes in cucumber resembles that of a number of other plants. However, cucumber, due to its greater size, is an attractive species for more detailed studies of the fine regulation of spatial and temporal expression of key genes. This in turn, can facilitate the quantitative investigation of the relationships between different promotor motifs, the expression levels of each of these three genes, and metabolite accumulation profiles.
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| 4. |
- Eriksson, Leif A., 1964-, et al.
(author)
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Tetrazole derivatives as cytochrome p450 inhibitors
- 2019
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Patent (pop. science, debate, etc.)abstract
- According to the invention there is provided a compound of formula I, wherein R1 and R2 have meanings given in the description, which compounds are useful in the treatment of skin disorders and other diseases.
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| 5. |
- O'Hara, Andrew, 1983-, et al.
(author)
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Regulation of Arabidopsis gene expression by low fluence rate UV-B independently of UVR8 and stress signaling
- 2019
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In: Photochemical and Photobiological Sciences. - : RSC Publishing. - 1474-905X .- 1474-9092. ; 18:7, s. 1675-1684
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Journal article (peer-reviewed)abstract
- UV-B exposure of plants regulates expression of numerous genes concerned with various responses. Sudden exposure of non-acclimated plants to high fluence rate, short wavelength UV-B induces expression via stress-related signaling pathways that are not specific to the UV-B stimulus, whereas low fluence rates of UV-B can regulate expression via the UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8). However, there is little information about whether non-stressful, low fluence rate UV-B treatments can activate gene expression independently of UVR8. Here, transcriptomic analysis of wild-type and uvr8 mutant Arabidopsis exposed to low fluence rate UV-B showed that numerous genes were regulated independently of UVR8. Moreover, nearly all of these genes were distinct to those induced by stress treatments. A small number of genes were expressed at all UV-B fluence rates employed and may be concerned with activation of eustress responses that facilitate acclimation to changing conditions. Expression of the gene encoding the transcription factor ARABIDOPSIS NAC DOMAIN CONTAINING PROTEIN 13 (ANAC13) was studied to characterise a low fluence rate, UVR8-independent response. ANAC13 is induced by as little as 0.1 μmol m−2 s−1 UV-B and its regulation is independent of components of the canonical UVR8 signaling pathway COP1 and HY5/HYH. Furthermore, UV-B induced expression of ANAC13 is independent of the photoreceptors CRY1, CRY2, PHOT1 and PHOT2 and phytochromes A, B, D and E. ANAC13 expression is induced over a range of UV-B wavelengths at low doses, with maximum response at 310 nm. This study provides a basis for further investigation of UVR8 and stress independent, low fluence rate UV-B signaling pathway(s).
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| 6. |
- Rodriguez-Calzada, Tania, et al.
(author)
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Effect of UV-B radiation on morphology, phenolic compound production, gene expression, and subsequent drought stress responses in chili pepper (Capsicum annuum L.)
- 2019
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In: Plant physiology and biochemistry (Paris). - Paris, France : Elsevier. - 0981-9428 .- 1873-2690. ; 134, s. 94-102
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Journal article (peer-reviewed)abstract
- It has been suggested that accumulation of flavonoids could be a key step in development of plant tolerance to different environmental stresses. Moreover, it has been recognized that abiotic stresses such as drought and UV-B radiation (280-315 nm) induce phenolic compound accumulation, suggesting a role for these compounds in drought tolerance. The aim of the present study was to evaluate the effect of UV-B exposure on chili pepper (Capsicum annuum, cv. ‘Coronel’) plant performance, phenolic compound production, and gene expression associated with response to subsequent drought stress. Additionally, the phenotypic response to drought stress of these plants was studied. UV-B induced a reduction both in stem length, stem dry weight and number of floral primordia. The largest reduction in these variables was observed when combining UV-B and drought. UV-B-treated well-watered plants displayed fructification approximately 1 week earlier than non-UV-B-treated controls. Flavonoids measured epidermally in leaves significantly increased during UV-B treatment. Specifically, UV-B radiation significantly increased chlorogenic acid and apigenin 8-C-hexoside levels in leaves and a synergistic increase of luteolin 6-C-pentoside-8-C-hexoside was obtained by UV-B and subsequent drought stress. Gene expression of phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS) genes also increased during UV-B treatments. On the other hand, expression of genes related to an oxidative response, such as mitochondrial Mn-superoxide dismutase (Mn-SOD) and peroxidase (POD) was not induced by UV-B. Drought stress in UV-B-treated plants induced mitochondrial Mn-SOD gene expression. Taken together, the UV-B treatment did not induce significant tolerance in plants towards drought stress under the conditions used.
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| 7. |
- Wu, Min, 1986, et al.
(author)
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Proline 411 biases the conformation of the intrinsically disordered plant UVR8 photoreceptor C27 domain altering the functional properties of the peptide
- 2019
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Journal article (peer-reviewed)abstract
- UVR8 (UV RESISTANCE LOCUS 8) is a UV-B photoreceptor responsible for initiating UV-B signalling in plants. UVR8 is a homodimer in its signalling inactive form. Upon absorption of UV radiation, the protein monomerizes into its photoactivated state. In the monomeric form, UVR8 binds the E3 ubiquitin ligase COP1 (CONSTITUTIVELY PHOTOMORPHOGENIC 1), triggering subsequent UV-B-dependent photomorphogenic development in plants. Recent in vivo experiments have shown that the UVR8 C-terminal region (aa 397-423; UVR8(C27)) alone is sufficient to regulate the activity of COP1. In this work, CD spectroscopy and NMR experiments showed that the UVR8(C27) domain was non-structured but gained secondary structure at higher temperatures leading to increased order. Bias-exchange metadynamics simulations were also performed to evaluate the free energy landscape of UVR8(C27). An inverted free energy landscape was revealed, with a disordered structure in the global energy minimum. Flanking the global energy minimum, more structured states were found at higher energies. Furthermore, stabilization of the low energy disordered state was attributed to a proline residue, P411, as evident from P411A mutant data. P411 is also a key residue in UVR8 binding to COP1. UVR8(C27) is therefore structurally competent to function as a molecular switch for interaction of UVR8 with different binding partners since at higher free energies different structural conformations are being induced in this peptide. P411 has a key role for this function.
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