UV and blue light signalling: pathways regulating chalcone synthase gene expression in <i>Arabidopsis</i>

Jenkins, Gareth I.; Long, Joanne C.; Wade, Helena K.; Shenton, Matthew R.; Bibikova, Tatiana N.

doi:10.1046/j.1469-8137.2001.00151.x

Cited by 147 publications

(114 citation statements)

References 80 publications

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“…9E). These results were in conformity with earlier studies in which a 10-fold increase in CHS expression of mature Arabidopsis leaves was reported (Jenkins et al, 2001). The lower transcript level of ReCHS1 as compared with that of ReCHS2 correlates with earlier studies on G. max in which only the CHS1 member of the gene family showed induction Figure 6.…”

Section: Effects Of Abiotic Elicitors On Rechs Expression Vis-à-vis Fsupporting

confidence: 92%

“…It was first shown in Arabidopsis (Arabidopsis thaliana) that UV and blue light could induce the expression of CHS genes (Jenkins et al, 2001). The plant tissues treated with UV light showed a gradual increase in the expression of ReCHS1 up to a maximum of 2-fold at 9 h post induction, whereas a steep increase was observed in the transcript level of ReCHS2, which showed a nearly 5-fold increase at 6 h followed by a 12-fold increase at 9 h (Fig.…”

Section: Effects Of Abiotic Elicitors On Rechs Expression Vis-à-vis Fmentioning

confidence: 99%

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Functional Promiscuity of Two Divergent Paralogs of Type III Plant Polyketide Synthases

et al. 2016

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Plants effectively defend themselves against biotic and abiotic stresses by synthesizing diverse secondary metabolites, including health-protective flavonoids. These display incredible chemical diversity and ubiquitous occurrence and confer impeccable biological and agricultural applications. Chalcone synthase (CHS), a type III plant polyketide synthase, is critical for flavonoid biosynthesis. It catalyzes acyl-coenzyme A thioesters to synthesize naringenin chalcone through a polyketidic intermediate. The functional divergence among the evolutionarily generated members of a gene family is pivotal in driving the chemical diversity. Against this backdrop, this study was aimed to functionally characterize members of the CHS gene family from Rheum emodi, an endangered and endemic high-altitude medicinal herb of northwestern Himalayas. Two full-length cDNAs (1,179 bp each), ReCHS1 and ReCHS2, encoding unique paralogs were isolated and characterized. Heterologous expression and purification in Escherichia coli, bottom-up proteomic characterization, high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry analysis, and enzyme kinetic studies using five different substrates confirmed their catalytic potential. Phylogenetic analysis revealed the existence of higher synonymous mutations in the intronless divergents of ReCHS. ReCHS2 displayed significant enzymatic efficiency (V max /K m ) with different substrates. There were significant spatial and altitudinal variations in messenger RNA transcript levels of ReCHSs correlating positively with metabolite accumulation. Furthermore, the elicitations in the form of methyl jasmonate, salicylic acid, ultraviolet B light, and wounding, chosen on the basis of identified cis-regulatory promoter elements, presented considerable differences in the transcript profiles of ReCHSs. Taken together, our results demonstrate differential propensities of CHS paralogs in terms of the accumulation of flavonoids and their relative substrate selectivities.Plants, as ground-anchored sessile creatures, invest significant amounts of energy in the production of secondary metabolites to combat environmental pressures. These metabolites often are produced through complex and highly regulated biosynthetic pathways under the influence of different enzymatic machineries. One of the important classes of secondary metabolites is phenylpropanoids. These represent a significant proportion of secondary metabolites, encompassing nearly 20% of total carbon in the terrestrial biosphere. Flavonoids exhibit remarkable chemical diversity and ubiquitous occurrence and play an important role in many aspects of plant development, like flower coloration, photoprotection, pollen development, cell wall growth, and response to stress conditions like UV light protection, herbivory, wounding, interaction with soil microbes, and defense against pathogens (Yu and Jez, 2008;Pandey et al., 2015). Apart from performing numerous imperative roles in plants, flavonoids also have been reported as poten...

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Section: Effects Of Abiotic Elicitors On Rechs Expression Vis-à-vis Fsupporting

confidence: 92%

Section: Effects Of Abiotic Elicitors On Rechs Expression Vis-à-vis Fmentioning

confidence: 99%

Functional Promiscuity of Two Divergent Paralogs of Type III Plant Polyketide Synthases

et al. 2016

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“…At the molecular level, the CHS gene encoding a key enzyme in flavonoid biosynthesis, chalcone synthase, is known to be induced by UV-B (e.g., Jenkins et al, 2001). Moreover, the HY5 protein was previously shown to bind CHS promoter sequences in vitro (Ang et al, 1998).…”

Section: Cop1 and Hy5 Are Required For Uv-b-mediated Hypocotyl Growthmentioning

confidence: 99%

“…This includes hypocotyl growth inhibition, flavonoid accumulation, and specific gene expression changes. A rather well-characterized gene activated by low levels of UV-B is CHALCONE SYNTHASE (CHS), encoding a key enzyme of phenylpropanoid biosynthesis (Jenkins et al, 2001). On a genome-wide level, recent array analyses for plant responses to UV-B radiation identified a broad range of activated and repressed genes that may now be linked to UV-B responses (e.g., Casati and Walbot, 2004;Ulm et al, 2004;Ulm and Nagy, 2005).…”

Section: Introductionmentioning

confidence: 99%

CONSTITUTIVELY PHOTOMORPHOGENIC1 Is Required for the UV-B Response in Arabidopsis

et al. 2006

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CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) is a negative regulator of photomorphogenesis in Arabidopsis thaliana. COP1 functions as an E3 ubiquitin ligase, targeting select proteins for proteasomal degradation in plants as well as in mammals. Among its substrates is the basic domain/leucine zipper (bZIP) transcription factor ELONGATED HYPOCOTYL5 (HY5), one of the key regulators of photomorphogenesis under all light qualities, including UV-B responses required for tolerance to this environmental threat. Here, we report that, in contrast with the situation in visible light, COP1 is a critical positive regulator of responses to low levels of UV-B. We show that in the cop1-4 mutant, flavonoid accumulation and genome-wide expression changes in response to UV-B are blocked to a large extent. COP1 is required for HY5 gene activation, and both COP1 and HY5 proteins accumulate in the nucleus under supplementary UV-B. SUPPRESSOR OF PHYTOCHROME A-105 family proteins (SPA1 to SPA4) that are required for COP1 function in dark and visible light are not essential in the response to UV-B. We conclude that COP1 performs a specific and novel role in the plants' photomorphogenic response to UV-B, coordinating HY5-dependent and -independent pathways, which eventually results in UV-B tolerance.

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“…It has often been speculated that UV-B may be perceived by a novel class of photoreceptor, but no such molecule has ever been identified. Moreover, although pharmacological, cell physiological, and genetic approaches have provided some insights into UV-B signal transduction processes (15)(16)(17), no UV-B-specific signaling pathway has been defined. Thus, understanding of the mechanisms of plant UV-B responses lags well behind knowledge of light responses mediated by the phytochrome, cryptochrome, and phototropin photoreceptors.…”

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confidence: 99%

A UV-B-specific signaling component orchestrates plant UV protection

Brown

Cloix

Jiang

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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UV-B radiation in sunlight has diverse effects on humans, animals, plants, and microorganisms. UV-B can cause damage to molecules and cells, and consequently organisms need to protect against and repair UV damage to survive in sunlight. In plants, low nondamaging levels of UV-B stimulate transcription of genes involved in UV-protective responses. However, remarkably little is known about the underlying mechanisms of UV-B perception and signal transduction. Here we report that Arabidopsis UV RESISTANCE LOCUS 8 (UVR8) is a UV-B-specific signaling component that orchestrates expression of a range of genes with vital UV-protective functions. Moreover, we show that UVR8 regulates expression of the transcription factor HY5 specifically when the plant is exposed to UV-B. We demonstrate that HY5 is a key effector of the UVR8 pathway, and that it is required for survival under UV-B radiation. UVR8 has sequence similarity to the eukaryotic guanine nucleotide exchange factor RCC1, but we found that it has little exchange activity. However, UVR8, like RCC1, is located principally in the nucleus and associates with chromatin via histones. Chromatin immunoprecipitation showed that UVR8 associates with chromatin in the HY5 promoter region, providing a mechanistic basis for its involvement in regulating transcription. We conclude that UVR8 defines a UV-B-specific signaling pathway in plants that orchestrates the protective gene expression responses to UV-B required for plant survival in sunlight.photomorphogenesis ͉ ultraviolet-B radiation ͉ UV RESISTANCE LOCUS 8 U V-B radiation (280-320 nm) is an integral component of sunlight. UV-B can cause damage to macromolecules, including DNA, and generate reactive oxygen species. Because UV-B affects the growth, development, reproduction, and survival of many organisms, there is concern that any further increases in ambient levels of UV-B, resulting from stratospheric ozone depletion may have a significant impact on natural and agricultural ecosystems (1-4). Hence, it is important to understand how plants and other organisms protect themselves against the potentially damaging effects of UV-B.Exposure to UV-B is obligatory for higher plants because of the need to maximize light capture for photosynthesis. The effects of UV-B on diverse species of plants have been reported in the literature, and it is evident that different responses are observed at different UV-B fluence rates (5, 6). Exposure to high amounts of UV-B causes tissue necrosis and induces the expression of stressassociated genes in part through activation of pathogen-defense and wound-signaling pathways (5-7). At ambient UV-B levels, crosstalk between wound and UV-B signaling pathways modifies plantinsect interactions (8). Importantly, exposure to low nondamaging levels of UV-B has numerous regulatory effects on plant morphology, development, physiology, and biochemical composition (1,5,6,9). Low fluence rates of UV-B promote the expression of a range of genes involved in UV-B protection (5, 6, 10, 11). These include genes c...

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UV and blue light signalling: pathways regulating chalcone synthase gene expression in Arabidopsis

Cited by 147 publications

References 80 publications

Functional Promiscuity of Two Divergent Paralogs of Type III Plant Polyketide Synthases

Functional Promiscuity of Two Divergent Paralogs of Type III Plant Polyketide Synthases

CONSTITUTIVELY PHOTOMORPHOGENIC1 Is Required for the UV-B Response in Arabidopsis

A UV-B-specific signaling component orchestrates plant UV protection

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