| 1. |
- Morales, Luis Orlando, 1974-, et al.
(författare)
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Are solar UV-B- and UV-A-dependent gene expression and metabolite accumulation in Arabidopsis mediated by the stress response regulator RADICAL-INDUCED CELL DEATH1?
- 2015
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Ingår i: Plant, Cell and Environment. - : Wiley. - 0140-7791 .- 1365-3040. ; 38:5, s. 878-891
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Tidskriftsartikel (refereegranskat)abstract
- Wavelengths in the ultraviolet (UV) region of the solar spectrum, UV-B (280-315nm) and UV-A (315-400nm), are key environmental signals modifying several aspects of plant physiology. Despite significant advances in the understanding of plant responses to UV-B and the identification of signalling components involved, there is limited information on the molecular mechanisms that control UV-B signalling in plants under natural sunlight. Here, we aimed to corroborate the previous suggested role for RADICAL-INDUCED CELL DEATH1 (RCD1) in UV-B signalling under full spectrum sunlight. Wild-type Arabidopsis thaliana and the rcd1-1 mutant were used in an experimental design outdoors where UV-B and UV-A irradiances were manipulated using plastic films, and gene expression, PYRIDOXINE BIOSYNTHESIS1 (PDX1) accumulation and metabolite profiles were analysed in the leaves. At the level of transcription, RCD1 was not directly involved in the solar UV-B regulation of genes with functions in UV acclimation, hormone signalling and stress-related markers. Furthermore, RCD1 had no role on PDX1 accumulation but modulated the UV-B induction of flavonoid accumulation in leaves of Arabidopsis exposed to solar UV. We conclude that RCD1 does not play an active role in UV-B signalling but rather modulates UV-B responses under full spectrum sunlight.
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| 2. |
- Morales, Luis Orlando, 1974-, et al.
(författare)
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Multiple Roles for UV RESISTANCE LOCUS 8 in Regulating Gene Expression and Metabolite Accumulation in Arabidopsis under Solar UV Radiation
- 2013
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Ingår i: Plant Physiology. - : American Society of Plant Biologists. - 0032-0889 .- 1532-2548. ; 161:2, s. 744-759
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Tidskriftsartikel (refereegranskat)abstract
- Photomorphogenic responses triggered by low fluence rates of ultraviolet-B radiation (UV-B, 280-315 nm) are mediated by the UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8). Beyond our understanding of the molecular mechanisms of UV-B perception by UVR8, there is still limited information on how the UVR8 pathway functions under natural sunlight. Here, wild-type Arabidopsis thaliana and the uvr8-2 mutant were used in an experiment outdoors where UV-A (315-400 nm) and UV-B irradiances were attenuated using plastic films. Gene expression, PYRIDOXINE BIOSYNTHESIS 1 (PDX1) accumulation and leaf metabolite signatures were analyzed. The results show that UVR8 is required for transcript accumulation of genes involved in UV protection, oxidative stress, hormone signal transduction and defence against herbivores under solar UV. Under natural UV-A irradiance, UVR8 is likely to interact with UV-A/blue light signaling pathways to moderate UV-B driven transcript and PDX1 accumulation. UVR8 both positively and negatively affects UV-A-regulated gene expression and metabolite accumulation, but is required for the UV-B induction of phenolics. Moreover, UVR8-dependent UV-B acclimation during the early stages of plant development may enhance normal growth under long-term exposure to solar UV.
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| 3. |
- Peivastegan, Bahram, et al.
(författare)
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Effect of wet storage conditions on potato tuber transcriptome, phytohormones and growth
- 2019
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Ingår i: BMC Plant Biology. - : Springer Science and Business Media LLC. - 1471-2229. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Stored potato (Solanum tuberosum L.) tubers are sensitive to wet conditions that can cause rotting in long-term storage. To study the effect of water on the tuber surface during storage, microarray analysis, RNA-Seq profiling, qRT-PCR and phytohormone measurements were performed to study gene expression and hormone content in wet tubers incubated at two temperatures: 4 °C and 15 °C. The growth of the plants was also observed in a greenhouse after the incubation of tubers in wet conditions. Results: Wet conditions induced a low-oxygen response, suggesting reduced oxygen availability in wet tubers at both temperatures when compared to that in the corresponding dry samples. Wet conditions induced genes coding for heat shock proteins, as well as proteins involved in fermentative energy production and defense against reactive oxygen species (ROS), which are transcripts that have been previously associated with low-oxygen stress in hypoxic or anoxic conditions. Wet treatment also induced senescence-related gene expression and genes involved in cell wall loosening, but downregulated genes encoding protease inhibitors and proteins involved in chloroplast functions and in the biosynthesis of secondary metabolites. Many genes involved in the production of phytohormones and signaling were also affected by wet conditions, suggesting altered regulation of growth by wet conditions. Hormone measurements after incubation showed increased salicylic acid (SA), abscisic acid (ABA) and auxin (IAA) concentrations as well as reduced production of jasmonate 12-oxo-phytodienoic acid (OPDA) in wet tubers. After incubation in wet conditions, the tubers produced fewer stems and more roots compared to controls incubated in dry conditions. Conclusions: In wet conditions, tubers invest in ROS protection and defense against the abiotic stress caused by reduced oxygen due to excessive water. Changes in ABA, SA and IAA that are antagonistic to jasmonates affect growth and defenses, causing induction of root growth and rendering tubers susceptible to necrotrophic pathogens. Water on the tuber surface may function as a signal for growth, similar to germination of seeds.
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| 4. |
- Purhonen, Janne, et al.
(författare)
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Mitochondrial complex III deficiency drives c-MYC overexpression and illicit cell cycle entry leading to senescence and segmental progeria
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Accumulating evidence suggests mitochondria as key modulators of normal and premature aging, yet whether primary oxidative phosphorylation (OXPHOS) deficiency can cause progeroid disease remains unclear. Here, we show that mice with severe isolated respiratory complex III (CIII) deficiency display nuclear DNA damage, cell cycle arrest, aberrant mitoses, and cellular senescence in the affected organs such as liver and kidney, and a systemic phenotype resembling juvenile-onset progeroid syndromes. Mechanistically, CIII deficiency triggers presymptomatic cancer-like c-MYC upregulation followed by excessive anabolic metabolism and illicit cell proliferation against lack of energy and biosynthetic precursors. Transgenic alternative oxidase dampens mitochondrial integrated stress response and the c-MYC induction, suppresses the illicit proliferation, and prevents juvenile lethality despite that canonical OXPHOS-linked functions remain uncorrected. Inhibition of c-MYC with the dominant-negative Omomyc protein relieves the DNA damage in CIII-deficient hepatocytes in vivo. Our results connect primary OXPHOS deficiency to genomic instability and progeroid pathogenesis and suggest that targeting c-MYC and aberrant cell proliferation may be therapeutic in mitochondrial diseases.
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| 5. |
- Siipola, Sari M., et al.
(författare)
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Epidermal UV-A absorbance and whole leaf flavonoid composition in pea respond more to solar blue light than solar UV radiation
- 2015
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Ingår i: Plant, Cell and Environment. - : Blackwell Publishing. - 0140-7791 .- 1365-3040. ; 38:5, s. 941-952
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Tidskriftsartikel (refereegranskat)abstract
- Plants synthesize phenolic compounds in response to certain environmental signals or stresses. One large group of phenolics, flavonoids, is considered particularly responsive to ultraviolet (UV) radiation. However, here we demonstrate that solar blue light stimulates flavonoid biosynthesis in the absence of UV‐A and UV‐B radiation. We grew pea plants (Pisum sativum cv. Meteor) outdoors, in Finland during the summer, under five types of filters differing in their spectral transmittance. These filters were used to (1) attenuate UV‐B; (2) attenuate UV‐B and UV‐A < 370 nm; (3) attenuate UV‐B and UV‐A; (4) attenuate UV‐B, UV‐A and blue light; and (5) as a control not attenuating these wavebands. Attenuation of blue light significantly reduced the flavonoid content in leaf adaxial epidermis and reduced the whole‐leaf concentrations of quercetin derivatives relative to kaempferol derivatives. In contrast, UV‐B responses were not significant. These results show that pea plants regulate epidermal UV‐A absorbance and accumulation of individual flavonoids by perceiving complex radiation signals that extend into the visible region of the solar spectrum. Furthermore, solar blue light instead of solar UV‐B radiation can be the main regulator of phenolic compound accumulation in plants that germinate and develop outdoors.
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| 6. |
- Sipari, Nina, et al.
(författare)
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Metabolite Profiling of Paraquat Tolerant Arabidopsis thaliana Radical-induced Cell Death1 (rcd1) : A Mediator of Antioxidant Defence Mechanisms
- 2022
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Ingår i: Antioxidants. - : MDPI. - 2076-3921. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- RADICAL-INDUCED CELL DEATH1 (RCD1) is an Arabidopsis thaliana nuclear protein that is disrupted during oxidative stress. RCD1 is considered an important integrative node in development and stress responses, and the rcd1 plants have several phenotypes and altered resistance to a variety of abiotic and biotic stresses. One of the phenotypes of rcd1 is resistance to the herbicide paraquat, but the mechanisms behind it are unknown. Paraquat causes a rapid burst of reactive oxygen species (ROS) initially in the chloroplast. We performed multi-platform metabolomic analyses in wild type Col-0 and paraquat resistant rcd1 plants to identify pathways conveying resistance and the function of RCD1 in this respect. Wild type and rcd1 plants were clearly distinguished by their abundance of antioxidants and specialized metabolites and their responses to paraquat. The lack of response in rcd1 suggested constitutively active defense against ROS via elevated flavonoid, glutathione, β-carotene, and tocopherol levels, whereas its ascorbic acid levels were compromised under non-stressed control conditions when compared to Col-0. We propose that RCD1 acts as a hub that maintains basal antioxidant system, and its inactivation induces defense responses by enhancing the biosynthesis and redox cycling of low molecular weight antioxidants and specialized metabolites with profound antioxidant activities alleviating oxidative stress.
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| 7. |
- Sipari, Nina, et al.
(författare)
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Primary Metabolite Responses to Oxidative Stress in Early-Senescing and Paraquat Resistant Arabidopsis thaliana rcd1 (Radical-Induced Cell Death1)
- 2020
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Ingår i: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Rcd1 (radical-induced cell death1) is an Arabidopsis thaliana mutant, which exhibits high tolerance to paraquat [methyl viologen (MV)], herbicide that interrupts photosynthetic electron transport chain causing the formation of superoxide and inhibiting NADPH production in the chloroplast. To understand the biochemical mechanisms of MV-resistance and the role of RCD1 in oxidative stress responses, we performed metabolite profiling of wild type (Col-0) and rcd1 plants in light, after MV exposure and after prolonged darkness. The function of RCD1 has been extensively studied at transcriptomic and biochemical level, but comprehensive metabolite profiling of rcd1 mutant has not been conducted until now. The mutant plants exhibited very different metabolic features from the wild type under light conditions implying enhanced glycolytic activity, altered nitrogen and nucleotide metabolism. In light conditions, superoxide production was elevated in rcd1, but no metabolic markers of oxidative stress were detected. Elevated senescence-associated metabolite marker levels in rcd1 at early developmental stage were in line with its early-senescing phenotype and possible mitochondrial dysfunction. After MV exposure, a marked decline in the levels of glycolytic and TCA cycle intermediates in Col-0 suggested severe plastidic oxidative stress and inhibition of photosynthesis and respiration, whereas in rcd1 the results indicated sustained photosynthesis and respiration and induction of energy salvaging pathways. The accumulation of oxidative stress markers in both plant lines indicated that MV-resistance in rcd1 derived from the altered regulation of cellular metabolism and not from the restricted delivery of MV into the cells or chloroplasts. Considering the evidence from metabolomic, transcriptomic and biochemical studies, we propose that RCD1 has a negative effect on reductive metabolism and rerouting of the energy production pathways. Thus, the altered, highly active reductive metabolism, energy salvaging pathways and redox transfer between cellular compartments in rcd1 could be sufficient to avoid the negative effects of MV-induced toxicity.
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| 8. |
- Waszczak, Cezary, et al.
(författare)
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Synthesis and import of GDP-l-fucose into the Golgi affect plant–water relations
- 2023
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Ingår i: New Phytologist. - 0028-646X .- 1469-8137. ; 241:2, s. 747-63
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Tidskriftsartikel (refereegranskat)abstract
- Land plants evolved multiple adaptations to restrict transpiration. However, the underlying molecular mechanisms are not sufficiently understood. We used an ozone-sensitivity forward genetics approach to identify Arabidopsis thaliana mutants impaired in gas exchange regulation. High water loss from detached leaves and impaired decrease of leaf conductance in response to multiple stomata-closing stimuli were identified in a mutant of MURUS1 (MUR1), an enzyme required for GDP-l-fucose biosynthesis. High water loss observed in mur1 was independent from stomatal movements and instead could be linked to metabolic defects. Plants defective in import of GDP-l-Fuc into the Golgi apparatus phenocopied the high water loss of mur1 mutants, linking this phenotype to Golgi-localized fucosylation events. However, impaired fucosylation of xyloglucan, N-linked glycans, and arabinogalactan proteins did not explain the aberrant water loss of mur1 mutants. Partial reversion of mur1 water loss phenotype by borate supplementation and high water loss observed in boron uptake mutants link mur1 gas exchange phenotypes to pleiotropic consequences of l-fucose and boron deficiency, which in turn affect mechanical and morphological properties of stomatal complexes and whole-plant physiology. Our work emphasizes the impact of fucose metabolism and boron uptake on plant–water relations.
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