TY - JOUR A1 - Kamranfar, Iman A1 - Xue, Gang-Ping A1 - Tohge, Takayuki A1 - Sedaghatmehr, Mastoureh A1 - Fernie, Alisdair R. A1 - Balazadeh, Salma A1 - Mueller-Roeber, Bernd T1 - Transcription factor RD26 is a key regulator of metabolic reprogramming during dark-induced senescence JF - New phytologist : international journal of plant science N2 - Leaf senescence is a key process in plants that culminates in the degradation of cellular constituents and massive reprogramming of metabolism for the recovery of nutrients from aged leaves for their reuse in newly developing sinks. We used molecular-biological and metabolomics approaches to identify NAC transcription factor (TF) RD26 as an important regulator of metabolic reprogramming in Arabidopsis thaliana. RD26 directly activates CHLOROPLAST VESICULATION (CV), encoding a protein crucial for chloroplast protein degradation, concomitant with an enhanced protein loss in RD26 over-expressors during senescence, but a reduced decline of protein in rd26 knockout mutants. RD26 also directly activates LKR/SDH involved in lysine catabolism, and PES1 important for phytol degradation. Metabolic profiling revealed reduced c-aminobutyric acid (GABA) in RD26 overexpressors, accompanied by the induction of respective catabolic genes. Degradation of lysine, phytol and GABA is instrumental for maintaining mitochondrial respiration in carbon-limiting conditions during senescence. RD26 also supports the degradation of starch and the accumulation of mono-and disaccharides during senescence by directly enhancing the expression of AMY1, SFP1 and SWEET15 involved in carbohydrate metabolism and transport. Collectively, during senescence RD26 acts by controlling the expression of genes across the entire spectrum of the cellular degradation hierarchy. KW - Arabidopsis KW - fatty acid KW - primary metabolism KW - protein and amino acid degradation KW - respiration KW - senescence Y1 - 2018 U6 - https://doi.org/10.1111/nph.15127 SN - 0028-646X SN - 1469-8137 VL - 218 IS - 4 SP - 1543 EP - 1557 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Araujo, Wagner L. A1 - Nunes-Nesi, Adriano A1 - Nikoloski, Zoran A1 - Sweetlove, Lee J. A1 - Fernie, Alisdair R. T1 - Metabolic control and regulation of the tricarboxylic acid cycle in photosynthetic and heterotrophic plant tissues JF - Plant, cell & environment : cell physiology, whole-plant physiology, community physiology N2 - The tricarboxylic acid (TCA) cycle is a crucial component of respiratory metabolism in both photosynthetic and heterotrophic plant organs. All of the major genes of the tomato TCA cycle have been cloned recently, allowing the generation of a suite of transgenic plants in which the majority of the enzymes in the pathway are progressively decreased. Investigations of these plants have provided an almost complete view of the distribution of control in this important pathway. Our studies suggest that citrate synthase, aconitase, isocitrate dehydrogenase, succinyl CoA ligase, succinate dehydrogenase, fumarase and malate dehydrogenase have control coefficients flux for respiration of -0.4, 0.964, -0.123, 0.0008, 0.289, 0.601 and 1.76, respectively; while 2-oxoglutarate dehydrogenase is estimated to have a control coefficient of 0.786 in potato tubers. These results thus indicate that the control of this pathway is distributed among malate dehydrogenase, aconitase, fumarase, succinate dehydrogenase and 2-oxoglutarate dehydrogenase. The unusual distribution of control estimated here is consistent with specific non-cyclic flux mode and cytosolic bypasses that operate in illuminated leaves. These observations are discussed in the context of known regulatory properties of the enzymes and some illustrative examples of how the pathway responds to environmental change are given. KW - metabolic control analysis KW - metabolic regulation KW - respiration KW - Solanum lycopersicum (tomato) KW - TCA cycle Y1 - 2012 U6 - https://doi.org/10.1111/j.1365-3040.2011.02332.x SN - 0140-7791 VL - 35 IS - 1 SP - 1 EP - 21 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Jose Clemente-Moreno, Maria A1 - Omranian, Nooshin A1 - Saez, Patricia A1 - Maria Figueroa, Carlos A1 - Del-Saz, Nestor A1 - Elso, Mhartyn A1 - Poblete, Leticia A1 - Orf, Isabel A1 - Cuadros-Inostroza, Alvaro A1 - Cavieres, Lohengrin A1 - Bravo, Leon A1 - Fernie, Alisdair R. A1 - Ribas-Carbo, Miquel A1 - Flexas, Jaume A1 - Nikoloski, Zoran A1 - Brotman, Yariv A1 - Gago, Jorge T1 - Cytochrome respiration pathway and sulphur metabolism sustain stress tolerance to low temperature in the Antarctic species Colobanthus quitensis JF - New phytologist : international journal of plant science N2 - Understanding the strategies employed by plant species that live in extreme environments offers the possibility to discover stress tolerance mechanisms. We studied the physiological, antioxidant and metabolic responses to three temperature conditions (4, 15, and 23 degrees C) of Colobanthus quitensis (CQ), one of the only two native vascular species in Antarctica. We also employed Dianthus chinensis (DC), to assess the effects of the treatments in a non-Antarctic species from the same family. Using fused LASSO modelling, we associated physiological and biochemical antioxidant responses with primary metabolism. This approach allowed us to highlight the metabolic pathways driving the response specific to CQ. Low temperature imposed dramatic reductions in photosynthesis (up to 88%) but not in respiration (sustaining rates of 3.0-4.2 mu mol CO2 m(-2) s(-1)) in CQ, and no change in the physiological stress parameters was found. Its notable antioxidant capacity and mitochondrial cytochrome respiratory activity (20 and two times higher than DC, respectively), which ensure ATP production even at low temperature, was significantly associated with sulphur-containing metabolites and polyamines. Our findings potentially open new biotechnological opportunities regarding the role of antioxidant compounds and respiratory mechanisms associated with sulphur metabolism in stress tolerance strategies to low temperature. KW - Antarctica KW - antioxidant capacity KW - low temperature KW - photosynthesis KW - respiration KW - stress tolerance KW - sulphur metabolism Y1 - 2019 U6 - https://doi.org/10.1111/nph.16167 SN - 0028-646X SN - 1469-8137 VL - 225 IS - 2 SP - 754 EP - 768 PB - Wiley CY - Hoboken ER -