TY - THES A1 - Sedaghatmehr, Mastoureh T1 - Unraveling the regulatory mechanisms of heat stress memory in Arabidopsis thaliana Y1 - 2017 ER - TY - JOUR A1 - Sedaghatmehr, Mastoureh A1 - Müller-Röber, Bernd A1 - Balazadeh, Salma T1 - The plastid metalloprotease FtsH6 and small heat shock protein HSP21 jointly regulate thermomemory in Arabidopsis JF - Nature Communications N2 - Acquired tolerance to heat stress is an increased resistance to elevated temperature following a prior exposure to heat. The maintenance of acquired thermotolerance in the absence of intervening stress is called ‘thermomemory’ but the mechanistic basis for this memory is not well defined. Here we show that Arabidopsis HSP21, a plastidial small heat shock protein that rapidly accumulates after heat stress and remains abundant during the thermomemory phase, is a crucial component of thermomemory. Sustained memory requires that HSP21 levels remain high. Through pharmacological interrogation and transcriptome profiling, we show that the plastid-localized metalloprotease FtsH6 regulates HSP21 abundance. Lack of a functional FtsH6 protein promotes HSP21 accumulation during the later stages of thermomemory and increases thermomemory capacity. Our results thus reveal the presence of a plastidial FtsH6–HSP21 control module for thermomemory in plants. Y1 - 2016 U6 - https://doi.org/10.1038/ncomms12439 SN - 2041-1723 VL - 7 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Sedaghatmehr, Mastoureh A1 - Thirumalaikumar, Venkatesh P. A1 - Kamranfar, Iman A1 - Marmagne, Anne A1 - Masclaux-Daubresse, Celine A1 - Balazadeh, Salma T1 - A regulatory role of autophagy for resetting the memory of heat stress in plants JF - Plant, cell & environment : cell physiology, whole-plant physiology, community physiology N2 - As sessile life forms, plants are repeatedly confronted with adverse environmental conditions, which can impair development, growth, and reproduction. During evolution, plants have established mechanisms to orchestrate the delicate balance between growth and stress tolerance, to reset cellular biochemistry once stress vanishes, or to keep a molecular memory, which enables survival of a harsher stress that may arise later. Although there are several examples of memory in diverse plants species, the molecular machinery underlying the formation, duration, and resetting of stress memories is largely unknown so far. We report here that autophagy, a central self-degradative process, assists in resetting cellular memory of heat stress (HS) in Arabidopsis thaliana. Autophagy is induced by thermopriming (moderate HS) and, intriguingly, remains high long after stress termination. We demonstrate that autophagy mediates the specific degradation of heat shock proteins at later stages of the thermorecovery phase leading to the accumulation of protein aggregates after the second HS and a compromised heat tolerance. Autophagy mutants retain heat shock proteins longer than wild type and concomitantly display improved thermomemory. Our findings reveal a novel regulatory mechanism for HS memory in plants. KW - Arabidopsis KW - heat shock proteins KW - priming KW - resetting Y1 - 2019 U6 - https://doi.org/10.1111/pce.13426 SN - 0140-7791 SN - 1365-3040 VL - 42 IS - 3 SP - 1054 EP - 1064 PB - Wiley CY - Hoboken ER - 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 - Sedaghatmehr, Mastoureh A1 - Thirumalaikumar, Venkatesh P. A1 - Kamranfar, Iman A1 - Schulz, Karina A1 - Müller-Röber, Bernd A1 - Sampathkumar, Arun A1 - Balazadeh, Salma T1 - Autophagy complements metalloprotease FtsH6 in degrading plastid heat shock protein HSP21 during heat stress recovery JF - The journal of experimental botany : an official publication of the Society for Experimental Biology and of the Federation of European Societies of Plant Physiology N2 - Moderate and temporary heat stresses prime plants to tolerate, and survive, a subsequent severe heat stress. Such acquired thermotolerance can be maintained for several days under normal growth conditions, and can create a heat stress memory. We recently demonstrated that plastid-localized small heat shock protein 21 ( HSP21) is a key component of heat stress memory in Arabidopsis thaliana. A sustained high abundance of HSP21 during the heat stress recovery phase extends heat stress memory. The level of HSP21 is negatively controlled by plastid-localized metalloprotease FtsH6 during heat stress recovery. Here, we demonstrate that autophagy, a cellular recycling mechanism, exerts additional control over HSP21 degradation. Genetic and chemical disruption of both metalloprotease activity and autophagy trigger superior HSP21 accumulation, thereby improving memory. Furthermore, we provide evidence that autophagy cargo receptor ATG8-INTERACTING PROTEIN1 (ATI1) is associated with heat stress memory. ATI1 bodies co-localize with both autophagosomes and HSP21, and their abundance and transport to the vacuole increase during heat stress recovery. Together, our results provide new insights into the module for control of the regulation of heat stress memory, in which two distinct protein degradation pathways act in concert to degrade HSP21, thereby enabling cells to recover from the heat stress effect at the cost of reducing the heat stress memory. KW - Arabidopsis thaliana KW - ATI1 KW - FtsH6 KW - heat stress KW - HSP21 KW - plastid KW - selective autophagy KW - stress memory KW - stress recovery Y1 - 2021 U6 - https://doi.org/10.1093/jxb/erab304 SN - 0022-0957 SN - 1460-2431 VL - 72 IS - 21 SP - 7498 EP - 7513 PB - Oxford University Press CY - Oxford ER -