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To further our understanding of how sustained changes in temperature affect the carbon economy of rice (Oryza sativa), hydroponically grown plants of the IR64 cultivar were developed at 30°C/25°C (day/night) before being shifted to 25/20°C or 40/35°C. Leaf messenger RNA and protein abundance, sugar and starch concentrations, and gas‐exchange and elongation rates were measured on preexisting leaves (PE) already developed at 30/25°C or leaves newly developed (ND) subsequent to temperature transfer. Following a shift in growth temperature, there was a transient adjustment in metabolic gene transcript abundance of PE leaves before homoeostasis was reached within 24 hr, aligning with Rdark (leaf dark respiratory CO2 release) and An (net CO2 assimilation) changes. With longer exposure, the central respiratory protein cytochrome c oxidase (COX) declined in abundance at 40/35°C. In contrast to Rdark, An was maintained across the three growth temperatures in ND leaves. Soluble sugars did not differ significantly with growth temperature, and growth was fastest with extended exposure at 40/35°C. The results highlight that acclimation of photosynthesis and respiration is asynchronous in rice, with heat‐acclimated plants exhibiting a striking ability to maintain net carbon gain and growth when exposed to heat‐wave temperatures, even while reducing investment in energy‐conserving respiratory pathways.

Made available in DSpace on 2019-09-12T16:53:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2019 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) In tropical biomes, abrupt cold events frequently occur in subtropical regions and can be associated with large daily thermal fluctuations. The bromeliad Nidularium minutum Mez is a cold tolerant species from the Atlantic Rainforest, which grows in the subtropical latitude, where temperatures range from 2 to 30 degrees C. We hypothesized that N. minutum plants would implement rapid metabolic adjustments to ensure survival during sudden cold events that occur in seasons other than winter. N. minutum plants were cultivated at 10 degrees C. Under this condition, there was an observed increase in soluble sugar content and nitric oxide (NO) emission, as well as a high nitrate reductase (NR) activity observed within the 72 h of cold exposure, when compared with plants maintained at 25 degrees C. These responses coincided with a decrease in antioxidant activity and an increase in lipid peroxidation (LPO). After 72 h of cold exposure, a subset of plants were de-acclimated at 25 degrees C. These plants displayed reduced soluble sugar concentrations, NO emissions, NR activity and LPO. Additionally, there was an increase in anti-oxidant activity, which indicated that the plants were recovering from cold stress. Furthermore, it was found that plants maintained at 10 degrees C for 168 h acclimated to the cold by reducing the NO content and maintaining the increased sugar concentrations, thus resulting in a less intense stress response. We conclude that rapid changes in NO content, sugar concentrations and antioxidant activity are metabolic adjustments that occur during the acclimation and de-acclimation processes of this bromeliad to low temperatures. During abrupt thermal changes in subtropical regions, such adjustments could enhance cold tolerance and increase the chances of survival for this plant. [Carvalho, Camila Pereira; Nievola, Catarina Carvalho] Inst Bot SMA SP, Nucleo Pesquisa Plantas Ornamentals, Ave Miguel Stefano 3687, BR-04301902 Sao Paulo, SP, Brazil [Cardoso-Gustayson, Poliana] Univ Fed ABC, Ctr Ciencias Nat & Humans, BR-09606070 Sao Bernardo Do Campo, Brazil [Rodrigues, Edson] Universidade de Taubaté (Unitau), Inst Basico Biociencias, BR-12030180 Taubate, SP, Brazil [Braga, Marcia Regina] Inst Botan SMA SP, Nucleo Pesquisa Fisiol & Bioquim, BR-04301902 Sao Paulo, SP, Brazil [Mercier, Helenice] Univ Sao Paulo, Inst Biociencias, Dept Bot, BR-05508090 Sao Paulo, SP, Brazil

23 pags., 6 figs., Endoplasmic reticulum–plasma membrane contact sites (ER–PM CS) play fundamental roles in all eukaryotic cells. Arabidopsis thaliana mutants lacking the ER–PM protein tether synaptotagmin1 (SYT1) exhibit decreased PM integrity under multiple abiotic stresses, such as freezing, high salt, osmotic stress, and mechanical damage. Here, we show that, together with SYT1, the stress-induced SYT3 is an ER–PM tether that also functions in maintaining PM integrity. The ER–PM CS localization of SYT1 and SYT3 is dependent on PM phosphatidylinositol-4-phosphate and is regulated by abiotic stress. Lipidomic analysis revealed that cold stress increased the accumulation of diacylglycerol at the PM in a syt1/3 double mutant relative to wild-type while the levels of most glycerolipid species remain unchanged. In addition, the SYT1-green fluorescent protein fusion preferentially binds diacylglycerol in vivo with little affinity for polar glycerolipids. Our work, This work was supported by the Ministerio de Economıa y Competitividad, co-financed by the European Regional Development Fund (grant no. BIO2017-82609-R to M.A.B.), the Ministerio de Ciencia, Innovacion y Universidades (grant no. PGC2018-098789-B-I00 to N.R.-L.) UMA-FEDER (grant UMA18-FEDERJA-154 to N.R.-L.), and the Marie SkłodowskaCurie actions (grant no. H2020-655366-IIF- PLICO to M.A.B. and N.R.-L.). N.R.L. was supported by the Ramon y Cajal program RYC-2013-12699 (MINECO, Spain). J.P.-S. and S.G.-H. were funded by the Ministerio de Economıa y Competitividad in Formacion del Personal Investigador Fellowship (grant no. BES-2012-052324) and (PRE2018- 085284), respectively. R.P.H. and J.A.N. received support from the Biotechnology and Biological Sciences Research Council (BBSRC, UK) in the form of an Institute Strategic Programme Grant (grant no. BBS/E/C/000I0420). J.L. is supported by the Program of Introducing Talents of Discipline to Universities (111 Project, grant no. B13007). A.P.M. and J.P.-S. were supported by the Shanghai Center for Plant Stress Biology (Chinese Academy of Sciences), Chinese 1000 Talents Program. A.R. was supported by the Natural Sciences and Engineering Research Council of Canada (NSERCDiscovery Grant no. RGPIN-2019-05568). Support was also provided by AEI/FEDER, UE (grant nos. BIO2016-79187-R and PID2019-106987RB-I00 to J.P.-S.) and by the European Research Council under the European Union’s Seventh Framework Programme (grant no. FP7/2007-2013)/ERC grant agreement no. 742985 to J.F. and T-Rex (project number 682436 to D.V.D.).

Cross-talk between exogenous salicylic acid (SA) and endogenous phytohormone pathways affects the antioxidant defense system and its response to salt stress. The study presented here investigated the effects of SA treatment before and during salt stress on the levels of endogenous plant growth regulators in three barley cultivars with different salinity tolerances: Hordeum vulgare L. cvs. Akhisar (sensitive), Erginel (moderate), and Kalayc (tolerant). The cultivars' relative leaf water contents, growth parameters, proline contents, chlorophyll a/b ratios, and lipid peroxidation levels were measured, along with the activities of enzymes involved in detoxifying reactive oxygen species (ROS) including superoxide-dismutase, peroxidase, catalase, ascorbate-peroxidase, and glutathione-reductase. In addition, levels of several endogenous phytohormones (indole-3-acetic-acid, cytokinins, abscisic acid, jasmonic acid, and ethylene) were measured. Barley is known to be more salt tolerant than related plant species. Accordingly, none of the studied cultivars exhibited changes in membrane lipid peroxidation under salt stress. However, they responded differently to salt-stress with respect to their accumulation of phytohormones and antioxidant enzyme activity. The strongest and weakest increases in ABA and proline accumulation were observed in Kalayc and Akhisar, respectively, suggesting that salt-stress was more effectively managed in Kalayc. The effects of exogenous SA treatment depended on both the timing of the treatment and the cultivar to which it was applied. In general, however, where SA helped mitigate salt stress, it appeared to do so by increasing ROS scavenging capacity and antioxidant enzyme activity. SA treatment also induced changes in phytohormone levels, presumably as a consequence of SA-phytohormone salt-stress cross-talk. Internal Grant Agency of Palacky University [IGA_PrF_ 2019_ 020]; European Regional Development Fund-Project Plants as a tool for sustainable global development [CZ. 02.1.01/0.0/0.0/16_019/0000827] This work was supported by the Internal Grant Agency of Palacky University N. IGA_PrF_ 2019_ 020 and from European Regional Development Fund-Project Plants as a tool for sustainable global development (No. CZ. 02.1.01/0.0/0.0/16_019/0000827). We would also like to thank to Sees-editing Ltd., U.K. for English editing of the manuscript. WOS:000563538600009 2-s2.0-85089529111 PubMed: 32807910

The aim of this study was verification whether an 8-week-long swimming exercise training would induce adaptive changes in body weight in rats and whether possible changes would depend on aquatic environment temperature and animal sex. The exercisetrained groups swam 4 minutes a day, five days a week during eight week of housing. Exercise was performed by swimming in glass tanks containing tap water maintained according to group at 5 ±2°C (cold group) and 36 ±2°C (thermal neutral group). Before and after each week of the experiment, rats were weighed. When comparing the nature of changes in the body weight of rats exposed to swimming exercise training in cold water, attention should be paid to their dependence on sex. There were statistically significant changes in the nature of changes in body weight between male rats and female rats of the cold group (5°C) as early as experimental week 2 until the end of the experiment (p < 0.001). Interestingly, the females exposed to swimming exercise training at 5°C were the only group in which an increase in body weight occurred during experimental week 8 in relation to baseline values.

Perennial iyegrass (Lolium perenne L) is a widely cultivated cool-season grass species because of its high quality for forage and turf. Susceptibility to freezing damage limits its further use in temperate zones. The objective of this study was to identify candidate genes significantly associated with winter survival and spring regrowth in a global collection of 192 perennial ryegrass accessions. Significant differences in winter survival (WS), percentage of canopy green cover (CGC), chlorophyll index (Chl), and normalized difference vegetation index (NDVI) were found among accessions. After controlling population structure, LpLEA3 encoding a late embryogenesis abundant group 3 protein and LpCAT encoding a catalase were associated with CGC and Chl, while LpMnSOD encoding a magnesium superoxide dismutase and LpChl Cu-ZnSOD encoding a chlorophyll copper zinc superoxide dismutase were associated with NDVI or Chl. Significant association was also discovered between C-repeat binding factor LpCBF1b and WS. Three sequence variations identified in LpCAT, LpMnSOD, and LpChl Cu-ZnSOD were synonymous substitutions, whereas one pair of adjacent single nucleotide polymorphisms (SNPs) in LpLEA3 and one SNP in LpCBF1b resulted in amino acid change. The results demonstrated that allelic variation in LpLEA3 and LpCBF1b was closely related to winter survival and spring regrowth in perennial ryegrass. (C) 2015 Elsevier Ireland Ltd. All rights reserved.

In this study, one-year-old shoots of the olive (Olea europaea L.) cv. Gemlik were tested at artificial low temperatures (4, -5A degrees C, -10A degrees C, and -20A degrees C) every month for two years. For low temperature treatment, the degree of cell membrane injury in leaves and barks was determined by ion leakage method. In addition, with regard to antioxidative defense mechanism, activities of catalase (CAT, EC 1.11.1.6) and ascorbate peroxidase (APX, EC 1.11.1.11) enzymes were determined. Leaf and bark tissues subjected to 4A degrees C and -5A degrees C injured to a limited extent in all months. However, more than 50% injury occurred by temperatures equal to or colder than -10A degrees C treatments depending on the season. For -10A degrees C and -20A degrees C treatments, the lowest and the highest injury in leaf and bark tissues were detected during winter and summer seasons, respectively. We determined in this study that CAT and APX enzyme activities are generally higher during fall and winter compared with those in summer. On the other hand, CAT and APX enzyme activities started increasing during fall along with a decreasing freezing injury while the activities of these enzymes decreased to some extent during winter when freezing injury was the lowest. In addition, while CAT activity decreased with low temperature treatments, APX activity did not change until -5A degrees C treatment but decreased with decreasing temperatures starting from -10A degrees C depending on the month the tissue was obtained. In conclusion, olive plant shows considerable tolerance to low temperatures that are achieved after daily gradual decreases by increasing cell membrane stability through complicated mechanisms including antioxidative enzyme metabolisms. In addition, APX may be more effective in maintaining cold-hardiness of olive compared with CAT. Türkiye Cumhuriyeti Devlet Planlama Teşkilatı

Cultivation of chilling-tolerant ornamental crops at lower temperature could reduce the energy demands of heated greenhouses. To provide a better understanding of how sub-optimal temperatures (12 degrees C vs. 16 degrees C) affect growth of the sensitive Petunia hybrida cultivar 'SweetSunshine Williams', the transcriptome, carbohydrate metabolism, and phytohormone homeostasis were monitored in aerial plant parts over 4 weeks by use of a microarray, enzymatic assays and GC-MS/MS. The data revealed three consecutive phases of chilling response. The first days were marked by a strong accumulation of sugars, particularly in source leaves, preferential up-regulation of genes in the same tissue and down-regulation of several genes in the shoot apex, especially those involved in the abiotic stress response. The midterm phase featured a partial normalization of carbohydrate levels and gene expression. After 3 weeks of chilling exposure, a new stabilized balance was established. Reduced hexose levels in the shoot apex, reduced ratios of sugar levels between the apex and source leaves and a higher apical sucrose/hexose ratio, associated with decreased activity and expression of cell wall invertase, indicate that prolonged chilling induced sugar accumulation in source leaves at the expense of reduced sugar transport to and reduced sucrose utilization in the shoot. This was associated with reduced levels of indole-3-acetic acid and abscisic acid in the apex and high numbers of differentially, particularly up-regulated genes, especially in the source leaves, including those regulating histones, ethylene action, transcription factors, and a jasmonate-ZIM-domain protein. Transcripts of one Jumonji C domain containing protein and one expansin accumulated in source leaves throughout the chilling period. The results reveal a dynamic and complex disturbance of plant function in response to mild chilling, opening new perspectives for the comparative analysis of differently tolerant cultivars. BMBF/AgroCluster/WeGa - Horticulture Research Network State of Brandenburg Free State of Thuringia Federal Republic of Germany

Effects of salt stress on the activity of peroxidase (PRX) isozyme and leaf proteins were studied in the three strawberry varieties, Camarosa, Tioga and Chandler. Plants were watered with modified 1/3 Hoagland nutrient solution containing 0 (control), 8.5, 17.0 and 34.0 mM NaCl for 30 days following 20 days acclimation. PRX activity was assayed in leaf extracts and PRX profiles of control and salt treated plants were performed by native polyacrylamide gel electrophoresis (PAGE). During the salt stress Tioga and Camarosa tolerated the cellular damage with less electrolyte leakage while Chandler exhibited a severe cellular damage with the highest (87.5% in 34.0 mM NaCl treatment) electrolyte leakage. Total soluble protein content was decreased by salinity in Tioga (from 11.35 to 5.86 mg center dot g(-1) DW) and Chandler (from 9.35 to 3.90 mg center dot g(-1) DW) while it was almost unchanged in Camarosa. Salt stress increased total and specific PRX activity as compared with the control in all the varieties. In native PAGE, one basic isoperoxidase band (Rf=0.27) was observed commonly with different band intensity in all the treatments. Therefore, it might be associated with lignification and recovery of cell membrane damage in strawberry plants under salt stress.

Plants of a domestic (Lycopersicon esculentum [L.] Mill. cv. Abunda) and a high-altitude wild Lycopersicon species (L. peruvianum Mill. LA 385) were grown at near-optimal (25/20 degrees C) or suboptimal (16/14 degrees C) temperature. Leaf discs from just fully expanded leaves were exposed to an irradiance of 1000 mu mol m(-2) s(-1) at 5 degrees C for 48 h. The effect of growth temperature on the susceptibility to photoinhibition of photosystem II (PSII) and its recovery, degradation of leaf pigments, chlorophyll (Chl) fluorescence quenching and xanthophyll cycle activity were examined. Leaves of L. esculentum and L. peruvianum plants grown at optimal temperature, were similarly susceptible to photodamage. Suboptimal-grown leaves of both species showed a higher tolerance to photoinhibition than optimal-grown leaves. In both species, recovery of photoinhibited PSII was more complete in leaves grown at suboptimal than at optimal temperature. In contrast to L. esculentum, suboptimal-grown leaves of L. peruvianum exhibited faster kinetics of recovery from photoinhibition than optimal-grown leaves. Light-induced degradation of leaf pigments in leaves grown at 16/14 degrees C was 2.3- and 2.7-times slower in L. esculentum and L. peruvianum, respectively, when compared with leaves grown at 25/20 degrees C. Non-photochemical quenching (NPQ) of Chl fluorescence developed faster in leaves of suboptimal-grown plants. and steady-slate levels were similar to 20% higher than in leaves of optimal-grown plants of both species. An increased pool size of xanthophyll cycle pigments together with a slightly higher conversion state, resulted in a 1.5- (L. esculentum) or 3-fold (L. peruvianum) higher maximal zeaxanthin content in suboptimal-, as compared with optimal-grown leaves. These results demonstrate that acclimation to suboptimal temperature increased the capacity to resist chilling-induced photodamage in both the domestic and the high-altitude wild Lycopersicon species. However. the acclimatory response was more pronounced in L. peruvianum than in L. esculentum, indicating a greater ability of the high-altitude wild species to acclimate its photosynthetic apparatus to suboptimal temperatures. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.

Winter wheat plants (Triticum aestivum L. cv. Urban), grown in nutrient solution, were exposed to differential shoot/root temperatures (i.e., 4/4, 4/20, 20/4 and 20/20 degrees C) for six weeks. Leaves grown at 4 degrees C showed an increase in frost tolerance from - 4 degrees C down to -11 degrees C, irrespective of root temperature. In 4/20 degrees C plants, high root temperature decreased the rate of hardening of the leaves, but did not influence the final level of frost tolerance. In roots grown at 4 degrees C frost tolerance increased from - 3 degrees C down to - 4 degrees C, independently of shoot temperature. An accumulation of soluble sugars in the leaves was only observed when both shoot and root were grown at 4 degrees C and was not correlated with final frost tolerance achieved. However, the rate of hardening was correlated with the soluble sugar concentration. An increase in root soluble sugar concentration was exclusively observed in roots exposed to a temperature of 4 degrees C, irrespective of shoot temperature. Proline concentration only increased in plant parts exposed to a temperature of 4 degrees C. The present results indicate that the importance of root temperature in low-temperature hardening of winter wheat is limited, even though exposure to differential root and shoot temperatures brought about pronounced changes in growth, soluble sugar concentration, insoluble sugar concentration and proline concentration in roots and leaves.

A functional abscisic acid (ABA)-induced protein phosphatase type 2C (PP2C) was previously isolated from beech ( Fagus sylvatica) seeds (FsPP2C2). Because transgenic work is not possible in beech, in this study we overexpressed this gene in Arabidopsis ( Arabidopsis thaliana) to provide genetic evidence on FsPP2C2 function in seed dormancy and other plant responses. In contrast with other PP2Cs described so far, constitutive expression of FsPP2C2 in Arabidopsis, under the cauliflower mosaic virus 35S promoter, produced enhanced sensitivity to ABA and abiotic stress in seeds and vegetative tissues, dwarf phenotype, and delayed flowering, and all these effects were reversed by gibberellic acid application. The levels of active gibberellins (GAs) were reduced in 35S: FsPP2C2 plants, although transcript levels of AtGA20ox1 and AtGA3ox1 increased, probably as a result of negative feedback regulation, whereas the expression of GASA1 was induced by GAs. Additionally, FsPP2C2-overexpressing plants showed a strong induction of the Responsive to ABA 18 (RAB18) gene. Interestingly, FsPP2C2 contains two nuclear targeting sequences, and transient expression assays revealed that ABA directed this protein to the nucleus. Whereas other plant PP2Cs have been shown to act as negative regulators, our results support the hypothesis that FsPP2C2 is a positive regulator of ABA. Moreover, our results indicate the existence of potential cross-talk between ABA signaling and GA biosynthesis.

Ectotherms rely for their body heat on surrounding temperatures. A key question in biology is why most ectotherms mature at a larger size at lower temperatures, a phenomenon known as the temperature–size rule. Since temperature affects virtually all processes in a living organism, current theories to explain this phenomenon are diverse and complex and assert often from opposing assumptions. Although widely studied, the molecular genetic control of the temperature–size rule is unknown. We found that the Caenorhabditis elegans wild-type N2 complied with the temperature–size rule, whereas wild-type CB4856 defied it. Using a candidate gene approach based on an N2 × CB4856 recombinant inbred panel in combination with mutant analysis, complementation, and transgenic studies, we show that a single nucleotide polymorphism in tra-3 leads to mutation F96L in the encoded calpain-like protease. This mutation attenuates the ability of CB4856 to grow larger at low temperature. Homology modelling predicts that F96L reduces TRA-3 activity by destabilizing the DII-A domain. The data show that size adaptation of ectotherms to temperature changes may be less complex than previously thought because a subtle wild-type polymorphism modulates the temperature responsiveness of body size. These findings provide a novel step toward the molecular understanding of the temperature–size rule, which has puzzled biologists for decades., Author Summary Biologists are fascinated by variation in body size, which is hardly surprising, considering that the range of body sizes spans orders of magnitude from bacteria to blue whales. Even within species, body sizes can vary dramatically. This intraspecies variation is intriguing because it suggests strong associations between body size and environment. Already in 1847, Bergmann noticed that mammals tend to be larger in colder environments. More recently similar relationships were found for ectotherms, which rely for their body heat on the temperature of their surroundings, where more than 85% of the species studied grew larger at lower temperatures. This phenomenon, dubbed the temperature–size rule, has caused a renewed interest to understand how temperature affects body size. Yet the control of the temperature–size rule remains enigmatic, and the hypotheses proposed have been inconclusive. In this paper the authors show that a single nucleic acid change in one gene is required for regulation of the temperature–size rule in the nematode C. elegans. Using protein modelling they also show that this subtle change in DNA decreases the function of the encoded protein. The data suggest that temperature adaptation can be simple and far less complex than previously thought.

Fumigation of winter wheat with H2S during low temperature acclimation substantially reduced the development of freezing tolerance of the leaves. After 6 weeks of low temperature exposure (3-degrees-C), the freezing tolerance was increased by 6 and 2-degrees-C at 0 and 0.25-mu-l l-1 H2S, respectively. Changes in levels of cellular constituents (c. g. amino acids, sugars), which are characteristic for an increased freezing tolerance, were much less pronounced upon H2S fumigation. Besides, H2S fumigation diminished shoot growth at low temperature. At 20-degrees-C, H2S fumigation did not affect both freezing tolerance of the leaves and shoot growth. The role of glutathione in the development of freezing tolerance was evaluated. Low temperature exposure resulted in a rapid increase in the water-soluble non-protein-sulfhydryl content (mainly glutathione) of the leaves: it was maximal after 3 days of exposure (two-fold). Fumigation of wheat with 0.25-mu-l l-1 H2S during low temperature exposure resulted in a further increase (up to six-fold) in the sulfhydryl content.