Extreme Temperature Stress Research Articles

Melatonin alleviates cadmium toxicity and abiotic stress by promoting glandular trichome development and antioxidant capacity in Nicotiana tabacum

Melatonin is a well-known signaling molecule that mediates a range of physiological activities and various stress reactions in plants. We comprehensively tested the effect of melatonin on the development of root hairs and glandular trichomes and found that melatonin pretreatment of tobacco seeds significantly increased the length of root hairs. Furthermore, melatonin-treated tobacco exhibited significantly higher density of trichomes and larger glandular heads on long-stalk glandular trichomes than untreated plants, which resulted in enhanced secretion in glandular trichomes. Exogenous melatonin enhanced the aphid resistance of plants by facilitating the accumulation of cembranoids in the glandular trichomes and alleviated cadmium toxicity by increasing the Cd-exudation capacity of long glandular trichomes. Metabolic analysis indicated that the contents of 108 metabolites significantly changed upon melatonin treatment, with the contents of those that are directly/indirectly involved in melatonin metabolism changing the most. Further, KEGG pathway analysis suggested that the metabolic pathways of amino acids, reducing sugar, secondary metabolites, indole alkaloid biosynthesis, purine, pyrimidine, and ABC transporters were greatly influenced by exogenous melatonin application. Moreover, metabolisms of melatonin-related antioxidants and pyrimidine nucleoside antibiotics were enhanced after melatonin treatment. Melatonin improved tobacco resistance to high salinity, drought, and extreme temperature stresses, as indicated by improved photosynthetic and antioxidant capacities in treated vs. untreated plants. This study lays a foundation for the comprehensive application of melatonin to increase the stress tolerance of plants.

Hydrogen sulphide-mediated alleviation and its interplay with other signalling molecules during temperature stress.

The sessile habit of plants does not provide choices to escape the environmental constraints, leading to negative impacts on their growth and development. This causes significant losses in the agriculture sector and raises serious issues on global food security. Extreme temperatures (high or low) influence several aspects of plant life and can cause reproduction malfunction. Therefore, a strategy for temperature amelioration is necessary for the management of agricultural productivity. Supplementation with various chemicals (e.g. phytohormones, gasotransmitters, osmolytes) is considered a good choice to manage plant stress. Gasotransmitters are well-recognized for stress mitigation in plants, among which hydrogen sulphide (H2 S) has proved promising to alleviate stress. Temperature (heat/cold) stress can stimulate the endogenous production of H2 S in plants, and many studies have reported the significance of H2 S for temperature stress amelioration. Here, H2 S led to positive changes in plant physiological, biochemical and molecular responses, which are usually compromised during stress. Further, H2 S also coordinate with other signalling components that act either upstream or downstream during stress mitigation. This review focuses on the significance of H2 S for mitigation of temperature stress, with a comprehensive discussion on cross-talk with other signalling components or supplements (e.g. NO, H2 O2 , salicylic acid, trehalose, proline). Finally, the review provides a rational assessment and holistic understanding of H2 S-mediated mitigation of extreme temperature stress and addresses the prospects for development of an effective strategy to manage temperature stress.

Stress Dependent Biofilm Formation and Bioactive Melanin Pigment Production by a Thermophilic Bacillus Species from Chilean Hot Spring.

Thermophilic bacteria able to survive extreme temperature stress are of great biotechnological interest due to their extracellular production of bioactive molecules as a part of a survival strategy, or by intracellular modifications. In the present study, thermophilic Bacillus haynesii CamB6, isolated from a Chilean hot spring, was studied for the formation of different stress response molecules. The polymeric pigment produced by the bacterial strain was characterized by different physicochemical techniques. On exposure to ranges of temperature (50–60 °C), pH (5.0–7.0), and sources of nitrogen and carbon (1–5 g·L−1), the bacteria responded with a biofilm network formation in a hydrophobic polystyrene surface. Biofilm formation under fed-batch conditions was also statistically validated. The bacteria showed a planktonic pellicle network formation in the presence of induced hypoxia and salinity stress (19.45 g·L−1) under static conditions. Salinity stress also resulted in the intracellular response of brown pigment production. The pigment was structurally and functionally characterized by UV-Vis absorbance and the presence of different characteristic peaks via FTIR analysis (bacterial pyomelanin fingerprints) were assessed. A high thermal stability and TGA profile indicated the brown pigment was a probable pyomelanin candidate. Micropyrolysis (Py-GC/MS) showed that isoprene, pyrrole, benzene, pyridine, and their derivatives were the major components detected. In addition, acetic acid, indole, phenol, and its derivatives were observed. The absence of sulfocompounds in the pyrolyzed products agreed with those reported in the literature for pyomelanin. The pigment surface morphology was analyzed via SEM, and the elemental composition via EDS also demonstrated the similarity of the brown pigment to that of the melanin family. The pyomelanin pigment was observed to be bioactive with promising antioxidant capacity (H2O2, Fe2+) compared to the standard antioxidant molecules. In conclusion, B. haynesii CamB6 demonstrated the formation of several biomolecules as a stress response mechanism that is bioactive, showing its probable biotechnological applications in future.

Simulation of Wheat Response to Future Climate Change Based on Coupled Model Inter-Comparison Project Phase 6 Multi-Model Ensemble Projections in the North China Plain.

Global climate change results in more extreme temperature events, which poses a serious threat to wheat production in the North China Plain (NCP). Assessing the potential impact of temperature extremes on crop growth and yield is an important prerequisite for exploring crop adaptation measures to deal with changing climate. In this study, we evaluated the effects of heat and frost stress during wheat sensitive period on grain yield at four representative sites over the NCP using Agricultural Production System Simulator (APSIM)-wheat model driven by the climate projections from 20 Global Climate Models (GCMs) in the Coupled Model Inter-comparison Project phase 6 (CMIP6) during two future periods of 2031–2060 (2040S) and 2071–2100 (2080S) under societal development pathway (SSP) 245 and SSP585 scenarios. We found that extreme temperature stress had significantly negative impacts on wheat yield. However, increased rainfall and the elevated atmospheric CO2 concentration could partly compensate for the yield loss caused by extreme temperature events. Under future climate scenarios, the risk of exposure to heat stress around flowering had no great change but frost risk in spring increased slightly mainly due to warming climate accelerating wheat development and advancing the flowering time to a cooler period of growing season. Wheat yield loss caused by heat and frost stress increased by −0.6 to 4.2 and 1.9–12.8% under SSP585_2080S, respectively. We also found that late sowing and selecting cultivars with a long vegetative growth phase (VGP) could significantly compensate for the negative impact of extreme temperature on wheat yields in the south of NCP. However, selecting heat resistant cultivars in the north NCP and both heat and frost resistant cultivars in the central NCP may be a more effective way to alleviate the negative effect of extreme temperature on wheat yields. Our findings showed that not only heat risk should be concerned under climate warming, but also frost risk should not be ignored.

Response and tolerance mechanism of food crops under high temperature stress: a review.

High temperature stress events are critical factors inhibiting crop yield. Meanwhile, world population is growing very rapidly and will be reached up to 9 billion by 2050. To feed increasing world population, it is challenging task to increase about 70% global food productions. Food crops have significant contribution toward global food demand and food security. However, consequences from increasing heat stress events are demolishing their abilities to survive and sustain yield when subjected to extreme high temperature stress. Therefore, there is dire need to better understand response and tolerance mechanism of food crops following exposure to heat stress. Here, we aimed to provide recent update on impact of high temperature stress on crop yield of food crops, pollination, pollinators, and novel strategies for improving tolerance of food crop under high temperature stress. Importantly, development of heat-resistant transgenic food crops can grant food security through transformation of superior genes into current germplasm, which are associated with various signaling pathways as well as epigenetic regulation in response to extreme high temperature stress.

Impact of Extreme Temperature and Soil Water Stress on the Growth and Yield of Soybean (Glycine max (L.) Merrill)

Climate change is a major environmental stressor that would adversely affect tropical agriculture, which is largely rain-fed. Associated with climate change is an increasing trend in temperature and decline in rainfall, leading to prolonged and repeated droughts. The purpose of this study was to determine the effect of climate variables such as temperature, relative humidity, vapor pressure deficit (VPD), and soil water on the phenology, biomass, and grain yield of soybean crops. A greenhouse experiment was set in a split plot design with three average environmental conditions as the main plots: E1 (36 °C, RH = 55%), E2 (34 °C, RH = 57%) and E3 (33 °C, RH = 44%). Additionally, there were three water treatments: W1 (near saturation), W2 (Field capacity), and W3 (soil water deficit) and two soybean varieties (Afayak and Jenguma). These treatments were replicated nine times. The results showed that high temperatures (E1) accelerated the crop development, particularly at flowering. Additionally, increased atmospheric demand for water under a high temperature environment resulted in high evapotranspiration, leading to high transpiration which probably reduced photosynthetic activity of the plants and thereby contributing to biomass and grain yield loss. Biomass and yield were drastically reduced for the combined effect of high temperature (E1) and drought (W3) as compared to combined effect of ambient temperature (E3) and well-watered condition (W1). Increasing temperatures and erratic rainfall distributions associated with climate change poses a potential threat to the soybean production in Ghana.

Responses of aquaculture fish to climate change‐induced extreme temperatures: A review

AbstractClimate change‐induced extreme temperature events are becoming more intense and frequent. For fish, temperature is the master abiotic factor that controls and limits fish development and physiology at all stages of aquaculture. Major physiological constraints at the individual level underpin changes in fish growth, hemato‐physiology, metabolism, immune and molecular stress responses to extreme temperature events. Extreme temperature impacts on fish vary among and within the diverse species depending on stress magnitude and associated factors. This review synthesizes the impacts of climate change‐induced extreme temperature events on neuroendocrine, oxidative, metabolic, osmotic, molecular, hemato‐biochemical, and immune responses in fish related to aquaculture. Besides, overall aspects of extreme temperature impacts on fish growth and reproduction are also discussed. Possible mitigation measures to maintain the fish's physiological fitness during extreme temperature events are also addressed. However, studies on the interactive effects of extreme temperature events with other associated environmental stressors are needed across a broader range of species to gain a better understanding of fish response and aquaculture performance during extreme temperature events. Moreover, for fish, studies on alternative species, development of stress‐tolerant strains, and the possibilities of nutritional mitigation measures as a potential option to combat extreme temperature stress are promising and should be pursued in future studies.

Flower development and fruit malformation in strawberries after short-term exposure to high or low temperature

Strawberry plants are at risk of exposure to short-term high daytime temperature (HTD) during flowering and exposure to short-term low temperature at night (LTN) during the coldest months of winter. The aim of this study was to identify the effects of short-term HTD or LTN on the different floral developments and fruit development, such as fruit malformation, flowering traits, stigma maturation, and pollen quality in ‘Seolhyang’ and ‘Maehyang’ strawberries. For the treatment of HTD, plants were treated at 35 °C, and for LTN treatment, plants were treated at 2 °C for consecutive days each. Days to flowering were shortened under HTD in both cultivars, while days to anther dehiscence were shortened under HTD. Stigma maturation was delayed by short-term extreme temperature stress in ‘Maehyang’. Short-term LTN before the flower petals appeared in the first and second flower clusters might cause high malformation rates in both cultivars. Pollen viability and the germination rate were decreased by HTD and LTN in both cultivars. There was a high correlation between the lower pollen germination rate and the higher percentage of malformed fruits under short-term LTN. These results suggest that even short-term exposure to low temperature in winter during cultivation should be controlled carefully considering developmental stages and cultivar-specific responses and that attention should be paid to the protection of strawberries.

Plant Hormones and Volatiles Response to Temperature Stress in Sweet Corn (Zea mays L.) Seedlings.

This work aims to emphasize on disclosing the regulative mechanism of sweet corn seedlings response to extreme temperature stress; transcriptomics and metabolomics for volatiles and plant hormones were integrated in this study. Results showed that low-temperature stress significantly impressed 20 volatiles; abscisic acid and salicylic acid accumulated, while auxin and jasmonic acid decreased. The regulatory patterns of vp14 and ABF for abscisic acid accumulation and signal transduction were elucidated in low-temperature stress. High-temperature stress influenced 31 volatiles and caused the reductions on zeatin, salicylic acid, jasmonic acid, and auxin. The up-regulation of an ARR-B gene emphasized its function on zeatin signal transduction under high-temperature stress. Correlations among gene modules, phytohormones, and volatiles were analyzed for building the regulative network of sweet corn seedlings under temperature stress. The attained result might build foundations for improving early development of sweet corn by biological intervention or genomic-level modulation.

Characteristic and expression of Hsp70 and Hsp90 genes from Tyrophagus putrescentiae and their response to thermal stress

The development of insects is critically affected by temperature, which therefore plays an important role in the control of stored grain pests. Extreme temperature stress conditions lead to biological responses in mites, such as the synthesis of heat shock proteins. Tyrophagus putrescentiae (Tp) is a pest mite in stored grain that has negative effects on both economy and health. Since T. putrescentiae population dynamics are strongly influenced by temperature, in the present study we have cloned the cDNA of HSP70 and HSP90 (referred to as TpHSP70-1, TpHSP70-2 and TpHSP90) and determined their expression by fluorescence real time quantitative PCR. TpHSP70 and TpHSP90 showed high homology with similar genes in other species and the open reading frames of TpHSP70-1, TpHSP70-2 and TpHSP90 encoded proteins of 665, 661 and 718 amino acid residues, respectively. Under thermal stress, expression of TpHsp70-1 and TpHsp90 was up-regulated at higher temperatures, suggesting their role in the defense against thermal stress.

Modeling the response of winter wheat phenology to low temperature stress at elongation and booting stages

Accurately predicting crop development stage is key to simulating growth and yield formation in crop models. Low temperature stress is a major limitation to global wheat production and can significantly slow down wheat development rate. In a four-year environment-controlled phytotron experiments, detailed phenology datasets were obtained for low temperature stress treatments with different temperature levels and durations. Six widely-used temperature response functions (Linear, Bilinear Triangular, Trapezoidal, Bell-shaped, and Sin) for wheat phenology estimation were combined with WheatGrow model to simulate the low temperature stress effects on elongation-anthesis durations in order to test whether the effects of low temperature stress can be captured by current temperature response functions. In addition, a new algorithm for quantifying daily thermal sensitivity (DTS) was proposed and applied in the six temperature response functions to improve the prediction ability of phenology submodel under low temperature stress. The result indicates that anthesis stage was significantly delayed under low temperature stress at elongation and booting stages. All six original temperature response routines underestimated the delay of wheat development rate caused by low temperature stress, and the Linear and Triangular temperature response routines showed better performance than other four functions. A new improved DTS algorithm (DTSimproved) was proposed which can better quantify the delay of wheat development rate during low temperature stress and the recovery of development rate after low temperature stress. Model validation results show that compared with the DTSoriginal routine, all six improved phenology submodels (DTSimproved) significantly reduced the simulation error under low temperature stress, with the RMSE of elongation-anthesis duration under extreme low temperature stress (Tmin<0) decreased by 53.6% and 36.7% for cv.Yangmai16 and cv.Xumai30, respectively. Therefore, the newly improved routine for wheat phenology under low temperature stress can significantly reduce the uncertainties in model-based impact assessments under low temperature stress.

Sustainable wildlife protection on the Qingzang Plateau

Besides its ecological services to China and even Asia, the Qingzang Plateau (QP) hosts a rich variety of wildlife species. During the last century, wildlife population decreased quickly on the QP, driven by human interventions. Recently, wildlife has witnessed rapid recovery mainly propelled by a series of wildlife conservation policies. However, some cautions merit attentions to sustain wildlife restoration and conservation on the QP. This paper casted an overview of environmental and social-economic changes on the QP affecting wildlife subsistence. Results show that QP has been warming, which can benefit wildlife recovery by easing extreme low temperature stresses. The fast growing social economy across the QP lays a solid economic foundation for investing on wildlife protection. Measures such as establishing conservation areas, constructing wildlife pathway corridors, and encouraging herdsman moving out from wildlife rich regions, have boosted wildlife recovery. However, wildlife recovery is constrained by the limited carrying capacity of the ecosystem, left by domestic livestock. Additionally, fences intended to delineate conservation areas or to separate each type of grassland use, have brought about profound side effects on wildlife through fragmentation of their habitats. It is recommended to set up the fence in a more ecological way, which can be achieved by bypassing the wildlife frequent pathway and using materials devoid of steel barb. Only considering both opportunities and problems simultaneously, can the wildlife protection on the QP be sustained.

Challenge in Crop Production to Combat Complicated High Temperature Stresses

Global warming triggers complicated heat stresses to crop production on the Earth. Previously, most breeding programs focus on producing crop tolerate with short-term extreme high temperature stress. Hence, few recent studies have suggested that the plants adapting to extreme heat stress may be not always suitable for long-term mild high temperature stress. Therefor we propose challenges in crop production/ breeding which need to be conquered in the future.

Effect of salicylic acid on growth and yield under abiotic stress: An overview

Biotic and abiotic stresses are the major constraint to limit the production of crops in agriculture. Biotic stress includes attack of insect, pest, bacteria, virus and fungus while extreme and low temperature, drought, flood, salinity and heavy metal stress are the major cause of abiotic stress. The reduction in the performance of plant growth was started from the negative effect of chlorophyll synthesis or degradation under wide range of environmental stress. The generation of harmful free radicles or reactive oxygen species (ROS) like O2, H2O2 and OH. Salicylic acid (SA) improves plant growth and development by improving rate of photosynthesis by protecting the damage of chloroplast, protein and DNA against the wide range of environmental stress including both biotic and abiotic stress. Application of SA also accelerate the production of osmolyte like proline and antioxidant enzymes like CAT, POD, SOD that help to scavenge free radicles safely from the cell.

Cross-Stress Adaptation in a Piezophilic and Hyperthermophilic Archaeon From Deep Sea Hydrothermal Vent.

Hyperthermophiles, living in environments above 80°C and usually coupling with multi-extreme environmental stresses, have drawn great attention due to their application potential in biotechnology and being the primitive extant forms of life. Studies on their survival and adaptation mechanisms have extended our understanding on how lives thrive under extreme conditions. During these studies, the “cross-stress” behavior in various organisms has been observed between the extreme high temperature and other environmental stresses. Despite the broad observation, the global view of the cross-stress behavior remains unclear in hyperthermophiles, leaving a knowledge gap in our understanding of extreme adaptation. In this study, we performed a global quantitative proteomic analysis under extreme temperatures, pH, hydrostatic pressure (HP), and salinity on an archaeal strain, Thermococcus eurythermalis A501, which has outstanding growth capability on a wide range of temperatures (50–100°C), pH (4–9), and HPs (0.1–70 MPa), but a narrow range of NaCl (1.0–5.0 %, w/v). The proteomic analysis (79.8% genome coverage) demonstrated that approximately 61.5% of the significant differentially expressed proteins (DEPs) responded to multiple stresses. The responses to most of the tested stresses were closely correlated, except the responses to high salinity and low temperature. The top three enriched universal responding processes include the biosynthesis and protection of macromolecules, biosynthesis and metabolism of amino acids, ion transport, and binding activities. In addition, this study also revealed that the specific dual-stress responding processes, such as the membrane lipids for both cold and HP stresses and the signal transduction for both hyperosmotic and heat stresses, as well as the sodium-dependent energetic processes might be the limiting factor of the growth range in salinity. The present study is the first to examine the global cross-stress responses in a piezophilic hyperthermophile at the proteomic level. Our findings provide direct evidences of the cross-stress adaptation strategy (33.5% of coding-genes) to multiple stresses and highlight the specific and unique responding processes (0.22–0.63% of coding genes for each) to extreme temperature, pH, salinity, and pressure, which are highly relevant to the fields of evolutionary biology as well as next generation industrial biotechnology (NGIB).

Highly variable taxa-specific coral bleaching responses to thermal stresses

Complex histories of chronic and acute sea surface temperature (SST) stresses are expected to trigger taxon- and location-specific responses that will ultimately lead to novel coral communities. The 2016 El Niño-Southern Oscillation provided an opportunity to examine large-scale and recent environmental histories on emerging patterns in 226 coral communities distributed across 12 countries from East Africa to Fiji. Six main coral communities were identified that largely varied across a gradient of Acropora to massive Porites dominance. Bleaching intensity was taxon-specific and was associated with complex interactions among the 20 environmental variables that we examined. Coral community structure was better aligned with the historical temperature patterns between 1985 and 2015 than the 2016 extreme temperature event. Additionally, bleaching responses observed during 2016 differed from historical reports during past warm years. Consequently, coral communities present in 2016 are likely to have been reorganized by both long-term community change and acclimation mechanisms. For example, less disturbed sites with cooler baseline temperatures, higher mean historical SST background variability, and infrequent extreme warm temperature stresses were associated with Acropora-dominated communities, while more disturbed sites with lower historical SST background variability and frequent acute warm stress were dominated by stress-resistant massive Porites corals. Overall, the combination of taxon-specific responses, community-level reorganization over time, geographic variation, and multiple environmental stressors suggest complex responses and a diversity of future coral communities that can help contextualize management priorities and activities.

Melatonin: A master regulator of plant development and stress responses.

Melatonin is a pleiotropic molecule with multiple functions in plants. Since the discovery of melatonin in plants, numerous studies have provided insight into the biosynthesis, catabolism, and physiological and biochemical functions of this important molecule. Here, we describe the biosynthesis of melatonin from tryptophan, as well as its various degradation pathways in plants. The identification of a putative melatonin receptor in plants has led to the hypothesis that melatonin is a hormone involved in regulating plant growth, aerial organ development, root morphology, and the floral transition. The universal antioxidant activity of melatonin and its role in preserving chlorophyll might explain its anti-senescence capacity in aging leaves. An impressive amount of research has focused on the role of melatonin in modulating postharvest fruit ripening by regulating the expression of ethylene-related genes. Recent evidence also indicated that melatonin functions in the plant's response to biotic stress, cooperating with other phytohormones and well-known molecules such as reactive oxygen species and nitric oxide. Finally, great progress has been made towards understanding how melatonin alleviates the effects of various abiotic stresses, including salt, drought, extreme temperature, and heavy metal stress. Given its diverse roles, we propose that melatonin is a master regulator in plants.

Expression of HSP70 family mRNAs in albino northern snakehead, Channa argus: Response to extreme temperature stress and bacterial infection

The wild albino northern snakehead, Channa argus, has only been found in Jialing Rivers System of China so far. It is easy to be affected by the environmental factors such as temperature changes and bacterial infection, thus causing a huge economic loss. Therefore, this study cloned a 2,213 bp cDNA that encodes a protein of heat shock protein 70 (CaHSP70), which has an open reading frame (ORF) that encodes 639 amino acids and the corresponding polypeptides of 70.50 kDa. And the oretical isoelectric point (pI) of CaHSP70 is 5.79. Additionally, we also cloned a cDNA for heat shock cognate protein 70 (CaHSC70) with a total length of 2,300 bp. And the ORF of CaHSC70 encodes 648 amino acids and 71.18 kDa peptides. The pI of CaHSC70 is 5.22. Moreover, the cDNA length of stress-70 protein mitochondrial (CaHSPA9) is 2,944 bp with an ORF that encodes 679 amino acids, polypeptides of 73.74 kDa, and a pI of 6.68. The quantitative real-time PCR (qRT-PCR) analysis showed that the mRNA expression levels of CaHSP70, CaHSC70, and CaHSPA9 genes were tissue-specific in the control groups. After the heat shock at 37 °C, the mRNA expression levels of CaHSP70 were extremely significantly upregulated in the kidney, liver, spleen, and brain tissues, while fewer mRNA expression levels of CaHSC70 and CaHSPA9 showed a relatively induction in these tissues. In contrast, after the cold shock at 8.5 °C, fewer mRNA expression levels of CaHSP70, CaHSC70, and CaHSPA9 showed the changes of expression in all the tissues, compared to heat shock. In addition, CaHSP70, CaHSC70, and CaHSPA9 mRNA expression levels showed an overall trend of first upregulating and then falling after Edwardsiella tarda (strain No. DL1,476) challenge. In conclusion, this study demonstrated that temperature had a great effect on the mRNA expression levels of CaHSP70, CaHSC70, and CaHSPA9, and the mRNA expression levels of these three genes were also sensitive to pathogen infection, especially CaHSP70 in the albino C. argus.

Protein Glycation in Plants-An Under-Researched Field with Much Still to Discover.

Recent research has identified glycation as a non-enzymatic post-translational modification of proteins in plants with a potential contributory role to the functional impairment of the plant proteome. Reducing sugars with a free aldehyde or ketone group such as glucose, fructose and galactose react with the N-terminal and lysine side chain amino groups of proteins. A common early-stage glycation adduct formed from glucose is Nε-fructosyl-lysine (FL). Saccharide-derived reactive dicarbonyls are arginine residue-directed glycating agents, forming advanced glycation endproducts (AGEs). A dominant dicarbonyl is methylglyoxal—formed mainly by the trace-level degradation of triosephosphates, including through the Calvin cycle of photosynthesis. Methylglyoxal forms the major quantitative AGE, hydroimidazolone MG-H1. Glucose and methylglyoxal concentrations in plants change with the developmental stage, senescence, light and dark cycles and also likely biotic and abiotic stresses. Proteomics analysis indicates that there is an enrichment of the amino acid residue targets of glycation, arginine and lysine residues, in predicted functional sites of the plant proteome, suggesting the susceptibility of proteins to functional inactivation by glycation. In this review, we give a brief introduction to glycation, glycating agents and glycation adducts in plants. We consider dicarbonyl stress, the functional vulnerability of the plant proteome to arginine-directed glycation and the likely role of methylglyoxal-mediated glycation in the activation of the unfolded protein response in plants. The latter is linked to the recent suggestion of protein glycation in sugar signaling in plant metabolism. The overexpression of glyoxalase 1, which suppresses glycation by methylglyoxal and glyoxal, produced plants resistant to high salinity, drought, extreme temperature and other stresses. Further research to decrease protein glycation in plants may lead to improved plant growth and assist the breeding of plant varieties resistant to environmental stress and senescence—including plants of commercial ornamental and crop cultivation value.

Comparison of wheat simulation models for impacts of extreme temperature stress on grain quality

Shifting temperature patterns on global and regional scales accredited to climate change will bring more low-temperature stress (LTS) and high-temperature stress (HTS) events to further deteriorate wheat yield and quality. Crop models can serve as a beneficial platform for quantifying the impact of both high and low-temperature events on grain yield (GY) and grain quality. Wheat grain protein concentration (GPC) and grain protein yield (GPY), as two important measurements of wheat quality for nutrition value, is often ignored in crop modeling efforts to improve grain yield under climate change. This study was undertaken for comprehensive comparison of four broadly used wheat simulation models (DSSAT-CERES-Wheat, DSSAT-Nwheat, WheatGrow, and APSIM-Wheat) in quantifying and simulating the responses of wheat grain quality (GPC and GPY) under LTS and HTS at critical growth stages, and to identify gaps in simulating wheat grain protein concentration and protein yield for crop model improvement. Four-year environment-controlled phytotron experiments were conducted with two wheat varieties under LTS (at joining and booting stages) and HTS (at anthesis, grain filling, and combined stress at anthesis and grain filling stages). For per unit increase in cold degree days (CDD, degree days below 2 °C) at jointing and booting stages and heat degree days (HDD, degree days over 30 °C) at anthesis, grain filling and combined stress at anthesis and grain filling stages, GPC was increased by 0.2% to 0.4% and 1.1% to 1.6%, while GPY was decreased by 2.1% to 4.5% and 0.3% to 1.7%, respectively. Most of the crop models tended to reproduce some HTS impacts better during grain filling than at anthesis, but all the tested models call for improvements in simulating LTS at different stages, especially for GPY. Our results indicated the need of incorporating response functions of extreme temperature stresses into grain quality models to adapt to future climate scenarios.