Effects Of High Temperature Stress Research Articles

Pollen, ovules, and pollination in pea: Success, failure, and resilience in heat.

Field pea (Pisum sativum), a major grain legume crop, is autogamous and adapted to temperate climates. The objectives of this study were to investigate effects of high temperature stress on stamen chemical composition, anther dehiscence, pollen viability, pollen interactions with pistil and ovules, and ovule growth and viability. Two cultivars ("CDC Golden" and "CDC Sage") were exposed to 24/18°C (day/night) continually or to 35/18°C for 4 or 7days. Heat stress altered stamen chemical composition, with lipid composition of "CDC Sage" being more stable compared with "CDC Golden." Heat stress reduced pollen viability and the proportion of ovules that received a pollen tube. After 4days at 35°C, pollen viability in flower buds decreased in "CDC Golden," but not in "CDC Sage." After 7days, partial to full failure of anthers to dehisce resulted in subnormal pollen loads on stigmas. Although growth (ovule size) of fertilized ovules was stimulated by 35°C, heat stress tended to decrease ovule viability. Pollen appears susceptible to stress, but not many grains are needed for successful fertilization. Ovule fertilization and embryos are less susceptible to heat, but further research is warranted to link the exact degree of resilience to stress intensity.

Identifying changes in the wheat kernel proteome under heat stress using iTRAQ

Wheat (Triticum aestivum L.) is one of the three major global food crops. High-temperature stress can affect its yield and quality. Studies of the effect of high-temperature stress on wheat kernel development are important because they can reveal the stability of wheat quality and lead to the genetic improvement of wheat quality traits. In this study, the isobaric tags for relative and absolute quantitation (iTRAQ) method was adopted to analyze changes in the protein expression profile of wheat cultivars under high temperature stress. The protein content of wheat grain increased under heat stress, while the SDS-sedimentation value and starch content decreased. Grain filling was deficient under high temperature stress, which reduced thousand-kernel weight but did not affect wheat kernel length. The 207 differentially expressed proteins identified in Gaocheng 8901 under heat stress were associated with energy metabolism, growth and development, and stress response. Gene Ontology enrichment analysis showed that the annotated proteins that were differentially expressed in Gaocheng 8901 under heat stress were involved mainly in stimulus response, abiotic stress response, stress response, and plasma membrane. A set of 78 differentially expressed proteins were assigned to 83 KEGG signaling/metabolic pathways. KEGG pathway enrichment analysis showed that this set of proteins was significantly enriched in members of 51 pathways, and the proteins participated mainly in protein synthesis in the endoplasmic reticulum, starch and sucrose metabolism, and reaction on ribosomes. Five differentially expressed proteins were involved in protein–protein interaction networks that may greatly influence the yield and quality of wheat grain. In wheat, high-temperature stress leads to a variety of effects on protein expression and may ultimately cause changes in yield and quality.

Effects of high temperature stress and traits associated with tolerance in wheat

Effects of high temperature stress and traits associated with tolerance in wheat

Effect of high temperature stress on heat shock protein expression and antioxidant enzyme activity of two morphs of the mud crab Scylla paramamosain

The present study aimed to investigate the effect rapid temperature change from moderate temperature to high temperatures on heat shock protein (HSP) expression and antioxidant enzyme activities in mud crabs. Two mud crabs, one with one spine on the outer margin of the carpus of cheliped (Sp1) and another with two spines (Sp2), were acclimated at 25 °C and then transferred to a 33 °C environment, and HSP expression and antioxidant enzyme activity were assessed. HSP70 and HSP60 were markedly up-regulated in the gills and hepatopancreas of Sp1 and Sp2 after exposure to 35 °C. Exposure to 35 °C also significantly increased superoxide dismutase and catalase activity in the gills of Sp1 and Sp2, with transient changes in hepatopancreas. Apart from changes in antioxidant enzyme activities, HSPs were highly up-regulated after exposure to 37 °C, especially for HSP70. Gill HSP70 expression in Sp2 was 6.1 folds that of the control after 24 h of exposure to 37 °C, and 9.2 folds that of Sp1. Moreover, exposure to 37 °C further up-regulated HSP70 in the hepatopancreas of Sp1, compared to that in Sp2. Hence, HSPs play important roles in thermotolerance in S. paramamosain and Sp1 might have a stronger tolerance to hyperthermal stress than Sp2.

Decreased photosynthetic rate under high temperature in wheat is due to lipid desaturation, oxidation, acylation, and damage of organelles

BackgroundHigh temperature is a major abiotic stress that limits wheat (Triticum aestivum L.) productivity. Variation in levels of a wide range of lipids, including stress-related molecular species, oxidative damage, cellular organization and ultrastructural changes were analyzed to provide an integrated view of the factors that underlie decreased photosynthetic rate under high temperature stress. Wheat plants of cultivar Chinese Spring were grown at optimum temperatures (25/15 °C, maximum/minimum) until the onset of the booting stage. Thereafter, plants were exposed to high temperature (35/25 °C) for 16 d.ResultsCompared with optimum temperature, a lower photosynthetic rate was observed at high temperature which is an interplay between thylakoid membrane damage, thylakoid membrane lipid composition, oxidative damage of cell organelle, and stomatal and non-stomatal limitations. Triacylglycerol levels were higher under high temperature stress. Polar lipid fatty acyl unsaturation was lower at high temperature, while triacylglycerol unsaturation was the same at high temperature and optimum temperature. The changes in lipid species indicates increases in activities of desaturating, oxidizing, glycosylating and acylating enzymes under high temperature stress. Cumulative effect of high temperature stress led to generation of reactive oxygen species, cell organelle and membrane damage, and reduced antioxidant enzyme activity, and imbalance between reactive oxygen species and antioxidant defense system.ConclusionsTaken together with recent findings demonstrating that reactive oxygen species are formed from and are removed by thylakoid lipids, the data suggest that reactive oxygen species production, reactive oxygen species removal, and changes in lipid metabolism contribute to decreased photosynthetic rate under high temperature stress.

Improved photosynthetic efficacy of maize (Zea mays) plants with arbuscular mycorrhizal fungi (AMF) under high temperature stress

In this study, pot experiments were performed to investigate the effects of high temperature stress (44 °C) in maize plants colonized with and without arbuscular mycorrhizal fungi (AMF). Various parameters characterizing photosynthetic activity were measured in order to estimate the photosynthetic efficiency in maize plants. It was observed that density of active reaction centers of PSII, quantum efficiency of photosystem II (PSII), linear electron transport, excitation energy trapping, performance index, net photosynthesis rate increased in AMF (+) plants at 44 °C ± 0.2 °C. Efficiency of primary photochemical reaction (represented as Fv/Fo) increased in AMF (+) plants as compared to AMF (−) plants. AMF seems to have protected water splitting complex followed by enhanced primary photochemistry of PSII under high temperature. Basic morphological parameters like leaf width, plant height and cob number increased in AMF (+) plants as compared to AMF (−) plants. AMF (+) plants grew faster than AMF (−) plants due to larger root systems. Chl content increased in AMF (+) plants as compared to AMF (−) maize plants. AMF hyphae likely increased Mg uptake which in turn increased the total chlorophyll content in AMF (+) maize plants. This subsequently led to a higher production in photosynthate and biomass. Thus AMF (+) plants have shown better photosynthesis performance as compared to AMF (−) maize plants under high temperature stress.

Hydrogen-rich water pretreatment alters photosynthetic gas exchange, chlorophyll fluorescence, and antioxidant activities in heat-stressed cucumber leaves

Hydrogen gas (H2) has recently been recognized as an important plant bio-regulator, inducing tolerance to several abiotic stresses. However, any role for H2 in amelioration of high-temperature-induced stress remains largely unknown. We investigated the mechanism of hydrogen-rich water (HRW)-mediated enhancement of heat-tolerance in cucumber seedlings exposed to high-temperature stress. The 3 weeks seedlings were pretreated with 50 or 100% HRW for 7 days, the effects on photosynthesis, chlorophyll content, chlorophyll fluorescence parameters, electrolyte leakage, lipid peroxidation, and antioxidant activity were examined when cucumber seedlings subjected for 3 days to heat stress treatment. With respect to samples treat with high temperature stress alone, HRW pretreatment remarkably alleviated stress-induced effects on the above parameters. Furthermore, after 3 days of treatment, HRW pretreatment also significantly increased the activities of antioxidative enzymes, promoted high-level accumulation of osmoprotectants, and upregulated HSP70 expression in cucumber leaves. All of these data suggest that pretreatment with exogenous HRW partially alleviated the detrimental effects of high-temperature stress on the growth of cucumber seedlings by improving the photosynthetic capacity, increasing the antioxidant response, and promoting the accumulation of HSP70 and osmolytes. Therefore, HRW pretreatment may improve cucumber seedlings heat-tolerance.

Comparative transcriptional profiling of Gracilariopsis lemaneiformis in response to salicylic acid- and methyl jasmonate-mediated heat resistance.

Culturing the economically important macroalga Gracilariopsis lemaneiformis (Rhodophyta) is limited due to the high temperatures in the summertime on the southern Chinese coast. Previous studies have demonstrated that two phytohormones, salicylic acid (SA) and methyl jasmonate (MJ), can alleviate the adverse effects of high-temperature stress on Gp. lemaneiformis. To elucidate the molecular mechanisms underlying SA- and MJ-mediated heat tolerance, we performed comprehensive analyses of transcriptome-wide gene expression profiles using RNA sequencing (RNA-seq) technology. A total of 14,644 unigenes were assembled, and 10,501 unigenes (71.71%) were annotated to the reference databases. In the SA, MJ and SA/MJ treatment groups, 519, 830, and 974 differentially expressed unigenes were detected, respectively. Unigenes related to photosynthesis and glycometabolism were enriched by SA, while unigenes associated with glycometabolism, protein synthesis, heat shock and signal transduction were increased by MJ. A crosstalk analysis revealed that 216 genes were synergistically regulated, while 18 genes were antagonistically regulated by SA and MJ. The results indicated that the two phytohormones could mitigate the adverse effects of heat on multiple pathways, and they predominantly acted synergistically to resist heat stress. These results will provide new insights into how SA and MJ modulate the molecular mechanisms that counteract heat stress in algae.

Foliar or Subirrigation Silicon Supply Mitigates High Temperature Stress in Strawberry by Maintaining Photosynthetic and Stress-Responsive Proteins

Silicon (Si) is the second most abundant element in the soil and is known to help in crop productivity. Si improves photosynthesis as well as remediates nutrient imbalances and abiotic stresses in plants. The impact and the importance of different sources, concentration, and supply of Si in improving the propagation of horticultural crops are limited. Thus, the present study focused on the supply, concentration, and source of Si on two important Korean strawberry cultivars ‘Sulhyang’ and ‘Maehyang’ under temperature stress. The high temperature (41 °C) resulted in oxidative stress in the form of H2O2 and O2 1− localizations in the -Si- and Si-treated plants as compared to 25 or 33 °C in both cultivars. However, Si, especially that from K2SiO3 source, had the ability to relieve the stress level. The immunoblots of two important photosynthetic proteins PsaA and PsbA showed decreased expression levels in the -Si plants under 41 °C temperature stress, whereas the expression levels were retained in the Si-supplied plants, particularly with K2SiO3 as the Si source. In both 25 and 33 °C, no changes in expressions of PsaA and PsbA were observed. Interestingly, the expression of three important stress-responsive proteins, superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT), were abundantly increased in the Si-treated plants under high-temperature stress (41 °C) and decreased in the –Si-treated plants except in those grown in 25 or 33 °C. The observed responses to silicon supply in high temperature stressed-plants indicate that Si, particularly in the form of K2SiO3, has a significant role in limiting the negative effects of high temperature stress by maintaining the photosynthetic proteins and stress-responsive proteins of the ascorbate glutathione defense mechanism. Moreover, these results also depict that Si application is a good way to maintain the health of plants at the propagation stage even under high temperatures of greenhouses.

Simulated heat waves during maize reproductive stages alter reproductive growth but have no lasting effect when applied during vegetative stages

Due to climate change, heat waves are predicted to become more frequent and severe. While long-term studies on temperature stress have been conducted on important crops such as maize (Zea mays), the immediate or long-term effects of short duration but extreme high temperature events during key developmental periods on physiological and yield parameters are unknown. Therefore, heat waves were applied to field-grown maize in east central Illinois using infrared heating technology. The heat waves warmed the canopy approximately 6°C above ambient canopy temperatures for three consecutive days during vegetative development (Wv1) and during an early reproductive stage (silking; Wv2). Neither treatment affected aboveground vegetative biomass, and Wv1 did not significantly reduce reproductive biomass. However, Wv2 significantly reduced total reproductive biomass by 16% (p<0.1) due to significant reductions in cob length (p<0.1), cob mass (p<0.05), and husk mass (p<0.05). Although not statistically significant, seed yield was also reduced by 13% (p=0.15) and kernel number by 10% (p=0.16) in the Wv2 treatment. Soil water status was unaffected in both treatments, and leaf water potential and midday photosynthesis were only transiently reduced by heating with complete recovery after the treatment period. Therefore, the reduction in Wv2 reproductive biomass was most likely due to greater sensitivity of reproductive structures to direct effects of high temperature stress.

Sulfhydral compounds mitigate the adverse effect of high temperature stress in contrasting wheat genotypes

Sulfhydral Compounds Mitigate the Adverse Effect of High Temperature Stress in Contrasting Wheat Genotypes The experiment was conducted to investigate the role of foliar sprays of thiourea (500,1000 ppm), thioglycolic acid (100,200 ppm) and dithiothreitol (25,50 ppm) under high temperature stress on physiology, growth and productivity of heat tolerant (Raj 4083) and heat susceptible (PBW 373) wheat genotypes. These genotypes were sown on 15th November (normal) and 15th December (heat stress) in field conditions under standard package and practices. The sulfhydral compounds were sprayed at jointing (45 DAS) and anthesis (60 DAS) stages. Results showed that photosynthetic parameters, water status, membrane stability index, pigment contents and yield reduced significantly under temperature stress conditions in both the genotypes. The foliar application of thiourea, thioglycolic acid and dithiothreitol increased or maintained these parameters efficiently in tolerant as well as susceptible genotypes. The heat susceptibility index decreased whereas heat tolerance index increased on account of sulfhydral spray. It is concluded that the foliar application of thiourea, thioglycolicacid and dithiothreitol improved the production potential of wheat genotypes under stress conditions; however, the application of dithiothreitol 50 ppm performed the best for mitigating the adverse effects of high temperature stress in wheat....

Upregulation of Superoxide Dismutase and Catalase along with Proline Accumulation Mediates Heat Tolerance in Lentil (Lens culinaris Medik.) Genotypes during Reproductive Stage

Heat stress during reproductive stage of lentil leads to array of physiological and morphological changes affecting lentil production. The effect of high temperature stress (30°-35°) was studied on thirty three lentil genotypes during winter (rabi) trial 2013–2014. Six genotypes comprising three tolerant (LL1372, LL1361, LL1396) and three sensitive (EC78390, LL1380, LL1390) were selected which further raised under timely sown (TS) and late sown (LS) conditions during winter (rabi) trial 2014–15 for biochemical analysis. The higher accumulation of proline content along with higher activities of superoxide dismutase (SOD) and catalase (CAT) was observed in late sown tolerant genotypes, might be helping in reducing oxidative stress caused by reactivite oxygen species (ROS). The higher accumulation of malondialdehyde (MDA) and hydrogen peroxide (H2O2) content was found in sensitive genotypes might be responsible for membrane damage. The positive and significant correlation was observed in CAT, SOD, and proline whereas these three biochemical parameters showed negative correlation with MDA and hydrogen peroxide content.

Respuestas al estrés por calor en los cultivos. II. Tolerancia y tratamiento agronómico.

El objetivo de esta revisión fue describir las respuestas de las plantas y los mecanismos de tolerancia al estrés térmico, así como el uso de prácticas agronómicas para mitigar los efectos del estrés por alta temperatura en los cultivos. Se introduce el balance de energía de las hojas y los doseles como enlace entre la temperatura de las plantas y el aire. Se describen los efectos de las altas temperaturas sobre las relaciones hídricas, la fotosíntesis y la partición de los asimilados, y las respuestas morfológicas y fenológicas de algunos cultivos al estrés por calor. Se presenta la agronomía de respuesta para la prevención y remediación del estrés causado por calor, que se abordó desde el punto de vista del mejoramiento genético, del manejo agronómico, la farmacéutica y prácticas hortícolas variadas. Por último, se describen algunas prácticas agronómicas utilizadas para reducir los efectos negativos del estrés por alta temperatura en los cultivos, como el uso de coberturas del suelo, sombra natural o arti cial, y la aplicación de sustancias hormonales, protectoras y otros productos de la industria toquímica moderna.

Phenological sensitivity to high temperature stress determines dry matter partitioning and yield in potato

Effect of high temperature stress through different dates of planting and growing inside temperature tunnel were investigated in two contrasting potato cultivars Kufri Surya and Kufri Chipsona-3. High temperature exposure at early, late and tunnel environment delayed tuber initiation and shortened the bulking duration of both the potato cultivars. High temperature significantly decreased crop growth rate, tuber growth rate and net assimilation rate. Under high temperature, K. Chipsona-3 and K. Surya recorded 26–71% and 16–40% reduction in marketable yield. Yield attributes such as number of tubers, mean tuber weight and dry matter of tubers were significantly reduced in K. Chipsona-3. Moreover, higher phenological sensitivity of K. Chipsona-3 under high temperature stress resulted in reduced dry matter partitioning towards tuber. Our results demonstrated that phenological shift under high temperature stress is critical during tuber initiation that decides number of tubers and marketable yield in potato. Temperature inside poly-house tunnel was most detrimental for tuber initiation as well as bulking stage. Thus, precautions should to be taken to explain yield losses under growth chamber or tunnel conditions, which do not represent natural field conditions. Among two potato cultivars, K. Surya showed higher temperature tolerance as compared to K. Chipsona-3 under all high temperature environments. This could be attributed to higher assimilate partitioning efficiency of K. Surya towards tuber during bulking phase.

Physiological traits for improving high temperature stress tolerance in rice

High temperature stress is projected to be one of the major stresses of limiting rice productivity worldwide in future climate change scenario. This review explicates the key physiological traits for tailoring high temperature tolerance in rice. These physiological traits can be used to explore the genetic variability among rice germplasm and to develop the improved genotypes through breeding programs. Traits influenced under high day and night temperature are highlighted for understanding differential temporal and phenological regulation. Application of plant hormones and inorganic elicitor molecules to induce short term acclimation response have been shown to be useful for mitigating high temperature stress effects specifically when applied at critical growth stge.

CGMP-Dependent Protein Kinase Inhibition Extends the Upper Temperature Limit of Stimulus-Evoked Calcium Responses in Motoneuronal Boutons of Drosophila melanogaster Larvae.

While the mammalian brain functions within a very narrow range of oxygen concentrations and temperatures, the fruit fly, Drosophila melanogaster, has employed strategies to deal with a much wider range of acute environmental stressors. The foraging (for) gene encodes the cGMP-dependent protein kinase (PKG), has been shown to regulate thermotolerance in many stress-adapted species, including Drosophila, and could be a potential therapeutic target in the treatment of hyperthermia in mammals. Whereas previous thermotolerance studies have looked at the effects of PKG variation on Drosophila behavior or excitatory postsynaptic potentials at the neuromuscular junction (NMJ), little is known about PKG effects on presynaptic mechanisms. In this study, we characterize presynaptic calcium ([Ca2+]i) dynamics at the Drosophila larval NMJ to determine the effects of high temperature stress on synaptic transmission. We investigated the neuroprotective role of PKG modulation both genetically using RNA interference (RNAi), and pharmacologically, to determine if and how PKG affects presynaptic [Ca2+]i dynamics during hyperthermia. We found that PKG activity modulates presynaptic neuronal Ca2+ responses during acute hyperthermia, where PKG activation makes neurons more sensitive to temperature-induced failure of Ca2+ flux and PKG inhibition confers thermotolerance and maintains normal Ca2+ dynamics under the same conditions. Targeted motoneuronal knockdown of PKG using RNAi demonstrated that decreased PKG expression was sufficient to confer thermoprotection. These results demonstrate that the PKG pathway regulates presynaptic motoneuronal Ca2+ signaling to influence thermotolerance of presynaptic function during acute hyperthermia.

Effects of short-term post-anthesis high-temperature stress on dynamic process of accumulation of grain protein and its composition in rice (Oryza sativa L.)

Extremely high temperature decreases grain yield and grain quality in rice (Oryza sativa L.). To investigate the effects of short-term post-anthesis high-temperature stress on accumulation of grain protein and protein compositions in rice, 2-year experiments were carried out in phytotron with two different cultivars, Nanjing 41 (NJ41, heat-sensitive) and Wuxiangjing 14 (WJ14, heat-tolerant), under different conditions of high-temperature levels and durations during anthesis and grain-filling stages. The results showed that grain protein content and its components (albumin, globulin, and glutelin) increased with rising temperature levels and durations, while prolamin content decreased. The contents of total protein, storage protein, albumin, globulin, and prolamin in NJ41 were more sensitive to different temperature levels than those in WJ14. Moreover, the contents of albumin and prolamin in NJ41 changed greater under temperature durations than those in WJ14. The effects of high-temperature stress on accumulation of grain protein and composition were more sensitive to high-temperature levels and durations during anthesis stage than those during grain-filling stage. The results could help us further understand the physiochemical processes governing rice yield and quality under high-temperature conditions during rice anthesis and grain-filling stages.

Effect of high-temperature stress on microalgae at the end of the logarithmic phase for the efficient production of lipid

ABSTRACTEfficient production of microalgae lipid is significant for the production of renewable biodiesel. In the present study, the high temperature of 40°C as stress environment was tested for stimulating lipid accumulation after the microalgae (Scenedesmus quadricauda) cells in suitable conditions grew to the end of the logarithmic phase. Different stress cultivation times of 1, 2, 3, 4, 5 and 6 days were studied. Interestingly, the lipid content and productivity reached 33.5% and 23.2 mg/L d after one day stress cultivation, showing substantial improvements of 39.6% and 33.3% compared with that in the untreated (day 0) microalgae cells, respectively. Longer stress time led to the decrease of biomass and lipid content compared with the untreated microalgae. However, a maximum protein content of 58.7% was obtained after six days. The stress cultivation at the end of the microalgae exponential phase for one day at a high temperature of 40°C could be a very useful industrial approach for efficiently promoting lipid content and biodiesel production.

The Effect of High-Temperature Stress on Bt Protein Content and Nitrogen Metabolism in the Boll Shell of Bt Cotton

The Effect of High-Temperature Stress on Bt Protein Content and Nitrogen Metabolism in the Boll Shell of Bt Cotton

Effects of high temperature stress on enzymatic and nonenzymaticantioxidants and proteins in strawberry plants

The mechanism of tolerance to high temperatures was investigated in two strawberry (Fragaria x ananassa Duch) cultivars, 'Redlands Hope' ('R. Hope', heat tolerant) and 'Cal. Giant 3' ('CG3', heat sensitive). Leaves were collected from plants that were exposed to gradual heat stress and heat-shock stress separately. The contents of nonenzymatic antioxidants such as ascorbic acid (AsA) and glutathione (GSH) and the activities of enzymatic antioxidants such as ascorbate peroxidase (APX) (EC 1.11.1.11), catalase (CAT) (EC 1.11.1.6), and glutathione reductase (GR) (EC. 1.6.4.2) were measured followed by heat treatments. Additionally, proline content was determined, and heat shock proteins (HSPs) were analyzed with an immunoblotting method to investigate protein markers involved in the heat-stress tolerance of strawberry plants. The contents of AsA and GSH did not change depending on heat stress type, temperatures, or cultivars. While APX and CAT activities increased with high temperatures, GR activity was almost unchanged. The proline content of the cultivars increased in both treatments. Anti-HSP60 immunoblots revealed that a 23 kDa polypeptide was detected during the heat acclimation of strawberry cultivars. The intensity of the heat shock protein in 'R. Hope' plants was more than in 'CG3' plants. Thus, the accumulation of 23 kDa heat shock protein was correlated with the heat tolerance of the cultivars. In conclusion, strawberry leaf tissues of 'R. Hope' were found to enhance the structural stability of cellular membranes under high temperature by increasing both the activity of such enzymes as CAT and APX to activate the antioxidative systems and the expression of 23 kDa HSP.