Research Progress of Heat-tolerance of Brassica campestris ssp. Chinensis

Brassica campestris ssp. chinensis, also known as non-heading Chinese cabbage, is an important vegetable widely distributed in southern China. High temperature is the most common adversity factor in vegetable production, because Brassica campestris ssp. chinensis is a thermophilic vegetable, which can＇t well grow at high temperature. In summer and autumn, high temperature stress would prevent Brassica campestris ssp. chinensis from growing and result in poor quality of its seedlings, seriously influencing yield and quality of the vegetable in later period. In this paper, present situation and latest advances in heat resistance research of Brassica campestris ssp. chinensis in recent years were reviewed at home and abroad. The research tendency in Bassica campestris ssp. chinensis was also described, providing reference for breeding of heat-resistant Brassica campestris ssp. chinensis.

Genetic Analysis of Cold Tolerance at Seedling Stage and Heat Tolerance at Anthesis in Rice (Oryza sativa L.)

A set of 240 introgression lines derived from the advanced backcross population of a cross between a japonica cultivar,Xiushui 09,and an indica breeding line,IR2061,was developed to dissect QTLs affecting cold tolerance （CT） at seedling stage and heat tolerance （HT） at anthesis.Survival rate of seedlings （SRS） and spikelet fertility （SF）,the index traits of CT and HT,showed significant differences between the two parents under stresses.A total of four QTLs （qSRS1,qSRS7,qSRS11a and qSRS11b） for CT were identified on chromosomes 1,7,11,and the Xiushui 09 alleles increased SRS at all loci except qSRS7.Four QTLs for SF were identified on chromosomes 4,5,6,and 11.These QTLs could be classified into two major types based on their behaviors under normal and stress conditions.The first was QTL expressed only under normal condition;and the second QTL was apparently stress induced and only expressed under stress.Among them,two QTLs （qSF4 and qSF6） which reduced the trait difference between heat stress and normal conditions must have contributed to HT because of their obvious contribution to trait stability,and the IR2061 allele at the qSF6 and the Xiushui 09 allele at the qSF4 improved HT,respectively.No similar QTL was found between CT at seedling stage and HT at anthesis.Therefore,it is possible to breed a new variety with CT and HT by pyramiding the favorable CT-and HT-improved alleles at above loci from Xiushui 09 and IR2061,respectively,through marker-assisted selection （MAS）.

Screening for Spikelet Fertility and Validation of Heat Tolerance in a Large Rice Mutant Population

A total of 10 000 M4 individuals in Jao Hom Nil (JHN) mutant population was treated with high temperature (40 ℃ to 45 ℃) during the day time (6 h) from the booting to the harvesting stages, and ambient temperature (33 ℃ to 35℃) was used as the control. The results of screening and yield trials found that the mutant line M9962 had a high spikelet fertility of 78% under heat stress. In addition, the other mutant lines, including M3181 and M7988, had a spikelet fertility of approximately 70%. However, the JHN wild type, Sin Lek, RD15 and RD33 had very low spikelet fertility of 34%, 14%, 9% and 4%, respectively. The lower spikelet fertility at an elevated temperature resulted in a dramatic decrease of filled grain and contributed to a loss in 100-grain weight. M9962 is a potential genetic stock for use in a heat tolerance breeding programme. In addition, spikelet fertility at high temperature was representative of heat tolerance and can be used as a screening trait for heat tolerance during the reproductive phase on a large scale.

Establishment of Nasal Tolerance to Heat Shock Protein-60 Alleviates Atherosclerosis by Inducing TGF-β-dependent Regulatory T Cells

Mounting evidence supports that a newly identified regulatory T cell (Treg),CD4+LAP+ Treg,is associated with oral tolerance induction and following inhibition of atherosclerosis,but little is described about whether nasal tolerance to antigen likewise induces the novel Tregs production and the relevant antiatherosclerotic benefit.We investigated the effect of nasal administration of heat shock protein-60 (HSP60) on atherogenesis.HSP60 or phosphate buffer solution (PBS) was nasally adminis-tered to six-week-old male ApoE-/-mice.At the 10th week after the nasal administration,there was a significant decrease in atherosclerotic plaque areas of aortic roots in the HSP60-treated mice as com-pared with those in the PBS-treated mice.Atherosclerosis suppression was accompanied with a signifi-cant increase in CD4+LAP+ and CD4+CD25+Foxp3+ Tregs and a concurrently increased production of TGF-β in the HSP60-treated mice.The protective effect of HSP60 was offset by injection of anti-TGF-βantibody.It is concluded that nasal administration of HSP60 can inhibit atherosclerotic formation through immune tolerance which is established by Tregs depending on the induction of anti-inflammatory cytokine TGF-β.Immune tolerance induced by nasal administration of HSP60 may provide an alternative therapeutic method for atherosclerosis.

Germplasm Innovation of Heat Tolerance in Rice for Irrigated Lowland Conditions in the Philippines

Heat-tolerant varieties, such as N22 and Dular, which were used in this study, usually have low yield potential and undesirable plant characteristics but combining them with high yielding and improved rice varieties, new heat-tolerant rice genotypes with high yield potential can be achieved. In this study, phenotyping and selecting desirable materials from various crosses were performed under high temperature conditions during the reproductive stage. Screening was performed in the field and glasshouse to select individuals with heat tolerance and high yield potential. Several advanced breeding lines from Gayabyeo/N22 cross produced desirable individuals with heat tolerance, resistance to pests and diseases, and high yield potential. The genetic variation in percent sterility among the selected backcross populations grown in high temperature environments showed that large number of plants can be identified and selected with lower percent sterility.

Identification for Heat Tolerance in Backcross Recombinant Lines and Screening of Backcross Introgression Lines with Heat Tolerance at Milky Stage in Rice

The present study aimed at breeding new rice germplasms with similar genome but significantly differed in heat tolerance during the grain filling stage.A total of 791 BC1F8 backcross recombinant lines,derived from the cross of Xieqingzao B /N22 //Xieqingzao B,were used as materials.Each rice line was separated evenly into two groups,and the heat tolerance of all rice lines were evaluated at natural high temperature in fields.The rice lines with heat tolerant index higher than 90% or lower than 40% were selected to compare the phenotypic characters and further identify heat tolerance at the early milky stage in a phytotron.Rice lines with similar phenotypic characters but significantly differed in heat tolerance at the milky stage were analyzed by 887 simple sequence repeat markers that were evenly distributed on the 12 rice chromosomes.In the result,12(6 pairs) rice lines with similar phenotypic characters but significantly differed in heat tolerance at the milky stage were obtained.Molecular marker analysis indicated that the genomic polymorphism between 703T and 704S was the smallest in the 6 pairs of rice lines,with only 16 polymorphic sites,including 22 different alleles.The application of these two backcross introgression rice lines for future study on the mechanisms of heat tolerance in rice at the milky stage will be theoretically beneficial in reducing the interference caused by genetic differences from experimental materials.

Genetic improvement of heat tolerance in wheat:Recent progress in understanding the underlying molecular mechanisms

As a cool season crop, wheat(Triticum aestivum L.) has an optimal daytime growing temperature of 15 ℃ during the reproductive stage. With global climate change, heat stress is becoming an increasingly severe constraint on wheat production. In this review, we summarize recent progress in understanding the molecular mechanisms of heat tolerance in wheat. We firstly describe the impact of heat tolerance on morphology and physiology and its potential effect on agronomic traits. We then review recent discoveries in determining the genetic and molecular factors affecting heat tolerance, including the effects of phytohormone signaling and epigenetic regulation. Finally, we discuss integrative strategies to improve heat tolerance by utilization of existing germplasm including modern cultivars, landraces and related species.

Identification of Heat Tolerance Linked Molecular Markers of Chinese Cabbage(Brassica campestris L.ssp.pekinensis)

Genetically stable population of recombination inbred line (RIL) was derived from a cross between a heat tolerant line 177 and a heat sensitive line 276 of Chinese cabbage (Brassica campestris L. ssp. pekinensis) by single seed descent. The RILs were analyzed using isozyme, RAPD and AFLP techniques in order to find molecular markers that are linked to heat tolerance quantitative trait loci (QTL). The results of variance analysis of single factor indicated that there were 9 molecular markers closely linked with heat tolerance QTL, including 5 AFLP markers, 3 RAPD markers and 1 PGM isozyme marker. Total genetic contribution of these makers to heat tolerance was 46.7%. Five of the nine markers distributed in one linkage group, the remaining 4 markers were located in separate groups. Thus the 9 heat tolerance linked markers distributed in 5 independent locations in the genome of Chinese cabbage.

Effect of Coat Characteristics on Physiological Traits and Heat Tolerance of West African Dwarf Sheep in Southern Nigeria

This experiment was conducted to investigate the effect of coat characteristics on physiological traits and heat tolerance of dwarf sheep in southern Nigeria. A total number of twenty West African dwarf male sheep with an average weight of 9.00 ± 0.52 kg and aged 10 months old were used for the experiment. The dwarf sheep were assigned to four treatment groups in a completely randomized design with five sheep per treatment group. The compared treatment groups were TA (black coat colour sheep with low coat depth and short hair length), TB (black coat colour sheep with high coat depth and long hair length), TC (light brown coat colour sheep with low coat depth and short hair length) and TD (light brown coat colour sheep with high coat depth and long hair length). The results obtained in the study showed that midday was significantly (P 0.05) affected by morning, midday and evening. Rectal temperature (40.09℃), respiratory rate (21.01 breaths/min), pulse rate (87.49 beats/min), heat tolerance coefficient (97.10%), haemoglobin (9.04 g/l), blood cell (10.84 × 106/μl), white blood cell (12.06 × 106/μl) and glucose (50.10 mg/dl) were significantly (P 0.05) did not occur in total protein, albumin and globulin among treatment groups. It is concluded that coat characteristics have significant effects on physiological indices and heat tolerance in Nigeria.

Effect of the C.–1388 A>G polymorphism in chicken heat shock transcription factor 3 gene on heat tolerance

Heat stress is one of the main factors that inlfuence poultry production. Heat shock proteins (HSPs) are known to affect heat tolerance. The formation of HSPs is regulated by heat shock transcription factor 3 (HSF3) in chicken. A DNA pool was established for identifying single nucleotide polymorphisms (SNPs) of the chicken HSF3, and 13 SNPs were detected. The bioinformatic analysis showed that 8 SNPs had the capacity to alter the transcription activity of HSF3. The dual luciferase report gene assay showed that there was a signiifcant difference (P<0.01) in the Firelfy luciferase/Renil a luciferase ratio (F/R) of C.–1 703 A>G (S1) and C.–1 388 A>G (S4) sites at the 5′-untranslated region (UTR) of chicken HSF3. The elec-trophoretic mobility shift assay showed that the S4 site was a transcription binding factor. The analysis of the association of the S1 and S4 sites with heat tolerance index revealed that the S4 site was signiifcantly correlated with the CD3+T cel , corticosterone, and T3 levels in Lingshan chickens and with the heterophil/lymphocyte value in White Recessive Rock. These results showed that the S4 site at the 5′ UTR of chicken HSF3 might have an impact on heat tolerance in summer and could be used as a potential marker for the selection of chicken with heat tolerance in the future.

Evaluation of a new method for quantification of heat tolerance in different wheat cultivars

Heat stress seriously affects wheat production in many regions of the world. At present, heat tolerance research remains one of the least understood fields in wheat genetics and breeding and there is a lack of effective methods to quantify heat stress and heat tolerance in different wheat cultivars. The objective of this study was to use various wheat cultivars to evaluate stress intensity(δ) and a new method for quantification of heat tolerance and compare this technique with three other currently utilized methods. This new parameter for heat tolerance quantification is referred to as the heat tolerance index(HTI) and is an indicator of both yield potential and yield stability. Heat treatments were applied in a controlled setting when anthesis had been reached for 80% of the wheat. The stress intensity evaluation indicated heat shock was the main factor associated with kernel weight reduction while grain yield reduction was mainly associated with chronic high temperature. The methods evaluation showed that a temperature difference of 5°C from natural temperatures was a suitable heat treatment to compare to the untreated controls. HTI was positively correlated with yield under heat stress(r=0.8657, δ=0.15, in 2009–2010; r=0.8418, δ=0.20, in 2010–2011; P<0.01), and negatively correlated with yield reduction rate(r=–0.8344, in 2009–2010; r=–0.7158, in 2010–2011; P<0.01). The results of this study validated the use of HTI and temperature difference control for quantifying wheat heat tolerance that included the yield potential and the stability of different wheat cultivars under heat stress. Additionally, 10 wheat cultivars showed high HTI and should be further tested for their heat confirming characteristics for use in wheat heat tolerance breeding.

“Three‐in‐one”strategy:Heat regulation and conversion enhancement of a multifunctional separator for safer lithium-sulfur batteries

The safety problems encountered with lithium–sulfur batteries(LSBs)hinder their development for practical applications.Herein,a highly thermally conductive separator was constructed by cross‐weaving super‐aligned carbon nanotubes(SA‐C)on super‐aligned boron nitride@carbon nanotubes(SA‐BC)to create a composite film(SA‐BC/SA‐C).This separator was used to fabricate safe LSBs with improved electrochemical performance.The highly aligned separator structure created a uniform thermal field that could rapidly dissipate heat accumulated during continuous operation due to internal resistance,which prevented the development of extremely high temperatures.The array of boron nitride nanosheets endowed the composite separator with a large number of adsorption sites,while the highly graphitized carbon nanotube skeleton accelerated the catalytic conversion of high‐valence polysulfides into low‐valence polysulfides.The arrayed molecular brush design enabled the regulation of local current density and ion flux,and considerably alleviated the growth of lithium dendrites,thus promoting the smooth deposition of Li metal.Consequently,a battery constructed with the SA‐BC/SA‐C separator showed a good discharge capacity of 685.2 mAh g−1 over 300 cycles(a capacity decay of 0.026%per cycle)at 2 C and 60°C.This“three‐in‐one”multifunctional separator design strategy constitutes a new path forward for overcoming the safety problems of LSBs.

Wheat genotypes tolerant to heat at seedling stage tend to be also tolerant at adult stage:The possibility of early selection for heat tolerance breeding

Wheat production is seriously influenced by extreme hot weather,which has attracted increasing attention.It is important to compare wheat responses to heat at seedling and reproductive stages,to explore the potential relationship between the performances at different growing stages and the possibility of early selection to accelerate heat tolerance breeding.In this study,forty wheat genotypes were screened under heat stress at both seedling and adult stages.It was found that root lengths at seedling stage were severely reduced by heat stress with significant variations among wheat genotypes.Heat-tolerant genotypes at seedling stage showed less root length decrease than susceptible ones.Wheat genotypes tolerant at seedling stage showed higher yield at adult stage after heat treatment.The performances of wheat genotypes screened under heat stress at seedling and adult stages were ranked by seedling damage index and adult damage index.A significant positive relationship was found between heat tolerance at seedling stage and at adult stage(r=0.6930),suggesting a similar tolerant/susceptible mechanism at different plant growth stages and the possibility of early selection at seedling stage for breeding heat tolerance.Extremely tolerant and susceptible genotypes with consistent performances at seedling and adult stages were genetically compared and associated SNP markers and linked candidate genes were identified.

Improvement of heat-tolerance by training I. Evaluation of effects of long-distance running and march training on heat-tolerance

in order to verify the heat-tolerance effect, two trainings, 90 min marching with load (WBGT 24. 6～35.6℃) and 10 km running (WBGT 25.0～31.1℃) were performed in laboratory and field under hot climate.Ten to twelve times (days) of training were carried out

Effects of Streptomyces microflavus Extract on Heat Tolerance of Tall Fescue

Heat stress in summer is a major factor limiting use of cool-season grasses in Shanghai area, China. The objectives of this study were to investigate effects of a crude extract product of a new strain of Streptomyces microflavus (TSS) on turf performance and physiological activities of tall fescue (Festuca arundinacea) in response to heat stress. Plants of tall fescue cultivar ‘Barlexus’ were exposed to 38/33 (°C) (day/night) high temperature in growth chamber after TSS applications. High temperature induced about 3.5 fold increases of initial shoot extension rate and clipping yield (6 d) and led to quick decline of plant growth after 18 d. TSS inhibited the extent of initial increases of shoot extension rate and clipping yield and maintained a longer period of steady growth under the heat stress. TSS also decreased the decline of leaf chlorophyll content, TNC, shoot density, and turf quality induced by heat stress. The results suggested that TSS application improved turf performance under heat stress, and the greater improvement of heat tolerance was associated with higher dose of application. This positive effect on heat tolerance could be related to the decreased carbohydrate consumption and loss, and reduced decomposition of leaf chlorophyll.

Improvement of heat-tolerance by training I. Evaluation of effects of combined of march and cross-country race on heat-tolerance

in order to improve the acquired level of heat acclimatization (HA) by training, on the basis of singlemode march training (SMT) or single-mode cross-country race training (SCT) , combined training method of march and cross-country race in the heat was adopted in this experiment ,and the effect of the training on heat tolerance was analyzed. Eight young males were asked to perform a simulated SMT and SCT for 90 min on a treadmill in a hot climate chamber (Td 32. 7℃ , WBGT 28. 4℃ ) once daily for 10 to 12 d within two weeks. The results showed that rectal temperature (Tr) was reduced by 0. 61℃ , heart rate (Hr) by 8. 5 b/min,sweat volume (SV)by 0. 220 kg, physiological strain index (PSI)by 0. 620,systolic pressure (SP)and diastolic pressure (DP) had a little change, pulse pressure (PP) and stroke volume (StV) increased , and cardiac output (CO) decreased a little at the middle stage and increased at the late stage due to Hr change. The standardized bicycle ergometer test (SBE test) in the heat (Td 37℃)has proved that these physiological indexes post-training had significant improvements ,as compared with those pre-training, suggesting that the combined training could raise heat-tolerance and was superior to the SMT in improving acquired heat acclimatization in same training duration and times , and to the SCT in regulating body temperature and cardiovascular function and in prolonging heat tolerance duration.

Physiological Mechanism of Thermotolerance in Wheat (<i>Triticum aestivum</i>Lin.) Seedlings

A research work was performed under sub-tropical condition (24&deg;8'N, 90&deg;0'E) at Bangabandhu Sheikh Mujibur Rahman Agricultural University with three wheat genotypes (BARI Gom 25, BARI Gom 26 and Pavon 76) to observe the mobilization of seed reserve and seedling growth under normal (15&deg;C/25&deg;C) and elevated (25&deg;C/35&deg;C) temperature in growth chamber. The effect of high temperature on wheat seedling was observed in terms of mobilized seed reserve, respiration and transpiration efficiency and seedling growth. At 35&deg;C temperature, maximum mobilization of seed reserve was observed in BARI Gom varieties (BARI Gom 25 and 26) but the respiration efficiency was higher in Pavon 76 in comparison to other genotypes. Maximum loss of respiration and transpiration at 35&deg;C temperature was found to produce low seedling growth in Pavon 76. It appeared from the result that at high temperature the maximum mobilized seed reserve and subsequently minimum loss of respiration and transpiration collectively contributed a positive role for better seedling growth in BARI Gom 25 and BARI Gom 26. Therefore the better mobilized seed reserve and subsequently minimum loss of respiration and transpiration during seedling development are indicators of the thermo tolerance in growing wheat seedling.

Compatible Solutes in the Akinetes of the Terrestrial Cyanobacterium <i>Nostoc</i>sp. HK-01 Contribute to Its Heat Tolerance

The detailed mechanisms that facilitate the heat tolerance of terrestrial cyanobacteria have not been completely elucidated, although several reports have revealed aspects of the heat tolerance mechanisms of several other organisms. The dormant cells, called akinetes, of the terrestrial cyanobacterium Nostoc sp. HK-01 can revive after dry heat exposure at 100℃ for more than 10 h. We investigated the compatible solutes that protect the biomolecules in Nostoc sp. HK-01 akinetes using colonies containing various proportions of akinetes. We extracted the intracellular substances from each colony with 80% ethanol, which we purified with a series of analytical columns and analyzed by high-performance liquid chromatography and liquid chromatography-electrospray ionization-mass spectrometry. The compatible solutes were screened for their ability to prevent protein aggregation upon heating using the model enzyme lactate dehydrogenase. We detected an accumulation of glucosylglycerol, betaine, and glycine in akinetes. In addition, we confirmed that betaine, glycine, sucrose, and trehalose contributed to the prevention of the protein aggregation. The levels of sucrose and glycine in the colonies were approximately 1000× higher than those of glucosylglycerol, betaine, or trehalose. Our results indicated that sucrose and glycine are the main compatible solutes in the hydrophilic fractions of the cell extracts of Nostoc sp. HK-01 akinetes.

Physiological Response to High Temperature and Evaluation of Heat Tolerance of Different Grape Cultivars

[Objectives]This study was conducted to investigate the differences in the physiological responses of different grape cultivars to high temperature.[Methods]The 19 tested cultivars were selected from the grape germplasm resources pool of Turpan Research Institute of Xinjiang Academy of Agricultural Sciences.Twelve physiological indexes including gas exchange parameters,chlorophyll content,antioxidant enzyme activity and proline content were determined in grape leaves under field conditions during the middle period of local natural high temperature period(July,daily maximum air temperature>35℃).The heat tolerance of different cultivars was evaluated by fuzzy membership function analysis and optimum partitioning clustering of ordered samples.[Results](1)Under natural high temperature conditions in Turpan,the 19 tested grape cultivars responded differently to high temperature.‘Red Globe’,‘Fujiminori’,‘Beta’,‘Hetianhuang’had strong heat tolerance,while‘Thompson Seedless’,‘Hongqi Tezaomeigui’,‘Shuijing Wuhe’,‘Victoria’,‘Yatomi Rosa’and‘Crimson Seedless’had weak heat tolerance.(2)Among the 12 physiological indexes,malondialdehyde content and antioxidant enzyme activity were mostly different among various grape cultivars.The grape cultivars with strong heat tolerance,‘Red Globe’and‘Fujiminori’,had relatively lower malondialdehyde contents,while‘Beta’and‘Hetianhuang’had relatively higher malondialdehyde contents.But they had higher activity of antioxidant enzymes.(3)The results of fuzzy membership function analysis showed that the cumulative membership value(AR)of each physiological index was consistent with its apparent heat tolerance performance,suggesting that AR can be a potential index for the evaluation of heat tolerance of grape cultivars.Further cluster analysis classified the tested cultivars as strong,medium and weak.‘Red Globe’,‘Fujiminori’,‘Beta’and‘Hetianhuang’had strong heat tolerance.[Conclusions]This study provides a reference for grape cultivation under high temperature and stress and breeding of heat-tolerant varieties.

Determination of the High Temperature Stress Tolerances of Bread Wheat Genotypes

Thirty bread wheat genotypes were used as material during the 2014-2015 cropping season. The experimental layout was a randomized complete block design with 3 replications. The sowing rate was 500 seeds square meter. Sowing was done in plots of 6 rows （1.2 m × 5 m, spaced 20 cm apart） in Namlk Kemal University, Faculty of Agriculture, Field Crops Department experimental area. Two sowing times were performed. First sowing was made in November suggested usual （standard） and second one was made in January as delayed sown in order to push growing stages of plants into periods in which heat stress is expected will be effected. Sowing times were allotted to main-plots while genotypes were allotted to sub-plots. When the bread wheat varieties and lines used in the experiment are evaluated in terms of tolerance to high temperature, it was shown that Dropia and Nota varieties and CIMMYT-HTN 2014/15-2, CIMMYT-HTN 2014/15 -6, CIMMYT-HTN 2014/15 - 10 lines were better tolerance to high temperature. However, it was noticed that these genotypes were not included in the first groups in terms of grain yield. It is possible to utilize these genotypes as a genitor in cross-breeding programs for breeding studies for tolerance to high temperatures.