The different patterns of post-heat stress responses in wheat genotypes: the role of the transthylakoid proton gradient in efficient recovery of leaf photosynthetic capacity

Increased average air temperatures and more frequent and prolonged periods of high ambient temperature (HT) associated with global warming will increasingly affect worldwide poultry production. It is thus important to understand how HT impacts poultry physiology and to identify novel approaches to facilitate improved adaptation and thereby maximize poultry growth, health and welfare. Amino acids play a role in many physiological functions, including stress responses, and their relative demand and metabolism are altered tissue-specifically during exposure to HT. For instance, HT decreases plasma citrulline (Cit) in chicks and leucine (Leu) in the embryonic brain and liver. The physiological significance of these changes in amino acids may involve protection of the body from heat stress. Thus, numerous studies have focused on evaluating the effects of dietary administration of amino acids. It was found that oral l-Cit lowered body temperature and increased thermotolerance in layer chicks. When l-Leu was injected into fertile broiler eggs to examine the cause of reduction of Leu in embryos exposed to HT, in ovo feeding of l-Leu improved thermotolerance in broiler chicks. In ovo injection of l-Leu was also found to inhibit weight loss in market-age broilers exposed to chronic HT, giving rise to the possibility of developing a novel biotechnology aimed at minimizing the economic losses to poultry producers during summer heat stress. These findings and the significance of amino acid metabolism in chicks and market-age broilers under HT are summarized and discussed in this review.

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Arabidopsis Target of Rapamycin Coordinates With Transcriptional and Epigenetic Machinery to Regulate Thermotolerance

Frontiers in Plant Science ◽

10.3389/fpls.2021.741965 ◽

2021 ◽

Vol 12 ◽

Author(s):

Mohan Sharma ◽

Muhammed Jamsheer K. ◽

Brihaspati Narayan Shukla ◽

Manvi Sharma ◽

Prakhar Awasthi ◽

...

Keyword(s):

Heat Stress ◽

Stress Responses ◽

Target Of Rapamycin ◽

Dependent Manner ◽

Heat Shock Factors ◽

Promoter Regions ◽

Stress Protection ◽

Epigenetic Machinery ◽

Adaptation To Heat

Global warming exhibits profound effects on plant fitness and productivity. To withstand stress, plants sacrifice their growth and activate protective stress responses for ensuring survival. However, the switch between growth and stress is largely elusive. In the past decade, the role of the target of rapamycin (TOR) linking energy and stress signalling is emerging. Here, we have identified an important role of Glucose (Glc)-TOR signalling in plant adaptation to heat stress (HS). Glc via TOR governs the transcriptome reprogramming of a large number of genes involved in heat stress protection. Downstream to Glc-TOR, the E2Fa signalling module regulates the transcription of heat shock factors through direct recruitment of E2Fa onto their promoter regions. Also, Glc epigenetically regulates the transcription of core HS signalling genes in a TOR-dependent manner. TOR acts in concert with p300/CREB HISTONE ACETYLTRANSFERASE1 (HAC1) and dictates the epigenetic landscape of HS loci to regulate thermotolerance. Arabidopsis plants defective in TOR and HAC1 exhibited reduced thermotolerance with a decrease in the expression of core HS signalling genes. Together, our findings reveal a mechanistic framework in which Glc-TOR signalling through different modules integrates stress and energy signalling to regulate thermotolerance.

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bZIP17 regulates heat stress tolerance at reproductive stage in Arabidopsis

aBIOTECH ◽

10.1007/s42994-021-00062-1 ◽

2021 ◽

Author(s):

Juan Gao ◽

Mei-Jing Wang ◽

Jing-Jing Wang ◽

Hai-Ping Lu ◽

Jian-Xiang Liu

Keyword(s):

Heat Stress ◽

Stress Responses ◽

High Throughput Sequencing ◽

Reproductive Stage ◽

Heat Stress Response ◽

Unfolded Protein ◽

Heat Stress Tolerance ◽

The Unfolded Protein Response ◽

Protein Response

AbstractHigh temperature elicits a well-conserved response called the unfolded protein response (UPR) to bring protein homeostasis in the endoplasmic reticulum (ER). Two key UPR regulators bZIP28 and bZIP60 have been shown to be essential for maintaining fertility under heat stress conditions in Arabidopsis, however, the function of transcriptional activator bZIP17, a paralog of bZIP28, in heat stress response at reproductive stage is not reported. Here we found that bzip17 mutant plants were sensitive to heat stress in terms of silique length and fertility comparing to that of wildtype (WT) Arabidopsis plants, and transcriptomic analysis showed that 1380 genes were specifically up-regulated and 493 genes were specifically down-regulated by heat stress in the flowers of WT plants comparing to that in bzip17 mutant plants. These bZIP17-dependent up-regulated genes were enriched in responses to abiotic stresses such as water deprivation and salt stress. Further chromatin immuno-precipitation coupled with high-throughput sequencing (ChIP-Seq) uncovered 1645 genes that were direct targets of bZIP17 in MYC-bZIP17 expressing seedlings subjected to heat stress. Among these 1645 genes, ERSE-II cis-element was enriched in the binding peaks of their promoters, and the up-regulation of 113 genes by heat stress in flowers was dependent on bZIP17. Our results revealed direct targets of bZIP17 in flowers during heat stress responses and demonstrated the important role of bZIP17 in maintaining fertility upon heat stress in plants.

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The Physiological Basis of Improved Heat Tolerance in Selected Emmer-Derived Hexaploid Wheat Genotypes

Frontiers in Plant Science ◽

10.3389/fpls.2021.739246 ◽

2021 ◽

Vol 12 ◽

Author(s):

Smi Ullah ◽

Richard Trethowan ◽

Helen Bramley

Keyword(s):

Heat Stress ◽

Heat Tolerance ◽

Stress Responses ◽

Selection Process ◽

Abiotic Stress Tolerance ◽

Grain Filling ◽

Complex Nature ◽

Physiological Basis ◽

Wheat Genotypes ◽

Short Period

Wheat is sensitive to high-temperature stress with crop development significantly impaired depending on the severity and timing of stress. Various physiological mechanisms have been identified as selection targets for heat tolerance; however, the complex nature of the trait and high genotype × temperature interaction limits the selection process. A three-tiered phenotyping strategy was used to overcome this limitation by using wheat genotypes developed from the ancient domesticated wheat, emmer (Triticum dicoccon Schrank), which was considered to have a wide variation for abiotic stress tolerance. A contrasting pair of emmer-based hexaploid lines (classified as tolerant; G1 and susceptible; G2) developed from a backcross to the same recurrent hexaploid parent was chosen based on heat stress responses in the field and was evaluated under controlled glasshouse conditions. The same pair of contrasting genotypes was also subsequently exposed to a short period of elevated temperature (4 days) at anthesis under field conditions using in-field temperature-controlled chambers. The glasshouse and field-based heat chambers produced comparable results. G1 was consistently better adapted to both extended and short periods of heat stress through slow leaf senescence under heat stress, which extended the grain filling period, increased photosynthetic capacity, increased grain filling rates, and resulted in greater kernel weight and higher yield. The use of a combination of phenotyping methods was effective in identifying heat tolerant materials and the mechanisms involved.

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Transcriptome analysis of the role of autophagy in plant response to heat stress

PLoS ONE ◽

10.1371/journal.pone.0247783 ◽

2021 ◽

Vol 16 (2) ◽

pp. e0247783

Author(s):

Yan Zhang ◽

Haoxuan Min ◽

Chengchen Shi ◽

Gengshou Xia ◽

Zhibing Lai

Keyword(s):

Gene Expression ◽

Heat Stress ◽

Heat Tolerance ◽

Stress Responses ◽

Critical Role ◽

Plant Response ◽

Wild Type ◽

Altered Expression ◽

Regulated Gene Expression

Autophagy plays a critical role in plant heat tolerance in part by targeting heat-induced nonnative proteins for degradation. Autophagy also regulates metabolism, signaling and other processes and it is less understood how the broad function of autophagy affects plant heat stress responses. To address this issue, we performed transcriptome profiling of Arabidopsis wild-type and autophagy-deficient atg5 mutant in response to heat stress. A large number of differentially expressed genes (DEGs) were identified between wild-type and atg5 mutant even under normal conditions. These DEGs are involved not only in metabolism, hormone signaling, stress responses but also in regulation of nucleotide processing and DNA repair. Intriguingly, we found that heat treatment resulted in more robust changes in gene expression in wild-type than in the atg5 mutant plants. The dampening effect of autophagy deficiency on heat-regulated gene expression was associated with already altered expression of many heat-regulated DEGs prior to heat stress in the atg5 mutant. Altered expression of a large number of genes involved in metabolism and signaling in the autophagy mutant prior to heat stress may affect plant response to heat stress. Furthermore, autophagy played a positive role in the expression of defense- and stress-related genes during the early stage of heat stress responses but had little effect on heat-induced expression of heat shock genes. Taken together, these results indicate that the broad role of autophagy in metabolism, cellular homeostasis and other processes can also potentially affect plant heat stress responses and heat tolerance.

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The Alternative Sigma Factor SigH Regulates Major Components of Oxidative and Heat Stress Responses in Mycobacterium tuberculosis

Journal of Bacteriology ◽

10.1128/jb.183.20.6119-6125.2001 ◽

2001 ◽

Vol 183 (20) ◽

pp. 6119-6125 ◽

Cited By ~ 192

Author(s):

Sahadevan Raman ◽

Taeksun Song ◽

Xiaoling Puyang ◽

Stoyan Bardarov ◽

William R. Jacobs ◽

...

Keyword(s):

Oxidative Stress ◽

Mycobacterium Tuberculosis ◽

Heat Stress ◽

Heat Shock ◽

Stress Responses ◽

Sigma Factor ◽

Inducible Expression ◽

Alternative Sigma Factor ◽

And Oxidative Stress

ABSTRACT Mycobacterium tuberculosis is a specialized intracellular pathogen that must regulate gene expression to overcome stresses produced by host defenses during infection. SigH is an alternative sigma factor that we have previously shown plays a role in the response to stress of the saprophyte Mycobacterium smegmatis. In this work we investigated the role ofsigH in the M.tuberculosis response to heat and oxidative stress. We determined that a M. tuberculosis sigHmutant is more susceptible to oxidative stresses and that the inducible expression of the thioredoxin reductase/thioredoxin genestrxB2/trxC and a gene of unknown function, Rv2466c, is regulated by sigH via expression from promoters directly recognized by SigH. We also determined that thesigH mutant is more susceptible to heat stress and that inducible expression of the heat shock genes dnaK andclpB is positively regulated by sigH. The induction of these heat shock gene promoters but not of other SigH-dependent promoters was markedly greater in response to heat versus oxidative stress, consistent with their additional regulation by a heat-labile repressor. To further understand the role ofsigH in the M.tuberculosis stress response, we investigated the regulation of the stress-responsive sigma factor genessigE and sigB. We determined that inducible expression of sigE is regulated bysigH and that basal and inducible expression ofsigB is dependent on sigE andsigH. These data indicate that sigH plays a central role in a network that regulates heat and oxidative-stress responses that are likely to be important in M.tuberculosis pathogenesis.

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Heat stress and hydrocortisone are independent stimulators of triiodothyronine-induced growth hormone production in cultured rat somatotrophic tumour cells

Acta Endocrinologica ◽

10.1530/acta.0.1240417 ◽

1991 ◽

Vol 124 (4) ◽

pp. 417-424 ◽

Cited By ~ 2

Author(s):

Lawrence E. Shapiro ◽

Claire P. Katz ◽

Susan H. S. Wasserman ◽

Charles R. DeFesi ◽

Martin I. Surks

Keyword(s):

Growth Hormone ◽

Heat Stress ◽

Stress Responses ◽

Glucocorticoid Receptors ◽

Sedimentation Coefficient ◽

Hormone Production ◽

Serum Supplement ◽

Mrna Content

Abstract. We have reported that, in cultured GC cells, the stress of incubation at 41°C enhances thyroid hormone stimulation of growth hormone (GH) in a manner similar to the effects observed in a model of nonthyroidal disease in rats. Since glucocorticoids are potentially involved in stress responses both in vivo and in cell culture, we studied the role of glucocorticoid in the enhancement of (which are rat somatotrophic tumor cells) triiodothyronine (T3)-induced GH synthesis due to heat stress. Hydrocortisone addition increased T3-induced GH synthesis and GH mRNA content in cultured GC cells at both 37°C and 41°C. Depletion of glucocorticoid endogenous to serum supplement of the tissue culture medium did not prevent the enhancement of T3-induced GH synthesis that occurred during incubation at 41°C. The levels and affinity of glucocorticoid cytosolic receptors were not enhanced during incubation at 41°C. Lastly, no change in the sedimentation coefficient of the cytosolic glucocorticoid receptor or in its translocation into the nucleus occurred during incubation at 41°C. Thus, the enhancement of T3-induced GH production in GC cells by heat stress appeared independent of the effect of glucocorticoids and not mediated through glucocorticoid receptors.

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