For a long time, hydrogen sulfide (H2S) has been considered as merely a toxic by product of cell metabolism, but nowadays is emerging as a novel gaseous signal molecule, which participates in seed germination, plant growth and development, as well as the acquisition of stress tolerance including cross-adaptation in plants. Cross-adaptation, widely existing in nature, is the phenomenon in which plants expose to a moderate stress can induce the resistance to other stresses. The mechanism of cross-adaptation is involved in a complex signal network consisting of many second messengers such as Ca2+, abscisic acid, hydrogen peroxide and nitric oxide, as well as their crosstalk. The cross-adaptation signaling is commonly triggered by moderate environmental stress or exogenous application of signal molecules or their donors, which in turn induces cross-adaptation by enhancing antioxidant system activity, accumulating osmolytes, synthesizing heat shock proteins, as well as maintaining ion and nutrient balance. In this review, based on the current knowledge on H2S and cross-adaptation in plant biology, H2S homeostasis in plant cells under normal growth conditions; H2S signaling triggered by abiotic stress; and H2S-induced cross-adaptation to heavy metal, salt, drought, cold, heat, and flooding stress were summarized, and concluded that H2S might be a candidate signal molecule in plant cross-adaptation. In addition, future research direction also has been proposed.

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Hydrogen Sulfide: A Signal Molecule in Plant Cross-Adaptation.

Soybean is an important crop that is continually threatened by abiotic stresses, especially drought and heat stress At molecular levels, reduced yields due to drought and heat stress can be seen as a result of alterations in metabolic homeostasis of vegetative tissues At present an incomplete understanding of abiotic stress-associated metabolism and identification of associated metabolites remains a major gap in soybean stress research A study with a goal to profile leaf metabolites under control conditions (28/24 °C), drought [28/24 °C, 10% volumetric water content (VWC)], and heat stress (43/35 °C) was conducted in a controlled environment Analyses of non-targeted metabolomic data showed that in response to drought and heat stress, key metabolites (carbohydrates, amino acids, lipids, cofactors, nucleotides, peptides and secondary metabolites) were differentially accumulated in soybean leaves The metabolites for various cellular processes, such as glycolysis, the tricarboxylic acid (TCA) cycle, the pentose phosphate pathway, and starch biosynthesis, that regulate carbohydrate metabolism, amino acid metabolism, peptide metabolism, and purine and pyrimidine biosynthesis, were found to be affected by drought as well as heat stress Computationally based regulatory networks predicted additional compounds that address the possibility of other metabolites and metabolic pathways that could also be important for soybean under drought and heat stress conditions Metabolomic profiling demonstrated that in soybeans, keeping up with sugar and nitrogen metabolism is of prime significance, along with phytochemical metabolism under drought and heat stress conditions

https://www.mdpi.com/2223-7747/6/2/21/pdf

Metabolomic Profiling of Soybeans (Glycine max L.) Reveals the Importance of Sugar and Nitrogen Metabolism under Drought and Heat Stress.

Cytochrome P450s (CYPs) are the largest enzyme family involved in NADPH- and/or O2-dependent hydroxylation reactions across all the domains of life. In plants and animals, CYPs play a central role in the detoxification of xenobiotics. In addition to this function, CYPs act as versatile catalysts and play a crucial role in the biosynthesis of secondary metabolites, antioxidants, and phytohormones in higher plants. The molecular and biochemical processes catalyzed by CYPs have been well characterized, however, the relationship between the biochemical process catalyzed by CYPs and its effect on several plant functions was not well established. The advent of next-generation sequencing opened new avenues to unravel the involvement of CYPs in several plant functions such as plant stress response. The expression of several CYP genes are regulated in response to environmental stresses, and they also play a prominent role in the crosstalk between abiotic and biotic stress responses. CYPs have an enormous potential to be used as a candidate for engineering crop species resilient to biotic and abiotic stresses. The objective of this review is to summarize the latest research on the role of CYPs in plant stress response.

Role of Cytochrome P450 Enzymes in Plant Stress Response.

Ambient temperatures are predicted to rise in the future owing to several reasons associated with global climate changes. These temperature increases can result in heat stress- a severe threat to crop production in most countries. Legumes are well-known for their impact on agricultural sustainability as well as their nutritional and health benefits. Heat stress imposes challenges for legume crops and has deleterious effects on the morphology, physiology, and reproductive growth of plants. High-temperature stress at the time of the reproductive stage is becoming a severe limitation for production of grain legumes as their cultivation expands to warmer environments and temperature variability increases due to climate change. The reproductive period is vital in the life cycle of all plants and is susceptible to high-temperature stress as various metabolic processes are adversely impacted during this phase, which reduces crop yield. Food legumes exposed to high-temperature stress during reproduction show flower abortion, pollen and ovule infertility, impaired fertilization, and reduced seed filling, leading to smaller seeds and poor yields. Through various breeding techniques, heat tolerance in major legumes can be enhanced to improve performance in the field. Omics approaches unravel different mechanisms underlying thermotolerance, which is imperative to understand the processes of molecular responses toward high-temperature stress.

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Food Legumes and Rising Temperatures: Effects, Adaptive Functional Mechanisms Specific to Reproductive Growth Stage and Strategies to Improve Heat Tolerance

Drought and heat stress cause losses in wheat productivity in major growing regions worldwide, and both the occurrence and the severity of these events are likely to increase with global climate change. Water deficits and high temperatures frequently occur simultaneously at sensitive growth stages, reducing wheat yields by reducing grain number or weight. Although genetic variation and underlying quantitative trait loci for either individual stress are known, the combination of the two stresses has rarely been studied. Complex and often antagonistic physiology means that genetic loci underlying tolerance to the combined stress are likely to differ from those for drought or heat stress tolerance alone. Here, we review what is known of the physiological traits and genetic control of drought and heat tolerance in wheat and discuss potential physiological traits to study for combined tolerance. We further place this knowledge in the context of breeding for new, more tolerant varieties and discuss opportunities and constraints. We conclude that a fine control of water relations across the growing cycle will be beneficial for combined tolerance and might be achieved through fine management of spatial and temporal gas exchange.

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The physiological and genetic basis of combined drought and heat tolerance in wheat.

Drought and heat are among the major abiotic stresses that affect soybean crops worldwide. During the current investigation, the effect of drought, heat, and drought plus heat stresses was compared in the leaves of two soybean varieties, Surge and Davison, combining 2D-DIGE proteomic data with physiology and biochemical analyses. We demonstrated how 25 differentially expressed photosynthesis-related proteins affect RuBisCO regulation, electron transport, Calvin cycle, and carbon fixation during drought and heat stress. We also observed higher abundance of heat stress-induced EF-Tu protein in Surge. It is possible that EF-Tu might have activated heat tolerance mechanisms in the soybean. Higher level expressions of heat shock-related protein seem to be regulating the heat tolerance mechanisms. This study identifies the differential expression of various abiotic stress-responsive proteins that regulate various molecular processes and signaling cascades. One inevitable outcome from the biochemical and proteomics assays of this study is that increase of ROS levels during drought stress does not show significant changes at the phenotypic level in Davison and this seems to be due to a higher amount of carbonic anhydrase accumulation in the cell which aids the cell to become more resistant to cytotoxic concentrations of H2O2.

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Leaf Proteome Analysis Reveals Prospective Drought and Heat Stress Response Mechanisms in Soybean.

Heat stress is one of the major abiotic stresses that plants encounter. Heat stress causes billions of dollars in losses of agricultural crops worldwide. Here, we summarize the molecular and whole genome responses due to heat stress in plants. It has been reported that there are cascades of biochemical reactions that lead to heat stress. In most cases, heat stress is coupled with drought stress response. With the advancements in genomic tools, we have more information on genes, which are up- or down-regulated in plants due to heat stress. The heat-stressed plants may exhibit various physiological responses, including stomatal closure, suppressed photosynthesis, stunted growth, etc. Microarray and transcriptome sequencing gave us the tools to perform genome-wide expression profiling in heat-stressed plants. Understanding how gene expression in heat-stressed plants works will help us to discover novel heat stress-tolerant genes. These genes could be overexpressed in crop plants to make transgenic heat-tolerant agricultural crops. Climate change and global warming are major concerns for us and production of thermotolerant plants could address the issue of global crop loss due to heat and drought stresses.

Molecular Physiology of Heat Stress Responses in Plants

Abstract Paulownia elongata is a short-rotation fast growing tree and is known for high biomass accumulation and carbon sequestration potential. Optimization of protocols for nucleic acid extraction, PCR, RT-PCR, and other molecular biology techniques are required for better understanding of cellulose synthesis and to assess the potential of Paulownia as a biofuel tree. The main objective of this work was to study a putative cellulose synthase amplicon expression under various environmental conditions and evaluate the potentials of Paulownia as a biofuel tree. Using cross-species PCR an amplicon representative of a putative cellulose synthase gene from Paulownia was identified. This 177-bp long DNA sequence was 46% similar with cellulose synthase genes from Arabidopsis as expected. Gene specific primers for this particular Paulownia cellulose synthase gene were designed and reverse transcription PCR was performed to confirm its transcription. We report an inexpensive cDNA dot-blot method to study expression of this gene under various environmental conditions. We observed that cold and, to a lesser extent, heat stress downregulated its expression. This information will help to understand cellulose deposition in plant cell wall under stressful conditions. To the best of our knowledge this is the first characterization of a cDNA sequence from Paulownia elongata.

Cross-species PCR and field studies on Paulownia elongata: A potential bioenergy crop

Cellulase is a widely used enzyme for saccharification of plant cell walls for the production of biofuels. In our work, we tested an ethanol inducible native alcA promoter from Aspergillus nidulans in Escherichia coli (E. coli) and tobacco. The alcA promoter was fused with a cellulase gene and then the promoter was compared with other widely used promoters, namely, T5 and cauliflower mosaic virus (CaMV) 35S in E. coli. We also tested the activity of alcA promoter in tobacco by transiently expressing a green fluorescent protein gene under the control of alcA promoter. We concluded from our quantitative polymerase chain reaction (qPCR) results that when alcA promoter was expressed along with AlcR transcription factor, the alcA promoter was 11 times more active than the T5 promoter. The qPCR data suggested that there may be a direct correlation between AlcR concentrations and alcA activity, indicating a key role of the activator AlcR in the regulation of the alcA promoter. Our work on inducible promoter syst...

https://www.tandfonline.com/doi/pdf/10.1080/13102818.2015.1065711

Transcriptional analyses of an ethanol inducible promoter in Escherichia coli and tobacco for production of cellulase and green fluorescent protein

Background Nowadays, grandparents have a major role in taking care of their grandchildren. Also, caring for grandchildren is a common and normative experience for many Iranian grandparents. The present study aimed to compare the quality of life of physically active and inactive grandmothers caring and non-caring for grandchildren. Methods This analytical cross-sectional study was conducted on 300 grandmothers at the age range of 50 to 70 years old, who lived in Bojnurd, northeastern Iran (2018). Data were collected using the questionnaires of 36-Item Short Form Health Survey (SF-36) and Baecke Physical Activity, and demographic information. Results The total scores of quality of life in caring physically active, physically inactive, non-caring physically active and non-caring physically inactive grandmothers were 76.95±6.33, 71.74±9.41, 75.56±5.9, and 56.06±11.23, respectively. There was a significant difference in the comparison of the quality of life score in caring grandmothers in two active and inactive groups (P<0.001). In addition, the quality of life score of non-caring grandmothers indicated a significant difference in physically active and inactive grandmothers (P<0.001). Conclusion According to the results of this study, it seems that caring physically active grandmothers have higher quality of life. It can be suggested that the grandmothers who care for their grandchildren may improve their health and quality of life by incorporating the programs to increase physical activities in their daily life.

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Homa Hemmati

Papers

Leaf Proteome Analysis Reveals Prospective Drought and Heat Stress Response Mechanisms in Soybean.

Molecular Physiology of Heat Stress Responses in Plants

Cross-species PCR and field studies on Paulownia elongata: A potential bioenergy crop

Transcriptional analyses of an ethanol inducible promoter in Escherichia coli and tobacco for production of cellulase and green fluorescent protein

Comparison of the Quality of Life of Physically Active and Inactive Grandmothers Caring and Non-caring for Grandchildren: A Cross-Sectional Study