Lower Water Loss Rates Research Articles

Overexpression of tyrosine decarboxylase (MdTYDC) enhances drought tolerance in Malus domestica

Dopamine is produced in plants and plays a vital role in improving plant responses to abiotic stress. Tyrosine decarboxylase (TYDC) synthesizes tyramine from tyrosine, thereby providing the substrate for dopamine production. However, the function of TYDC in response to drought stress in apple plants remains unclear. In this study, transgenic apple plants that overexpressed MdTYDC were exposed to drought, in order to explore the biological function of TYDC in drought stress. Overexpression of MdTYDC significantly increased apple dopamine content. Transgenic apple plants that overexpressed MdTYDC exhibited less electrolyte leakage, a lower water loss rate, higher photosynthetic pigment contents, and enhanced photosynthetic performance under drought conditions. MdTYDC overexpression also improved reducing power by increasing the ratios of ascorbate to dehydroascorbate and reduced to oxidized glutathione. It influenced leaf water retention capacity and stomatal movement by modulating cellular abscisic acid (ABA) levels and ABA sensitivity. Transcriptomic analyses indicated that MdTYDC overexpression enhanced drought tolerance by regulating the expression of ABA- and drought-related transcription factors, including those from the NAC, ERF, and WRKY families. These results provide evidence for the involvement of MdTYDC and dopamine in enhancing the drought tolerance of apple plants.

Urban rooftop-nesting Common Nighthawk chicks tolerate high temperatures by hyperthermia with relatively low rates of evaporative water loss

Abstract Heat tolerance for many birds under climate and land use change scenarios could be compromised in the future. Common Nighthawks (Chordeiles minor) belong to the Caprimulgiformes, a generally heat-tolerant order, but few studies have assessed heat tolerance in Caprimulgiform chicks, which might be particularly susceptible to heat stress. In the midwestern United States, nighthawks primarily nest on flat graveled rooftops in urban areas, as natural nesting habitats are limited. Urban rooftop-nesting nighthawks are likely exposed to higher environmental temperatures than birds nesting at more thermally buffered natural sites, and evaporative cooling might be impeded by the typically high summer humidity in their Midwest breeding range. This combination of heat and humidity might negatively impact heat tolerance of nighthawk chicks. We exposed 7- to 14-day-old nighthawk chicks (n = 15) from rooftop nests to ambient temperatures (Tas) up to 51°C and at typical summer dew points. Chicks initiated gular flutter at a mean ambient temperature of 42.4 ± 3.4°C (mean ± SE). Evaporative water loss (EWL) rates increased significantly with increasing temperature above 44.0 ± 1.5°C. Chicks showed little evidence of lower and upper bounds of the thermal neutral zone over the range of temperatures (30–44°C) for which we measured oxygen consumption. Body mass loss was significantly positively correlated with temperature during heat exposure trials. Chicks tolerated Tas up to 51°C and body temperatures (Tbs) up to 48°C, which, along with the high temperatures at which gular flutter and high rates of EWL were initiated, suggest that nighthawk chicks are tolerant of high ambient temperatures, even with relatively high humidity. Given the high rates of mass loss and high Tbs at hot ambient temperatures, chick heat tolerance mechanisms could be detrimental for rooftop-nesting nighthawks given projected increasing trends for both heat and humidity in the midwestern United States.

Trans-marine dispersal inferred from the saltwater tolerance of lizards from Taiwan

Dehydration and hypersalinity challenge non-marine organisms crossing the ocean. The rate of water loss and saltwater tolerance thus determine the ability to disperse over sea and further influence species distribution. Surprisingly, this association between physiology and ecology is rarely investigated in terrestrial vertebrates. Here we conducted immersion experiments to individuals and eggs of six lizard species differently distributed across Taiwan and the adjacent islands to understand if the physiological responses reflect the geographical distribution. We found that Plestiodon elegans had the highest rate of water loss and the lowest saltwater tolerance, whereas Eutropis longicaudata and E. multifasciata showed the lowest rate of water loss and the highest saltwater tolerance. Diploderma swinhonis, Hemidactylus frenatus, and Anolis sagrei had medium measurements. For the eggs, only the rigid-shelled eggs of H. frenatus were incubated successfully after treatments. While, the parchment-shelled eggs of E. longicaudata and D. swinhonis lost or gained water dramatically in the immersions without any successful incubation. Combined with the historical geology of the islands and the origin areas of each species, the inferences of the results largely explain the current distribution of these lizards across Taiwan and the adjacent islands, pioneerly showing the association between physiological capability and species distribution.

A natural antisense transcript acts as a negative regulator for the maize drought stress response gene ZmNAC48.

Although plant-specific NAC transcription factors play crucial roles in response to abiotic stress, few reports describe the regulation of NAC genes in maize (Zea mays) by the cis-natural antisense transcripts (cis-NATs). In this study, 521 NAC genes from Gramineae were classified, of which 51 NAC genes contained cis-NATs. ZmNAC48 and cis-NATZmNAC48 co-localized to the same cell nucleus, and both transcripts responded to drought stress. Arabidopsis plants overexpressing ZmNAC48 had improved drought tolerance, lower rate of water loss, enhanced stomatal closure, and higher rates of survival. Transient expression in both maize protoplasts and tobacco leaves indicated that cis-NATZmNAC48 reduced ZmNAC48 expression. Western blotting and ribosome profiling analyses confirmed that cis-NATZmNAC48 lacked protein coding potential. Furthermore, the cis-NAT-derived small-interfering RNAs (nat-siRNAs) generated from the overlapping regions of ZmNAC48 and cis-NATZmNAC48 were detected in maize and transgenic Arabidopsis. Cis-NATZmNAC48 overexpressing maize showed higher water loss rate, increased stomatal opening, and had more dead leaves. Expression of ZmNAC48 and nat-siRNA was decreased in these plants. Taken together, our study indicates that both ZmNAC48 and cis-NATZmNAC48 are involved in plant drought stress responses, and that the double-stranded RNA-dependent mechanism is involved in the interaction between cis-NATZmNAC48 and ZmNAC48. Additionally, cis-NATZmNAC48 may negatively regulate ZmNAC48 to affect stomatal closure of maize.

Overexpression of the wheat NAC transcription factor TaSNAC4-3A gene confers drought tolerance in transgenic Arabidopsis

NAC transcription factors (TFs) play critical roles in plant abiotic stress responses. However, information on the roles of NAC TFs is limited in wheat (Triticum aestivum L.). In this study, we isolated three wheat TaSNAC4 homeologous genes, TaSNAC4-3A, TaSNAC4-3B, and TaSNAC4-3D, and characterized the function of TaSNAC4-3A in plant drought tolerance. TaSNAC4 is highly expressed in seedling leaves, and expression is induced by various abiotic stresses. Transient expression and transactivation assays showed that TaSNAC4-3A is localized to the nucleus, and the C-terminal region has transcriptional activation activity. Overexpression of TaSNAC4-3A in Arabidopsis led to stimulated germination and root growth when exposed to salt and osmotic stresses, and drought stress tolerance was significantly increased in the TaSNAC4-3A transgenic lines. When compared to the control plants, the transgenic lines overexpressing TaSNAC4-3A exhibited reduced stomatal aperture size under drought stress, and therefore had lower water loss rates. In addition, the overexpression of TaSNAC4-3A led to abscisic acid (ABA) hypersensitivity at the root elongation and seed germination stages. Further transcriptomic analysis demonstrated that there was a significant up-regulation of stress responsive genes in the TaSNAC4-3A transgenic lines. Our findings have revealed the important role of TaSNAC4-3A in plant drought tolerance.

Transcriptional variation analysis of Arabidopsis ecotypes in response to drought and salt stresses dissects commonly regulated networks.

Salinity and drought conditions commonly result in osmotic and oxidative stresses, while salinity additionally causes ionic stress. In this study, we identified specific genes regulated by osmotic and ionic stresses in five Arabidopsis ecotypes. Shahdara (SHA) and C24 ecotypes were more tolerant to salt and drought stresses at the seedling growth stage, as evidenced by lower water loss rate, lower electrolyte leakage, and higher survival rate when compared to the other three ecotypes under drought and salinity conditions. Transcriptomic analysis revealed that 3700 and 2242 genes were differentially regulated by salt and osmotic stresses, respectively. Totally 78.1% of upregulated and 62.0% of downregulated genes by osmotic stress were also commonly regulated by salt stress. Gene ontology term enrichment analysis showed that auxin indole-3-acetic acid (IAA), abscisic acid, cytokinin, and gibberellic acid pathways were regulated by the osmotic stress, while IAA, jasmonic acid, and ethylene pathways were changed by the ionic stress. The nutrient and water uptake pathways were regulated by both the osmotic and ionic stresses, whereas ion transportation and kinase pathways were modulated by the ionic stress. Additionally, we characterized bHLH61 as a negative regulator in response to salt and drought stresses. This study provided new clues of plant responses to salt and drought stresses.

Effects of Si in nutrient solution on leaf cuticles

The benefits of silicon for different plant species have been described in many studies in both soilless and traditional soil culture systems. The aim of this work was to quantify the effect of Si on leaf cuticles under different fertigation regimes and the relationship of this effect to water, potassium and nitrate absorption, vegetative growth and plant protection. Cucumber, melon and pepper plants were transplanted into coconut fiber containers with Si in the nutrient solution at 0.6 mM (+Si) and without Si (-Si) under optimal fertigation (OF) and moderate deficit fertigation (DF) conditions. Absorption of water, nitrate and potassium, vegetative growth, leaf firmness, loss of water through cuticle transpiration, cuticle thickness, number of trichomes and Si content in the epidermis and trichomes were measured. Trichome numbers, cuticle thickness and Si content were examined using light and SEM microscopes equipped for X-ray microanalysis. Resistance to two pathogens, Botrytis cinerea and Erysiphe cichoracearum, was also measured. The results show a loss of growth in the three cv. under DF that was alleviated when Si was supplied in the nutrient solution. +Si significantly improved water absorption and decreased leaf loss, which may explain the improvement shown in the growth parameters. +Si showed clear and significant growth increases in both the epidermis and the cuticle, which could justify both the observed greater resistance to diseases and the lower rates of water loss from the leaves. The three cv. showed high concentrations of Si in the trichomes, even under -Si treatments with a mean Si concentration lower than that in the +Si treatments.

Divergence of Desiccation-Related Traits in Sitobion avenae from Northwestern China.

Simple SummaryIncreasing frequency and intensity of drought has been causing increasing vulnerability for many ecosystems around the globe; thus, it is critical to understand how insects evolve in changing environments. We collected and genotyped samples of the wheat aphid Sitobion avenae from arid areas of northwestern China, and then examined their desiccation-related traits. We found both desiccation-resistant and -nonresistant genotypes, providing clear evidence of genetic divergence in desiccation resistance of this aphid. Wingless individuals tended to have higher desiccation resistance than winged ones. Extensive analyses of desiccation-related traits showed that modulation of water loss rates could be the primary mechanism underlying aphids’ resistance against desiccation stress. The content of cuticular hydrocarbons (especially methyl-branched alkanes) and their high plasticity could be closely linked to water loss rates in aphids, thereby modulating their desiccation resistance. This study can provide insights into how insects adapt to desiccating environments, and has particular relevance to the prediction of insect pest outbreaks under future warming scenarios.The impact of drought on insects has become increasingly evident in the context of global climate change, but the physiological mechanisms of aphids’ responses to desiccating environments are still not well understood. We sampled the wheat aphid Sitobion avenae (Fabricius) (Hemiptera: Aphididae) from arid areas of northwestern China. Both desiccation-resistant and -nonresistant genotypes were identified, providing direct evidence of genetic divergence in desiccation resistance of S. avenae. Resistant genotypes of wingless S. avenae showed longer survival time and LT50 under the desiccation stress (i.e., 10% relative humidity) than nonresistant genotypes, and wingless individuals tended to have higher desiccation resistance than winged ones. Both absolute and relative water contents did not differ between the two kinds of genotypes. Resistant genotypes had lower water loss rates than nonresistant genotypes for both winged and wingless individuals, suggesting that modulation of water loss rates could be the primary strategy in resistance of this aphid against desiccation stress. Contents of cuticular hydrocarbons (CHC) (especially methyl-branched alkanes) showed significant increase for both resistant and nonresistant genotypes after exposure to the desiccation stress for 24 h. Under desiccation stress, survival time was positively correlated with contents of methyl-branched alkanes for resistant genotypes. Thus, the content of methyl-branched alkanes and their high plasticity could be closely linked to water loss rate and desiccation resistance in S. avenae. Our results provide insights into fundamental aspects and underlying mechanisms of desiccation resistance in aphids, and have significant implications for the evolution of aphid populations in the context of global warming.

Potato E3 ubiquitin ligase PUB27 negatively regulates drought tolerance by mediating stomatal movement

The ubiquitin-proteasome system (UPS) is one of the main ways of eukaryotic protein degradation and post-translational modification. It has proven as an essential process for plants to respond to abiotic stresses. Plant U-box (PUB) protein acts as a ubiquitin ligase, which recognizes and ubiquitinates the target proteins. Many PUBs have been involved in water stress in Arabidopsis and rice, but similar comprehensive studies in potato remained limited. In this study, the overexpressed and interfered transgenic potato plants of StPUB27 were obtained and their performances were evaluated under osmotic stress. The result showed that overexpression of StPUB27 accelerated the dehydration of detached leaves companied with greater stomatal conductance, while the down-regulated StPUB27 expression by RNA interference (RNAi) showed a smaller stomatal conductance and a lower rate of water loss in detached leaves, thus showing higher tolerance to osmotic stress. In addition, no significant changes in the proline content were observed between StPUB27 overexpressed and RNAi potato plants. The result demonstrated that potato E3 ubiquitin ligase PUB27 may negatively regulate drought tolerance by mediating stomatal conductance.

Postharvest Spectral Light Composition Affects Chilling Injury in Anthurium Cut Flowers.

The effect of the lighting environment during postharvest storage of ornamentals has largely been neglected in previous research. Anthurium is a cold-sensitive species originating from tropical climates and is widely cultivated all around the world for its colorful spathes. To investigate the effects of light spectrum on the performance of Anthurium cut flowers under cold storage, two cultivars [Calore (red spathe) and Angel (withe spathe)] were placed at low temperature (4°C), either in darkness (D) or under different light spectra [red (R), blue (B), 70:30% red:blue (RB), and white (W)] at an intensity of 125 µmol.m−2.s−1. In both cultivars, the longest and shortest vase lives were observed in spathes exposed to the R and B spectra, respectively. In both cultivars, electrolyte leakage (EL) of spathe was highest under the B and W spectra and lowest under the R spectrum. The highest rate of flower water loss from the spathes was observed under the B-containing light spectra, whereas the lowest rate of water loss was observed in D and under the R spectrum. Negative correlations were observed between EL and vase life and between anthocyanin concentration and EL for both Anthurium cultivars. A positive correlation was found between anthocyanin concentration and vase life. For both Anthurium cultivars, spectral light composition with higher percentage of B resulted in higher EL and as a result shorter vase life in cut flowers under cold storage condition. The negative effect of the B light spectrum on vase life of Anthurium can be explained through its effect on water loss and on oxidative stress and membrane integrity. The quality of Anthurium cut flowers should benefit from environments with restricted B light spectrum during postharvest handling.

Measurement of Oxygen Transport through Separators in Flooded Batteries

An in-depth understanding of oxygen transport in flooded lead acid batteries is necessary to better understand and mitigate water loss in the next generation of batteries for start-stop vehicle applications. The presence of the oxygen cycle leads to a lower rate of water loss observed during intermittent drive cycle testing compared to the gassing that would be calculated from the integrated overcharge current into the battery [1]. A model of the oxygen cycle in flooded lead acid batteries has been proposed [2] but until recently the oxygen transport through the separator-electrolyte system hasn’t been measured.A method for measuring oxygen transport through the separator-electrolyte system has been developed which uses electrodes harvested from commercial batteries. In this method, the separator is sealed between two chambers of a test cell, one containing the positive electrode and the other containing the negative electrode plus a reference. A constant stream of oxygen is delivered to the positive side of the cell using an air pump and diffuser. The negative side is purged, sealed and constantly stirred. The cell is charged and allowed to rest at OCV. Oxygen diffuses from the constant source on the positive side to the negative side where it oxidizes some of the negative active mass. This creates a measurable capacity change at the negative electrode which can be measured during a potentiostatically-controlled recharge cycle.We will report on measurements of oxygen transport through the separator-electrolyte system for different separator materials in a flooded cell using commercial lead acid electrodes. Results are compared with modeling of the oxygen cycle and related to factors in the separator which influence the oxygen transport rate, such as porosity, pore size distribution and tortuosity,.[1] Wirth, 16ELBC, 07 September 2018, Vienna Austria[2] Meissner, Scientific Workshop: High-Temperature Durability Tests for Advanced Lead 12-V Batteries, 30 January 2017, Kloster Eberbach, Germany

MfPIF1 of Resurrection Plant Myrothamnus flabellifolia Plays a Positive Regulatory Role in Responding to Drought and Salinity Stresses in Arabidopsis.

Phytochrome-interacting factors (PIFs), a subfamily of basic helix-loop-helix (bHLH) transcription factors (TFs), play critical roles in regulating plant growth and development. The resurrection plant Myrothamnus flabellifolia possesses a noteworthy tolerance to desiccation, but no PIFs related to the response to abiotic stress have been functionally studied. In this study, a dehydration-inducible PIF gene, MfPIF1, was cloned and characterized. Subcellular localization assay revealed that MfPIF1 is localized predominantly in the nucleus. Overexpression of MfPIF1 in Arabidopsis thaliana led to enhanced drought and salinity tolerance, which was attributed to higher contents of chlorophyll, proline (Pro), soluble protein, and soluble sugar, activities of antioxidant enzymes as well as lower water loss rate, malondialdehyde (MDA) content, and reactive oxygen species (ROS) accumulation in transgenic lines compared with control plants. Moreover, MfPIF1 decreased stomatal aperture after drought and abscisic acid (ABA) treatment, and increased expression of both ABA biosynthesis and ABA-responsive genes including NCED3, P5CS, and RD29A. Overall, these results indicated that MfPIF1 may act as a positive regulator to drought and salinity responses, and therefore could be considered as a potential gene for plant genetic improvement of drought and salinity tolerance.

Overexpression of grapevine VvNAC08 enhances drought tolerance in transgenic Arabidopsis

NAC [No apical meristem (NAM), Arabidopsis transcription activation factor (ATAF), Cup-shaped cotyledon (CUC)] transcription factors (TFs) play an important role in plant growth and response to various environmental stress. Drought stress is the primary factor limiting the growth and fruit quality of grapevines worldwide. However, the biological function of the NAC family members in grapevine is not clear. In this study, we reported that VvNAC08, a novel NAC transcription factor gene, was expressed after drought, salicylic acid (SA) and abscisic acid (ABA), jasmonic acid (JA) and melatonin (MT) treatments in grapevine. VvNAC08 was expressed in various tissues. The open reading frame (ORF) of VvNAC08 was 792 bp, encoding 263 amino acids. The VvNAC08 protein could bind to NACRS [CGTA/CACG] in yeast. When subjected to drought and dehydration stress, VvNAC08-overexpression (OE) Arabidopsis had a higher survival rate and a lower water loss rate than wild type (WT) plants. Under drought conditions, transgenic Arabidopsis overexpressing VvNAC08 had a lower malondialdehyde (MDA), H2O2 contents, but a higher peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) activities as well as more proline content. Moreover, the expressions of marker genes, including ABI5, AREB1, COR15A, COR47, P5CS, RD22, and RD29A, were up-regulated in VvNAC08-overexpression lines when subjected to drought treatments. The results suggest that the transgenic Arabidopsis overexpressing VvNAC08 enhances resistance to drought while up-regulating the expressions of ABA- and stress-related genes.

Optical, structural, mechanical and thermal characterization of antioxidant ethylene vinyl alcohol copolymer films containing betalain-rich beetroot

New antioxidant films based on ethylene vinyl alcohol (EVOH) copolymer containing betalain-rich red beet were successfully manufactured and characterized to develop bioactive packaging for food products. Two types of red beet (powder and extract) at different proportions (0.1, 0.5, 1.0, 1.5, 2.0 and 2.5 % (w/w)) were incorporated into EVOH films, with attention focused on the optical, chemical, thermal, structural, and mechanical and antioxidant properties. The incorporation of any red beet type into EVOH resulted in purple-colored and semi-crystalline thin films, without modifying their thermal stability and mechanical properties. The addition of the beet extract led to a film with higher color intensity, antioxidant activity and lower water loss rate, whereas the addition of powdered beet resulted in an improved UV barrier compared to the extract. The results showed that new antioxidant food packaging films based on EVOH could be realized by utilizing beetroot extract or powder obtained from natural resources.

Characterization of wheat homeodomain-leucine zipper family genes and functional analysis of TaHDZ5-6A in drought tolerance in transgenic Arabidopsis

BackgroundMany studies in Arabidopsis and rice have demonstrated that HD-Zip transcription factors play important roles in plant development and responses to abiotic stresses. Although common wheat (Triticum aestivum L.) is one of the most widely cultivated and consumed food crops in the world, the function of the HD-Zip proteins in wheat is still largely unknown.ResultsTo explore the potential biological functions of HD-Zip genes in wheat, we performed a bioinformatics and gene expression analysis of the HD-Zip family. We identified 113 HD-Zip members from wheat and classified them into four subfamilies (I-IV) based on phylogenic analysis against proteins from Arabidopsis, rice, and maize. Most HD-Zip genes are represented by two to three homeoalleles in wheat, which are named as TaHDZX_ZA, TaHDZX_ZB, or TaHDZX_ZD, where X denotes the gene number and Z the wheat chromosome on which it is located. TaHDZs in the same subfamily have similar protein motifs and intron/exon structures. The expression profiles of TaHDZ genes were analysed in different tissues, at different stages of vegetative growth, during seed development, and under drought stress. We found that most TaHDZ genes, especially those in subfamilies I and II, were induced by drought stress, suggesting the potential importance of subfamily I and II TaHDZ members in the responses to abiotic stress. Compared with wild-type (WT) plants, transgenic Arabidopsis plants overexpressing TaHDZ5-6A displayed enhanced drought tolerance, lower water loss rates, higher survival rates, and higher proline content under drought conditions. Additionally, the transcriptome analysis identified a number of differentially expressed genes between 35S::TaHDZ5-6A transgenic and wild-type plants, many of which are involved in stress response.ConclusionsOur results will facilitate further functional analysis of wheat HD-Zip genes, and also indicate that TaHDZ5-6A may participate in regulating the plant response to drought stress. Our experiments show that TaHDZ5-6A holds great potential for genetic improvement of abiotic stress tolerance in crops.

Overexpression of a Rice Monosaccharide Transporter Gene (OsMST6) Confers Enhanced Tolerance to Drought and Salinity Stress in Arabidopsis thaliana

Monosaccharide transporter (MSTs) is a large family of integral membrane proteins that plays a crucial role in cell-to-cell and long-distance distribution of sugars throughout the plant. It has long been regarded as one of the most essential components in a myriad of plant physiological functions such as carbohydrate partitioning, sugar signaling, and environmental stress response. In the present study, an in vivo functional analysis of a rice monosaccharide transporter gene, namely OsMST6, has been conducted using a transgenic approach to understand its role in plant responses to abiotic stress. Physiological traits analysis indicated that the transgenic lines had a relatively lower water loss rate, higher relative water content (1.3–2.2-fold), increased cell membrane stability (1.5–2-fold), and higher total soluble sugar content (2.8–3.5-fold) compared to the parental lines. Furthermore, the overexpression of OsMST6 was also found to enhance both drought and salt tolerance in transgenic Arabidopsis thaliana. Taken together, these results suggested that OsMST6 may be involved in the adaptation of rice plant to water stress by maintaining the water status of plant cells. This study provides insight into the function of OsMST6, which may have potential application in the generation of transgenic abiotic stress-tolerant plants.

The Soybean GmNAC019 Transcription Factor Mediates Drought Tolerance in Arabidopsis in an Abscisic Acid-Dependent Manner.

Being master regulators of gene expression, transcription factors (TFs) play important roles in determining plant growth, development and reproduction. To date, many TFs have been shown to positively mediate plant responses to environmental stresses. In the current study, the biological functions of a stress-responsive NAC [NAM (No Apical Meristem), ATAF1/2 (Arabidopsis Transcription Activation Factor1/2), CUC2 (Cup-shaped Cotyledon2)]-TF encoding gene isolated from soybean (GmNAC019) in relation to plant drought tolerance and abscisic acid (ABA) responses were investigated. By using a heterologous transgenic system, we revealed that transgenic Arabidopsis plants constitutively expressing the GmNAC019 gene exhibited higher survival rates in a soil-drying assay, which was associated with lower water loss rate in detached leaves, lower cellular hydrogen peroxide content and stronger antioxidant defense under water-stressed conditions. Additionally, the exogenous treatment of transgenic plants with ABA showed their hypersensitivity to this phytohormone, exhibiting lower rates of seed germination and green cotyledons. Taken together, these findings demonstrated that GmNAC019 functions as a positive regulator of ABA-mediated plant response to drought, and thus, it has potential utility for improving plant tolerance through molecular biotechnology.

Genomic Analysis of Stress Associated Proteins in Soybean and the Role of GmSAP16 in Abiotic Stress Responses in Arabidopsis and Soybean.

Stress associated proteins (SAPs) containing A20/AN1 zinc finger domains have emerged as novel regulators of stress responses. In this study, 27 SAP genes were identified in soybean. The phylogenetic relationships, exon–intron structure, domain structure, chromosomal localization, putative cis-acting elements, and expression patterns of SAPs in various tissues under abiotic stresses were analyzed. Among the soybean SAP genes, GmSAP16 was significantly induced by water deficit stress, salt, and abscisic acid (ABA) and selected for further analysis. GmSAP16 was located in the nucleus and cytoplasm. The overexpression of GmSAP16 in Arabidopsis improved drought and salt tolerance at different developmental stages and increased ABA sensitivity, as indicated by delayed seed germination and stomatal closure. The GmSAP16 transgenic Arabidopsis plants had a higher proline content and a lower water loss rate and malondialdehyde (MDA) content than wild type (WT) plants in response to stresses. The overexpression of GmSAP16 in soybean hairy roots enhanced drought and salt tolerance of soybean seedlings, with higher proline and chlorophyll contents and a lower MDA content than WT. RNA inference (RNAi) of GmSAP16 increased stress sensitivity. Stress-related genes, including GmDREB1B;1, GmNCED3, GmRD22, GmDREB2, GmNHX1, and GmSOS1, showed significant expression alterations in GmSAP16-overexpressing and RNAi plants under stress treatments. These results indicate that soybean SAP genes play important roles in abiotic stress responses.

Variation in field body temperature and total evaporative water loss along an environmental gradient in a diurnal ectotherm

AbstractThe maintenance of optimal body temperatures has profound consequences on all aspects of ectotherms life history, like fitness and performance, and has been the subject of research for decades. In contrast, for reptiles, comparatively less is known on the potential effects of water balance on physiology, ecology and behaviour. In recent years, several recent studies are pointing out the importance of studying thermoregulation and water balance within the same framework. Here, we used a Mediterranean lizard, Psammodromus algirus, to investigate how field body temperature and water loss rates may vary among populations, between sexes and along an altitudinal gradient. We found little variation in field body temperatures among populations, while within each population, field body temperature may change daily, seasonally and differ between sexes. On the contrary, water loss rates decreased with elevation and showed no seasonal trend or difference between sexes. Microclimatic data indicated that highland lizards experienced more fluctuating conditions, a factor that may explain their lower water loss rates. Other factors, like inter‐population differences in ectoparasite intensity, might also contribute in explaining the observed patterns. We present here the first data for a lacertid lizard on the inter‐population variability and sexual difference in water loss rates and point out that water balance may play a fundamental role in regulating lizard activity during the hottest and driest period of the year.

Водоудерживающая способность хвои в популяциях основных лесообразующих видов хвойных в лесах таежной зоны Сибири

The limits of individual variation of trees by the water-retaining capacity of needles in populations of forest-forming coniferous species (Scots pine, Siberian pine, Siberian spruce and Siberian fir) growing in the conditions of the mountainous, middle and northern taiga of Central and Eastern Siberia were studied. It is found that among the compared evergreen species, Scots pine and Siberian pine are characterized by the highest intrapopulation variation in the rate of needles dehydration; Siberian spruce and Siberian fir are characterized by greater variability in the ability of needles to water absorption. However, in samples of the last twospecies, the share of trees with a low rate of water loss is quite large, even in wet habitats. In more drought-resistant pine species there is a smaller part of trees, which quickly evaporate moisture and have a high water capacity of needles. While a smaller part of trees of Siberian spruce and Siberian fir are less resistant to dehydration and differ by low water capacity of needles. While in Siberian spruce and Siberian fir a smaller part are trees less resistant to dehydration with low water capacity of needles. We revealed the significant differences between species in mixed stands and between geographic populations of species by water-retaining capacityof needles. The highest values of this indicator were obtained for Scots pine and Siberian spruce from Yakutia, as well as for old-growth trees of Siberian pine from the Western Sayan. The necessity of preserving old-growth stands and trees, characterized by the greatest drought resistance of needles, especially hygrophilous dark coniferous species in a changing climate is emphasized.The obtained data and correlations between the used features allow us to estimate one of the components of drought resistance of taiga populations of coniferous species and their intrapopulation diversity.For citation: Tikhonova N.А., Tikhonova I.V. Water Retaining Capacity of Needles in Populations of the Main Forest-Forming Coniferous Species in the Forests of the Taiga Zone of Siberia. Lesnoy Zhurnal [Forestry Journal], 2019, no. 5, pp. 83–94. DOI: 10.17238/issn0536-1036.2019.5.83Funding: The research is carried out within the framework of the budget project No. 0346-2016-0301 of the West-Siberian Branch of Sukachev Institute of Forest SB RAS and the Federal Research Center “Krasnoyarsk Science Center SB RAS” with the partial financial support from the Russian Foundation for Basic Research, the Government of Krasnoyarsk Territory, and the Krasnoyarsk Regional Fund of Science in the framework of the research project No. 18-44-240002.