Physiological Assays Research Articles

Investigation of the antifungal activity of the dicarboximide fungicide iprodione against Bipolaris maydis

Southern corn leaf blight (SCLB), mainly caused by Bipolaris maydis, is a destructive disease of maize worldwide. Iprodione is a widely used dicarboximide fungicide (DCF); however, its antifungal activity against B. maydis has not been well studied until now. In this study, the sensitivity of 103 B. maydis isolates to iprodione was determined, followed by biochemistry and physiology assays to ascertain the fungicide's effect on the morphology and other biological properties of B. maydis. The results indicated that iprodione exhibited strong inhibitory activity against B. maydis, and the EC50 values in inhibiting mycelial growth ranged from 0.088 to 1.712 μg/mL, with a mean value of 0.685 ± 0.687 μg/mL. After treatment with iprodione, conidial production of B. maydis was decreased significantly, and the mycelia branches increased with obvious shrinkage, distortion and fracture. Moreover, the expression levels of the osmotic pressure-related regulation genes histidine kinase (hk) and Ssk2-type mitogen-activated protein kinase (ssk2) were upregulated, the glycerin content of mycelia increased significantly, the relative conductivity of mycelia increased, and the cell wall membrane integrity was destroyed. The in vivo assay showed that iprodione at 200 μg/mL provided 79.16% protective efficacy and 90.92% curative efficacy, suggesting that the curative effect was better than the protective effect. All these results proved that iprodione exhibited strong inhibitory activity against B. maydis and provided excellent efficacy in controlling SCLB, indicating that iprodione could be an alternative candidate for the control of SCLB in China.

The carboxyl-terminal TSP1-homology domain is the biologically active effector peptide of matricellular protein CCN5 that counteracts profibrotic CCN2

Cellular Communication Network (CCN) proteins have multi-modular structures important for their roles in cellular responses associated with organ development and tissue homeostasis. CCN2 has previously been reported to be secreted as a preproprotein that requires proteolytic activation to release its bioactive carboxyl-terminal fragment. Here, our goal was to resolve whether CCN5, a divergent member of the CCN family with converse functions relative to CCN2, releases the TSP1 homology domain as its bioactive signaling entity. The recombinant CCN5 or CCN3 TSP1 homology domains were produced in ExpiCHO-S or DG44 CHO cells as secretory fusion proteins appended to the carboxyl-terminal end of His-Halo-Sumo or amino-terminal end of human albumin, and purified from the cell culture medium. We tested these fusion proteins in various phosphokinase signaling pathways or cell physiologic assays. Fusion proteins with the CCN5 TSP1 domain inhibited key signaling pathways previously reported to be stimulated by CCN2, irrespective of fusion partner. The fusion proteins also efficiently inhibited CCN1/2-stimulated cell migration and gap closure following scratch wound of fibroblasts. Fusion protein with the CCN3 TSP1 domain inhibited these functions with similar efficacy and potency as that of the CCN5 TSP1 domain. The CCN5 TSP1 domain also recapitulated a positive regulatory function previously assigned to full-length CCN5, i.e. induction of estrogen receptor-α mRNA expression in triple negative MDA-MB-231 mammary adenocarcinoma cells and inhibited epithelial-to-mesenchymal transition and CCN2-induced mammosphere formation of MCF7 adenocarcinoma cells. In conclusion, the CCN5 TSP1 domain is the bioactive entity that confers the biologic functions of unprocessed CCN5.

Physiological and transcriptome analyses reveal that mid-fruit load improves the strength of source and sink in grapevine (Vitis Vinifera L.)

• In the present study, the assay for biochemical and molecular mechanism were used by 13 C labeling, full-length RNA-seq and gene transformation. • We make a conclusion that 50%FL significantly improved the source and sink strength. As a prime candidate gene, overexpression of VvPUP1 in grape cells improved its sugar accumulation. • These results demonstrates that the optimal fruit load was about 50%. Appropriately adjusting fruit loads (FL) can promote plant productivity in the field. In the present study, physiological, transcriptomic, and gene function assays were conducted by 13 C labeling, full-length RNA-seq, and gene transformation. A comparative analysis of three different FL treatments (25%FL, 50%FL, and 100% FL) was performed to identify the mechanism that response to different FL. The results showed that 50%FL significantly improved the source strength by enhancing photosynthesis. The sink strength of 50%FL also reached the maximum when considering soluble sugar, weight, 13 C allocation, sugar metabolism-related enzyme activity, and composition in berries, and yield. In addition, full-length transcriptome profiling exploited 1,098 differently expressed genes (DEGs) in 25%FL and 100%FL, and 1,479 DEGs in 50%FL and 100%FL, respectively. Thirty-four genes, including PUP1 and FBA1 , were identified in carbon transport and metabolism-related pathways. As a major candidate gene, VvPUP1 was found to enhance sugar accumulation when overexpressed in grape cells. The transgenic cells had high soluble sugar contents and sucrose synthase (SS), neutral invertase (NI), and sucrose phosphate synthase (SPS) activities. Overexpression of VvPUP1 in tomatoes increased fruit size and weight, soluble sugar concentration, and the expression levels of SlSUS1, SlSPS1 , and SlBGLU13 , suggesting that VvPUP1 can promote berry enlargement and sugar accumulation. These results provide novel insights into the response of grapevine to different FL, demonstrating the differences in the source (leaf) and sink (berry) strength among different FL grapes.

Intercommunication between Voltage-Gated Calcium Channels and Estrogen Receptor/Estrogen Signaling: Insights into Physiological and Pathological Conditions

Voltage-gated calcium channels (VGCCs) and estrogen receptors are important cellular proteins that have been shown to interact with each other across varied cells and tissues. Estrogen hormone, the ligand for estrogen receptors, can also exert its effects independent of estrogen receptors that collectively constitute non-genomic mechanisms. Here, we provide insights into the VGCC regulation by estrogen and the possible mechanisms involved therein across several cell types. Notably, most of the interaction is described in neuronal and cardiovascular tissues given the importance of VGCCs in these electrically excitable tissues. We describe the modulation of various VGCCs by estrogen known so far in physiological conditions and pathological conditions. We observed that in most in vitro studies higher concentrations of estrogen were used while a handful of in vivo studies used meager concentrations resulting in inhibition or upregulation of VGCCs, respectively. There is a need for more relevant physiological assays to study the regulation of VGCCs by estrogen. Additionally, other interacting receptors and partners need to be identified that may be involved in exerting estrogen receptor-independent effects of estrogen.

A Pan-Transcriptome Analysis Indicates Efficient Downregulation of the FIB Genes Plays a Critical Role in the Response of Alfalfa to Cold Stress.

Alfalfa (Medicago sativa L.) is a perennial forage legume that is widely distributed throughout the world, and cold stress is an important environmental factor limiting the growth and production of alfalfa in cold regions. However, little is known of the molecular mechanisms regarding cold tolerance in alfalfa. Here, we conducted physiological metabolism assays and pan-transcriptome sequencing on eight cultivars of alfalfa under cold stress conditions. The results of the RNA-seq analysis showed that the genes are "oxidoreductase activity" and "transcription regulator activity", suggesting that genes with such functions are more likely to play important roles in the response to cold stress by alfalfa. In addition, to identify specific gene modules and hub genes in response to alfalfa cold stress, we applied weighted gene co-expression network (WGCNA) analyses to the RNA-seq data. Our results indicate that the modules of genes that focus on the ATPase complex, ribosome biogenesis, are more likely to be involved in the alfalfa response to cold stress. It is important to note that we identified two fibronectin (FIB) genes as hub genes in alfalfa in response to cold stress and that they negatively regulate alfalfa response to chilling stress, and it is possible that dormant alfalfa is more effective at down-regulating FIB expression and therefore more resistant to cold stress.

Microbial cell membrane properties and intracellular metabolism regulate individual level microbial responses to acid stress

Community- and individual-level soil microbial traits greatly depend on environmental conditions, especially soil pH. Given substantial spatio-temporal variations in soil pH, microorganisms exhibit acid tolerance to some extent, although the underlying mechanisms of microbial tolerance capacities remain understudied. In this study, ten microbial species with different functions (plant growth promoting, pathogen biocontrol, and nutrient cycling functions) were cultured under different acid treatments to investigate the acid tolerance capacity and the underlying physiological mechanisms for acid tolerance of these microbial species. Microbial species exhibited substantially different acid tolerance capacities, making them survival at pH from 3.5 to 5.0. Cellular physiological assays further indicated that three aspects could contribute to the acid tolerance capacity of soil microorganisms in the present study, i.e., shield effect by regulating the fluidity of cell membrane to prevent H+ from entering into cells, neutralizing effect by promoting the internal metabolic activities to produce metabolic chemicals such as amino acids and urea that could consume more intracellular H+, and pumping effect by regulating the H+-ATPase activity to extrude H+ out of cells, although it cannot be denied that other pathways may also function. However, these pathways did not make the same contribution to the acid tolerance capacity of different microbial species, suggesting that the regulators and underlying mechanisms depended greatly on microbial species. Further studies that combine omics technologies to discern tradeoff among microbial traits such as resource allocation, stress tolerance, etc., would be helpful to clarify the molecular mechanisms underlying microbial tolerance to the environmental stressors such as soil acidification.

Assessing the Effect of Irrigation Using Different Water Resources on Characteristics of Mild Cadmium-Contaminated Soil and Tomato Quality

As the world economy and society have developed quickly, the amount of farmland soil pollution has become alarming, which has seriously threatened global food security. It is necessary to take effective measures on the moderately contaminated soil to produce high-quality food and to protect food security worldwide by effective use of land resources. Our experimental design was to study the changes in soil physicochemical properties and tomato yield and quality indicators by irrigating tomatoes on cadmium-contaminated soil with two different water qualities (reclaimed water irrigation: RW; tap water irrigation: TW) through drip irrigation devices. Tomato quality indicators were determined using plant physiological assays, as well as vitamin C (VC), total acidity (TA), protein content (PC), and soluble sugar content (SS). We tested five different types of cadmium-contaminated soils (less than 0.60 mg/kg, 0.60–1.20 mg/kg, 1.20–1.80 mg/kg, 1.80–2.40 mg/kg, 2.40–3.00 mg/kg) against RW and TW, and performed high-throughput sequencing of the soils to obtain environmental results for soil microbial diversity. The results reveal that compared with the TW condition, soil nutritional status was increased with the irrigated RW. The yield of the tomatoes increased by 52.03–94.03% than TW. The results of the study showed significant and highly significant relationships between tomato quality indicators (TA, SS, yield) and soil physical and chemical properties indicators (p < 0.01, 0.05). For instance, the RW increased the SOM by 6.54–12.13%, the TP by 0.48–24.73%, the yield of the tomatoes by 52.03–94.03% than TW, while the cadmium content did not show significant differences (p < 0.05), and the cadmium content did not increase the soil’s pollution level. Compared with TW treatment, RW treatment alleviated the inhibition of soil microbial diversity by cadmium and RW also increased its soil microbial diversity. The relative abundance of Proteobacteria, Gemmatimonadetes, and Bacteroidetes in the RW condition were higher than in the TW condition at different cadmium concentrations. In conclusion, RW improved the overall quality conditions of soil and the diversity of microbial communities, and did not aggravate the pollution degree of cadmium-contaminated soil, and affected the yield of tomatoes positively. RW can be an effective irrigation technique to reduce the use of clean water.

Physiological and biochemical assay of drought stress responses in eggplant (Solanum melongena L.) inoculated with commercial inoculant of Azotobacter chroococum and Azotobacter vinelandii

• Decreased RWC, g s values of plants under drought stress, and especially K, Ca and Mg accumulations and protein contents in the root increased significantly with rhizobacteria inoculation. • Higher levels of total phenolic compounds and proline were accumulated in inoculated plants compared to uninoculated plants. • Higher antioxidant enzymatic activities were observed in inoculated stressed plants, and MDA was reduced. • Results were found to be important in that the inoculant with Azotobacter chroococum and Azotobacter vinelandii has the potential to diminish the negative effects of drought stress in eggplant . The aim of this study is to examine the effects of commercial rhizobacteria inoculant on eggplant plants grown under drought stress conditions. Commercial inoculant containing Azotobacter chroococum and Azotobacter vinelandii rhizobacteria species was applied to eggplant plants by root inoculation and the plants were exposed to different levels of drought stress (moderate drought stress-MS and severe drought stress-SS). To determine the growth-promoting ability of inoculation with rhizobacteria, changes in plant morphology (shoot-root fresh and dry weights, shoot length and diameter) and physiology (relative water content-RWC, stomatal conductivity-g s , K, Ca, Mg and Na accumulations in shoot and root, photosynthetic pigment contents) were investigated. To determine the impacts of the inoculant on the potential of increasing the drought tolerance of eggplant, besides the enzyme activities of superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR), non-enzymatic antioxidant activities such as antochiyanin, total phenolic substance, proline were investigated. In addition, H 2 O 2 and malondialdehyde (MDA) contents were analyzed to resolve whether drought stress causes oxidative damage in eggplant. The increase in the severity of drought caused a decrease in plant growth and shoot-root fresh and dry weights. Nevertheless, these adverse effects of drought stress were alleviated by inoculation. Decreased RWC, g s values of plants under drought stress, and especially K, Ca and Mg accumulations and protein contents in the root increased significantly with inoculation. On the other hand, Chlorophyll (Chl) (Chl a , Chl b , Chl a + b ) and carotenoid contents were significantly increased in leaves under uninoculated MS and SS. Inoculation with rhizobacteria reduced the increase in photosynthetic pigment contents. Depending on the severity of stress, higher levels of total phenolic compounds and proline were accumulated in inoculated plants compared to uninoculated plants. However, higher SOD, CAT, and GR enzymatic activities were observed in inoculated stressed plants, and membrane lipid peroxidation was reduced. These results were found to be important in that the commercial bacterial inoculant has the potential to diminish the negative effects of drought stress in eggplant and supports the stress tolerance of the plant by mitigating the drought-related oxidative damage.

Phosphite treatment can improve root biomass and nutrition use efficiency in wheat.

Phosphite represents a reduced form of phosphate that belongs to a class of crop growth-promoting chemicals termed biostimulants. Previous research has shown that phosphite application can enhance root growth, but its underlying mechanism, especially during environmental stresses, remains elusive. To uncover this, we undertook a series of morphological and physiological analyses under nutrient, water and heat stresses following a foliar application in wheat. Non-invasive 3D imaging of root system architecture directly in soil using X-ray Computed Tomography revealed that phosphite treatment improves root architectural traits and increased root biomass. Biochemical and physiological assays identified that phosphite treatment significantly increases Nitrate Reductase (NR) activity, leaf photosynthesis and stomatal conductance, suggesting improved Nitrogen and Carbon assimilation, respectively. These differences were more pronounced under heat or drought treatment (photosynthesis and photosystem II stability) and nutrient deficiency (root traits and NR). Overall our results suggest that phosphite treatment improves the ability of plants to tolerate abiotic stresses through improved Nitrogen and Carbon assimilation, combined with improved root growth which may improve biomass and yield.

CsMYB Transcription Factors Participate in Jasmonic Acid Signal Transduction in Response to Cold Stress in Tea Plant (Camellia sinensis).

Low-temperature stress is an increasing problem for the cultivation of tea (Camellia sinensis), with adverse effects on plant growth and development and subsequent negative impacts on the tea industry. Methyl jasmonate (MeJA), as a plant inducer, can improve the cold-stress tolerance in tea plants. R2R3-MYB transcription factors (TFs) are considered potentially important regulators in the resistance to cold stress in plants. However, the molecular mechanisms, by which MYB TFs via the jasmonic acid pathway respond to cold stress in the tea plant, remain unknown. In this study, physiological and biochemical assays showed that exogenous MeJA application could effectively promote ROS scavenging in the tea plant under cold stress, maintaining the stability of the cell membrane. Sixteen R2R3-MYB TFs genes were identified from the tea plant genome database. Quantitative RT-PCR analysis showed that three CsMYB genes were strongly induced under a combination of MeJA and cold-stress treatment. Subcellular localization assays suggest CsMYB45, CsMYB46, and CsMYB105 localized in the nucleus. Exogenous MeJA treatment enhanced the overexpression of CsMYB45, CsMYB46, and CsMYB105 in E. coli and improved the growth and survival rates of recombinant cells compared to an empty vector under cold stress. Yeast two-hybrid and bimolecular fluorescence complementation experiments confirmed that CsMYB46 and CsMYB105 interacted with CsJAZ3, CsJAZ10, and CsJAZ11 in the nucleus. Taken together, these results highlight that CsMYB45, CsMYB46, and CsMYB105 are not only key components in the cold-stress signal response pathway but also may serve as points of confluence for cold stress and JA signaling pathways. Furthermore, our findings provide new insight into how MYB TFs influence cold tolerance via the jasmonic acid pathway in tea and provide candidate genes for future functional studies and breeding.

Tolerance, Adaptation, and Cell Response Elicited by Micromonospora sp. Facing Tellurite Toxicity: A Biological and Physical-Chemical Characterization.

The intense use of tellurium (Te) in industrial applications, along with the improper disposal of Te-derivatives, is causing their accumulation in the environment, where oxyanion tellurite (TeO32−) is the most soluble, bioavailable, and toxic Te-species. On the other hand, tellurium is a rare metalloid element whose natural supply will end shortly with possible economic and technological effects. Thus, Te-containing waste represents the source from which Te should be recycled and recovered. Among the explored strategies, the microbial TeO32− biotransformation into less toxic Te-species is the most appropriate concerning the circular economy. Actinomycetes are ideal candidates in environmental biotechnology. However, their exploration in TeO32− biotransformation is scarce due to limited knowledge regarding oxyanion microbial processing. Here, this gap was filled by investigating the cell tolerance, adaptation, and response to TeO32− of a Micromonospora strain isolated from a metal(loid)-rich environment. To this aim, an integrated biological, physical-chemical, and statistical approach combining physiological and biochemical assays with confocal or scanning electron (SEM) microscopy and Fourier-transform infrared spectroscopy in attenuated total reflectance mode (ATR-FTIR) was designed. Micromonospora cells exposed to TeO32− under different physiological states revealed a series of striking cell responses, such as cell morphology changes, extracellular polymeric substance production, cell membrane damages and modifications, oxidative stress burst, protein aggregation and phosphorylation, and superoxide dismutase induction. These results highlight this Micromonospora strain as an asset for biotechnological purposes.

DAF-16 and SKN-1 mediate Anti-aging and Neuroprotective efficacies of “thai ginseng” Kaempferia parviflora Rhizome extract in Caenorhabditis elegans

BACKGROUND: The rhizomes of Kaempferia parviflora (KP), have been traditionally used for treating various ailments with 5,7-dimethoxyflavone (DMF) as a prominent compound. OBJECTIVE: To investigate the anti-aging and neuroprotective properties of KP and DMF in Caenorhabditis elegans. METHODS: C. elegans (wild-type (N2), transgenic and mutant strains) were treated with KP and DMF and were monitored for lifespan and neuroprotection through physiological assays, fluorescence microscopy and qPCR analysis. Molecular docking studies were employed to identify the interaction mode of DMF with DAF-16 and SKN-1. RESULTS: KP and DMF significantly increased the lifespan of N2 along with modulating pharyngeal pumping and lipofuscin accumulation. They also exhibited neuroprotection in Aβ transgenic strains by improving lifespan and delaying paralysis. Further, they reduced ROS accumulation significantly in worms exposed to UV-A, thereby exhibiting anti-photoaging potential. KP and DMF could activate SKN-1, DAF-16 which was evident from molecular docking and qPCR analysis. The DAF-2 and DAF-16 mutants did not exhibit any variations in lifespan upon treatment with KP and DMF suggesting the involvement of the DAF-16 mediated pathway in regulating the anti-aging and neuroprotective effects. CONCLUSION: Our findings suggest that KP with DMF as an active ingredient is a potential nutraceutical for aging and associated disorders.

Improved Tolerance of Lactiplantibacillus plantarum in the Presence of Acid by the Heterologous Expression of trxA from Oenococcus oeni

Oenococcus oeni is the main microorganism that undergoes malolactic fermentation (MLF) in the winemaking industry due to its excellent adaptability to harsh wine environments. The start of MLF is often delayed or even fails, and low pH appears to be a crucial parameter. To study the function of the trxA gene in acid stress, a plasmid containing the trxA gene of O. oeni SD-2a was heterologously expressed in Lactiplantibacillus plantarum WCFS1. The recombinant strain (WCFS1-trxA) grew better than the control strain (WCFS1-Vector) under acid stress. The expression of thioredoxin system genes was much higher in the recombinant strain compared with the control strain under acid stress. In addition, a series of physiological and biochemical assays were conducted. The ATP content was lower in the recombinant strain, while the cell membrane fluidity and integrity improved in the recombinant strain. Moreover, reactive oxygen species (ROS) accumulation, intracellular GSH level, and superoxide dismutase (SOD) activity assays showed that the recombinant strain decreased the intracellular reactive oxygen species (ROS) accumulation by improving the SOD activity. In conclusion, heterologous expression of trxA improves the SOD activity of L. plantarum WCFS1, reducing bacterial ROS and increasing cell membrane fluidity and integrity, enhancing the tolerance of Lactiplantibacillus plantarum WCFS1 under acid stress.

A Transcriptomic Analysis of Phenotypic Plasticity in Crassostrea virginica Larvae under Experimental Acidification.

Ocean acidification (OA) is a major threat to marine calcifiers, and little is known regarding acclimation to OA in bivalves. This study combined physiological assays with next-generation sequencing to assess the potential for recovery from and acclimation to OA in the eastern oyster (Crassostrea virginica) and identify molecular mechanisms associated with resilience. In a reciprocal transplant experiment, larvae transplanted from elevated pCO2 (~1400 ppm) to ambient pCO2 (~350 ppm) demonstrated significantly lower mortality and larger size post-transplant than oysters remaining under elevated pCO2 and had similar mortality compared to those remaining in ambient conditions. The recovery after transplantation to ambient conditions demonstrates the ability for larvae to rebound and suggests phenotypic plasticity and acclimation. Transcriptomic analysis supported this hypothesis as genes were differentially regulated under OA stress. Transcriptomic profiles of transplanted and non-transplanted larvae terminating in the same final pCO2 converged, further supporting the idea that acclimation underlies resilience. The functions of differentially expressed genes included cell differentiation, development, biomineralization, ion exchange, and immunity. Results suggest acclimation as a mode of resilience to OA. In addition, the identification of genes associated with resilience can serve as a valuable resource for the aquaculture industry, as these could enable marker-assisted selection of OA-resilient stocks.

Effects of exogenous selenium application on nutritional quality and metabolomic characteristics of mung bean (Vigna radiata L.).

Selenium (Se) biofortification is an important strategy for reducing hidden hunger by increasing the nutritional quality of crops. However, there is limited metabolomic information on the nutritional quality of Se-enriched mung beans. In this study, physiological assays and LC–MS/MS based widely targeted metabolomics approach was employed to reveal the Se biofortification potential of mung bean by evaluating the effect of Se on mung bean nutraceutical compounds and their qualitative parameters. Physiological data showed that foliar application of 30 g ha−1 Se at key growth stages significantly increased the content of Se, protein, fat, total phenols, and total flavonoids content in two mung bean varieties. Widely targeted metabolomics identified 1,080 metabolites, among which L-Alanyl-L-leucine, 9,10-Dihydroxy-12,13-epoxyoctadecanoic acid, and 1-caffeoylquinic acid could serve as biomarkers for identifying highly nutritious mung bean varieties. Pathway enrichment analysis revealed that the metabolic pathways of different metabolites were different in the Se-enriched mung bean. Specifically, P1 was mainly enriched in the linoleic acid metabolic pathway, while P2 was mainly enriched in the phosphonate and phosphinate metabolic pathways. Overall, these results revealed the specific Se enrichment mechanism of different mung bean varieties. This study provides new insights into the comprehensive improvement of the nutritional quality of mung beans.

Picea wilsonii Transcription Factor PwNAC38 Promotes Drought and Salt Tolerance in Transgenic Arabidopsis and Apple Calli

The mechanism of Picea wilsonii adapting to abiotic stress remains largely unknown. NAC (NAM, ATAF and CUC) transcription factors play significant roles in plant response to adverse environments. In this study, based on our previous RNA-seq, we analyzed the expression patterns of PwNAC38, and revealed its functions in the process of PwNAC38-mediated stress responses. An open-reading frame, encoding PwNAC38 protein with 330 amino acids, was isolated from the cDNA library, a process which can be induced by drought, salt and ABA treatment. Subcellular localization and yeast experiments showed that PwNAC38 was a nuclear-localized transcription factor, and could form homodimers. The full length of PwNAC38 showed transcriptional activity, while the truncated segments, C-PwNAC38 (156–330 aa) and N-PwNAC38 (1–156 aa), did not. The constitutive expression of PwNAC38 (OE lines) in Arabidopsis did not exert influence on the growth of transgenic plants under normal conditions, whereas transgenic seedlings showed higher survival rates, and the seeds had stronger vigor and a higher germination rate under drought and salt stress. The seed germination and root growth of PwNAC38 OE lines were significantly inhibited in the presence of ABA, suggesting the hypersensitivity of PwNAC38 to ABA treatment. Physiological assays showed that the activity of antioxidant enzymes, such as SOD and POD, increased, and that the accumulation of superoxide anion decreased, in OE lines under stress conditions. Moreover, overexpression of PwNAC38 significantly improved drought and salt tolerance in apple calli. A qRT-PCR assay showed that overexpression of PwNAC38 in Arabidopsis promoted the expression of drought or ABA-responsive genes ATHB-7, ANAC019, ERD1, DREB2A, RD29A, ABI5 and NCED3. Taken together, our results revealed that PwNAC38 is positively involved in plants’ response to drought and salt stress by enhancing ROS scavenging efficiency, and is partially dependent on the ABA signaling pathway.

Seahorse brood pouch morphology and control of male parturition in Hippocampus abdominalis

IntroductionSyngnathids (seahorses, pipefishes and seadragons) are among the few vertebrates that display male pregnancy. During seahorse pregnancy, males incubate developing embryos embedded in a placenta within a fleshy brood pouch, before expelling fully developed neonates at parturition. The mechanisms underpinning seahorse parturition are poorly understood. MethodsWe examined the morphology of the brood pouch using microcomputed tomography and histological techniques, in combination with physiological assays, to examine how male pot-bellied seahorses (Hippocampus abdominalis) control labour. In female-pregnant vertebrates, nonapeptide hormones (such as vasopressin- and oxytocin-like hormones) produce contractions of gestational smooth muscle to produce labour. ResultsHistological analysis of the seahorse brood pouch reveals only scattered small smooth muscle bundles in the brood pouch, and in-vitro application of isotocin (a teleost nonapeptide hormone) to the brood pouch do not produce measurable muscle contractions. Micro-computed tomography shows differences in size and orientation of the anal fin assembly between male and female pot-bellied seahorses, and histological analysis reveals large skeletal muscle bundles attached to the anal fin bones at the male brood pouch opening. DiscussionWe conclude that seahorse parturition may be facilitated by contraction of these muscles, which, in combination with body movements, serves to gape open the pouch and expel the neonates. Future biomechanical studies are needed to test this hypothesis.

Elevating Air Temperature May Enhance Future Epidemic Risk of the Plant Pathogen Phytophthora infestans.

Knowledge of pathogen adaptation to global warming is important for predicting future disease epidemics and food production in agricultural ecosystems; however, the patterns and mechanisms of such adaptation in many plant pathogens are poorly understood. Here, population genetics combined with physiological assays and common garden experiments were used to analyze the genetics, physiology, and thermal preference of pathogen aggressiveness in an evolutionary context using 140 Phytophthora infestans genotypes under five temperature regimes. Pathogens originating from warmer regions were more thermophilic and had a broader thermal niche than those from cooler regions. Phenotypic plasticity contributed ~10-fold more than heritability measured by genetic variance. Further, experimental temperatures altered the expression of genetic variation and the association of pathogen aggressiveness with the local temperature. Increasing experimental temperature enhanced the variation in aggressiveness. At low experimental temperatures, pathogens from warmer places produced less disease than those from cooler places; however, this pattern was reversed at higher experimental temperatures. These results suggest that geographic variation in the thermal preferences of pathogens should be included in modeling future disease epidemics in agricultural ecosystems in response to global warming, and greater attention should be paid to preventing the movement of pathogens from warmer to cooler places.

The divergence of brassinosteroid sensitivity between rice subspecies involves natural variation conferring altered internal auto-binding of OsBSK2.

Japonica/geng and indica/xian are two major rice (Oryza sativa) subspecies with multiple divergent traits, but how these traits are related and interact within each subspecies remains elusive. Brassinosteroids (BRs) are a class of steroid phytohormones that modulate many important agronomic traits in rice. Here, using different physiological assays, we revealed that japonica rice exhibits an overall lower BR sensitivity than indica. Extensive screening of BR signaling genes led to the identification of a set of genes distributed throughout the primary BR signaling pathway with divergent polymorphisms. Among these, we demonstrate that the C38/T variant in BR Signaling Kinase2 (OsBSK2), causing the amino acid change P13L, plays a central role in mediating differential BR signaling in japonica and indica rice. OsBSK2L13 in indica plays a greater role in BR signaling than OsBSK2P13 in japonica by affecting the auto-binding and protein accumulation of OsBSK2. Finally, we determined that OsBSK2 is involved in a number of divergent traits in japonica relative to indica rice, including grain shape, tiller number, cold adaptation, and nitrogen-use efficiency. Our study suggests that the natural variation in OsBSK2 plays a key role in the divergence of BR signaling, which underlies multiple divergent traits between japonica and indica.

Altered properties and structures of root exudate polysaccharides in a root hairless mutant of barley.

Root exudates and rhizosheaths of attached soil are important features of growing roots. To elucidate factors involved in rhizosheath formation, wild-type (WT) barley (Hordeum vulgare L. cv. Pallas) and a root hairless mutant, bald root barley (brb), were investigated with a combination of physiological, biochemical, and immunochemical assays. When grown in soil, WT barley roots bound ∼5-fold more soil than brb per unit root length. High molecular weight (HMW) polysaccharide exudates of brb roots had less soil-binding capacity than those of WT root exudates. Carbohydrate and glycan monoclonal antibody analyses of HMW polysaccharide exudates indicated differing glycan profiles. Relative to WT plants, root exudates of brb had reduced signals for arabinogalactan-protein (AGP), extensin, and heteroxylan epitopes. In contrast, the root exudate of 2-week-old brb plants contained ∼25-fold more detectable xyloglucan epitope relative to WT. Root system immunoprints confirmed the higher levels of release of the xyloglucan epitope from brb root apices and root axes relative to WT. Epitope detection with anion-exchange chromatography indicated that the increased detection of xyloglucan in brb exudates was due to enhanced abundance of a neutral polymer. Conversely, brb root exudates contained decreased amounts of an acidic polymer, with soil-binding properties, containing the xyloglucan epitope and glycoprotein and heteroxylan epitopes relative to WT. We, therefore, propose that, in addition to physically structuring soil particles, root hairs facilitate rhizosheath formation by releasing a soil-binding polysaccharide complex.