Simulated Drought Conditions Research Articles

Assessing the Impact of Drought on Arsenic Exposure from Private Domestic Wells in the Conterminous United States.

This study assesses the potential impact of drought on arsenic exposure from private domestic wells by using a previously developed statistical model that predicts the probability of elevated arsenic concentrations (>10 μg per liter) in water from domestic wells located in the conterminous United States (CONUS). The application of the model to simulate drought conditions used systematically reduced precipitation and recharge values. The drought conditions resulted in higher probabilities of elevated arsenic throughout most of the CONUS. While the increase in the probability of elevated arsenic was generally less than 10% at any one location, when considered over the entire CONUS, the increase has considerable public health implications. The population exposed to elevated arsenic from domestic wells was estimated to increase from approximately 2.7 million to 4.1 million people during drought. The model was also run using total annual precipitation and groundwater recharge values from the year 2012 when drought existed over a large extent of the CONUS. This simulation provided a method for comparing the duration of drought to changes in the predicted probability of high arsenic in domestic wells. These results suggest that the probability of exposure to arsenic concentrations greater than 10 μg per liter increases with increasing duration of drought. These findings indicate that drought has a potentially adverse impact on the arsenic hazard from domestic wells throughout the CONUS.

Zinc regulates the hydraulic response of maize root under water stress conditions

Zinc (Zn) is involved in plant growth and stress resistance and is known to increase crop yield. Here, we investigated the effect of Zn on water absorption in the roots of maize (Zea mays L.), a crop which is sensitive to Zn deficiency, during water stress conditions. Seedlings of the maize variety “Zhengdan 958” were cultivated with 0.1 or 6 μM ZnSO4·7H2O. To simulate drought stress, three-week-old seedlings were exposed to 15% polyethylene glycol (PEG). Root growth parameters, root antioxidant enzyme activity, root hydraulic conductivity, root aquaporin gene expression, root and leaf anatomy structure, leaf water potential, chlorophyll content, leaf area, and gas exchange parameters were measured. Under water stress, moderate Zn treatment promoted root growth; maintained root and leaf anatomy structural integrity. Moderate Zn significantly increased roots hydraulic conductivity (51%) and decreased roots antioxidant enzyme activity (POD: −11.1%, CAT: −35.1%, SOD: −3.1%) compared with low-level Zn under water stress. The expression of ZmPIP1;1, ZmPIP1;2, and ZmPIP2;2 was significantly higher with moderate Zn treatment than that of low-level Zn treatment. The leaf water potential, chlorophyll content, leaf area, and gas exchange parameters with moderate Zn treatment increased significantly under water stress compared with low-level Zn treatment. The moderate concentration of Zn improved root hydraulic conductivity in maize and increased resistance to simulated drought conditions by maintaining root structural integrity, decreasing antioxidant enzyme activity, and increasing aquaporin gene expression. Moderate Zn application increased root water absorption and leaf transpiration, thereby maintaining maize water balance under water stress conditions.

Assessment of drought conditions over Vietnam using standardized precipitation evapotranspiration index, MERRA-2 re-analysis, and dynamic land cover

Study regionVietnam. Study focusIn recent years Vietnam has experienced historical drought events possibly affected by climate change, but the analysis is challenging due to lack of necessary observations for monitoring drought conditions. The goal of this study is to analyze the characteristics of droughts over a 30-year period, using three spatial-resolution MERRA-2 datasets in Vietnam. The Standardized Precipitation Evapotranspiration Index (SPEI) was used as an index for drought based on precipitation and temperature. We also estimated the impacts of drought on agriculture using annual land cover datasets. New hydrological insights for the regionsOur results identified significant increasing trends in precipitation in Northern Vietnam and decreasing trends in Southern Vietnam. The increasing trends in temperature occurred mainly in Southern Vietnam. These trends in rainfall and temperature resulted in an increasing trend in drought frequency and severity in Southern Vietnam, especially in the South-Central Region and the Mekong Delta. The comparison between the observed drought records and modeled drought index demonstrated that the simulated drought conditions are better at higher spatial resolution. The area under drought in agricultural lands calculated using dynamic land-cover data sets resulted in a better agreement with observed records. Our findings reveal the feasibility of using a model-based drought index in data-sparse areas for long-term trend drought analysis, and for practical applications of advanced re-analysis products in water resource management.

Fire weather effects on flammability of indigenous and invasive alien plants in coastal fynbos and thicket shrublands (Cape Floristic Region).

BackgroundGlobally, and in the Cape Floristic Region of South Africa, extreme fires have become more common in recent years. Such fires pose societal and ecological threats and have inter alia been attributed to climate change and modification of fuels due to alien plant invasions. Understanding the flammability of different types of indigenous and invasive alien vegetation is essential to develop fire risk prevention and mitigation strategies. We assessed the flammability of 30 species of indigenous and invasive alien plants commonly occurring in coastal fynbos and thicket shrublands in relation to varying fire weather conditions.MethodsFresh plant shoots were sampled and burnt experimentally across diverse fire weather conditions to measure flammability in relation to fire weather conditions, live fuel moisture, fuel load and vegetation grouping (fynbos, thicket and invasive alien plants). Flammability measures considered were: burn intensity, completeness of burn, time-to-ignition, and the likelihood of spontaneous ignition. We also investigated whether the drying of plant shoots (simulating drought conditions) differentially affected the flammability of vegetation groups.ResultsFire weather conditions enhanced all measures of flammability, whereas live fuel moisture reduced burn intensity and completeness of burn. Live fuel moisture was not significantly correlated with fire weather, suggesting that the mechanism through which fire weather enhances flammability is not live fuel moisture. It furthermore implies that the importance of live fuel moisture for flammability of evergreen shrublands rests on inter-specific and inter-vegetation type differences in fuel moisture, rather than short-term intra-specific fluctuation in live fuel moisture in response to weather conditions. Fuel load significantly increased burn intensity, while reducing ignitability. Although fire weather, live fuel moisture, and fuel load had significant effects on flammability measures, vegetation and species differences accounted for most of the variation. Flammability was generally highest in invasive alien plants, intermediate in fynbos, and lowest in thicket. Fynbos ignited rapidly and burnt completely, whereas thicket was slow to ignite and burnt incompletely. Invasive alien plants were slow to ignite, but burnt with the highest intensity, potentially due to volatile organic composition. The drying of samples resulted in increases in all measures of flammability that were comparable among vegetation groups. Flammability, and by implication fire risk, should thus not increase disproportionately in one vegetation group compared to another under drought conditions—unless the production of dead fuels is disproportionate among vegetation groups. Thus, we suggest that the dead:live fuel ratio is a potentially useful indicator of flammability of evergreen shrublands and that proxies for this ratio need to be investigated for incorporation into fire danger indices.

Analysis and Prioritization the Effective Factors on Increasing Farmers Resilience Under Climate Change and Drought

California is severely exposed to drought and damage due to the climate change and drought belt, which has a major impact on agriculture. So, after the drought crisis, there are various reactions from farmers. The extent of the damage caused by the socioeconomic, environment and the extent of the resistance of farmers to this crisis is manifested in a variety of ways. Recognizing the population’s resilience and the involved human groups is a tool for preventing a catastrophe-based increase in life-threatening areas in high-risk areas. Sometimes the inability to manage this phenomenon (especially under the climate change) leads to farmers’ desertification and agricultural land release, which itself indicates a low level of resilience and resilience to the crisis. The recent drought under the climate change condition in California and the severity of the damage sustained by farmers continue to be vulnerable. The present study seeks to prioritize and prioritize resilience of farmers to the crisis under the climate change. This study simulated drought condition with using PDSI value for current and future time period. In order to calculate PDSI values, the climatic parameters extracted from CMIP5 models and downscaled under the scenario of RCP 8.5. Also in order to understand the resilience of the agriculture activities under the climate change, this study was performed using statistical tests and data from the questionnaire completed in the statistical population of 320 farmers in the Tulare region in California. The findings of the research by t test showed that the average level of effective factors in increasing the resilience of farmers in the region is low. This is particularly significant in relation to the factors affecting government policies and support. So that only the mean of five variables is higher than the numerical desirability of the test and the other 15 variables do not have a suitable status for increasing the resilience of the farmers. Also, the results of the Vikor model showed that most of the impact on their resilience to drought and climate change was the development of agricultural insurance, the second important impact belongs to drought monitoring system, climate change and damage assessment, and variable of attention to knowledge is in third place of the important factor.

Lipophorin receptor regulates the cuticular hydrocarbon accumulation and adult fecundity of the pea aphid Acyrthosiphon pisum.

Cuticular hydrocarbons form a barrier that protects terrestrial insects from water loss via the epicuticle. Lipophorin loads and transports lipids, including hydrocarbons, from one tissue to another. In some insects, the lipophorin receptor (LpR), which binds to lipophorin and accepts its lipid cargo, is essential for female fecundity because it mediates the incorporation of lipophorin by developing oocytes. However, it is unclear whether LpR is involved in the accumulation of cuticular hydrocarbons and its precise role in aphid reproduction remains unknown. We herein present the results of our molecular characterization, phylogenetic analysis, and functional annotation of the pea aphid (Acyrthosiphon pisum) LpR gene (ApLpR). This gene was transcribed throughout the A. pisum life cycle, but especially during the embryonic stage and in the abdominal cuticle. Furthermore, we optimized the RHA interference (RNAi) parameters by determining the ideal dose and duration for gene silencing in the pea aphid. We observed that the RNAi-based ApLpR suppression significantly decreased the internal and cuticular hydrocarbon contents as well as adult fecundity. Additionally, a deficiency in cuticular hydrocarbons increased the susceptibility of aphids to desiccation stress, with decreased survival rates under simulated drought conditions. Moreover, ApLpR expression levels significantly increased in response to the desiccation treatment. These results confirm that ApLpR is involved in transporting hydrocarbons and protecting aphids from desiccation stress. Furthermore, this gene is vital for aphid reproduction. Therefore, the ApLpR gene of A. pisum may be a novel RNAi target relevant for insect pest management.

The effect of arid growing conditions on water deficit and chlorophyll content of the winter wheat varieties with various productivity

Relevance. The current paper has presented the study results of the effect of arid growing conditions on water deficit and foliage pigment (chlorophyll) of winter wheat varieties with various productivity.Methods. The study was conducted in 2017–2019. The objects of study were the winter durum wheat varieties ‘Eyrena’, ‘Yubilyarka’, ‘Yakhont’, ‘Yantarina’, ‘Oniks’, ‘Lazurit’ developed in the FSBSI “Agricultural Research Center “Donskoy”. There have been used such methods in the current study as the testing of varieties on drought tolerance in conditions of simulated drought (“zasushnik”) proposed by V.V. Maimistov (1988); the method of identification of chlorophyll content in winter wheat leaves proposed by I.G. Shmatko (1976); the method of identification of residual water deficit proposed by L.S. Litvinov (1988).Results. According to the study results there have been identified the most stable, productive winter wheat varieties ‘Yantarina’ and ‘Lazurit’, which possess mechanisms of adaptation to the water stress conditions. The varieties ‘Yantarina’ and ‘Lazurit’ also possess large productivity and chlorophyll content, as well as the smallest rise of residual water deficit in the increasing aridity with 169.7 and 159.5 g/m2, 1.4 and 1.9 mg/100 g of raw weight, 24.6 and 25.7%, respectively.

Screening of Some Selected Indian Maize Cultivars to Simulated Drought Condition

Drought is a major constraint to get an optimum yield of any crop under changing environment. A total of 12 Indian accessions of maize seedlings was screened initially by performing relative water content (RWC) under water deficit condition. Three (RJ-2020, BPCH-6, and EC-3161) landraces that showed a higher RWC than DTSYN11 were finally selected for further studies. Four landraces maintained RWC above 80% under 4th and 8th day stress periods. Higher contents of chlorophyll were recorded significantly in EC-3161 and in RJ-2020 as compared to DTSYN11 under the 8th day of stress. RWC showed a decline in BPCH-6 (72.54%) and in RJ-2020 (72.65%) and proline was significantly increased up to 10 and 13-fold, respectively. Therefore, this research has identified three unfamiliar maize landraces that possess the capacity to be drought tolerance when under water deficit and watering condition. In addition to their useful applications in breeding program, they are valuable resources to elucidate genetic profiling that enhance the capacity to exhibit drought tolerance in Indian maize cultivars.

Action potential propagation effect on gas exchange of ABA-mutant microtomato after re-irrigation stimulus

During their life cycles, plants are often subjected to periods of fluctuation between water deficit and re-irrigation events. Efficient communication and rapid signaling between the shoot and root systems are needed for adaptive stress responses. Abscisic acid (ABA) and the hydraulic signal are the main long-distance signals responsive to water deficit. Nevertheless, ABA is susceptible to interactions with electrical signals and may not be sufficient as a sign of stress in plants. Therefore, we aimed to investigate the relationship between hydraulic, chemical and electrical signals after a re-irrigation stimulus to induce changes in gas exchange of ABA mutant microtomato plants. Three genotypes of tomato, cultivar Micro-Tom (MT) (MTwt), the isogenic mutant MTnotabilis (MTnot) and transgenic MTsp12::NCED (MTNCED), were exposed to 7, 4 and 11 days under simulated drought conditions, respectively. Then, the plants were re-irrigated and we simultaneously evaluated gas exchange, electric potential and the propagation of action potentials. We found that water deficit affected the water potential of the plants and induced increased depolarization of the plasma membrane electric potential in Mtwt and MTnot. In response to re-irrigation, all genotypes propagated action potentials from root to shoot. In MTwt, the electrical signal induced increases in photosynthesis, stomatal conductance and transpiration rate. By contrast, in ABA-mutants, the gas exchange variables were reduced. These results were related to the effect of ABA and possibly JA on stomatal control and pH changes inactivating photosynthesis.

Identification of transcription factors interacting with a 1274\u2009bp promoter of MaPIP1;1 which confers high-level gene expression and drought stress Inducibility in transgenic Arabidopsis thaliana

BackgroundDrought stress can severely affect plant growth and crop yield. The cloning and identification of drought-inducible promoters would be of value for genetically-based strategies to improve resistance of crops to drought.ResultsPrevious studies showed that the MaPIP1;1 gene encoding an aquaporin is involved in the plant drought stress response. In this study, the promoter pMaPIP1;1, which lies 1362 bp upstream of the MaPIP1;1 transcriptional initiation site, was isolated from the banana genome..And the transcription start site(A) is 47 bp before the ATG. To functionally validate the promoter, various lengths of pMaPIP1;1 were deleted and fused to GUS to generate pMaPIP1;1::GUS fusion constructs that were then transformed into Arabidopsis to generate four transformants termed M-P1, M-P2, M-P3 and M-P4.Mannitol treatment was used to simulate drought conditions. All four transformants reacted well to mannitol treatment. M-P2 (− 1274 bp to − 1) showed the highest transcriptional activity among all transgenic Arabidopsis tissues, indicating that M-P2 was the core region of pMaPIP1;1. This region of the promoter also confers high levels of gene expression in response to mannitol treatment. Using M-P2 as a yeast one-hybrid bait, 23 different transcription factors or genes that interacted with MaPIP1;1 were screened. In an dual luciferase assay for complementarity verification, the transcription factor MADS3 positively regulated MaPIP1;1 transcription when combined with the banana promoter. qRT-PCR showed that MADS3 expression was similar in banana leaves and roots under drought stress. In banana plants grown in 45% soil moisture to mimic drought stress, MaPIP1;1 expression was maximized, which further demonstrated that the MADS3 transcription factor can synergize with MaPIP1;1.ConclusionsTogether our results revealed that MaPIP1;1 mediates molecular mechanisms associated with drought responses in banana, and will expand our understanding of how AQP gene expression is regulated. The findings lay a foundation for genetic improvement of banana drought resistance.

Highlights of strategies adapted by two Pennisetum glaucum (L.) R. Br. races in a simulated drought stress experiment

Pearl millet (Pennisetum glaucum) is an important staple food crop in Asia and Africa. The most severe abiotic stress that hinders growth and development of crop is Drought. Four genotypes of P. glaucum were grown for 4 weeks in a greenhouse facility with the aim to identify several physiological responses observed after 12 days of drought stress and transcriptional profiling related to drought tolerance. Distinct parameters like relative water content (RWC), water use efficiency (WUE), stomata quantification (SI%), electron transport rate (ETR), photochemical (qP) and non-photochemical quenching (qNP) were measured under simulated drought condition for the selected four genotypes. The genotypes were grouped into two pearl millet races viz., nigritarum and globosum. Genotype 1P35451 of the nigritarum race showed augmentation in dry weight (DW) and tolerance index (TI) under the condition of decreased soil water due to transpiration. It exhibited a remarkable ability for recovery of leaf after an imposed drought condition in RWC, WUE and SI. Also, the transcriptional expression of CBF, RubSc and PIP 2;3 genes indicated that they were quick to respond to drought. CBF gene has proven to be useful for evaluating the ability to withstand drought in both races. RubSc and PIP2:3 displayed a pronounced increase in their expression level in nigritarum race. However, the drought tolerant genotype 1P13013 of globosum functioned in stomatal movement which is well linked with the expression of the Nicotinamide Adenine Dinucleotide Phosphate (NADP) enzyme. Therefore, the results indicate that mRNA expression of genes in both races under drought stress provides information on their ability to resist drought and could supply valuable molecular information for drought-tolerant elite breeding programs in the future.

Screening for Drought Tolerance in Maize (Zea mays L.) Germplasm Using Germination and Seedling Traits under Simulated Drought Conditions.

Maize is known to be susceptible to drought stress, which negatively affects vegetative growth and biomass production, as well as the formation of reproductive organs and yield parameters. In this study, 27 responsive traits of germination (G) and seedlings growth were evaluated for 40 accessions of the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) germplasm collection, under no stress and simulated drought stress treatments by 10%, 15%, and 20% of polyethylene glycol (PEG). The three treatments significantly reduced G% and retarded seedlings growth, particularly the 15% and 20% PEG treatments; these two treatments also resulted in a significant increase of abnormal seedlings (AS). The heritability (H2) and correlations of the traits were estimated, and drought tolerance indices (DTIs) were calculated for traits and accessions. The H2 of G% values were reduced, and H2 for AS% increased as the PEG stress increased. Positive correlations were found between most trait pairs, particularly shoot and root traits, with 48 highly significant correlations under no stress and 25 highly significant correlations under the 10% PEG treatments, particularly for shoot and root traits. The medium to high heritability of shoot and root seedling traits provides a sound basis for further genetic analyses. PCA analysis clearly grouped accessions with high DTIs together and the accessions with low DTIs together, indicating that the DTI indicates the stress tolerance level of maize germplasm. However, the resemblance in DTI values does not clearly reflect the origin or taxonomic assignments to subspecies and varieties of the examined accessions.

Drought tolerance of transgenic rice overexpressing maize C<sub>4</sub>-PEPC gene related to increased anthocyanin synthesis regulated by sucrose and calcium

In order to reveal the role of sucrose (Suc) in early drought response in plants, transgenic rice (Oryza sativa L.) plants overexpressing the maize (Zea mays L.) C4-phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) gene (C4-pepc) (PC) and their untransformed wild type (WT) were used under 12 % (m/v) polyethylene glycol 6000 to simulate drought conditions. The results showed that PC has higher relative water content, the increased Suc content, and anthocyanin accumulation than WT during PEG treatment. By spraying 1 % Suc and 1 % Suc non-metabolic analog, turanose, on these plants, Suc in PC leaves increased anthocyanin content and Ca2+ content. Further experiments using the Ca2+ chelator (EGTA), Ca2+ channel antagonist (ruthenium red), and abscisic acid inhibitor (nordihydroguaiaretic acid), showed that, in PC plants, Suc content is closely related to the expression of sucrose nonfermenting-1-related protein kinases 2 (SnRK2s) such as SAPK8, SAPK9, and SAPK10 via abscisic acid, and the SnRK3 such as SnRK3.1, SnRK 3.4, and SnRK3.21 via Ca2+ and calcineurin B-like as well. Furthermore, the target genes associated with anthocyanin synthesis phenylalanine ammonia lyase, chalcone isomerase, chalcone synthase, flavonoid-3-hydrogenase, flavonoid-3'-hydrogenase, dihydroflavonone reductase, and anthocyanin synthase, their regulated genes basic helix-loop-helix (bHLH) proteins OsB1 and OsB2, R2R3-MYB transcription factor OsC1, and some transcription factors (constitutively photomorphogenic 1, elongated hypocotyl 5, and purple acid phosphatase gene 2) in PC plants also increased via Suc and Ca2+ during the PEG treatment. Some Suc tranporter genes OsSUT1 and OsSUT5 in PC lines during PEG treatment further showed an enhancement for the function of the signal of Suc. Thereby, increasing anthocyanin biosynthesis via Suc and Ca2+ signaling cascade is one of the important mechanisms on drought tolerance in the PC lines.

Вплив праймування абсцизовою кислотою на ріст і післястресове відновлення пшениці і спельти за дії модельованої помірної ґрунтової посухи

Вплив праймування абсцизовою кислотою на ріст і післястресове відновлення пшениці і спельти за дії модельованої помірної ґрунтової посухи

The change in the leaf conducting system of the winter wheat samples under the conditions of simulated drought

The current paper has considered the effect of the development degree of the leaf conducting systems and the head-bearing internode on kernel weight per head of the winter wheat grown in the conditions of insufficient moisture supply and optimal moisture. The study of out among 13 winter wheat samples developed by the FSBSI “Agricultural Research Center “Donskoy”. The area of the conducting vascular bundle of winter wheat ranged from 0.208 mm2 10-4 (‘Shef’, ‘586/13’) to 0.364 mm2 10-4 (‘Krasa Dona’) (a trial) and from 0.381 mm2 10-4 (‘Etyud’) to 0.350 mm2 10-4 (‘Zhavoronok’) (a control). The maximum development degree of wheat leaf conducting system in the trials was identified in the varieties ‘Krasa Dona’ (4.01 mm2 10-4) and ‘Ambar’ (4.22 mm2 10-4), and in the control these were the varieties ‘Polina’ (2.59 mm2 10-4) and ‘Ambar’ (2.62 mm2 10-4). The maximum values of the area of the leaf conducting system and kernel weight per head were shown by the varieties ‘Krasa Dona’ (4.01 mm2 10-4 and 0.37 g) and ‘Ambar’ (4.22 mm2 10-4 and 0.39 g).

Grain quality of elite bread wheat genotypes under non-stress and drought-stress conditions

ABSTRACTGrain quality, including protein content, is a key determinant of marketability and end-user acceptance of bread wheat (Triticum aestivum L.). This study determined the grain quality of bread wheat genotypes under simulated terminal drought (TD) and well-watered (WW) conditions for selecting suitable genotypes for breeding. The amount of gliadin (Gli), gluten (Glu), glutenin (Glut), gliadin: glutenin ratio (Gli: Glut ratio) and total protein content (TPC) were determined in 24 elite heat- and drought-tolerant bread wheat genotypes sourced from the International Maize and Wheat Improvement Center (CIMMYT). The experiment was conducted under rainout shelter (RS) and glasshouse (GH) environments. Genotype-by-environment interaction was significant (p ≤ 0.001) for grain quality traits. Positive correlations were observed between Gli and Gli : Glut ratio (r = 0.97), and Glut and Glu (r = 0.97). The correlation between Glut and Gli : Glut ratio was negative (r = -0.58) under TD condition. Under TD condition and in RS, positive but relatively small correlations were found between TPC and Gli (r = 0.19), Glut (r = 0.16), Gli: Glu ratio (r = 0.04) and Glu (r = 0.22). The trend was similar under GH condition in TD where positive and low correlation values were detected between TPC and Gli (r = 0.19), Glut (r = 0.29), Gli: Glu ratio (r = 0.14) and Glu (r = 0.33). This suggested selection for higher TPC may result in limited improvement of protein-fractions. Heat- and drought-tolerant wheat genotypes, such as LM95, LM90, LM85, LM82, LM73, LM71, LM62, LM60, LM55, LM44, and LM41, with improved quality attributes, were identified for breeding and production.

Germination and seedling growth responses of Sri Lankan grown Sesame/Thala (Sesamum indicum L.) for simulated drought conditions

The agriculture sector is often challenged by dry weather, thus a better understanding of growth responses of crops to changes in climate is imperative. However, drought responses of many economical crops are yet to be comprehensively studied. Therefore, this research was carried out to investigate the responses of 10 Sri Lankan grown sesame varieties/cultivars: Uma, Malee, Idal, Pokuru, Black-seeded sesame and its wild relatives, to reduced water availability during germination and seedling growth. Drought conditions were simulated in a laboratory with three different treatments [polyethylene glycol (PEG) 6000, mannitol and sodium chloride] at 0, - 0.25, - 0.5 and -1.0 MPa water potentials under complete randomised design with 10 replicates each having eight seeds per petri plate per variety/cultivar. The final germination percentage of sesame seeds after 10 days was calculated. Seedlings were further exposed to the same treatments and their root and shoot lengths were measured after 10 days. Germination was assessed using binary data analysis and the seedling data were subjected to ANOVA. Results revealed that the highest tension of PEG (-1.00 MPa) inhibited seed germination and the emergence of seedlings, while that of mannitol (-1.00 MPa) negatively affected seedling growth only (p

Analysis of the complete genome sequence of Brevibacterium frigoritolerans ZB201705 isolated from drought- and salt-stressed rhizosphere soil of maize

PurposeTo analyze the complete genome sequence of the Brevibacterium frigoritolerans ZB201705, a Brevibacterium strain was isolated from the maize rhizosphere in drought- and salt-stressed soil, and the activity of the strain under simulated drought and high salt conditions was assessed.MethodsWe used a combination of the PacBio RS and Illumina sequencing platforms to obtain the complete genome sequence of B. frigoritolerans ZB201705.ResultsThe genome consists of 5,475,560 bp in a linear chromosome with no gaps, 4,391 protein-coding sequences, 39 ribosomal RNAs, and 81 transfer RNAs. The genome analysis revealed many putative gene clusters involved in defense mechanisms. In addition, an activity analysis of the strain under high-salt and simulated drought conditions helped clarify its potential tolerance to these abiotic stresses.ConclusionsOur data revealed the complete genome sequence of the new isolated strain, and showed that it produces many proteins involved in drought and salt stress responses, suggesting that B. frigoritolerans ZB201705 may be a potential factor to increase crop yield under abiotic stresses. The information provided here on the genome of B. frigoritolerans ZB201705 provides valuable insight into rhizobacteria-mediated plant salt and drought tolerance and rhizobacteria-based solutions for agriculture under abiotic stress.

Overexpression of the trehalose-6-phosphate phosphatase OsTPP3 increases drought tolerance in rice

Trehalose plays an important role in mediating stress responses in plants, and trehalose-6-phosphate synthases and trehalose-6-phosphate phosphatases are essential for trehalose biosynthesis. Here, we address the function of rice (Oryza sativa) OsTPP3. We analyzed the expression of OsTPP3 in different tissues and stress conditions, and generated OsTPP3-overexpressing rice plants. These plants showed a higher tolerance to simulated drought conditions (10% PEG treatment) than wild-type (WT) plants. Reverse-transcription quantitative PCR analysis indicated that transcript levels of genes related to stress responses and abscisic acid biosynthesis were significantly higher in the OsTPP3 overexpressors than in WT plants. These results highlight the importance of OsTPP3 in conferring drought tolerance in rice.

Effect of nitrogen application on the phytochemical production in Jatropha curcas L. (Angiosperms: Euphorbiaceae) during drought conditions

Nitrogen is an important nutrient for the successful metabolism of plants, but its occurrence in soil is always very limited. This nutrient has a significant role to preserve plants during various stress conditions by altering the production rate of phytochemicals as defense weapons. Hence, this study was carried out to analyze the effect of nitrogen supply on the phytochemical composition and relative water content in Jatropha curcas L. under a simulated drought condition. The selected seedlings were grown from stem cuttings and categorized into different treated three groups along with the control. After the completion of the experiment, the growth pattern and phytochemical production were investigated. An increased malondialdehyde activity (MDA) was reported with a reduction in relative water content (RWC) of the leaf and in the biomass of seedlings under drought stress. A significant decrease in the levels of alkaloids, phenol, flavonoids and tannins with an increase in saponins and terpenoids was also observed in only simulated drought stressed plants. While a significant increase in the levels of total alkaloid, tannins, flavonoids and phenols was observed in those plants where exogenous nitrogen was supplied before the start of drought periods, unlike in treated and control plants. Therefore, it was revealed that application of Nitrogen enabled the plants to possess protective mechanism through the production of phytochemicals that facilitate the cell membrane to reduce the detrimental effects caused by drought stress.