Leaf Soluble Protein Research Articles

Expression of an insecticidal fern protein in cotton protects against whitefly.

Whitefly (Bemisia tabaci) damages field crops by sucking sap and transmitting viral diseases. None of the insecticidal proteins used in genetically modified (GM) crop plants to date are effective against whitefly. We report the identification of a protein (Tma12) from an edible fern, Tectaria macrodonta (Fee) C. Chr., that is insecticidal to whitefly (median lethal concentration = 1.49 μg/ml in in vitro feeding assays) and interferes with its life cycle at sublethal doses. Transgenic cotton lines that express Tma12 at ∼0.01% of total soluble leaf protein were resistant to whitefly infestation in contained field trials, with no detectable yield penalty. The transgenic cotton lines were also protected from whitefly-borne cotton leaf curl viral disease. Rats fed Tma12 showed no detectable histological or biochemical changes, and this, together with the predicted absence of allergenic domains in Tma12, indicates that Tma12 might be well suited for deployment in GM crops to control whitefly and the viruses it carries.

A quantitative proteomic approach to highlight Phragmites sp. adaptation mechanisms to chemical stress induced by a textile dyeing pollutant

Phragmites sp. is present worldwide in treatment wetlands though the mechanisms involved in the phytoremediation remain unclear. In this study a quantitative proteomic approach was used to study the prompt response and adaptation of Phragmites to the textile dyeing pollutant, Acid Orange 7 (AO7). Previously, it was demonstrated that AO7 could be successfully removed from wastewater and mineralized in a constructed wetland planted with Phragmites sp. This azo dye is readily taken up by roots and transported to the plant aerial part by the xylem. Phragmites leaf samples were collected from a pilot scale vertical flow constructed wetland after 0.25, 3.25 and 24.25h exposure to AO7 (400mgL−1) immediately after a watering cycle used as control. Leaf soluble protein extraction yielded an average of 1560 proteins in a broad pI range (pH3–10) by two-dimensional gel electrophoresis. A time course comparative analysis of leaf proteome revealed that 40 proteins had a differential abundance compared to control (p<0.05) within a 3.25h period. After 24.25h in contact with AO7, leaf proteome was similar to control. Adaptation to AO7 involved proteins related with cellular signalling (calreticulin, Ras-related protein Rab11D and 20S proteasome), energy production and conversion (adenosine triphosphate synthase beta subunit) carbohydrate transport and metabolism (phosphoglucose isomerase, fructose-bisphosphate aldolase, monodehydroascorbate reductase, frutockinase-1 and Hypothetical protein POPTR_0003s12000g and the Uncharacterized protein LOC100272772) and photosynthesis (sedoheptulose-1,7-bisphosphatase and ferredoxin-NADP+ reductase). Therefore, the quantitative proteomic approach used in this work indicates that mechanisms associated with stress cell signalling, energy production, carbohydrate transport and metabolism as well as proteins related with photosynthesis are key players in the initial chemical stress response in the phytoremediation process of AO7.

Effects of elevated temperature and CO2 concentration on growth and leaf quality of Morus alba seedlings.

To estimate the potential effects of climate change on the growth and leaf quality of Morus alba, one-year-old M. alba seedlings were exposed 60 d under four treatments, i.e., elevated temperature (ET, +2 ℃), elevated CO2 concentration (EC, +300 ppm CO2), elevated temperature and CO2 concentration (ETC, +2 ℃ & +300 ppm CO2), and control treatment (CK). The results showed that basal diameter, leaf number, total leaf area, leaf dry mass, leaf dry mass fraction and soluble protein were 9.9%, 17.4%, 23.0%, 9.2%, 10.1% and 23.1% higher under ET than those under CK, respectively. EC significantly increased the stem, root and total dry biomass by 10.7%, 15.9% and 9.2% compared with CK, respectively, whereas leaf quality was similar between EC and CK. Compared with CK, leaf number, height, diameter, total leaf area, the leaf, root and total dry biomass, leaf soluble sugar content and crude protein content increased significantly by 28.8%, 9.1%, 19.4%, 32.6%, 12.4%, 17.2%, 10.1%, 45.8% and 11.9% in ETC while the leaf crude fibre content decreased by 16.8%. Our results indicated that climate change had a positive effect on the growth and leaf quality of M. alba in a short period.

Breaking the rules of Rubisco catalysis.

The canon of knowledge on the catalytic properties of the photosynthetic enzyme Rubisco has shackled efforts to understand its diversity. Now the chains are off. While investigating the variability in Rubisco function among diatoms, Young et al. (see pages 3445–3456 in this issue) have demonstrated that it is our thinking, not Rubisco catalysis, that has been constrained. The photosynthetic CO2-fixing enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), is renowned for its slow catalytic rate and difficulty in distinguishing between the substrate of photosynthesis, CO2, and one of the products, O2. The oxygenase activity was discovered 45 years ago (Bowes et al., 1971), nearly 20 years after the discovery of the carboxylase activity (Quayle et al., 1954; Weissbach et al., 1954). The photorespiratory losses associated with Rubisco oxygenation are substantial (Sharkey, 1988), and the persistence of oxygenation throughout 3.5 billion years of evolution – particularly the last 400 million years when the O2 and CO2 pressures in the atmosphere have favored substantial oxygenation and photorespiration – is still a mystery (Hagemann et al. 2016). It is conceivable that evolutionary constraints related to the origins of Rubisco from enzymes with roles in sulfur metabolism (Ashida et al., 2003) may have imposed limitations on the catalytic mechanism for CO2 fixation, though none have come to light. Oxygenation has also been proposed as an energy dissipative mechanism that would be beneficial under some stressful conditions (Osmond, 1981), but this does not explain why it exists in all Rubiscos, including those from anaerobic organisms (Andrews and Lorimer, 1987). The inefficiency of Rubisco is due not only to the strong competitive interaction of O2 and CO2 at the active site, but also to a slow catalytic turnover rate per active site (k cat) and a low affinity for CO2 (high K C). Substrate-saturated k cat values (maximum CO2 fixation per catalytic site) occur in the range 1–12s–1 and the k cat/K C ratios (which reflect the ability of Rubisco to function when CO2 is limiting) occur in the range 2–40×104 M–1 s–1 (Badger et al., 1998). This feeble catalytic potency at limiting CO2 is several orders of magnitude slower than the diffusion limit to catalysis that many enzymes approach (108–109 M–1 s–1) and it means that plants need copious amounts of Rubisco (as much as 50% of soluble leaf protein, consuming up to 25% of leaf nitrogen) to support adequate rates of photosynthesis in our current atmosphere (Andrews and Lorimer, 1987). The requirement for such large quantities of Rubisco gives it the dubious honor of being the most abundant protein on Earth (Ellis, 1979). Even with so much Rubisco present, it is still often the rate-limiting enzyme in photosynthesis.

A Fusion between Domains of the Human Bone Morphogenetic Protein-2 and Maize 27 kD γ-Zein Accumulates to High Levels in the Endoplasmic Reticulum without Forming Protein Bodies in Transgenic Tobacco.

Human Bone Morphogenetic Protein-2 (hBMP2) is an osteoinductive agent physiologically involved in bone remodeling processes. A commercialized recombinant hBMP2 produced in mammalian cell lines is available in different clinical applications where bone regeneration is needed, but widespread use has been hindered due to an unfavorable cost/effective ratio. Protein bodies are very large insoluble protein polymers that originate within the endoplasmic reticulum by prolamine accumulation during the cereal seed development. The N-terminal domain of the maize prolamin 27 kD γ-zein is able to promote protein body biogenesis when fused to other proteins. To produce high yield of recombinant hBMP2 active domain (ad) in stably transformed tobacco plants we have fused it to the γ-zein domain. We show that this zein-hBMP2ad fusion is retained in the endoplasmic reticulum without forming insoluble protein bodies. The accumulation levels are above 1% of total soluble leaf proteins, indicating that it could be a rapid and suitable strategy to produce hBMP2ad at affordable costs.

Copper phytoremediation potential of Calandula officinalis L. and the role of antioxidant enzymes in metal tolerance

Cu phytoremediation potential of an ornamental plant, Calandula officinalis, was explored in terms of growth responses, photosynthetic activities and antioxidant enzymes such as SOD, CAT and GPX. The results showed that this plant had high Cu tolerance of up to 400mg/kg, which is far above the phytotoxic range for non hyperaccumulators. It grew normally in soils at all the doses (150–400mg/kg) without showing external signs of phytotoxicity. At 150mg/kg, flowering was augmented; root and shoot biomass, root lengths and leaf soluble protein contents remained same as that of the control. However, chlorophyll and carotenoid pigment contents declined significantly along with significant elevations in lipid peroxidation, at all the doses. Elevations of antioxidant enzymes reflected stress as well as probable mitigation of reactive oxygen species due to Cu stress. Except for the highest conc. (400mg/kg), leaf accumulation of Cu was higher than root accumulations. The Cu accumulation peaked at 300mg/kg Cu in soil, with leaf and root accumulations to be respectively, 4675 and 3995µg/g dry wt., far more than the minimum of 1000µg/g dry wt. for a Cu hyperaccumulator. The plant root at all the doses tolerated Cu, with the tolerance index ranging from 94–62.7. The soil to plant metal uptake capacity, indicated by extraction coefficient and the root to shoot translocation, indicated by translocation factor, at all the doses of Cu were >1, pointed towards efficient phytoremediation potential.

Electrophoresis Study of Wheat (&amp;lt;i&amp;gt;Triticumaestivum&amp;lt;/i&amp;gt; L.) Protein Changes Under Salinity Stress

Salinity problem with its vast spread on the earth is one of the main factors which limits crop production. One of the methods to overcome this problem is taking advantage of the resistant genotypes. Investigation of changes resulting from the stress in an electrophoretic profile of proteins and understanding its relation with the tolerance and susceptibility of cultivars is an important criterion for identifying such cultivars. In this study, 4 wheat cultivars with different degrees of tolerance were grown in hydroponic culture under salinity treatment (0, 70, 140 and 210 mM NaCl). Leaf sampling was done on 5 leaf stage. Studying the electrophoretic pattern of the leaf soluble proteins in salinity and control treatments showed fundamental similarities among the cultivars. No polypeptide bands belonging to the specific cultivars or to one of the salinity treatments were observed. The study of protein changes by electrophoretic analysis under salinity treatment may be useful for understanding the salinity tolerance of genotypes.

Expression, subcellular localization, and enzyme activity of a recombinant human extra-cellular superoxide dismutase in tobacco (Nicotiana benthamiana L.)

Human extracellular superoxide dismutase (hEC-SOD) is an enzyme that scavenges reactive oxygen species (ROS). Because of its antioxidant activity, hEC-SOD has been used as a therapeutic protein to treat skin disease and arthritis in mammalian systems. In this study, codon-optimized hEC-SOD was expressed in tobacco (Nicotiana benthamiana L.) via a plant-based transient protein expression system. Plant expression binary vectors containing full-length hEC-SOD (f-hEC-SOD) and modified hEC-SOD (m-hEC-SOD), in which the signal peptide and heparin-binding domain were deleted, were constructed for the cytosolic-, endoplasmic reticulum (ER)-, and chloroplast-localizations in tobacco leaf mesophyll cells. The results demonstrated that f-hEC-SOD was more efficiently expressed in the cytosolic fractions than in the ER or chloroplasts of tobacco cells. Our data further indicated that differently localized f-hEC-SOD and m-hEC-SOD displayed SOD enzyme activities, suggesting that the hEC-SODs expressed by plants may be functionally active. The f-hEC-SOD was expressed up to 3.8% of the total leaf soluble protein and the expression yield was calculated to be 313.7 μg f-hEC-SOD per g fresh weight of leaf. Overall, our results reveal that it was possible to express catalytically active hEC-SODs by means of a transient plant expression system in tobacco leaf cells.

Characterization of the rice RbcS3 promoter and its transit peptide for use in chloroplast-targeted expression

Here, we report characterization of an RbcS promoter and its transit peptide for use in chloroplast-targeted expression. RbcS3 that encodes a small subunit of ribulose bisphosphate carboxylase/oxygenase is of great interest due to its green tissue-specific expression such as leaf and leaf sheaths. We isolated the RbcS3 promoter and its transit peptide sequence and linked to GFP for characterization in transgenic plants. Our qRT-PCR analysis on leaves and roots of transgenic plants revealed that GFP transcript levels were higher by fivefold in leaves of RbcS3:TP3:GFP transgenic lines than in those of the RbcS3:GFP transgenic lines, suggesting that the transcript levels were increased by chloroplast-targeted expression, as shown in previously characterized RbcS1:TP1 system. The transit peptide sequence TP3 was sufficient to target GFP to chloroplasts as observed in protoplasts of RbcS3:TP3:GFP transgenic lines. GFP fluorescence in RbcS3:GFP plants was detected only in the cytosol. The GFP protein levels in leaves of RbcS3:TP3:GFP plants were 0.12–0.23 % of the total soluble leaf proteins. These levels were higher or comparable to those of PGD1:GFP plants (GFP driven by a constitutive promoter PGD1). Taken together, these results indicate that the fusion of the RbcS3 promoter to its transit peptide, RbcS3:TP3, provides a chloroplast-targeting expression system.

Sclerotium rolfsii lectin expressed in tobacco confers protection against Spodoptera litura and Myzus persicae

Bacillus thuringiensis (Bt) toxins expressed in GM crops provide effective protection against chewing-type insects but fail to control damage by sucking pests, leading to a search for a newer class of efficient entomotoxic proteins. In this direction lectins with novel sugar-binding properties showing toxicity to a wide range of agricultural insect pests are being evaluated for the insecticidal efficacy. Our previous study demonstrated the potential toxic effect of O-glycans sugar-specific Sclerotium rolfsii lectin (SRL) supplemented through an artificial diet on the growth and survival of Spodoptera litura larvae by binding to midgut epithelial cells. Considering the significance of its entomotoxic property, we cloned the SRL gene and expressed it in a prokaryotic host, which showed 97 % sequence homology to the native SRL. Recombinant SRL (recSRL) exhibited a carbohydrate-binding property and insecticidal activity similar to native SRL. The SRL gene was transferred into tobacco plants by Agrobacterium-mediated transformation and expressed constitutively using a CaMV35S promoter. Integration and stability of the SRL gene was confirmed by Southern hybridization. recSRL expressed in the transgenic tobacco leaves was analyzed by Western blotting and quantified by ELISA, which accounted for 0.47 % of the total soluble leaf proteins. Bioassays conducted on second instar S. litura larvae fed on transgenic tobacco leaves showed 90 % larval mortality in 48 h and in planta assays using M. persicae demonstrated an 81.90 % population reduction. These findings indicated that the ectopically expressed SRL conferred protection against target pests of lepidopteran and hemipteran orders.

English

Rice is one of the important cereal crops drastically affected by water scarcity in rice ecosystems. In a pot study, the impact of externally applied gibberellic acid (GA3), indole acetic acid (IAA) and kinetin was investigated on assimilates mobilization and yield parameters of rice under water stress. Twenty five days seedlings of two rice genotypes KS-133 and Basmati-2000 were transplanted in soil filled pots and sprayed with GA3, IAA and kinetin each of 10 M concentration at panicle initiation stage. Water stress was imposed to plants 80 days after transplanting for 10 days. Water stress (p≤ 0.05) reduced leaf chlorophyll content and yield of rice but increased the concentration of proline, leaf soluble protein and enhanced mobility of assimilates from leaves to grains. Application of GA3 and kinetin significantly (p≤ 0.05) increased chlorophyll content, growth and yield attributes in both genotypes under water stress conditions. However, IAA application did not improve the grain yield in rice genotypes under water stress. The positive impact of GA3 and kinetin spray was imitated in the form of enhanced solute accumulation; enhanced growth and greater grain assimilate deposition. This may be concluded that GA3 and kinetin can be applied exogenously prior to flower initiation in rice to reduce panicle sterility by increasing assimilates mobility under water deficit for optimal economic yield. © 2016 Friends Science Publishers

English

In this study, we investigated the effects of 2,4-Dichlorophenoxy acetic acid (2,4-D) treatment on selected physiological parameters and fruit quality of wax apple fruits under field conditions. Foliar spray of 2,4-D at 0, 5, 10 and 20 mg L-1 concentrations were used from bud stage to the 3rd week of fruit development. Physiological parameters determined included net photosynthesis, stomatal conductivity, chlorophyll content and chlorophyll fluorescence. Net photosynthetic rate and photosynthetic efficiency via chlorophyll fluorescence significantly (p≤0.05) increased with 5 and 10 mg L-1 2, 4-D treatments. Furthermore, 5 mg L-1 2,4-D reduced bud and fruit drop, increased fruit weight and dry matter content in leaves. An improved fruit set, enhanced fruit growth, faster color development and advanced maturity were also recorded in treated plants. In addition, fruit yield increased by 39 and 48% with 5 and 10 mg L-1 2,4-D treatments, respectively. Fruit K+ content, total sugar, protein content and chalcone synthase (CHS) activities increased with 2,4-D treatments. Increased leaf soluble protein and elevated sucrose phosphate synthase (SPS) activity were also observed in 5 mg L-1 treated plants. Positive correlation between photosynthesis rate and SPS activity of leaves (R2=0.98) and between CHS activity and color development of fruits (R2=0.98) were recorded in 5 mg L-1 treatments. The results also suggested that 5 and 10 mg L-1 2,4-D treatments are promising for enhancing plant productivity and fruit quality in wax apple trees under field conditions.

The Response of Physiological Characteristics, Expression of OSC Genes, and Accumulation of Triterpenoids in Betula platyphylla Sukto MeJA and SA Treatment

The pentacyclic triterpenoids from birch (Betula platyphylla suk) have broad pharmacological activities and can be potentially used for the development of anti-cancer and anti-AIDS drugs. In this study, we explored the effects of spraying 3-year-old white birch with different concentration of methyl jasmonate (MeJA) and salicylic acid (SA) on the expression of key genes in triterpenoid biosynthesis pathways and on the accumulation and physiological characteristics of triterpenoids in birch saplings. The results showed that spraying different concentration of MeJA and SA could obviously promote accumulation of total triterpenoids in 3-year-old white birch. The triterpenoid content in the stem bark was increased by 46.11 %, reaching 81.86 mg/g, after 1 day of treatment with 1 mmol·L−1 MeJA (MJ2), and by 45.07 %, reaching 91.4 mg/g, after 14 days of treatment with 5 mmol·L−1 SA (SA1). In addition, MeJA and SA treatment increased the contents of chlorophyll a and b, antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as photosynthetic performance, and affected the content of soluble sugar and soluble protein in birch leaf. Fluorescence quantitative polymerase chain reaction (qPCR) results showed that MeJA and SA treatment deferentially enhanced the key gene expression of cycloartenol synthase (BPX and BPX2), lupeol synthase (BPW) and beta-amyrin synthase (BPY) in triterpenoid synthesis pathway in birch bark and leaves. The results showed that MeJA and SA induced triterpenoid synthesis of birch plant is closely related with not only the expression of key genes of triterpenoid synthesis pathway but also photosynthesis, anti-stress response and physiological indexes, suggesting that regulation of triterpenoid synthesis of birch by MeJA and SA may involve in more complex mechanisms at physiological and molecular levels.

Comparative growth and physiological responses of two wheat (Triticum aestivum L.) cultivars differing in salt tolerance to salinity and cyclic drought stress

Two cultivars of wheat (Triticum aestivum L.) with differential salinity tolerance were compared by evaluating the growth attributes, pigment composition and accumulation of Na+, K+, Zn2+, Fe 2+, Mn 2+ and proline. Wheat cultivars Al-Moiaya (AM) (salt tolerant) and Habbe-Druma (HD) (salt sensitive) were subjected to four levels of salinity (1.21 dS m−1, 4.4 dS m−1, 8.8 dS m−1 and 13.2 dS m−1) in factorial combinations with three drought stress (FC 30%, FC 60% and FC 90%) treatments in a randomized complete block design. Plant dry weight, leaf area ratio (LAR), soluble protein and total chlorophyll (Chl) content were higher in AM than HD. Salt-tolerant AM maintains a higher K+/ Na+ ratio and thereby is able to grow better than the salt-sensitive HD under both the stresses. The lower foliar Na+ in AM resulted in retention of higher Chl content, reflected in the strong positive correlations between plant ion status and Chl contents (Na+-Chl r2 = 0.83; Chl- Fe2+ r2 = 0.76; Zn2+ r2 = 0.93 and Mn2+ r2 = 0.88). In conclusion, our results suggested that the K+/Na+ ratio, exclusion of Na+ and ion homeostasis play much more important roles in the tolerance to salinity and drought stress than the compatible osmolyte, proline.

Novel expression system for enhanced synthesis of antimicrobial peptide cecropin P1 in plants

A gene of antimicrobial peptide cecropin P1 (CP1) was inserted into the vector plasmid pPCV91 under the control of promoter 35S RNA of cauliflower mosaic virus (CaMV 35S) containing four enhancer sequences CaMV 35S and nontranslated leader sequence Ω RNA of tobacco mosaic virus. The recombinant vector obtained was used for agrobacterial transformation of tobacco plants (Nicotiana tabacum L., variety Samsun) with the polymerase chain reaction (PCR)-based method. The presence of gene CP1 in the genome of plants was proven by western-blot analysis and testing the antibiotic activity of plant extracts. In different plant lines, the level of cecropin P1 synthesis amounted 0.02–0.2% of total soluble plant leaf protein. The transgenic plants, unlike the control ones, displayed enhanced tolerance to phytopathogenic microorganisms and oxidative stress. It was established that the ability of the transgenic plants to express cecropin P1 is transmitted to progeny.

Nitrogen assimilation and transpiration: key processes conditioning responsiveness of wheat to elevated [CO2] and temperature.

Although climate scenarios have predicted an increase in [CO(2)] and temperature conditions, to date few experiments have focused on the interaction of [CO(2)] and temperature effects in wheat development. Recent evidence suggests that photosynthetic acclimation is linked to the photorespiration and N assimilation inhibition of plants exposed to elevated CO(2). The main goal of this study was to analyze the effect of interacting [CO(2)] and temperature on leaf photorespiration, C/N metabolism and N transport in wheat plants exposed to elevated [CO(2)] and temperature conditions. For this purpose, wheat plants were exposed to elevated [CO(2)] (400 vs 700 µmol mol(-1)) and temperature (ambient vs ambient + 4°C) in CO(2) gradient greenhouses during the entire life cycle. Although at the agronomic level, elevated temperature had no effect on plant biomass, physiological analyses revealed that combined elevated [CO(2)] and temperature negatively affected photosynthetic performance. The limited energy levels resulting from the reduced respiratory and photorespiration rates of such plants were apparently inadequate to sustain nitrate reductase activity. Inhibited N assimilation was associated with a strong reduction in amino acid content, conditioned leaf soluble protein content and constrained leaf N status. Therefore, the plant response to elevated [CO(2)] and elevated temperature resulted in photosynthetic acclimation. The reduction in transpiration rates induced limitations in nutrient transport in leaves of plants exposed to elevated [CO(2)] and temperature, led to mineral depletion and therefore contributed to the inhibition of photosynthetic activity.

The intrinsically disordered protein LEA7 from Arabidopsis thaliana protects the isolated enzyme lactate dehydrogenase and enzymes in a soluble leaf proteome during freezing and drying

The accumulation of Late Embryogenesis Abundant (LEA) proteins in plants is associated with tolerance against stresses such as freezing and desiccation. Two main functions have been attributed to LEA proteins: membrane stabilization and enzyme protection. We have hypothesized previously that LEA7 from Arabidopsis thaliana may stabilize membranes because it interacts with liposomes in the dry state. Here we show that LEA7, contrary to this expectation, did not stabilize liposomes during drying and rehydration. Instead, it partially preserved the activity of the enzyme lactate dehydrogenase (LDH) during drying and freezing. Fourier-transform infrared (FTIR) spectroscopy showed no evidence of aggregation of LDH in the dry or rehydrated state under conditions that lead to complete loss of activity. To approximate the complex influence of intracellular conditions on the protective effects of a LEA protein in a convenient in-vitro assay, we measured the activity of two Arabidopsis enzymes (glucose-6-P dehydrogenase and ADP-glucose pyrophosphorylase) in total soluble leaf protein extract (Arabidopsis soluble proteome, ASP) after drying and rehydration or freezing and thawing. LEA7 partially preserved the activity of both enzymes under these conditions, suggesting its role as an enzyme protectant in vivo. Further FTIR analyses indicated the partial reversibility of protein aggregation in the dry ASP during rehydration. Similarly, aggregation in the dry ASP was strongly reduced by LEA7. In addition, mixtures of LEA7 with sucrose or verbascose reduced aggregation more than the single additives, presumably through the effects of the protein on the H-bonding network of the sugar glasses.

Physiological and Yield Responses of Faba bean (Vicia faba L.) to Drought Stress in Managed and Open Field Environments

AbstractWater scarcity is threatening the sustainability of global food grain production systems. Devising management strategies and identification of crop species and genotypes are direly required to meet the global food demands with limited supply. This study, consisted of two independent experiments, was conducted to compare faba bean (Vicia faba L.) genotypes Giza Blanka, Goff‐1, Hassawi‐1, Hassawi‐2 and Gazira‐2 in terms of physiological attributes and yield under water‐limited environments. In first experiment, conducted in a growth chamber, osmotic stress of −0.78, −0.96, −1.19 and −1.65 MPa was induced using polyethylene glycol for 4 weeks. In second experiment, conducted in open field for two consecutive growing seasons, water deficit treatments were applied 3 weeks after sowing. In this experiment, irrigation was applied when an amount of evaporated water from the ‘class A pan’ evaporation reached 50 mm (well watered), 100 mm (moderate drought) and 150 mm (severe drought). Water deficit, applied in terms of osmotic stress or drought, reduced the root and shoot length, related leaf water contents, total chlorophyll contents and efficiency of photosystem‐II, plant height, grain yield and related attributes in faba bean; increased the leaf free proline, leaf soluble proteins and malondialdehyde contents, and triggered the maturity in tested faba bean genotypes. However, substantial genetic variation was observed in the tested genotypes in this regard. For instance, root length of genotypes Giza Blanka and Hassawi‐2 decreased gradually, whereas it was increased in genotypes Goff‐1, Hassawi‐1 and Gazira‐2 with increase in the level of osmotic stress. Genotypes Gazira‐2 and Hassawi‐2 had better relative leaf water contents, leaf free proline and soluble proteins under water deficit conditions; however, these were minimum in genotype Giza Blanka. Better accumulation of leaf free proline, soluble proteins, and maintenance of chlorophyll contents, tissue water, efficiency of photosystem‐II and grain weight in water‐limited conditions helped some genotypes like Hassawi‐2 to yield better. Future breeding programs for developing new faba bean genotypes for water‐limited environments may consider these traits.

TiO2 nanoparticle biosynthesis and its physiological effect on mung bean (Vigna radiata L.)

TiO2 nanoparticle (NPs) biosynthesis is a low cost, ecofriendly approach developed using the fungi Aspergillus flavus TFR 7. To determine whether TiO2 NPs is suitable for nutrient, we conducted a two part study; biosynthesis of TiO2 NP and evaluates their influence on mung bean. The characterized TiO2 NPs were foliar sprayed at 10mgL−1 concentration on the leaves of 14 days old mung bean plants. A significant improvement was observed in shoot length (17.02%), root length (49.6%), root area (43%), root nodule (67.5%), chlorophyll content (46.4%) and total soluble leaf protein (94%) as a result of TiO2 NPs application. In the rhizosphere microbial population increased by 21.4–48.1% and activity of acid phosphatase (67.3%), alkaline phosphatase (72%), phytase (64%) and dehydrogenase (108.7%) enzyme was observed over control in six weeks old plants owing to application of TiO2 NPs. A possible mechanism has also been hypothesized for TiO2 NPs biosynthesis.

Drought degree constrains the beneficial effects of a fungal endophyte on Atractylodes lancea.

Plants, fungal endophytes (FEs) and the changing environment interact with each other forming an interlaced network. This study evaluates nonadditive and interactive effects of the FE Acremonium strictum and drought treatment on Atractylodes lancea plantlets. By applying FEs (meristem cultures of At. lancea, fungal inoculation of Ac. strictum and plantlet acclimatization) and drought treatment (regular watering, mild drought, severe drought), a research system of At. lancea ramets under different treatments was established. During 12 days of drought treatment, the plantlets' physiological responses and basic growth traits were measured and analysed. Although drought and FE presence affected plantlet traits to differing degrees, the interactive effects of the two were more pronounced. In particular under mild drought treatment, the FE conferred drought tolerance to plantlets by enhancing leaf soluble sugars, proteins, proline and antioxidant enzyme activity; decreasing the degree of plasmalemma oxidation; and increasing the host's abscisic acid level and root:shoot ratio. When exposed to regular watering or severe drought, these effects were not significant. Plant traits plasticity was conferred by dual effects of drought stress and FEs, and these factors are interactive. Although FEs can help plants cope with drought stress, the beneficial effects are strictly constrained by drought degree. During finite environmental stress, FEs can benefit plants, and for this reason, they may alleviate the effects of climate change on plants. However, because the benefits of FEs are highly context dependent, the role of FEs in a changing background should be re-assessed.