Protect Wheat Seedlings Research Articles

Exogenous glutathione protected wheat seedling from high temperature and water deficit damages

High temperatures (HT) and drought are two major factors restricting wheat growth in the early growth stages. This study investigated the role of glutathione (GSH) amendment (0.0, 0.5, 1.0, and 2.0 mM) to soil in mitigating the adverse effect of HT (33 °C, with 25 °C as a control), water regimes (60% of field capacity and control), and their combinations. HT decreased the length, project area, surface area, volume, and forks of the root, while drought had the reverse effect. Shoot length, leaf area, leaf relative water content, and shoot and root dry matter were significantly decreased by HT and drought, and their combined impact was more noticeable. GSH significantly promoted the root system, shoot growth, and leaf relative water content. The combined treatment reduced chlorophyll a, chlorophyll b, and total chlorophyll. However, 0.5 mM GSH raised chlorophyll a, chlorophyll b, and total chlorophyll by 28.6%, 41.4%, and 32.5%, respectively, relative to 0.0 mM GSH. At combined treatment, 0.5 mM GSH decreased malondialdehyde (MDA) by 29.5% and increased soluble protein content by 24.1%. GSH meaningfully enhanced the activity of superoxide dismutase, catalase, and ascorbate peroxide in different treatments. This study suggested that GSH could protect wheat seedlings from the adverse effects of HT and/or drought stresses.

Priming with the green leaf volatile (Z)-3-hexeny-1-yl acetate enhances drought resistance in wheat seedlings

Various studies showed that green leaf volatiles play vital roles in biotic and abiotic stresses. However, their role in drought resistance has never been studied. In order to investigate the possible role of (Z)-3-hexeny-1-yl acetate (Z-3-HAC, a type of green leaf volatile), various physiology experiments were performed to understand the physiological mechanisms of Z-3-HAC in alleviating wheat drought stress. Drought-resistant wheat seedlings were primed with 100 μM Z-3-HAC at the four-leaf stage before drought treatment. Morphological analysis showed that the primed seedlings grew better and showed higher biomass accumulation in both shoots and roots under drought stress. Additionally, exogenous Z-3-HAC significantly increased the total root length, total root surface area, and total root volume of the seedlings under drought stress. In primed seedlings, physiological measurements showed that the relative water content (RWC), net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), maximal photochemical efficiency of photosystem II (PSII) (Fv/Fm), photochemical activity of PSII (Fv′/Fm′), total chlorophyll content, activities of antioxidant enzymes, and osmolyte accumulation were higher than the control under drought conditions. Furthermore, relative electrolyte conductivity (REC), intercellular CO2 concentration (Ci), reactive oxygen species (ROS) accumulation, and malondialdehyde (MDA) content were significantly lower than the non-primed seedlings. Lastly, principal component analysis (PCA) indicated that Z-3-HAC protected wheat seedlings against damage from drought stress mainly through antioxidant and osmoregulatory systems. This study opens a new field of Z-3-HAC application, and provides a new opportunity to improve wheat drought resistance.

Effect of Trichoderma asperellum on Wheat Plants' Biochemical and Molecular Responses, and Yield under Different Water Stress Conditions.

Eight Trichoderma strains were evaluated for their potential to protect wheat seedlings against severe (no irrigation within two weeks) water stress (WS). Considering the plant fresh weight and phenotype, T. asperellum T140, which displays 1-aminocyclopropane-1-carboxylic acid deaminase activity and which is able to produce several phytohormones, was selected. The molecular and biochemical results obtained from 4-week-old wheat seedlings linked T140 application with a downregulation in the WS-response genes, a decrease in antioxidant activities, and a drop in the proline content, as well as low levels of hydrogen peroxide and malondialdehyde in response to severe WS. All of these responses are indicative of T140-primed seedlings having a higher tolerance to drought than those that are left untreated. A greenhouse assay performed under high nitrogen fertilization served to explore the long-term effects of T140 on wheat plants subjected to moderate (halved irrigation) WS. Even though all of the plants showed acclimation to moderate WS regardless of T140 application, there was a positive effect exerted by T. asperellum on the level of tolerance of the wheat plants to this stress. Strain T140 modulated the expression of a plant ABA-dependent WS marker and produced increased plant superoxide dismutase activity, which would explain the positive effect of Trichoderma on increasing crop yields under moderate WS conditions. The results demonstrate the effectiveness of T. asperellum T140 as a biostimulant for wheat plants under WS conditions, making them more tolerant to drought.

Effect of Piriformospora indica-Induced Systemic Resistance and Basal Immunity Against Rhizoctonia cerealis and Fusarium graminearum in Wheat.

Wheat is among the top 10 and most widely grown crops in the world. However, wheat is often infected with many soil-borne diseases, including sharp eyespot, mainly caused by the necrotrophic fungus Rhizoctonia cerealis, and Fusarium head blight (FHB), caused by Fusarium graminearum, resulting in reduced production. Piriformospora indica is a root endophytic fungus with a wide range of host plants, which increases their growth and tolerance to biotic and abiotic stresses. In this study, the capability of P. indica to protect wheat seedlings against R. cerealis and F. graminearum was investigated at the physiological, biochemical, and molecular levels. Our results showed that P. indica significantly reduced the disease progress on wheat caused by F. graminearum and R. cerealis in vivo, but not showed any antagonistic effect on F. graminearum and R. cerealis in vitro. Additionally, P. indica can induce systemic resistance by elevating H2O2 content, antioxidase activity, relative water content (RWC), and membrane stability index (MSI) compared to the plants only inoculated with F. graminearum or R. cerealis and control. RNA-seq suggested that transcriptome changes caused by F. graminearum were more severe than those caused by R. cerealis. The number of differentially expressed genes (DEGs) in the transcriptome can be reduced by the addition of P. indica: for F. graminearum reduced by 18% and for R. cerealis reduced 58%. The DEGs related to disease resistance, such as WRKY and MAPK, were upregulated by P. indica colonization. The data further revealed that the transcriptional resistance to F. graminearum and R. cerealis mediated by P. indica is quite different.

Silicon Dioxide Nanoparticles Induce Innate Immune Responses and Activate Antioxidant Machinery in Wheat Against Rhizoctonia solani.

The phytopathogenic basidiomycetous fungus, Rhizoctonia solani, has a wide range of host plants including members of the family Poaceae, causing damping-off and root rot diseases. In this study, we biosynthesized spherical-shaped silicon dioxide nanoparticles (SiO2 NPs; sized between 9.92 and 19.8 nm) using saffron extract and introduced them as a potential alternative therapeutic solution to protect wheat seedlings against R. solani. SiO2 NPs showed strong dose-dependent fungistatic activity on R. solani, and significantly reduced mycelial radial growth (up to 100% growth reduction), mycelium fresh and dry weight, and pre-, post-emergence damping-off, and root rot severities. Moreover, the impact of SiO2 NPs on the growth of wheat seedlings and their potential mechanism (s) for disease suppression was deciphered. SiO2 NPs application also improved the germination, vegetative growth, and vigor indexes of infected wheat seedlings which indicates no phytotoxicity on treated wheat seedlings. Moreover, SiO2 NPs enhanced the content of the photosynthetic pigments (chlorophylls and carotenoids), induced the accumulation of defense-related compounds (particularly salicylic acid), and alleviated the oxidative stress via stimulation of both enzymatic (POD, SOD, APX, CAT, and PPO) and non-enzymatic (phenolics and flavonoids) antioxidant defense machinery. Collectively, our findings demonstrated the potential therapeutic role of SiO2 NPs against R. solani infection via the simultaneous activation of a multilayered defense system to suppress the pathogen, neutralize the destructive effect of ROS, lipid peroxidation, and methylglyoxal, and maintain their homeostasis within R. solani-infected plants.

Potential of Trichoderma harzianum and Its Metabolites to Protect Wheat Seedlings against Fusarium culmorum and 2,4-D.

Wheat is a critically important crop. The application of fungi, such as Trichoderma harzianum, to protect and improve crop yields could become an alternative solution to synthetic chemicals. However, the interaction between the fungus and wheat in the presence of stress factors at the molecular level has not been fully elucidated. In the present work, we exposed germinating seeds of wheat (Triticum aestivum) to the plant pathogen Fusarium culmorum and the popular herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) in the presence of T. harzianum or its extracellular metabolites. Then, the harvested roots and shoots were analyzed using spectrometry, 2D-PAGE, and MALDI-TOF/MS techniques. Although F. culmorum and 2,4-D were found to disturb seed germination and the chlorophyll content, T. harzianum partly alleviated these negative effects and reduced the synthesis of zearalenone by F. culmorum. Moreover, T. harzianum decreased the activity of oxidoreduction enzymes (CAT and SOD) and the contents of the oxylipins 9-Hode, 13-Hode, and 13-Hotre induced by stress factors. Under the influence of various growth conditions, changes were observed in over 40 proteins from the wheat roots. Higher volumes of proteins and enzymes performing oxidoreductive functions, such as catalase, ascorbate peroxidase, cytochrome C peroxidase, and Cu/Zn superoxide dismutase, were found in the Fusarium-inoculated and 2,4-D-treated wheat roots. Additionally, observation of the level of 12-oxo-phytodienoic acid reductase involved in the oxylipin signaling pathway in wheat showed an increase. Trichoderma and its metabolites present in the system leveled out the mentioned proteins to the control volumes. Among the 30 proteins examined in the shoots, the expression of the proteins involved in photosynthesis and oxidative stress response was found to be induced in the presence of the herbicide and the pathogen. In summary, these proteomic and metabolomic studies confirmed that the presence of T. harzianum results in the alleviation of oxidative stress in wheat induced by 2,4-D or F. culmorum.

Histopathological aspects of resistance in wheat to Puccinia triticina, induced by Pseudomonas protegens CHA0 and β-aminobutyric acid

After perception of specific biotic or abiotic stimuli, such as root colonization by rhizobacteria or selected chemicals, plants can enhance their basal resistance against pathogens. Due to its likely sustainability, this induced resistance will be valuable for disease management in agriculture. This study examined resistance against wheat leaf rust (Puccinia triticina) induced by Pseudomonas protegens CHA0 (CHA0) and β-aminobutyric acid (BABA). Seed dressing with CHA0 reduced the number of sporulating pustules on leaves, and expression of resistance was visible as necrotic or chlorotic leaf flecks. Beneficial effect of CHA0 on wheat seedlings growth was observed in when they were challenged or not with leaf rust. BABA was tested at 10, 15 or 20 mM, and a dose-dependent reduction of leaf rust infections was observed with greatest protection at 20 mM. However, BABA treatment repressed plant growth at 20 mM. Balancing the BABA impact on plant growth and its protective capacity, 15 mM of the compound was selected as suitable to protect wheat seedlings against leaf rust, with the least impact on vegetative host growth. Histological aspects of the pathogen infection process was studied to understand mechanisms of behind the observed resistance. The pre-entry process was not affected by the two resistance inducers, but both treatments reduced fungus penetration and haustorium formation. Timing and amplitude of the resistance reactions were different after bacterial or chemical induction, leading to different levels of resistance. During fungal colonization of host tissues, high deposition of callose and accumulation of H2O2 in both CHA0- and BABA-treated plants indicated important contributions to resistance.

Herbisit Stres Korumasında Putresin: Buğdayda Genomik Kararsızlığı Azaltma ve DNA Metilasyon Değişiklikleri

Wheat is one of the most consumed and important food in worldwide. During its growing season, weeds around the cultivated areas grow rapidly and inhibit the normal growth and development, stable yield and quality of wheat seriously. The prevention and removal of weeds are achieved by herbicide treatments. Dicamba is one of the herbicides that is used in agricultural areas which may represent a potential genotoxic risk to off-target crops. The present study was aimed to evaluate the effect of dicamba (0.2, 0.4 and 0.6 ppm) which caused to destabilize of genomic template stability (GTS) and DNA methylation changes in Triticum aestivum L. seedlings by RAPD (Randomly Amplified Polymorphic DNA) and CRED-RA (Coupled Restriction Enzyme Digestion-Random Amplification) techniques, respectively. Also, Full Methylation Ratio and Methylation Ratio were computed according to data of CRED-RA patterns. It was determined that the damage raised with an increasing dose of dicamba. To minimalize the genotoxic effects of dicamba, putrescine (0.01, 0.1 and 1 ppm), a kind of polyamine, were used. Especially, 1 ppm of putrescine was the best concentration to revert the stress-exposed wheat seedlings. Polyamines are positively charged organic cations and hence they interact with negatively charged macromolecules such as DNA and RNA and stabilize them. The results of this experiment have clearly shown that putrescine could be used effectively to protect wheat seedlings from the effects of dicamba on DNA damage and DNA methylation changes, also RAPD and CRED-RA could be used as ideal techniques to get reliable and accurate results.

Exogenous Nitric Oxide Improves the Protective Effects of TiO2 Nanoparticles on Growth, Antioxidant System, and Photosynthetic Performance of Wheat Seedlings Under Drought Stress

Drought stress is one of the most important environmental constraints that negatively affect crop growth and production worldwide. Recently, nanotechnology has increasingly been applied to improve tolerance in plants exposed to abiotic stresses such as drought. A pot experiment was conducted to examine the influence of nitric oxide donor sodium nitroprusside (SNP: 100 μM) in presence of TiO2 nanoparticles (TiO2 NPs: 500, 1000, and 2000 mg kg−1) on wheat seedlings under drought stress conditions. Water deficit negatively affected growth and photosynthetic parameters with simultaneous increase in activity of antioxidant enzymes. Under severe drought stress, soil-applied 2000 mg kg−1 TiO2 NPs enhanced seedling dry weight (DW), relative water content (RWC), catalase (CAT) activity, ascorbate peroxidase (APX) activity, and proline content. Moreover, 2000 mg kg−1 TiO2 NPs enhanced total chlorophyll (total Chl), carotenoids (Car), stomatal conductance (gs), and transpiration (E) under severe drought stress. However, addition of 100 μM SNP in presence of 2000 mg kg−1 TiO2 NPs significantly increased seedling length (SL), superoxide dismutase (SOD) activity, total soluble proteins, net photosynthetic rate (Pn), and intercellular CO2 concentration (Ci). The aforementioned treatment also significantly reduced hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents under severe drought stress. Our results suggest that foliar application of SNP in the presence of TiO2 NPs can protect wheat seedlings against drought-induced oxidative damage.

Deletion of the Nonribosomal Peptide Synthetase Gene nps1 in the Fungus Clonostachys rosea Attenuates Antagonism and Biocontrol of Plant Pathogenic Fusarium and Nematodes.

Secondary metabolites produced by biological control agents may influence the outcome of their interactions with plant pathogenic microorganisms and plants. In the present study, we investigated the role of the nonribosomal peptide synthetase gene nps1 expressed by the biocontrol fungus Clonostachys rosea. A gene expression analysis showed that nps1 was induced during confrontations with the plant pathogenic fungus Botrytis cinerea. Gene deletion strains of nps1 displayed increased growth rates and conidiation. However, the nematicidal activity of culture filtrates from C. rosea Δnps1 strains was significantly weaker than that from wild-type filtrates (P ≤ 0.001); after 24 h of incubation with culture filtrates from nps1 deletion strains, only 13 to 33% of a mixed community of nematodes were dead compared with 42% of nematodes incubated with wild-type culture filtrates. The Δnps1 strains also showed reduced biocontrol efficacy during pot experiments, thus failing to protect wheat seedlings from foot rot disease caused by the plant pathogenic fungus Fusarium graminearum. Furthermore, C. rosea Δnps1 strains were not able to reduce populations of plant-parasitic nematodes in soil or in roots of wheat as efficiently as the wild-type strain. Both C. rosea wild-type and Δnps1 strains increased the dry shoot weight and shoot length of wheat by 20 and 13%, respectively. We showed that NPS1, a putative nonribosomal peptide synthetase encoded by nps1, is a biocontrol factor, presumably by producing a hitherto unknown nonribosomal peptide compound with antifungal and nematicidal properties that contributes to the biocontrol properties of C. rosea.

Effect of polyamines and nitric oxide in Piriformospora indica-induced resistance and basal immunity of wheat against Fusarium pseudograminearum

Fusarium crown rot of wheat is an important disease worldwide. The lack of commercial resistant cultivars and effective fungicides against Fusarium, make controlling the disease very difficult. Biocontrol can be an environmentally friendly method to reduce the progress of various diseases caused by Fusarium species. Piriformospora indica is a root endophytic fungus with a wide range of host plants, which increases their growth and tolerance to biotic and abiotic stresses. In this study, capability of P. indica to protect wheat seedlings against Fusarium pseudograminearum, causing crown rot, was investigated and the role of polyamines (PAs) and nitric oxide (NO) as signal molecules involved in plant defense pathways in induced resistance by this endophytic fungus was evaluated in this pathosystem for the first time. Our results showed that P. indica did not have any antagonistic effect on F. pseudograminearum in vitro but considerably reduced the disease progress on wheat seedlings and detached leaves. Also, P. indica increased plant growth parameters compared to the controls in greenhouse. Application of spermidine (Spd; a polyamine) and sodium nitroprusside (SNP; a NO donor) revealed that PAs and NO had significant effect on basal immunity and P. indica-induced resistance (Pi-IR) via elevation of H2O2 levels, guaiacol peroxidase (GPX) and catalase (CAT) activity, callose deposition, relative water content (RWC) and membrane stability index (MSI) compared to the plants only inoculated with F. pseudograminearum and uninoculated controls. In addition, our data demonstrated that PAs and NO synergistically enhanced basal resistance and Pi-IR against Fusarium crown rot in wheat plants.

Selenium protects wheat seedlings against salt stress-mediated oxidative damage by up-regulating antioxidants and osmolytes metabolism

Salinity stress hampers the growth of most crop plants and reduces yield considerably. Therefore, experiments were conducted on wheat (Triticum aestivum L.) plants for studying the role of selenium (5 and 10 μM Se) supplementation in strengthening the salinity stress tolerance. Exposure to salinity (100 mM NaCl) reduced growth in terms of length, fresh and dry biomass yield. Se was affective in ameliorating the deleterious effects of NaCl stress to significant levels when supplied at 5 μM concentrations compared to 10 μM. Application of Se at 5 μM concentration did not show significant impacts on the physiological and biochemical parameters studied. Plants supplemented with 5 μM Se exhibited the highest RWC, chlorophyll synthesis, and photosynthesis. Se supplementation reduced the NaCl-mediated oxidative damage by up-regulating the activity of enzymatic components of the antioxidant system and the accumulation of ascorbate and glutathione. Furthermore, 5 μM Se proved beneficial in enhancing proline and sugar accumulation in normal and NaCl-stressed seedlings providing extra osmolarity to maintain RWC and protect photosynthesis. Se also affected proline metabolism by modulating the activities of the γ-glutamyl kinase (γ-GK) and proline oxidase (PROX) leading to its greater synthesis and lesser degradation. Moreover, it was observed that Se declined the Na/K ratio and also improved nitrogen and Ca uptake. Conclusively, Se at low concentration can be beneficial in preventing salinity-mediated damage and further studies are required to unravel underlying mechanisms.

Bacteria Isolated from Treated Wastewater for Biofertilization and Crop Protection Against Fusarium spp. Pathogens

Bacteria isolated from bioaerosols emitted by a clarifier in a wastewater treatment plant (Dobre Miasto, Kosyń, Poland) were analyzed. A total of 27 morphologically different bacterial colonies were isolated, and 14 strains antagonistic towards Fusarium culmorum in vitro were selected for analysis. Most of the analyzed bacteria did not increase the germination capacity or the height of wheat seedlings. The only exception was strain PSDM20 which was characterized by multiple plant growth–promoting properties, but also by the lowest metabolic activity and lowest substrate assimilation. Strain PSDM16 deteriorated the status of wheat seedlings. Bacterial strains PSDM3, PSDM6, PSDM10, PSDM13, PSDM14, PSDM17, and PSDM20 prevented the deterioration of the biometric parameters of wheat seedlings exposed to F. culmorum and F. graminearum. Strains PSDM3, PSDM6, PSDM10, and PSDM17 most effectively protected wheat seedlings against infections caused by the above pathogens. Strain PSDM6 produced indole acetic acid (IAA), and it significantly contributed to plant elongation. Correlations were not observed between the growth-promoting properties, metabolic activity, and fungistatic properties of the evaluated bacteria. Pseudomonas putida PSDM3, Proteus penneri PSDM6, Enterobacter hormaechei PSDM10, and Advenella sp. PSDM17 were most effective in limiting the spread of Fusarium spp. infections in spring wheat, and they can be used as biological fungicides. The results of this study indicate that bacteria isolated from non-agricultural ecosystems are capable of protecting and fertilizing crops. The growth-promoting properties of bacterial strains of the genus Proteus are comparable with those of the widely investigated Pseudomonas spp. strains.

Comparative Effects of Benzoic Acid and Water Stress on Wheat Seedlings

In the present study, we compared the effects of allelochemical, water stress (WS) and their combinations on seedling growth, biochemical parameters and responses of antioxidative enzymes in Triticum aestivum L. The wheat seedlings were treated with 0.5, 1.0 and 1.5 mM concentrations of benzoic acid (BA), with and without water stress. Leaf water status, photosynthetic pigments, protein content, amount of proline and activities of nitrate reductase and antioxidant enzymes were examined. Allelopathic stress resulted in reduction of seedling height. Height of water stressed seedlings greatly decreased. The combined treatments, BA + WS further decreased the seedling height. BA treatment with and without water stress caused significant reduction in dry weight of the seedlings. BA and water stress decreased relative water content, pigments and protein content. Total soluble sugar content and nitrate reductase activity were variedly affected under all treatments. Proline content and lipid peroxidation increased in treatments with BA and water stress. Activity of superoxide dismutase increased significantly (P < 0.05) while catalase activity decreased in all treatments. Ascorbate peroxidase and guaiacol peroxidase activities were higher as compared with catalase which seems to protect wheat seedlings from oxidative stress. Water stress elevated the toxic effect of allelochemical.

Low-Molecular-Weightt Polysaccharides From Pyropia yezoensis Enhance Tolerance of Wheat Seedlings (Triticum aestivum L.) to Salt Stress.

Soil salinity is one of the major issues worldwide that affects plant growth and reduces agricultural productivity. Seaweed polysaccharides have been shown to promote crop growth and improve the resistance of plant to abiotic stresses. Pyropia yezoensis is a commercially important edible red alga in Southeast Asia. However, there is little research on the application of polysaccharides from P. yezoensis in agriculture. The molecular weight (MW) of polysaccharides influences their properties. Therefore, in this study, four representative polysaccharides from P. yezoensis (PP) with different MWs (MW: 3.2, 10.5, 29.0, and 48.8 kDa) were prepared by microwave-assisted acid hydrolysis. The relationship between the degradation of polysaccharides from P. yezoensis (DPP) and their effects on plant salt tolerance was investigated. The results showed that exogenous PP and DPPs increased wheat seedling shoot and root lengths, and fresh and dry weights, alleviated membrane lipid peroxidation, increased the chlorophyll content and enhanced antioxidant activities. The expression level examination analysis of several Na+/K+ transporter genes suggested that DPPs could protect plants from the damage of salt stress by coordinating the efflux and compartmentation of Na+. The results demonstrated that polysaccharides could regulate antioxidant enzyme activities and modulate intracellular ion concentration, thereby to protect plants from salt stress damage. Furthermore, there was a significant correlation between the tolerance of wheat seedlings to salt stress and MW of polysaccharides. The results suggested that the lower-MW samples (DPP1, 3.2 kDa) most effectively protect wheat seedlings against salt stress.

20-hydroxyecdysone protects wheat seedlings from salt stress

20-Hydroxyecdysone (20E), a molting hormone of insects, is the most abundant phytoecdysteroid (PE) produced by plants, where it represents a protective molecule against insect herbivores. The objective of the investigation is to determine the effect of 20E on the growth, physiological and biochemical characteristics and the transcript levels of antioxidant enzymes of wheat seedlings under salt stress. Our results showed that exogenous 20E was able to significantly alleviate salt-induced oxidative damage in wheat seedlings. It most likely acts by decreasing the concentration of malondialdehyde (MDA) and the rate of superoxide radical (O 2 •− ) generation, and by increasing the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), concentrations of ascorbic acid (AsA) and glutathione (GSH), and the gene expression levels of SOD , POD , CAT . It was suggested that foliar spraying with 20E could efficiently protect wheat seedlings against salt-induced oxidative stress. The results also show that 20E had a positive physiological effect on the growth of salt-stressed seedlings. This is the first report dealing with the effect of 20E pretreatment in the enhancing of wheat seedling tolerance under salt stress. https://doi.org/10.2298/ABS170722056L Received: July 22, 2017; Revised: November 14, 2017; Accepted: December 11, 2017; Published online: December 22, 2017 How to cite this article: Li J, Han X, Tang L, Wang C, Zhang W, Ma J. 20-hydroxyecdysone protects wheat seedlings from salt stress. Arch Biol Sci. 2018;70(2):379-86.

Comparasion of phenylalanine ammonia lyase response to lead and zinc stress in different wheat genotypes

Phenylalanine ammonia lyase response to zinc and lead toxicity of two different wheat genotypes (Triticum aestivum L. cv. Kıraç66 and Triticum durum Desf. cv. Kızıltan-91) were investigated in this study. The seedlings which were cultivated for 6 weeks in greenhouse conditions were harvested from the surface of soil. At the end of 6th weeks, seedlings were transferred to jars which filled full Hoagland nutrient solution. The zinc and lead stress treatments were carried out with addition of 0 (control), 100 mg/L, 200 mg/L, 300 mg/L zinc and lead in nutrient solution. It was determined that phenylalanine ammonia lyase activity increased in seedlings under zinc and lead stress. The highest phenylalanine ammonia lyase activity was determined in treatment 200 mg/L Pbon fourth day in cv. ‘Kızıltan-91’genotype. These data show that phenylalanine ammonia lyase activity appear to protect wheat seedlings against stressrelated damage

Novel bacterial seed treatment protects wheat seedlings from insect damage

Insecticidal seed treatments are used commonly worldwide to protect seedlings against root feeding insects. Organophosphate insecticides that have been used for seed treatments are being phased out and replaced with neonicotinoid insecticides. Concerns about the environmental impact of neonicotinoids have prompted a search for alternatives. Microbial insecticides are a biological alternative for seed treatments to target root feeding insects. Six field trials with organophosphate granules (diazinon, chlorpyrifos), neonicotinoid seed treatment (clothianidin) and microbial (Serratia entomophila) seed treatment targeting grass grub, a New Zealand scarab pest, were conducted in wheat crops at several sites over 4 years (2012–2015). Sites were selected each year that had potentially damaging populations of grass grub present during the trials. Untreated seeds led to significant losses of plants and wheat yield due to lower seedling establishment and ongoing plant losses from grass grub damage. Insecticide and microbial treatments increased plant survival in all trials compared with untreated seeds. Better plant survival was associated with higher yields from the insecticide treatments in four out of six trials. Neonicotinoid seed treatment alone gave similar yield increases to combined neonicotinoid seed treatment and organophosphate granules. Microbial seed treatment with S. entomophila gave similar yield increases to insecticide treatments in two out of six trials. Seed treatment with S. entomophila is an alternative for grass grub control; however, development of a commercial product requires effective scale-up of production, further research to improve efficacy, and viability of the live bacteria needs to be maintained on coated seed.

&amp;lt;i&amp;gt;Bacillus subtilis Strains&amp;lt;/i&amp;gt; with Antifungal Activity against the Phytopathogenic Fungi

Bacillus strains isolated from the rhizosphere soil of potato roots were evaluated for the potential antagonistic activity against fungal pathogens in vitro and in vivo. Two bacterial isolates were identified as new Bacillus subtilis strains by 16S rRNA and GyrB gene sequencing and were designated GM2 and GM5, respectively. Strains were characterized by their ability to inhibit growth of a number of phytopathogenic fungi. It was shown that GM5 strain inhibited growth of phytopathogenic fungi more effectively than GM2 strain. Both strains were capable of producing a number of hydrolytic enzymes as well as antimicrobial metabolites (ammonia and HCN). In addition, GM2 strain also produced siderophores. Four genes encoding antimicrobial peptides were identified in the genome of GM2 strain: ituC, bmyB, bacA and srfA. Genome of GM5 contained two genes encoding for antimicrobial peptides, srfA and fenD. Purified lipopeptide fraction from GM5 but not from GM2 strain was able to control Fusarium solani spread in the plate assay. Furthermore, Bacillus subtilis strain GM2 promoted growth of wheat but only GM5 strain was able to protect wheat seedlings from Fusarium oxysporum infection.

Silicon nanoparticles more effectively alleviated UV-B stress than silicon in wheat (Triticum aestivum) seedlings

The role of silicon (Si) in alleviating biotic as well as abiotic stresses is well known. However, the potential of silicon nanoparticle (SiNP) in regulating abiotic stress and associated mechanisms have not yet been explored. Therefore, in the present study hydroponic experiments were conducted to investigate whether Si or SiNp are more effective in the regulation of UV-B stress. UV-B (ambient and enhanced) radiation caused adverse effect on growth of wheat (Triticum aestivum) seedlings, which was accompanied by declined photosynthetic performance and altered vital leaf structures. Levels of superoxide radical and H2O2 were enhanced by UV-B as also evident from their histochemical stainings, which was accompanied by increased lipid peroxidation (LPO) and electrolyte leakage. Activities of superoxide dismutase and ascorbate peroxidase were inhibited by UV-B while catalase and guaiacol peroxidase, and all non-enzymatic antioxidants were stimulated by UV-B. Although, nitric oxide (NO) content was increased at all tested combinations, but its maximum content was observed under SiNps together with UV-B enhanced treatment. Pre-additions of SiNp as well as Si protected wheat seedlings against UV-B by regulating oxidative stress through enhanced antioxidants. Data indicate that SiNp might have protected wheat seedlings through NO-mediated triggering of antioxidant defense system, which subsequently counterbalance reactive oxygen species-induced damage to photosynthesis. Further, SiNp appear to be more effective in reducing UV-B stress than Si, which is related to its greater availability to wheat seedlings.