Take-all Of Wheat Research Articles

Associations Among Cultivar Cropping Sequence, 2,4-Diacetlyphloroglucinol-Producing Pseudomonad Populations, and Take-All Disease of Winter Wheat in Oregon.

Take-all of wheat (Triticum aestivum L.), caused by Gaeumannomyces tritici (syn. G. graminis var. tritici), is perhaps the most important soil-borne disease of wheat globally and can cause substantial yield losses under several cropping scenarios in Oregon. Though resistance to take-all has not been identified in hexaploid wheat, continuous cropping of wheat for several years can reduce take-all severity through the development of suppressive soils, a process called "take-all decline" (TAD). Extensive work has shown that TAD is driven primarily by members of the Pseudomonas fluorescens complex that produce 2,4-diacetlyphloroglucinol (DAPG), an antibiotic that is associated with antagonism and induced host resistance against multiple pathogens. Field experiments were conducted to determine the influence of agronomically relevant first year wheat cultivars on take-all levels and ability to accumulate DAPG-producing pseudomonads within their rhizospheres in second-year field trials and in greenhouse trials. One first year wheat cultivar consistently resulted in less take-all in second-year wheat and accumulated significantly more DAPG-producing pseudomonads than other cultivars, suggesting a potential mechanism for take-all reduction associated with that cultivar. An intermediate level of take-all suppression in other other cultivars was not clearly associated with population size of DAPG-producing pseudomonads, however. The first year cultivar effect on take-all dominated in subsequent plantings, and its impact was not specific to the first year cultivar. Our results confirm that wheat cultivars may be used to suppress take-all when deployed appropriately over cropping seasons, an approach that is cost effective, sustainable, and currently being utilized by some wheat growers in Oregon to reduce take-all.

Disease-Suppressive Soils Induce Systemic Resistance in Arabidopsis thaliana Against Pseudomonas syringae pv. tomato

Arabidopsis thaliana accession Col-0 seedlings were transferred into an autoclaved soil/sand mixture amended with either 10 or 20% (wt/wt) soil from fields in Washington State that are suppressive to take-all or Rhizoctonia root rot of wheat. Three weeks after transplanting, these plants had population sizes of 2,4-diacetylphloroglucinol (DAPG) or phenazine-1-carboxylic acid (PCA)-producing pseudomonads of greater than 5 × 105 colony forming units per gram fresh weight of root with rhizosphere soil. When the plants were challenge-inoculated with Pseudomonas syringae pv. tomato DC3000, both soils induced systemic resistance in the leaves against bacterial speck to a level similar to that induced by P. simiae WCS417r, P. fluorescens Q2-87 (DAPG+), P. brassicacearum Q8r1-96 and L5.1-96 (both DAPG+), and P. synxantha 2-79 (PCA+). Pasteurization of the soils before adding them into the soil/sand mixture eliminated DAPG- and PCA-producing pseudomonads from the Arabidopsis rhizosphere and significantly reduced induced systemic resistance activity. However, populations of total culturable aerobic bacteria were similar in the rhizosphere of plants grown in soil/sand mixes amended with untreated or pasteurized suppressive soils. This is the first report of induction of systemic resistance in Arabidopsis by take-all and Rhizoctonia-suppressive soils and the ability of PCA-producing P. synxantha 2-79 to induce resistance. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2024.

1,2,4-Triazole benzamide derivative TPB against Gaeumannomyces graminis var. tritici as a novel dual-target fungicide inhibiting ergosterol synthesis and adenine nucleotide transferase function.

Isopropyl 4-(2-chloro-6-(1H-1,2,4-triazol-1-yl)benzamido)benzoate (TPB) was a 1,2,4-triazole benzoyl arylamine derivative with excellent antifungal activity, especially against Gaeumannomyces graminis var. tritici (Ggt). Its mechanism of action was investigated by transmission electron microscopy (TEM) observation, assays of sterol composition, cell membrane permeability, intracellular ATP and mitochondrial membrane potential, and mPTP permeability, ROS measurement, RNA sequencing (RNA-seq) analysis. TPB interfered with ergosterol synthesis, reducing ergosterol content, increasing toxic intermediates, and finally causing biomembrane disruption such as increasing cell membrane permeability and content leakage, and destruction of organelle membranes such as coarse endoplasmic reticulum and vacuole. Moreover, TPB destroyed the function of adenine nucleotide transferase (ANT), leading to ATP transport obstruction in mitochondria, inhibiting mPTP opening, inducing intracellular ROS accumulation and mitochondrial membrane potential loss, finally resulting in mitochondrial damage including mitochondria swelled, mitochondrial membrane dissolved, and cristae destroyed and reduced. RNA-seq analyses showed that TPB increased the expression of ERG11, ERG24, ERG6, ERG5, ERG3 and ERG2 genes in ergosterol synthesis pathway, interfered with the expression of genes (NDUFS5, ATPeV0E, NCA2 and Pam17) related to mitochondrial structure, and inhibited the expression of genes (WrbA and GST) related to anti-oxidative stress. TPB exhibited excellent antifungal activity against Ggt by inhibiting ergosterol synthesis and destroying ANT function. So, TPB was a novel compound with dual-target mechanism of action and can be considered a promising novel fungicide for the control of wheat Take-all. The results provided new guides for the structural design of active compounds and powerful tools for pathogen resistance management. © 2023 Society of Chemical Industry.

RpoZ regulates 2,4-DAPG production and quorum sensing system in Pseudomonas fluorescens 2P24.

Pseudomonas fluorescens 2P24 was isolated from soil of natural decay associated with wheat take-all and it can effectively control soil-borne diseases caused by a variety of plant pathogens. 2,4-diacetylphloroglucinol (2,4-DAPG), is produced by P. fluorescens 2P24 and plays an important role in the prevention and control of plant diseases. To understand the resistant mechanism, in this study, we conducted experiments to explore the regulation role of rpoZ in the synthesis of the antibiotic 2,4-DAPG and regulation of QS system. A random mini-Tn5 mutagenesis procedure was used to screen regulators for phlA transcription in stain PM901, which containing a phlA∷lacZ transcriptional fusion reporter plasmid. We identified 12 insertion mutants could significantly change phlA gene expression. By analyzing the amino acid sequences of the interrupted gene, we obtained a mutant strain Aa4-29 destroyed the rpoZ gene, which encodes the omiga subunit. We constructed the plasmid of rpoZ mutant (pBBR-△rpoZ) transformed into competent cells of P. fluorescens 2P24 by electro-transformation assay. The strains of P. fluorescens 2P24/pBBR, 2P24-△rpoZ/pBBR, 2P24-△rpoZ/pBBR-rpoZ were used to evaluate the regulation role of rpoZ in 2,4-DAPG production and quorum sensing system. According to β-galactosidase activity, we found that rpoZ positively regulated the expression of phlA (a synthesis gene of 2,4-DAPG) and PcoI (a synthesis gene of PcoI/PcoR QS signal system) at the transcriptional level. The production of 2,4-DAPG antibiotic and signal molecule AHL was influenced by rpoZ. Further, rpoZ was involved in regulating rsmA expression. RpoZ also has a certain regulatory effect on rpoS transcription, but no effect on the transcription of phlF, emhABC and emhR. According to the biocontrol assay, P. fluorescens 2P24 strains with rpoZ showed obvious antagonism ability against the Rhizoctonia solani in cotton, while the mutant strain of rpoZ lost the biocontrol effect. RpoZ had a significant effect on the swimming and biofilm formation in P. fluorescens 2P24. Our data showed that rpoZ was an important regulator of QS system, 2,4-DAPG in P. fluorescens 2P24. This may imply that P. fluorescens 2P24 has evolved different regulatory features to adapt to different environmental threats.

Preparation of cinnamaldehyde nanoemulsions: Formula optimization, antifungal activity, leaf adhesion, and safety assessment

Plant essential oils have become an increasingly popular topic in agriculture due to their outstanding fungicidal activity, good biocompatibility and abundance of sources. Cinnamaldehyde is found in cinnamon essential oil and has good antifungal activity, but cinnamaldehyde also has negative characteristics such as high volatility, poor water solubility and easy oxidative degradation, which seriously hinder the potential of its antimicrobial properties and its application in agriculture. In this study, the effects of the surfactant ratio, concentration and emulsification method on the stability of cinnamaldehyde nanoemulsions were systematically investigated by observing the sample appearance, mean droplet size and differential scanning calorimetry (DSC) analysis. The results showed that the optimal formula of cinnamaldehyde nanoemulsion was a surfactant (R5:848) ratio of 1:1 and a concentration of 7%, and the emulsification method was E1: adding dropwise aqueous phase (deionized water) to the oil phase (cinnamaldehyde + surfactant). Cinnamaldehyde nanoemulsions showed good antifungal activity against rice sheath blight (Rhizoctonia solani), wheat sheath blight (Rhizoctonia cerealis) and wheat take-all (Gaeumannomyces graminis). The nanoemulsions also had excellent wetting properties on rice and wheat leaves, higher biosafety for nontarget environmental organisms such as zebrafish and earthworms, low cytotoxicity to human BASE-2B cells, and no inhibition of germination and growth of wheat and rice. The results of this research provide important ideas for the design of efficient, safe and environmentally friendly plant-derived fungicides.

Mapping Wheat Take-All Disease Levels from Airborne Hyperspectral Images Using Radiative Transfer Models

Take-all is a root disease that can severely reduce wheat yield, and wheat leaves with take-all disease show a large amount of chlorophyll loss. The PROSAIL model has been widely used for the inversion of vegetation physiological parameters with a clear physical meaning of the model and high simulation accuracy. Based on the chlorophyll deficiency characteristics, the reflectance data under different canopy chlorophyll contents were simulated using the PROSAIL model. In addition, inverse models of spectral reflectance profiles and canopy chlorophyll contents were constructed using a one-dimensional convolutional neural network (1D-CNN), and a transfer learning approach was used to detect the take-all disease levels. The spectral reflectance data of winter wheat acquired by an airborne imaging spectrometer during the filling period were used as input parameters of the model to obtain the chlorophyll content of the canopy. Finally, the results of the distribution of winter wheat take-all disease were mapped based on the relationship between take-all disease and the chlorophyll content of the canopy. The results showed that classification based on the deep learning model performed well for winter wheat take-all monitoring. This study can provide some reference basis for high-precision winter wheat take-all disease monitoring and can also provide some technical method references and ideas for remote sensing crop pest and disease remote sensing mapping.

Management of take-all disease caused by Gaeumannomyces graminis var. tritici in wheat through Bacillus subtilis strains.

Wheat (Triticum aestivum) is the second largest grain crop worldwide, and one of the three major grain crops produced in China. Take-all disease, caused by Gaeumannomyces graminis var. tritici (Ggt) infection, is a widespread and devastating soil-borne disease that harms wheat production. At present, the prevention and control of wheat take-all depend largely on the application of chemical pesticides. Chemical pesticides, however, not only lead to increased drug resistance of pathogens but also leave significant residues in the soil, causing serious environmental pollution. In this study, we investigated the application of Bacillus subtilis to achieve take-all disease control in wheat while reducing pesticide application. Antagonistic bacteria were screened by plate test, species identification of strains was performed by Gram staining and sequencing of 16s rDNA, secondary metabolite activity of strains was detected by clear circle method, strain compatibility and effect of compounding on Ggt were detected by plate, and the application prospects of specific strains were analyzed by greenhouse and field experiments. We found that five B. subtilis strains, JY122, JY214, ZY133, NW03, Z-14, had significant antagonistic effects against Ggt, and could secrete antimicrobial proteins including amylase, protease, and cellulase. Furthermore, Z-14 and JY214 cultures have also been shown to change the morphology of Ggt mycelium. These results also showed that Z-14, JY214, and their combination can control take-all disease in wheat at a reduced level of pesticide use. In summary, we screened two Bacillus spp. strains, Z-14 and JY214, that could act as antagonists that contribute to the biological control of wheat take-all disease. These findings provide resources and ideas for controlling crop diseases in an environmentally friendly manner.

Evaluation of Pseudomonas and Bacillus Strains as Potential Biocontrol Agents against Fusarium Wilt of Chickpea

Evaluation of Pseudomonas and Bacillus Strains as Potential Biocontrol Agents against Fusarium Wilt of Chickpea

Evaluation of the Phytotoxicity of 2,4-Diacetylphloroglucinol and Pseudomonas brassicacearum Q8r1-96 on Different Wheat Cultivars.

Pseudomonas brassicacearum Q8r1-96 and other 2,4-diacetylphloroglucinol (DAPG)-producing pseudomonads of the P. fluorescens complex possess both biocontrol and growth-promoting properties and play an important role in suppression of take-all of wheat in the Pacific Northwest (PNW) of the United States. However, P. brassicacearum can also reduce seed germination and cause root necrosis on some wheat cultivars. We evaluated the effect of Q8r1-96 and DAPG on the germination of 69 wheat cultivars that have been or currently are grown in the PNW. Cultivars varied widely in their ability to tolerate P. brassicacearum or DAPG. The frequency of germination of the cultivars ranged from 0 to 0.87 and 0.47 to 0.90 when treated with Q8r1-96 and DAPG, respectively. There was a significant positive correlation between the frequency of germination of cultivars treated with Q8r1-96 in assays conducted invitro and in the greenhouse. The correlation was greater for spring than for winter cultivars. In contrast, the effect of Q8r1-96 on seed germination was not correlated with that of DAPG alone, suggesting that DAPG is not the only factor responsible for the phytotoxicity of Q8r1-96. Three wheat cultivars with the greatest tolerance and three cultivars with the least tolerance to Q8r1-96 were tested for their ability to support root colonization by strain Q8r1-96. Cultivars with the greatest tolerance supported significantly greater populations of strain Q8r1-96 than those with the least tolerance to the bacteria. Our results show that wheat cultivars differ widely in their interaction with P. brassicacearum and the biocontrol antibiotic DAPG.

Winter Wheat Take-All Disease Index Estimation Model Based on Hyperspectral Data

Wheat take-all, caused by two variants of the fungus Gaeumannomyces gramnis (Sacc.) Arx & D. Olivier, was common in spring wheat areas in northwest and north China and occurred in winter wheat areas in north China. The yield of common disease areas was reduced by more than 20% and the yield of severe cases was reduced by more than 50%. Large-scale rapid and accurate estimation of the incidence of wheat take-all plays an important role in guiding field control and agricultural yield estimation. In this study, a portable ground spectrometer was used to collect the spectral reflectance in the 350–1050 nm band range of wheat canopy after take-all infection in the wheat grain filling stage and combined with the ground disease survey data.Then a winter wheat take-all disease index estimation model was proposed based on the spectral band division interval and selected band combination. According to the normalized difference spectral index (NDSI) and the determinative coefficient of the disease index formed by any two band combinations, the spectral index band combinations corresponding to the spectral index with high correlation in each region were screened by dividing spectral intervals. Partial least-squares regression was used to establish a binary and ternary disease index calibration model. The results showed that the model based on spectral indices of ternary variables had the highest coefficient of determination. Finally, the optimal regression model of wheat take-all disease condition index composed of NDSI(R590,R598), NDSI(R534,R742) and NDSI(R810,R834) was established: Y = 134.577 − 70.301 NDSI(R590,R598) − 223.533 NDSI(R534,R742) + 51.584 NDSI(R810,R834) (R2 = 0.743, RMSEP = 0.094, df = 15), which was the most suitable model for winter wheat take-all estimation. The construction of this model can provide new method and technical support for future evaluation and monitoring of wheat take-all disease on the field.

Biological Control of Take-All and Growth Promotion in Wheat by Pseudomonas chlororaphis YB-10.

Wheat is a worldwide staple food crop, and take-all caused by Gaeumannomyces graminis var. tritici can lead to a tremendous decrease in wheat yield and quality. In this study, strain YB-10 was isolated from wheat rhizospheric soil and identified as Pseudomonas chlororaphis by morphology and 16S rRNA gene sequencing. Pseudomonas chlororaphis YB-10 had extracellular protease and cellulase activities and strongly inhibited the mycelium growth of Gaeumannomyces graminis var. tritici in dual cultures. Up to 87% efficacy of Pseudomonas chlororaphis YB-10 in controlling the take-all of seedlings was observed in pot experiments when wheat seed was coated with the bacterium. Pseudomonas chlororaphis YB-10 was also positive for indole acetic acid (IAA) and siderophore production, and coating wheat seed with the bacterium significantly promoted the growth of seedlings at 107 and 108 CFU/mL. Furthermore, treatment with Pseudomonas chlororaphis YB-10 increased activities of the wheat defense-related enzymes POD, SOD, CAT, PAL and PPO in seedlings, indicating induced resistance against pathogens. Overall, Pseudomonas chlororaphis YB-10 is a promising new seed-coating agent to both promote wheat growth and suppress take-all.

Activity of Fengycin and Iturin A Isolated From Bacillus subtilis Z-14 on Gaeumannomyces graminis Var. tritici and Soil Microbial Diversity.

Bacillus subtilis Z-14 can inhibit phytopathogenic fungi, and is used as a biocontrol agent for wheat take-all disease. The present study used the soil-borne fungus Gaeumannomyces graminis var. tritici (Ggt), which causes wheat take-all disease, and the soil microbial community as indicators, and investigated the antifungal effects of fengycin and iturin A purified from strain Z-14 using high performance liquid chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, respectively. The results showed that fengycin destroyed the internal structure of Ggt cells by digesting the cytoplasm and organelles, forming vacuoles, and inducing hyphal shrinkage and distortion. Iturin A induced cell wall disappearance, membrane degeneration, intracellular material shrinkage, and hyphal fragmentation. A biocontrol test demonstrated a 100% control effect on wheat take-all when wheat seedlings were treated with fengycin at 100 μg/ml or iturin A at 500 μg/ml. Iturin A and fengycin both reduced the relative abundance of Aspergillus and Gibberella. At the genus level, iturin A reduced the relative abundance of Mortierella and Myrothecium, while fengycin reduced that of Fusarium. Only fengycin treatment for 7 days had a significant effect on soil bacterial diversity.

A novel encapsulation of Streptomyces fulvissimus Uts22 by spray drying and its biocontrol efficiency against Gaeumannomyces graminis, the causal agent of take-all disease in wheat.

Wheat is a valuable food source that is exposed to many diseases that reduce its quantity and quality. One of the most important diseases affecting wheat is take-all, caused by Gaeumannomyces graminis var. tritici. The application of bacterial inoculants into the soil can increase plant nutrient absorption and enhance the efficiency of probiotic bacteria. For increased beneficial bacteria efficiency, the encapsulation technique has been used in agriculture. The results of Fourier transform infrared (FTIR) and X-ray diffraction analysis (XRD) indicated that the prepared formulation is a mixture of gellan and chitosan. Using SEM, the spherical structure of the microcapsules was confirmed. It was observed that the increase in bacterial release was gradual, and the highest amount of bacteria was released (109 CFU mL-1 ) on the 50th day. Greenhouse experiments showed that plants treated with S. fulvissimus Uts22 microcapsules had the highest efficiency with 90% disease control. Moreover, the highest fresh and dry weights of roots and shoots were observed in this treatment. In this study, a new type of formulation aiming at controlling wheat take-all disease was developed through bacterial and nanoparticles loaded chitosan- gellan gum microcapsules with spray drying method. This formulation has many advantages, such as a large surface area and high internal porosity and increased water-holding capacity, while it also provides a proper habitat for bacteria to increase colonization rates and offers protection of the soil. © 2021 Society of Chemical Industry.

Take-All Disease: New Insights into an Important Wheat Root Pathogen.

Take-all disease, caused by the fungal root pathogen Gaeumannomyces tritici, is considered to be the most important root disease of wheat worldwide. Here we review the advances in take-all research over the last 15 years, focusing on the identification of new sources of genetic resistance in wheat relatives and the role of the microbiome in disease development. We also highlight recent breakthroughs in the molecular interactions between G. tritici and wheat, including genome and transcriptome analyses. These new findings will aid the development of novel control strategies against take-all disease. In light of this growing understanding, the G. tritici-wheat interaction could provide a model study system for root-infecting fungal pathogens of cereals.

Multifunctional manganese-based carboxymethyl chitosan hydrogels for pH-triggered pesticide release and enhanced fungicidal activity

Carboxymethyl chitosan (CMCS) has emerged as a promising biopolymer carrier for controlled release formulations of pesticide. In this study, manganese-based carboxymethyl chitosan hydrogel was facilely prepared to encapsulate and release fungicide prothioconazole in a controllable manner. The loading content (LC) and encapsulation efficiency (EE) of prothioconazole were optimized by orthogonal test. When scaled up under the optimal condition, the corresponding LC and EE were 22.17 % and 68.38 %, respectively. The result showed that the pH-triggered release behavior of prothioconazole for the hydrogels was consistent with swelling behavior. The pesticide rapidly released in neutral and slightly alkaline solutions than in acidic conditions. Moreover, the prepared hydrogel showed enhanced fungicidal ability against wheat take-all pathogen (Gaeumannomyces graminis var. tritic) compared to that of prothioconazole technical material. This research seeks to provide a promising approach to develop metal and polysaccharide-based hydrogels to control the pesticide release and reduce pesticide use in sustainable agriculture application.

Isolation and yield optimization of lipopeptides from Bacillus subtilis Z-14 active against wheat take-all caused by Gaeumannomyces graminis var. tritici.

Wheat take-all, caused by the soil-borne fungus Gaeumannomyces graminis var. tritici, is one of the major constraints on wheat production worldwide. Bacillus subtilis Z-14 exerts significant biocontrol activity against wheat take-all, and lipopeptide antibiotics are the main antifungal substances. Herein, lipopeptide antibiotics C14-C15 iturin A, C14-C16 fengycin A, and C15-C17 fengycin B from B. subtilis Z-14 culture filtrates were separated and identified by high-performance liquid chromatography, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, and mass spectrometry/mass spectrometry, respectively. The optimal medium components for Z-14 lipopeptide antibiotic production were 3.85g/L corn flour, 1.57g/L soybean meal, 0.03g/L FeSO4 ·7H2 O, 0.2g/L NaH2 PO4 ·2H2 O, and 0.4g/L Na2 HPO4 ·2H2 O. Quantification analysis by high-performance liquid chromatography showed that fengycins played a main role in antifungal activity against Gaeumannomyces graminis var. tritici. Quantitative reverse transcription polymerase chain reaction showed that lipopeptide synthesis genes fenD and ituC reached maximum expression levels after 48 h of fermentation. The strongest control of wheat take-all by Z-14 was achieved by adding 30mL of culture filtrate per 350g of soil in pot experiments, during which disease reduction reached 88.15%. This study provides theoretical support and a material basis for the prevention and treatment of wheat take-all disease.

Патогенність ізолятів гриба Gaeumannomyces Tritici (J.Walker) Hern.-Restr. & Crous – збудника офіобольозу та ефективність штамів р. Bacillus проти хвороби

Isolates of Gaeumannomyces spp. obtained from diseased roots of winter wheat showing take-all symptoms were characterized by pathogenicity. All isolates were more pathogenic on wheat and barley than on oat, and were identified as Gaeumannomyces tritici. Most isolates of G. tritici were characterized as middle pathogenic, the pathogenicity of one isolate was higher than those of others, and two isolates showed the lowest pathogenicity. In growth chamber assay, the effect of two Bacillus strains, B. subtilis 16 and B. pumilus 11, on take-all of wheat was studied. Pathogen inoculation was made by isolates of G. tritici of different pathogenicity. It was found that effective biological control depends on take-all severity, which, in turn, co-ordinates with the pathogenicity of fungal isolate. Applying the bacterial cells into the plant growth substrate stimulated the seedling growth when artificial inoculation was performed with a middle pathogenic isolate of G. tritici, and the disease severity was middle. There was no growth promotion by bacterial inoculant at slight disease severity. No stimulating effect was also observed at the high disease severity, where pathogen inoculation was performed with a highly pathogenic isolate of G. tritici.

Antifungal activity of the lemongrass and clove oil encapsulated in mesoporous silica nanoparticles against wheat's take-all disease

Combined application of plant essential oils (EOs) with known antimicrobial effects and silica nanocapsules with high loading capacity and protection capability of the EOs make them proper candidates for creating environmentally friendly fungicides. In this study, EOs of the Lemongrass (LGO) and Clove (CO) were used against Gaeumannomyces graminis var. tritici (Ggt), a causal agent of take-all disease of wheat. To provide controlled delivery of the EOs, they were encapsulated into mesoporous silica nanoparticles (MSNPs) and then compared to the effects of pure EOs both in- vitro and in- vivo. MSNPs were synthesized via the sol-gel process. Various techniques such as Fourier transform infrared spectroscopy (FTIR), the Brunauer–Emmett–Teller (BET), thermogravimetric analysis (TGA), and UV–Vis spectroscopy were used to evaluate the successful loading of the EOs into the pore of MSNPs. The encapsulation efficiency (EE) was calculated as high as 84.24% for LGO and 80.69% for CO, while loading efficiency (LE) was determined 36% and 29% for LGO and CO, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) displayed spherical shapes and porous structures with average diameters of 50–70 nm. Recognition of the main components of the EOs via gas chromatographic-mass spectrometry (GC–MS) before and after the EO loading, detected eugenol and citral as the most frequent compounds in LGO and CO, respectively. For antifungal test in- vitro, selected concentrations of the pure EOs, EOs loaded in MSNPs (EOs- MSNPs) and Mancozeb ® fungicide based on pre-tests were mixed using potato dextrose agar (PDA). The inhibition percentage (IP) of fungal growth at each concentration, as well as minimum inhibition concentration (MIC) and minimum fungicidal concentrations (MFC) were obtained. The results indicated that antifungal effects in the encapsulated form increased by up to three times. In- vivo, the sterile wheat seeds were treated with pure EOs, EOs-MSNPs, and mancozeb at MFC concentration. Also, in order to keep on the EOs-MSNPs around the seeds, sodium alginate was used. The consequences of in- vivo experiments indicated that rate of disease control in presence of EOs-MSNPs and mancozeb was the same (~70%) and higher than pure EOs (LGO: 57.44%, CO: 49%). Also, improving the growth parameters in wheat plant, the covering of the EOs-MSNPs in alginate, had better control (84%) than that of EOs-MSNPs alone. Further, the release kinetics studies showed a gradual release of LGO and CO from MSNPs for four weeks in water and for five weeks in the soil-plant system. To the best of our knowledge, this is the first report of the control effect of LGO, CO, and their nanocapsule in MSNPs against the take-all disease of wheat. These results showed that the EOs-MSNPs can be a safe product for the efficient control of take-all disease in wheat crop.

Wheat root transcriptional responses against Gaeumannomyces graminis var. tritici

Wheat root rot caused by Gaeumannomyces graminis var. tritici (Ggt) results in severe yield losses in wheat production worldwide. However, little is known about the molecular mechanism that regulates systemic symptom development in infected wheat. Fluorescent microscopy observation of the stained wheat roots infected by Ggt showed that lesions were visible when the fungus could be detected in the endodermis, pericycle and phloem at 5 days post inoculation (dpi), and rust symptoms were visible when there was extensive fungal colonization in the root cortex at 6 dpi. Transcriptome sequencing of Ggt-inoculated wheat roots and healthy control root samples was performed at 5 dpi to identify Ggt-induced gene expression changes in wheat roots at the time of lesion formation. A total of 3973 differentially expressed genes (DEGs) were identified, of which 1004 (25.27%) were up-regulated and 2969 (74.73%) were down-regulated in Ggt-inoculated wheat roots compared with those in control roots. GO annotation and KEGG pathway analysis of these DEGs revealed that many of them were associated with pathogen resistance, such as those involved in oxidation-reduction process, tryptophan biosynthesis process, and phenylpropanoid biosynthesis process. Analysis of DEGs revealed that 15 DEGs were involved in cellular regulation, 57 DEGs in signal transduction pathways, and 75 DEGs in cell wall reorganization, and 23 DEGs are pathogenesis-related proteins. Reverse transcription quantitative PCR (RT-qPCR) of 13 of those DEGs showed that these genes may play roles in wheat resistance against Ggt. Overall, this study represents the first transcriptional profiling of wheat roots in response to Ggt infection and further characterization of DEGs identified in this study may lead to better understanding of resistance against take-all in wheat.

Streptomyces Endophytes Promote Host Health and Enhance Growth across Plant Species.

Streptomyces bacteria are ubiquitous in soils and are well known for producing secondary metabolites, including antimicrobials. Increasingly, they are being isolated from plant roots, and several studies have shown they are specifically recruited to the rhizosphere and the endosphere of the model plant Arabidopsis thaliana Here, we test the hypothesis that Streptomyces bacteria have a beneficial effect on A. thaliana growth and could potentially be used as plant probiotics. To do this, we selectively isolated streptomycetes from surface-washed A. thaliana roots and generated high-quality genome sequences for five strains, which we named L2, M2, M3, N1, and N2. Reinfection of A. thaliana plants with L2, M2, and M3 significantly increased plant biomass individually and in combination, whereas N1 and N2 had a negative effect on plant growth, likely due to their production of polyene natural products which can bind to phytosterols and reduce plant growth. N2 exhibits broad-spectrum antimicrobial activity and makes filipin-like polyenes, including 14-hydroxyisochainin which inhibits the take-all fungus, Gaeumannomyces graminis var. tritici N2 antifungal activity as a whole was upregulated ∼2-fold in response to indole-3-acetic acid (IAA), suggesting a possible role during competition in the rhizosphere. Furthermore, coating wheat seeds with N2 spores protected wheat seedlings against take-all disease. We conclude that at least some soil-dwelling streptomycetes confer growth-promoting benefits on A. thaliana, while others might be exploited to protect crops against disease.IMPORTANCE We must reduce reliance on agrochemicals, and there is increasing interest in using bacterial strains to promote plant growth and protect against disease. Our study follows up reports that Arabidopsis thaliana specifically recruits Streptomyces bacteria to its roots. We test the hypotheses that they offer benefits to their A. thaliana hosts and that strains isolated from these plants might be used as probiotics. We isolated Streptomyces strains from A. thaliana roots and genome sequenced five phylogenetically distinct strains. Genome mining and bioassays indicated that all five have plant growth-promoting properties, including production of indole-3-acetic acid (IAA), siderophores, and aminocyclopropane-1-carboxylate (ACC) deaminase. Three strains significantly increased A. thaliana growth in vitro and in combination in soil. Another produces potent filipin-like antifungals and protected germinating wheat seeds against the fungal pathogen Gaeumannomyces graminis var. tritici (wheat take-all fungus). We conclude that introducing Streptomyces strains into the root microbiome provides significant benefits to plants.