Gaeumannomyces Graminis Research Articles

Characterization and Aggressiveness of Take-All Root Rot Pathogens Isolated from Symptomatic Bermudagrass Putting Greens.

Take-all root rot is a disease of ultradwarf bermudagrass putting greens caused by Gaeumannomyces graminis (Gg), Gaeumannomyces sp. (Gx), Gaeumannomyces graminicola (Ggram), Candidacolonium cynodontis (Cc), and Magnaporthiopsis cynodontis (Mc). Many etiological and epidemiological components of this disease remain unknown. Improving pathogen identification and our understanding of the aggressiveness of these pathogens along with growth at different temperatures will advance our knowledge of disease development to optimize management strategies. Take-all root rot pathogens were isolated from symptomatic bermudagrass root and stolon pieces from 16 different golf courses. Isolates of Gg, Gx, Ggram, Cc, and Mc were used to inoculate 'Champion' bermudagrass in an in planta aggressiveness assay. Each pathogen was also evaluated at 10, 15, 20, 25, 30, and 35°C to determine growth temperature optima. Infected plant tissue was used to develop a real-time PCR high-resolution melt assay for pathogen detection. This assay was able to differentiate each pathogen directly from infected plant tissue using a single primer pair. In general, Ggram, Gg, and Gx were the most aggressive while Cc and Mc exhibited moderate aggressiveness. Pathogens were more aggressive when incubated at 30°C compared with 20°C. While they grew optimally between 24.4 and 27.8°C, pathogens exhibited limited growth at 35°C and no growth at 10°C. These data provide important information on this disease and its causal agents that may improve take-all root rot management.

Monocotyledonous plants graft at the embryonic root-shoot interface.

Grafting is possible in both animals and plants. Although in animals the process requires surgery and is often associated with rejection of non-self, in plants grafting is widespread, and has been used since antiquity for crop improvement1. However, in the monocotyledons, which represent the second largest group of terrestrial plants and include many staple crops, the absence of vascular cambium is thought to preclude grafting2. Here we show that the embryonic hypocotyl allows intra- and inter-specific grafting in all three monocotyledon groups: the commelinids, lilioids and alismatids. We show functional graft unions through histology, application of exogenous fluorescent dyes, complementation assays for movement of endogenous hormones, and growth of plants to maturity. Expression profiling identifies genes that unify the molecular response associated with grafting in monocotyledons and dicotyledons, but also gene families that have not previously been associated with tissue union. Fusion of susceptible wheat scions to oat rootstocks confers resistance to the soil-borne pathogen Gaeumannomyces graminis. Collectively, these data overturn the consensus that monocotyledons cannot form graft unions, and identify the hypocotyl (mesocotyl in grasses) as a meristematic tissue that allows this process. We conclude that graft compatibility is a shared ability among seed-bearing plants.

Delving into defence: identifying the Pseudomonas protegens Pf-5 gene suite involved in defence against secreted products of fungal, oomycete and bacterial rhizosphere competitors.

Competitive behaviours of plant growth promoting rhizobacteria (PGPR) are integral to their ability to colonize and persist on plant roots and outcompete phytopathogenic fungi, oomycetes and bacteria. PGPR engage in a range of antagonistic behaviours that have been studied in detail, such as the production and secretion of compounds inhibitory to other microbes. In contrast, their defensive activities that enable them to tolerate exposure to inhibitory compounds produced by their neighbours are less well understood. In this study, the genes involved in the Pseudomonas protegens Pf-5 response to metabolites from eight diverse rhizosphere competitor organisms, Fusarium oxysporum, Rhizoctonia solani, Gaeumannomyces graminis var. tritici, Pythium spinosum, Bacillus subtilis QST713, Pseudomonas sp. Q2-87, Streptomyces griseus and Streptomyces bikiniensis subspecies bikiniensi, were examined. Proximity induced excreted metabolite responses were confirmed for Pf-5 with all partner organisms through HPLC before culturing a dense Pf-5 transposon mutant library adjacent to each of these microbes. This was followed by transposon-directed insertion site sequencing (TraDIS), which identified genes that influence Pf-5 fitness during these competitive interactions. A set of 148 genes was identified that were associated with increased fitness during competition, including cell surface modification, electron transport, nucleotide metabolism, as well as regulatory genes. In addition, 51 genes were identified for which loss of function resulted in fitness gains during competition. These included genes involved in flagella biosynthesis and cell division. Considerable overlap was observed in the set of genes observed to provide a fitness benefit during competition with all eight test organisms, indicating commonalities in the competitive response to phylogenetically diverse micro-organisms and providing new insight into competitive processes likely to take place in the rhizosphere.

Efficient Biocontrol of Gaeumannomyces graminis var. Tritici in Wheat: Using Bacteria Isolated from Suppressive Soils

“Take-all” disease is the most important biotic factor affecting cereal productivity, causing 30–50% of crop losses. The causal agent is the ascomycete soil-borne pathogen Gaeumannomyces graminis var. tritici (Ggt). Current control measures are ineffective, because Ggt can remain saprophytic in soils for long periods. Therefore, the study of the microbiome residing in suppressive soils (SS) is a promising niche of Ggt biocontrol. Here, we evaluated the efficiency of Serratia sp., Bacillus sp., and Acinetobacter sp. isolated from SS against the incidence of Ggt on wheat. Our results demonstrated that plants inoculated with the bacterial consortium in both greenhouse and field conditions were highly efficient in Ggt biocontrol, more so than individual strains. The disease reduction was evidenced by higher biomass production, fewer copies of the Ggt genome with a concomitant curtailment of blackening of roots, a decrease of lipid peroxidation, and an increase of superoxide dismutase activity. The ability of the microbial consortium over that of single strains could be attributable to interspecies communication as a strategy to biocontrol; i.e., higher chitinase activity. In conclusion, bacterial consortia from SS are an important niche of Ggt biocontrol, serving as a model for other soil-borne pathogens.

4-Ethylphenol, A Volatile Organic Compound Produced by Disease-Resistant Soybean, Is a Potential Botanical Agrochemical Against Oomycetes.

Oomycetes, represented by Phytophthora, are seriously harmful to agricultural production, resulting in a decline in grain quality and agricultural products and causing great economic losses. Integrated management of oomycete diseases is becoming more challenging, and plant derivatives represent effective alternatives to synthetic chemicals as novel crop protection solutions. Biologically active secondary metabolites are rapidly synthesized and released by plants in response to biotic stress caused by herbivores or insects, as well as pathogens. In this study, we identified groups of volatile organic compounds (VOCs) from soybean plants inoculated with Phytophthora sojae, the causal agent of soybean root rot. 4-Ethylphenol was present among the identified VOCs and was induced in the incompatible interaction between the plants and the pathogen. 4-Ethylphenol inhibited the growth of P. sojae and Phytophthora nicotianae and had toxicity to sporangia formation and zoospore germination by destroying the pathogen cell membrane; it had a good control effect on soybean root rot and tobacco black shank in the safe concentration range. Furthermore, 4-Ethylphenol had a potent antifungal activity against three soil-borne phytopathogenic fungi, Rhizoctonia solani, Fusarium graminearum, and Gaeumannomyces graminis var tritici, and four forma specialis of Fusarium oxysporum, which suggest a potential to be an eco-friendly biological control agent.

Antimicrobial Activity and Identification of the Biosynthetic Gene Cluster of X-14952B From Streptomyces sp. 135.

The bacterial genus Streptomyces is an important source of antibiotics, and genome mining is a valuable tool to explore the potential of microbial biosynthesis in members of this genus. This study reports an actinomycete strain 135, which was isolated from Qinghai-Tibet Plateau in China and displayed broad antimicrobial activity. The fermentation broth of strain 135 displayed strong antifungal activity (>70%) against Sclerotinia sclerotiorum, Botrytis cinerea, Valsa mali, Phytophthora capsici, Glomerella cingulata, Magnaporthe grisea, Bipolaris maydis, Exserohilum turcicum in vitro, meanwhile possessed significant preventive and curative efficacy against S. sclerotiorum, Gaeumannomyces graminis, and P. capsici on rape leaves (54.04 and 74.18%), wheat (90.66 and 67.99%), and pepper plants (79.33 and 66.67%). X-14952B showed the greatest antifungal activity against S. sclerotiorum and Fusarium graminearum which the 50% inhibition concentration (EC50) were up to 0.049 and 0.04 μg/mL, respectively. Characterization of strain 135 using a polyphasic approach revealed that the strain displayed typical features of the genus Streptomyces. 16S rRNA gene sequencing and phylogenetic analysis demonstrated that the isolate was most closely related to and formed a clade with Streptomyces huasconensis HST28T (98.96% 16S rRNA gene sequence similarity). Average nucleotide identity (ANI) and DNA-DNA hybridization (DDH) values in strain 135 and related type strains were both below the threshold of species determination (91.39 and 56.5%, respectively). OrthoANI values between strain 135 and related type strains are under the cutoff of determining species (<95%). The biosynthetic gene cluster (BGC) designated to X-14952B biosynthesis was identified through genome mining and the possible biosynthesis process was deduced.

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.

First Report of Fusarium culmorum and Microdochium bolleyi Causing Root Rot on Triticale in Kazakhstan.

Triticale (×Triticosecale Wittmack) is obtained from wheat × rye crossing. It is positioned between wheat and rye in terms of resistance to soilborne pathogens including Gaeumannomyces graminis var. tritici, Fusarium culmorum, F. avenaceum, and Bipolaris sorokiniana (Arseniuk and Góral 2015). In 2019, seven triticale fields were surveyed in Almaty Province, Kazakhstan to examine soil-borne fungal pathogens. A total of 28 symptomatic plants with stunting, rot or discolored root were collected to identify causal agents. The overall disease incidence was approximately 8 to 10% in the fields. Fungi were isolated from 3-5 mm pieces excised from symptomatic tissues. The pieces were exposed to surface disinfection in 1% sodium hypochlorite solution for 2 min, rinsed three times with sterile distilled water, blotted dry, and plated on 1/5 strength potato dextrose agar (PDA) amended with 0.01% streptomycin. Plates were left in the dark at 23°C for 7 days. A total of 34 fungal colonies were isolated of which nineteen isolates, originally from six fields showed the cultural characteristics of B. sorokiniana. This species was previously reported to cause common root rot on triticale in Kazakhstan (Özer et al. 2020). Ten isolates from four fields produced pale orange and cottony mycelium with red pigmentation on the agar, which is typical of Fusarium-like growth. The remaining isolates (n=5) from two fields produced salmon-colored and scarce aerial mycelium with no soluble pigmentation, similar to Microdochium spp. Fusarium isolates produced thick-walled and curved macroconidia with 3-4 septa (n=50, 25.7 to 37.6 × 4.1 to 7.3 μm in size) and notched basal cell on PDA, but microconidia were absent, which matches the description of F. culmorum (Wm.G. Sm.) Sacc. (Leslie and Summerell 2006). Microdochium isolates produced swollen, brown, and thick-walled chlamydospores and hyaline, one-celled, and thin-walled conidia (n=50, 5.4 to 9.3 × 1.5 to 3.0 μm in size) formed on ampullate and cylindrical conidiogenous cells on oatmeal agar (OA). These morphological features are consistent with previous observations for Microdochium bolleyi (R. Sprague) de Hoog & Herm.-Nijh. (Hong et al. 2008). To confirm morphological preliminary identifications, the portion of the translation elongation factor 1-alpha (EF1-α) gene was amplified with EF1/EF2 primers (O'Donnell et al. 1998) for representative Fusarium isolates (n=4) for each field. Additionally, the internal transcribed spacer (ITS) of ribosomal DNA was amplified with ITS1/ITS4 primers (White et al. 1990) for representative Microdochium isolates (n=2) for each field. BLASTn queries against NCBI GenBank revealed that the EF1-α sequences of Fusarium isolates (MW311081-MW311084) shared 100% identity with F. culmorum strain CBS 110262 (KT008433). The ITS sequences of M. bolleyi isolates (MW301448-MW301449) matched that of M. bolleyi strain CBS 137.64 (AM502264) with 100% sequence similarity. Pathogenicity test was conducted on pregerminated seeds of triticale cv. Balausa. A plastic pot (17 cm height, 9 cm in diam) was filled with a sterile mixture of vermiculite, peat, and soil (1:1:1, v/v/v). Mycelial plugs (1 cm in diam) were cut from the margin of a growing culture of representative isolates (Kaz_Fus123 and Kaz_Mb01) and placed onto the mixture in the pot. A sterile agar plug was employed as a control treatment. One pregerminated seed was put on the plug and covered with the mixture. The pots were transferred to a growth chamber set at 23 ± 2°C and a photoperiod of 14 hours. The experiment was performed twice using 5 replication pots per isolate. Four weeks after inoculation, discoloration of the crown was observed on all the inoculated roots, whereas no symptoms were observed on the control plants. Koch's postulates were fulfilled by reisolating and identifying the pathogen based on the morphology described above. This is the first report of M. bolleyi and F. culmorum causing root rot on triticale in Kazakhstan. Although B. sorokiniana is the most primary pathogen that may limit yield in the production of triticale in Kazakhstan, F. culmorum and M. bolleyi have been found to be less frequent and less aggressive pathogens, respectively. Further studies are needed to better understand the potential distribution and impact of these pathogens on triticale.

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.

Anti-phytopathogen terpenoid glycosides from the root bark of Chytranthus macrobotrys and Radlkofera calodendron

Chytranthus macrobotrys and Radlkofera calodendron are two Sapindaceae characterized by a lack of phytochemical data. Both root barks from the two Sapindaceae species were processed by ethanol extraction followed by the isolation of their primary constituents by liquid chromatography. This process yielded four previously undescribed terpenoid glycosides together with eight known analogues. Extracts and isolated compounds from C. macrobotrys and R. calodendron were then screened for antimicrobial activity against fifteen phytopathogens. The biological screening also involved extracts and pure compounds from Blighia unijugata and Blighia welwitschii, two Sapindaceae previously studied by our group. Phytopathogens were chosen based on their economic impact on agriculture worldwide. The selection was composed primarily of fungal species including; Pyricularia oryzae, Gaeumannomyces graminis var. tritici, Zymoseptoria tritici, Fusarium oxysporum, Botrytis cinerea, Pythium spp., Trichoderma spp. and Rhizoctonia solani. Furthermore, pure terpenoid glycosides were tested for the first time against wood-inhabiting phytopathogens such as; Phaeomoniella chlamydospora, Phaeoacremonium minimum, Fomitiporia mediterranea, Eutype lata and Xylella fastidiosa. Raw extracts exhibited different levels of activity dependent on the organism. Some pure compounds, including 3-O-α-L-arabinopyranosyl-(1 → 4)-β-D-xylopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (α-hederin), 3-O-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (macranthoside A) and 3-O-α-L-arabinopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (clemontanoside C), exhibited significant growth inhibitions on Pyricularia oryzae, Gaeumannomyces graminis var. tritici, Fomitiporia mediterranea and Zymoseptoria tritici. Monodesmoside triterpene saponins, in particular, exhibited MIC (IC100) values as low as 25 μg/ml and IC50 values as low as 10 μg/ml against these phytopathogens. Structure-activity relationships, as well as plant-microbe interactions, were discussed.

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.

Assessing Wheat Damage Caused by Gaeumannomyces graminis Using Plant Pathology Techniques, Image Analysis, and Satellite Data Image Analysis

Assessing Wheat Damage Caused by Gaeumannomyces graminis Using Plant Pathology Techniques, Image Analysis, and Satellite Data Image Analysis

Complexity of Gaeumannomyces species causing take-all root rot of St. Augustinegrass in Texas

ABSTRACT Gaeumannomyces graminis var. graminis (Ggg) has been the etiological agent of take-all root rot (TARR) in St. Augustinegrass (Stenotaphrum secundatum) and root decline of the other warm-season turfgrasses. Seventy-five Ggg isolates were obtained from St. Augustinegrass in central and east Texas. Evaluation of colony morphologies on potato dextrose agar (PDA) within 2 wk and follow-up multilocus phylogenic analyses revealed three phenotypic groups associated with different Gaeumannomyces species: (i) G. floridanus, highly melanized with round colony formation; (ii) G. arxii, none to slightly melanized with round colony formation; and (iii) G. graminicola, highly melanized with irregular colony formation. Further examination with representative isolates from each group revealed that their phenotypic characterizations supported the distinctive genetic groups within Ggg associated with St. Augustinegrass TARR. Gaeumannomyces floridanus isolates grew faster at warmer temperature (30 C) than G. arxii or G. graminicola. Pathogenicity assays using rice seedlings indicated that G. floridanus was more aggressive in disease symptom development than G. arxii or G. graminicola. A multilocus phylogeny reconstruction supported that most of Gaeumannomyces isolates tested in this study were separated into three phylogenetically distinct groups: G. floridanus, G. arxii, and G. graminicola. The resolution of intravarietal complexities of causal fungi of TARR is important for proper diagnostics and management strategies for TARR in St. Augustinegrass and other root-decline diseases in warm-season turfgrasses.

The impacts of take-all, drought and their interaction on Bromus wildenowii seed yield and the alleviation of these stresses by Trichoderma atroviride

ABSTRACT Take-all, caused by the fungal pathogen Gaeumannomyces graminis var. tritici (Ggt) is an important root disease of cereals and grasses. An increasing occurrence of very light seeds in some New Zealand perennial ryegrass (Lolium perenne L.) seed crops may have been associated with Ggt, but any Ggt effects on grass seed yield were unknown. A glasshouse experiment, using prairie grass (Bromus wildenowii Kunth) as a model system was used to investigate the effect of Ggt on seed yield in the presence and absence of moisture stress (drought), and to determine whether strains of the fungal symbiont Trichoderma atroviride would allow the plant to better cope with both the biotic and abiotic stresses. Ggt significantly reduced seed yield by reducing the number of seeds per plant, while moisture stress significantly reduced all seed yield components. There was a significant interaction between Ggt and moisture stress because the moisture stress induced seed yield loss was greater in the presence of Ggt than in the absence of Ggt. In the absence of both abiotic and biotic stress, Trichoderma treatment had no effect on seed yield. However, Trichoderma significantly reduced Ggt root infection and this led to an increased seed yield. In the presence of Ggt and moisture stress, Trichoderma further increased seed yield by around double the increase for individual stress. Whether similar responses can be obtained in the field is currently being investigated.

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.

The Spectrum of Weed Species and Fungal Pathogens in Stands of Alternative Fodder Crop Lolium Multiflorum Var. Westerwoldicum Growing up in a Drought-Prone Area in the Czech Republic

Annual ryegrass (Lolium multiflorum var. westerwoldicum) is cultivated in various areas of the world as a feed for live stock. Efforts to improve the production of high-quality feed in the face of deepening climate change have increased the demand for growing non-traditional types of crops, including ryegrass. The aims of the research were to determine the spectrum of weed and fungal pathogen species and to assess dangerous species of weeds and pathogens which negatively affect forage crops of annual ryegrass grown in dry conditions. In 2018-2019 the occurrence of weeds and fungal pathogens of ryegrass was evaluated in field conditions. The assessed lands were located in dry climatic conditions of South Moravia (Czech Republic). The vegetation recording was done on phytosociological plots of 12 m2. A total of 57 weed species were identified in the plots, where 12 species were toxic and 16 species were undesirable. The most problematic weeds and poisonous species were: Aethusa cynapium, Datura stramonium, Equisetum palustre, Euphorbia helioscopia, Fumaria officinalis and Solanum nigrum, which can cause health problems if present in cattle feed. A pathogenic infection caused by Blumeria graminis, Puccinia graminis var. graminicola and P. coronata var. coronata, Gaeumannomyces graminis and Drechslera sp. was identified on the ryegrass plants in the experimental plots during the vegetation. Blumeria graminis was the most abundant, but it did not endanger the final feed. The data was processed by CCA analysis.

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.

The Effect of Foliar Fertilization with Micronutrients on the Incidence and Severity of Leaf and Stem-base Diseases in Winter Triticale (x Triticosecale Witmm.) and Winter Rye (Secale cereale L.)

Winter triticale (Triticale) cv. Dinaro and winter rye (Secale cereale L.) cv. Dankowskie Diament were grown in 2012 and 2013 in a field-plot experiment in Tomaszkowo near Olsztyn (NE Poland). The experiment consisted of 7 treatments: absolute control (without fertilizers or the growth stimulator), control-NPK fertilizer, NPK fertilizer + micronutrients applied alone or in combination (4 treatments), NPK fertilizer + Nano-Gro growth stimulator. The severity of disease symptoms on the leaves and stem-bases of triticale and rye was evaluated throughout the growing season. Symptoms of powdery mildew on the leaves of winter triticale and winter rye were noted only in the growing season of 2013, and disease severity remained at a low level. In the growing season of 2012, weather conditions were conducive to the spread of Septoria tritici blotch (STB) and brown rust on triticale (the highest values of infection index were 41.6 and 23.8%, respectively), and scald and brown rust on rye (29.0 and 38.1%, respectively). Foliar application of micronutrients influenced the rates of infections caused by Zymoseptoria tritici and Puccinia recondita f. sp. tritici on triticale leaves. Symptoms of eyespot and Fusarium foot and root rot were noted on the stem-bases of both cereal species, whereas symptoms of take-all disease and sharp eyespot were observed sporadically. Significant differences were found between treatments in the severity of infections caused by Gaeumannomyces graminis on the stem-bases of triticale, and by Tapesia spp. and Rhizoctonia spp. on the stem-bases of rye.

Quantification of Pseudomonas protegens FD6 and Bacillus subtilis NCD-2 in soil and the wheat rhizosphere and suppression of root pathogenic Rhizoctonia solani AG-8

Bacillus subtilis strain NCD-2 and Pseudomonas protegens strain FD6 produce a range of antimicrobial metabolites known to be effective against soil-borne plant pathogens. Quantitative qPCR assays were designed from sequence characterized amplified fragment length polymorphisms (AFLP) diagnostic for each inoculant genotype. The qPCR minimum detection thresholds (MDT) for NCD-2 and FD6 ranged between 5.2 × 103 (log 3.71) and 1.5 × 106 (log 6.18) genome (cell) equivalents g−1 of soil or wheat root tissue and were independent of soil type. Wheat rhizosphere populations of strains FD6 and NCD-2 significantly declined during the first 14 days postinoculation and then remained stable for the next 14 days. Colonization of wheat roots, rhizosphere soil and bulk (non-rhizosphere) soil by FD6 was significantly greater than that of NCD-2. Strains FD6 and NCD-2 significantly decreased in vitro growth of wheat root pathogenic Rhizoctonia solani AG-8, Pythium irregulare and Gaeumannomyces graminis var. tritici, fungal antibiosis by FD6 greater than NCD-2. Wheat rhizosphere colonization by NCD-2 and FD6 significantly decreased abundance of R. solani AG-8 in the rhizosphere by 3- and 13-fold respectively, pathogen suppression increasing (21%–29%) foliar biomass of wheat seedlings to levels not significantly different to the non-diseased control. The qPCR assays developed in this study were used to monitor soil and rhizosphere populations of P. protegens FD6 and B. subtilis NCD-2 and their suppressive efficacies against R. solani AG-8 in wheat. These assays can be applied to monitor the dynamics of these inoculants in suppressing Rhizoctonia root rot and other crop diseases.