head blight
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2022 ◽  
Vol 23 (2) ◽  
pp. 895
Author(s):  
Yanping Yuan ◽  
Meiru Zhang ◽  
Jingjing Li ◽  
Chengdong Yang ◽  
Yakubu Saddeeq Abubakar ◽  
...  

Rab GTPases are key regulators of membrane and intracellular vesicle transports. However, the biological functions of FgRab1 are still unclear in the devastating wheat pathogen Fusarium graminearum. In this study, we generated constitutively active (CA) and dominant-negative (DN) forms of FgRAB1 from the wild-type PH-1 background for functional analyses. Phenotypic analyses of these mutants showed that FgRab1 is important for vegetative growth, cell wall integrity and hyphal branching. Compared to the PH-1 strain, the number of spores produced by the Fgrab1DN strain was significantly reduced, with obviously abnormal conidial morphology. The number of septa in the conidia of the Fgrab1DN mutant was fewer than that observed in the PH-1 conidia. Fgrab1DN was dramatically reduced in its ability to cause Fusarium head blight symptoms on wheat heads. GFP-FgRab1 was observed to partly localize to the Golgi apparatus, endoplasmic reticulum and Spitzenkörper. Furthermore, we found that FgRab1 inactivation blocks not only the transport of the v-SNARE protein FgSnc1 from the Golgi to the plasma membrane but also the fusion of endocytic vesicles with their target membranes and general autophagy. In summary, our results indicate that FgRab1 plays vital roles in vegetative growth, conidiogenesis, pathogenicity, autophagy, vesicle fusion and trafficking in F. graminearum.


2022 ◽  
Author(s):  
Jingya Zhao ◽  
Mengya Peng ◽  
Wenbo Chen ◽  
Xiaoping Xing ◽  
Yixuan Shan ◽  
...  

Fusarium pseudograminearum is a soil-borne, hemibiotrophic phytopathogenic fungus that causes Fusarium crown rot and Fusarium head blight in wheat. The basic leucine zipper proteins (bZIPs) are evolutionarily conserved transcription factors that play crucial roles in a range of growth and developmental processes and the responses to biotic and abiotic stresses. However, the roles of bZIP transcription factors remains unknown in F. pseudograminearum. In this study, a bZIP transcription factor Fpkapc was identified to localize to the nucleus in F. pseudograminearum. A mutant strain (Δfpkapc) was constructed to determine the role of Fpkapc in growth and pathogenicity of F. pseudograminearum. Transcriptomic analyses revealed that many genes involved in basic metabolism and oxidation-reduction processes were down-regulated, whereas many genes involved in metal iron binding were up-regulated in the Δfpkapc strain, compared with the wild type. Correspondingly, the mutant had severe growth defects and displayed abnormal hyphal tips. Conidiation in the Fpkapc mutant was reduced, with more conidia in smaller size and fewer septa than in the wild type. Also, relative to WT, the Δfpkapc strain showed greater replaced by increased tolerance to ion stress, but decreased tolerance to H2O2. The mutant caused smaller disease lesions on wheat and barley plants, but the significantly increased TRI genes expression, compared with the wild type. In summary, Fpkapc plays multiple roles in governing growth, development, stress responses, and virulence in F. pseudograminearum.


2022 ◽  
Vol 12 ◽  
Author(s):  
Andrea Ficke ◽  
Belachew Asalf ◽  
Hans Ragnar Norli

Plants and fungi emit volatile organic compounds (VOCs) that are either constitutively produced or are produced in response to changes in their physico-chemical status. We hypothesized that these chemical signals could be utilized as diagnostic tools for plant diseases. VOCs from several common wheat pathogens in pure culture (Fusarium graminearum, Fusarium culmorum, Fusarium avenaceum, Fusarium poae, and Parastagonospora nodorum) were collected and compared among isolates of the same fungus, between pathogens from different species, and between pathogens causing different disease groups [Fusarium head blight (FHB) and Septoria nodorum blotch (SNB)]. In addition, we inoculated two wheat varieties with either F. graminearum or P. nodorum, while one variety was also inoculated with Blumeria graminis f.sp. tritici (powdery mildew, PM). VOCs were collected 7, 14, and 21 days after inoculation. Each fungal species in pure culture emitted a different VOC blend, and each isolate could be classified into its respective disease group based on VOCs with an accuracy of 71.4 and 84.2% for FHB and SNB, respectively. When all collection times were combined, the classification of the tested diseases was correct in 84 and 86% of all cases evaluated. Germacrene D and sativene, which were associated with FHB infection, and mellein and heptadecanone, which were associated with SNB infection, were consistently emitted by both wheat varieties. Wheat plants infected with PM emitted significant amounts of 1-octen-3-ol and 3,5,5-trimethyl-2-hexene. Our study suggests that VOC blends could be used to classify wheat diseases. This is the first step toward a real-time disease detection in the field based on chemical signatures of wheat diseases.


Metabolites ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 48
Author(s):  
Laura Righetti ◽  
Sven Gottwald ◽  
Sara Tortorella ◽  
Bernhard Spengler ◽  
Dhaka Ram Bhandari

Fusarium Head Blight is the most common fungal disease that strongly affects Triticum spp., reducing crop yield and leading to the accumulation of toxic metabolites. Several studies have investigated the plant metabolic response to counteract mycotoxins accumulation. However, information on the precise location where the defense mechanism is taking place is scarce. Therefore, this study aimed to investigate the specific tissue distribution of defense metabolites in two Triticum species and use this information to postulate on the metabolites’ functional role, unlocking the “location-to-function” paradigm. To address this challenge, transversal cross-sections were obtained from the middle of the grains. They were analyzed using an atmospheric-pressure (AP) SMALDI MSI source (AP-SMALDI5 AF, TransMIT GmbH, Giessen, Germany) coupled to a Q Exactive HF (Thermo Fisher Scientific GmbH, Bremen, Germany) orbital trapping mass spectrometer. Our result revealed the capability of (AP)-SMALDI MSI instrumentation to finely investigate the spatial distribution of wheat defense metabolites, such as hydroxycinnamic acid amides, oxylipins, linoleic and α-linoleic acids, galactolipids, and glycerolipids.


2022 ◽  
Vol 12 (1) ◽  
Author(s):  
William T. Hay ◽  
James A. Anderson ◽  
Susan P. McCormick ◽  
Milagros P. Hojilla-Evangelista ◽  
Gordon W. Selling ◽  
...  

AbstractThe nutritional integrity of wheat is jeopardized by rapidly rising atmospheric carbon dioxide (CO2) and the associated emergence and enhanced virulence of plant pathogens. To evaluate how disease resistance traits may impact wheat climate resilience, 15 wheat cultivars with varying levels of resistance to Fusarium Head Blight (FHB) were grown at ambient and elevated CO2. Although all wheat cultivars had increased yield when grown at elevated CO2, the nutritional contents of FHB moderately resistant (MR) cultivars were impacted more than susceptible cultivars. At elevated CO2, the MR cultivars had more significant differences in plant growth, grain protein, starch, fructan, and macro and micro-nutrient content compared with susceptible wheat. Furthermore, changes in protein, starch, phosphorus, and magnesium content were correlated with the cultivar FHB resistance rating, with more FHB resistant cultivars having greater changes in nutrient content. This is the first report of a correlation between the degree of plant pathogen resistance and grain nutritional content loss in response to elevated CO2. Our results demonstrate the importance of identifying wheat cultivars that can maintain nutritional integrity and FHB resistance in future atmospheric CO2 conditions.


Toxins ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 45
Author(s):  
Elina Sohlberg ◽  
Vertti Virkajärvi ◽  
Päivi Parikka ◽  
Sari Rämö ◽  
Arja Laitila ◽  
...  

Fusarium head blight (FHB) is an economically important plant disease. Some Fusarium species produce mycotoxins that cause food safety concerns for both humans and animals. One especially important mycotoxin-producing fungus causing FHB is Fusarium graminearum. However, Fusarium species form a disease complex where different Fusarium species co-occur in the infected cereals. Effective management strategies for FHB are needed. Development of the management tools requires information about the diversity and abundance of the whole Fusarium community. Molecular quantification assays for detecting individual Fusarium species and subgroups exist, but a method for the detection and quantification of the whole Fusarium group is still lacking. In this study, a new TaqMan-based qPCR method (FusE) targeting the Fusarium-specific elongation factor region (EF1α) was developed for the detection and quantification of Fusarium spp. The FusE method was proven as a sensitive method with a detection limit of 1 pg of Fusarium DNA. Fusarium abundance results from oat samples correlated significantly with deoxynivalenol (DON) toxin content. In addition, the whole Fusarium community in Finnish oat samples was characterized with a new metabarcoding method. A shift from F. culmorum to F. graminearum in FHB-infected oats has been detected in Europe, and the results of this study confirm that. These new molecular methods can be applied in the assessment of the Fusarium community and mycotoxin risk in cereals. Knowledge gained from the Fusarium community analyses can be applied in developing and selecting effective management strategies for FHB.


Toxins ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 34
Author(s):  
Simon G. Edwards

Fusarium head blight (FHB) is an important disease of small grain cereals worldwide, resulting in reduced yield and quality as well as the contamination of harvested grains with mycotoxins. The key mycotoxin of concern is deoxynivalenol (DON), which has legislative and advisory limits in numerous countries. Cereal growers have a number of control options for FHB including rotation, cultivation, and varietal resistance; however, growers are still reliant on fungicides applied at flowering as part of an IPM program. Fungicides currently available to control FHB are largely restricted to triazole chemistry. This study conducted three field experiments to compare a new co-formulation of pydiflumetofen (a succinate dehydrogenase inhibitor (SDHI) with the tradename ADEPIDYN™) and prothioconazole (a triazole) against current standard fungicides at various timings (flag leaf fully emerged, mid-head emergence, early flowering, and late flowering) for the control of FHB and DON. Overall, the co-formulation showed greater efficacy compared to either pydiflumetofen alone or current fungicide chemistry. This greater activity was demonstrated over a wide range of spray timings (flag leaf fully emerged to late flowering). The availability of an SDHI with good activity against FHB and the resulting DON contamination of harvested grain will give growers an additional tool within an IPM program that will provide a greater flexibility of spray application windows and reduce fungicide resistance selection pressure.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhengxi Sun ◽  
Yi Hu ◽  
Yilei Zhou ◽  
Ning Jiang ◽  
Sijia Hu ◽  
...  

Abstract Background Fusarium head blight (FHB) caused by Fusarium graminearum is a devastating fungal disease of wheat. The mechanism underlying F. graminearum-wheat interaction remains largely unknown. tRNA-derived fragments (tRFs) are RNase-dependent small RNAs derived from tRNAs, and they have not been reported in wheat yet, and whether tRFs are involved in wheat-F. graminearum interactions remains unknown. Results Herein, small RNAs from the spikelets inoculated with F. graminearum and mock from an FHB-susceptible variety Chinese Spring (CS) and an FHB-resistant variety Sumai3 (SM) were sequenced respectively. A total of 1249 putative tRFs were identified, in which 15 tRFs was CS-specific and 12 SM-specific. Compared with mock inoculation, 39 tRFs were significantly up-regulated across both wheat varieties after F. graminearum challenge and only nine tRFs were significantly down-regulated. tRFGlu, tRFLys and tRFThr were dramatically induced by F. graminearum infection, with significantly higher fold changes in CS than those in SM. The expression patterns of the three highly induced tRFs were further validated by stem-loop qRT-PCR. The accumulation of tRFs were closely related to ribonucleases T2 family members, which were induced by F. graminearum challenge. The tRFs’ targets in host were predicted and were validated by RNA sequencing. Conclusion Integrative analysis of the differentially expressed tRFs and their candidate targets indicated that tRFGlu, tRFLys and tRFThr might negatively regulate wheat resistance to FHB. Our results unvealed the potential roles of tRFs in wheat-F. graminearum interactions.


Plant Disease ◽  
2022 ◽  
Author(s):  
Haoyu Wang ◽  
Disen Feng ◽  
Lingqiao Chen ◽  
Junhua Yang ◽  
Xichun Wang ◽  
...  

Members of the Fusarium graminearum species complex (FGSC) are the main causing agents of head blight, seedling blight, or stalk rot in wheat and other cereals worldwide. Surveys on species composition and mycotoxin production of FGSC populations have mainly focused on food crops such as wheat, maize, and barley, but little is known about the identity of FGSC pathogens present in pasture grass. In April 2021, a survey of grass diseases in the Hongya County (29.90661 N; 103.37313 E) in Sichuan Province was conducted to understand the etiology of stalk rot in perennial ryegrass (Lolium perenne). It was observed in several pastures that about 10% of yield loss in perennial ryegrass was caused by stalk rot. Affected plant stalks were brown to dark brown in colour and appeared soggy. As infections continued or under conditions of high humidity, some plant stalks also became flattened. Perennial ryegrass samples with symptoms of stalk rot or browning of the stem were collected. Symptomatic tissues were cut into short segments (approximately 5 mm), surface-sterilized in 3% sodium hypochlorite solution for 2 min, rinsed three times with sterile distilled water, air dried, plated onto potato dextrose agar (PDA), and then incubated in the dark at 28 °C. After 3 to 5 days, Fusarium-like fungal colonies with reddish-orange mycelium were collected and transferred to new PDA plates for further purification, and the purified cultures were obtained by single spore isolation. Four uniform isolates were obtained and their colonies on PDA resembled typical FGSC colonies (Leslie and Summerell 2006; O’Donnell et al. 2004). Colonies had an average radial growth rate of 8.5 to 11.0 mm/day at 28 °C in the dark on PDA. Conidial characteristics were studied on Spezieller Nährstoffarmer agar (SNA) as described by Wang et al. (2014). Macroconidia were falcate to almost straight, usually with parallel dorsal and ventral lines, 3- to 5-septate, 20.65 to 55.22 μm in length (average 39.16 μm), and 2.38 to 6.93 μm in width (average 4.42 μm) (n = 200). No microconidia were observed. The pathogenicity of the isolated Fusarium strains was then tested on healthy perennial ryegrass (variety Changjiang 1). Ryegrass plants grown for 2 months were inoculated by punching a hole in the stem using a sterile toothpick, followed by an injection of 20 μL macroconidia suspension at a concentration of 105 spores/mL. Ryegrass stems treated with water served as the control. Twenty plants were included in each treatment. After inoculation, the plants were grown in a growth chamber at 25 °C and 90% humidity for 24 h. Stalk tissues at the wound site turned brown after 3 days and the brown area then extended to regions above and below. No symptoms were observed in the water-treated controls. As well, the same pathogen was reisolated from the infected grass stems, but not from the controls. Thus, the isolated Fusarium spp. are a cause of stalk rot in perennial ryegrass based on the fulfillment of Koch’s postulates. To identify the Fusarium spp. to species level, portions of the translation elongation factor 1-α (TEF) gene sequences from all four strains were amplified and sequenced as described by Wang et al. (2015). The obtained sequences were identical, and a sequence of isolate SC1 was submitted to GenBank (accession no. MZ964308). BLASTn searches were conducted on the TEF sequence (607 bp) in two databases, revealing it had 100% similarity to the sequence of Fusarium meridionale strain DS27 (accession no. MN629330) in NCBI and strain NRRL28723 from FUSARIUM-ID (http://isolate.fusariumdb.org/). A concatenated four-gene phylogeny (supplementary figure) resolved SC1 and the type specimens of F. meridionale (NRRL28723, 29010, and 28436) in a monophyletic clade with 100% bootstrap support, confirming that the strain SC1 belongs to F. meridionale. Finally, trichothecene productions of F. meridionale strains were evaluated using rice cultures kept at 28 °C in the dark for two weeks, as described by Desjardins and Proctor (2011). LC-MS/MS analysis indicated that the fungus could produce NIV and 4ANIV in rice cultures with average concentrations of 1400.44 and 3144.10 μg/kg, respectively. To the best of our knowledge, this is the first report of F. meridionale causing disease in perennial ryegrass in China. Further research will be necessary to determine its distribution, aggressiveness, and trichothecene production.


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