Fusarium head blight of small grains in Pennsylvania: unravelling species diversity, toxin types, growth and triazole sensitivity

2021 ◽  
Author(s):  
Maira R. Duffeck ◽  
Ananda Y. Bandara ◽  
Dilooshi K. Weerasooriya ◽  
Alyssa Collins ◽  
Philip J. Jensen ◽  
...  

Fusarium graminearum is the main causal species of Fusarium head blight (FHB) globally. Recent changes in the trichothecene (toxin) types in the North American FHB pathogens support the need for continued surveillance. In this study, 461 isolates were obtained from symptomatic spikes of wheat, spelt, barley, and rye crops during 2018 and 2019. These were all identified to species and toxin types using molecular-based approaches. An additional set of 77 F. graminearum isolates obtained from overwintering crop residues during Winter 2012 were molecularly identified to toxin types. A subset of 31 F. graminearum isolates (15 15ADON and 16 3ADON) were assessed for mycelial growth, macroconidia, perithecia, and ascospore production, and sensitivity to two triazole fungicides. Ninety percent of isolates obtained from symptomatic spikes (n = 418) belonged to F. graminearum, with another four species found at a lower frequency (n = 39). F. graminearum isolates from symptomatic spikes were mainly of the 15ADON (95%), followed by 3ADON (4%), NIV (0.7%), and NX-2 (0.3%) toxin types. All F. graminearum isolates obtained from overwintering residue were of the 15ADON type. Toxin types could not be differentiated based on multivariate analysis of growth and reproduction traits. All isolates were sensitive to tebuconazole and metconazole fungicides in vitro. This study confirms the dominance of F. graminearum and suggests ecological and environmental factors that lead to similar composition of toxin types in Northern U.S. Our results are useful to assess the sustainability of FHB management practices and provide a baseline for future FHB surveys.

Plant Disease ◽  
2021 ◽  
Author(s):  
Bhavit Chhabra ◽  
Lovepreet Singh ◽  
Sydney Wallace ◽  
Adam Schoen ◽  
Yanhong Dong ◽  
...  

Fusarium head blight (FHB) primarily caused by Fusarium graminearum is a key disease of small grains. Diseased spikes show symptoms of premature bleaching shortly after infection and have aborted or shriveled seeds, resulting in reduced yields. The fungus also deteriorates quality and safety of the grain due to production of mycotoxins, especially deoxynivalenol (DON), which can result in grain being docked or rejected at the point of sale. Genetic host resistance to FHB is quantitative and no complete genetic resistance against this devastating disease is available. Alternative approaches to develop new sources of FHB resistance are needed. In this study, we performed extensive forward genetic screening of the M4 generation of an EMS induced mutagenized population of cultivar Jagger to isolate variants with FHB resistance. In field testing, 74 mutant lines were found to have resistance against FHB spread and 30 lines out of these also had low DON content. Subsequent testing over two years in controlled greenhouse conditions revealed ten M6 lines showing significantly lower FHB spread. Seven and six lines out of those 10 lines also had reduced DON content and lower FDKs, respectively. Future endeavors will include identification of the mutations that led to resistance in these variants.


2020 ◽  
Vol 13 (2) ◽  
pp. 235-246
Author(s):  
W.Q. Shi ◽  
L.B. Xiang ◽  
D.Z. Yu ◽  
S.J. Gong ◽  
L.J. Yang

Fusarium graminearum causes Fusarium head blight (FHB), a devastating disease that leads to extensive yield and quality loss in wheat and barley production. Integrated pest management (IPM) is required to control this disease and biofungicides, such as tetramycin, could be a novel addition to IPM strategies. The current study investigated in vitro tetramycin toxicity in Fusarium graminearum and evaluated its effectiveness for the control of Fusarium head blight FHB. Tetramycin was shown to affect three key aspects of Fusarium pathogenicity: spore germination, mycelium growth and deoxynivalenol (DON) production. The in vitro results indicated that tetramycin had strong inhibitory activity on the mycelial growth and spore germination. Field trials indicated that tetramycin treatment resulted in a significant reduction in both the FHB disease index and the level of DON accumulation. The reduced DON content in harvested grain was correlated with the amount of Tri5 mRNA determined by qRT-PCR. Synergistic effects between tetramycin and metconazole, in both the in vitro and field experiments were found. Tetramycin could provide an alternative option to control FHB.


Author(s):  
Tony Twamley ◽  
Mark Gaffney ◽  
Angela Feechan

AbstractFusarium graminearum and Zymoseptoria tritici cause economically important diseases of wheat. F. graminearum is one of the primary causal agents of Fusarium head blight (FHB) and Z. tritici is the causal agent of Septoria tritici blotch (STB). Alternative control methods are required in the face of fungicide resistance and EU legislation which seek to cut pesticide use by 2030. Both fungal pathogens have been described as either hemibiotrophs or necrotrophs. A microbial fermentation-based product (MFP) was previously demonstrated to control the biotrophic pathogen powdery mildew, on wheat. Here we investigated if MFP would be effective against the non-biotrophic fungal pathogens of wheat, F. graminearum and Z. tritici. We assessed the impact of MFP on fungal growth, disease control and also evaluated the individual constituent parts of MFP. Antifungal activity towards both pathogens was found in vitro but MFP only significantly decreased disease symptoms of FHB in planta. In addition, MFP was found to improve the grain number and weight, of uninfected and F. graminearum infected wheat heads.


Plant Disease ◽  
2021 ◽  
Author(s):  
Brian Mueller ◽  
Carol Groves ◽  
Damon L. Smith

Fusarium graminearum commonly causes Fusarium head blight (FHB) on wheat, barley, rice, and oats. Fusarium graminearum produces nivalenol and deoxynivalenol (DON) and forms derivatives of DON based on its acetylation sites. The fungus is profiled into chemotypes based on DON derivative chemotypes (3 acetyldeoxynivalenol (3ADON) chemotype; 15 acetyldeoxynivalenol (15ADON) chemotype) and/or the nivalenol (NIV) chemotype. The current study assessed the Fusarium population found on wheat and the chemotype profile of the isolates collected from 2016 and 2017 in Wisconsin. Fusarium graminearum was isolated from all locations sampled in both 2016 and 2017. Fusarium culmorum was isolated only from Door County in 2016. Over both growing seasons, 91% of isolates were identified as the 15ADON chemotype while 9% of isolates were identified as the 3ADON chemotype. Aggressiveness was quantified by area under disease progress curve (AUDPC). The isolates with the highest AUDPC values were from the highest wheat producing cropping districts in the state. Deoxynivalenol production in grain and sporulation and growth rate in vitro were compared to aggressiveness in the greenhouse. Our results showed that 3ADON isolates in Wisconsin were among the highest in sporulation capacity, growth rate, and DON production in grain. However, there were no significant differences in aggressiveness between the 3ADON and 15ADON isolates. The results of this research detail the baseline frequency and distribution of 3ADON and 15ADON chemotypes observed in Wisconsin. Chemotype distributions within populations of F. graminearum in Wisconsin should continue to be monitored in the future.


Toxins ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 399
Author(s):  
Hiroyuki Morimura ◽  
Michihiro Ito ◽  
Shigenobu Yoshida ◽  
Motoo Koitabashi ◽  
Seiya Tsushima ◽  
...  

Fusarium head blight (FHB) of cereals is a severe disease caused by the Fusarium graminearum species complex. It leads to the accumulation of the mycotoxin deoxynivalenol (DON) in grains and other plant tissues and causes substantial economic losses throughout the world. DON is one of the most troublesome mycotoxins because it is a virulence factor to host plants, including wheat, and exhibits toxicity to plants and animals. To control both FHB and DON accumulation, a biological control approach using DON-degrading bacteria (DDBs) is promising. Here, we performed a disease control assay using an in vitro petri dish test composed of germinated wheat seeds inoculated with F. graminearum (Fg) and DDBs. Determination of both grown leaf lengths and hyphal lesion lengths as a measure of disease severity showed that the inoculation of seeds with the DDBs Devosia sp. strain NKJ1 and Nocardioides spp. strains SS3 or SS4 were protective against the leaf growth inhibition caused by Fg. Furthermore, it was as effective against DON accumulation. The inoculation with strains SS3 or SS4 also reduced the inhibitory effect on leaves treated with 10 µg mL−1 DON solution (without Fg). These results indicate that the DDBs partially suppress the disease by degrading DON.


Sign in / Sign up

Export Citation Format

Share Document