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2021 National Fusarium Head Blight Forum


Pathogen Biology & Genetics (PBG)

Poster # 132

Population Diversity of Fusarium Species Causing Fusarium Head Blight in Wheat and Greenhouse Pathogenicity Tests of F. poae Isolated from Georgia

Authors & Affiliations:

Bikash Ghimire1, Mohamed Mergoum2,3, Anthony E. Glenn4, Kira L. Bowen5, Alfredo D. Martinez-Espinoza1, and James W. Buck1
1. Department of Plant Pathology, University of Georgia, Griffin Campus, Griffin, GA, USA 2. Department of Crop and Soil Sciences, University of Georgia, Griffin Campus, Griffin, GA, USA 3. Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Griffin Campus, Griffin, GA, USA 4. USDA-ARS, Toxicology & Mycotoxin Research Unit, Athens, GA, USA 5. Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA

Corresponding Author:

James W. Buck
The University of Georgia (UGA)
jwbuck@uga.edu

Abstract:

Recent outbreaks of Fusarium head blight (FHB) in Georgia have negatively impacted soft red winter wheat (SRWW) production; however, information on pathogen population is lacking. To explore the distribution and diversity of Fusarium species, we collected 212 isolates from symptomatic wheat heads and corn stubble by sampling 46 wheat and 55 corn fields across 72 counties of Georgia in 2018 and 2019. Pure cultured and single hyphal tipped isolates were subjected to genomic DNA extraction. The sequencing date from translation elongation factor 1-alpha (TEF1) locus was used for species level identification by querying publicly available sequence databases in NCBI GeneBank and Fusarium MLST. Trichothecene chemotypes were determined using chemotype-specific primers designed from the TRI3 and TRI12 loci. We identified that the majority (nearly 84%) of isolates from wheat were F. graminearum of which 78.0% were 15ADON chemotype, 19% NIV chemotype, and few remaining isolates of 3ADON chemotype. F. poae was the second largest group of species recovered from wheat and were distributed across six counties of Georgia. Interestingly, two-thirds of the total isolates from corn were resolved under Fusarium incarnatum-equisetum species complex (FIESC) with a very few (5%) presence of F. graminearum. Additionally, several other species were identified including F. armeniacum, F. proliferatum, F. verticillioides, F. fujikuroi, F. avenaceum, F. acuminatum, and F. chlamydosporum belonging to different species complexes. Greenhouse pathogenicity tests were conducted on five isolates of F. poae and one isolate of F. graminearum in three hosts: SRWW, durum wheat, and six-rowed barley, each consisting of two to three susceptible and moderately resistant cultivars. Significant effects of isolates, cultivars, and their interaction were observed on FHB traits with F. poae isolates causing up to 40% FHB severity (SEV) and 75% Fusarium-damaged kernel (FDK) and producing type A trichothecene T-2/HT-2 as high as 45 ppb. On the other hand, F. graminearum isolate produced nearly 90% SEV and FDK and up to 40 ppm DON, while no disease was observed on the mock-inoculated plants. Overall, our findings on the widespread distribution of FHB pathogens and the ability of F. poae isolates to cause disease in the greenhouse demonstrate that FHB outbreaks will likely continue in Georgia whenever environmental conditions favor and thus growers should consider integrated disease management strategies, whenever applicable. 

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