Pathogenicity of Fusarium graminearum and F. meridionale on soybean pod blight and trichothecene accumulation

Abstract

Soybean (Glycine max) is the most important crop in Argentina. At present Fusarium graminearum is recognized as a primary pathogen of soybean in several countries in the Americas, mainly causing seed and root rot and pre‐ and post‐emergence damping off. However, no information about infections at later growth stages of soybean development and pathogenicity of F. graminearum species complex is available. Therefore, the objectives of this study were to compare the pathogenicity of F. graminearum and F. meridionale isolates towards soybean under field conditions and to evaluate the degree of pathogenicity and trichothecene production of these two phylogenetic species that express different chemotypes. Six isolates of F. graminearum and F. meridionale were evaluated during 2012/13 and 2013/14 soybean growing seasons for pod blight severity, percentage of seed infected in pods and kernel weight reduction. The results showed a higher aggressiveness of both F. graminearum and F. meridionale species during the 2013/14 season. However, the differences in pathogenicity observed between the seasons were not reflected in a distinct trichothecene concentration in soybean seeds at maturity. Fusarium meridionale isolates showed similar pathogenicity to F. graminearum isolates but they were not able to produce this toxin in planta during the two field trials.

Diversity of the Seedborne Fungi and Pathogenicity of Fusarium Species Associated with Intercropped Soybean

“…These genera have previously been reported as the important pathogens of several soybean diseases, such as seedling blight, root rot and pod and seed decay by Fusarium spp. [ 4 , 10 , 25 , 27 , 37 ]; seedling blight and seed decay caused by Diaporthe/Phomopsis species complex [ 15 , 18 ]; soybean anthracnose caused by Colletotrichum spp. [ 21 , 38 ]; and leaf spot by Alternaria spp.…”

“…In general, the frequency of seedborne pathogens among and within seed samples may vary depending on geographical location, host genotype and agricultural practices [ 2 ]. Previous studies showed that only 33% of soybean seeds were infected by Fusarium species in Kansas [ 37 ]. Among nine Fusarium species found in soybean seeds, F. semitectum was the most frequent species in Kansas with the isolation frequency of 56.42% followed by F. proliferatum (19.25%) and F. verticillioides (13.20%), while F. equiseti (2.80%), F. fujikuroi (1.95%) and F. graminearum (0.33%) were isolated in low frequency among naturally infected seeds [ 25 , 40 , 41 ].…”

Fusarium graminearum species complex occurrence on soybean and F. graminearum sensu stricto inoculum maintenance on residues in soybean‐wheat rotation under field conditions

“…Members of the Fusarium graminearum species complex (FGSC) can colonize several crops causing diseases such as Fusarium head blight (FHB) in wheat, ear and stalk rot in maize and root rot in soybean (Martinelli et al 2004;McMullen et al 2012;Barros et al 2014;Chiotta et al 2016). Moreover, these species can contaminate grains with type B trichothecenes such as deoxynivalenol (DON), nivalenol (NIV) and its acetylated forms (Desjardins 2006), both associated with feed refusal, vomiting and suppressed immune functions in humans and animals (Pestka 2010).…”

“…Several studies have identified species within the FGSC as soybean pathogens in South America showing symptoms of infection such as seed and root rot and pre-and postemergence damping off (Martinelli et al 2004;Pioli et al 2004;Barros et al 2012Barros et al , 2014Chiotta et al 2016). These species persist on residues of host crops such as wheat or maize (Pereyra and Dill-Macky 2008;Guo et al 2010;Chiotta et al 2015a,b).…”

“…2014; Chiotta et al . 2016). Moreover, these species can contaminate grains with type B trichothecenes such as deoxynivalenol (DON), nivalenol (NIV) and its acetylated forms (Desjardins 2006), both associated with feed refusal, vomiting and suppressed immune functions in humans and animals (Pestka 2010).…”