Fusarium algeriense, sp. nov., a novel toxigenic crown rot pathogen of durum wheat from Algeria is nested within the Fusarium burgessii species complex

Authors: LARABA, IMANE - National Higher School Of Agronomy; KEDAD, ABDELAZZIZ - National Higher School Of Agronomy; BOUREGHDA, HOUDA - National Higher School Of Agronomy; ABDULLAH, NORA - National Higher School Of Agronomy; Vaughan, Martha; Proctor, Robert; Busman, Mark; O Donnell, Kerry

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/2017
Publication Date: 3/12/2018
Citation: Laraba, I., Keddad, A., Boureghda, H., Abdallah, N., Vaughan, M.M., Proctor, R.H., Busman, M., O'Donnell, K. 2018. Fusarium algeriense, sp. nov., a novel toxigenic crown rot pathogen of durum wheat from Algeria is nested within the Fusarium burgessii species complex. Mycologia. 106(6):935-950. https://doi.org/10.1080/00275514.2018.1425067.
DOI: https://doi.org/10.1080/00275514.2018.1425067

Interpretive Summary: Fusarium crown rot (FCR) poses a significant threat to small grain cereal production worldwide. Pathogens that are responsible for this economically important disease often reduce grain quality and yield. In addition, these molds frequently contaminate cereals with toxins that render them unsuitable for food or feed. Exposure to and consumption of toxin-contaminated cereals is a major food safety concern within the U.S. and throughout the world. Thus, the present research was conducted to assess whether strains of a novel species recovered from wheat exhibiting symptoms of FCR could induce this disease and produce toxins. Results of the pathogenicity experiment revealed that this novel fungus could induce crown rot on the susceptible spring wheat cultivar Norm. Searches of the whole-genome sequence of two strains indicated that this pathogen has the potential to produce several toxins, including beauvericin and fusarin. When strains were grown on a solid substrate, moniliformin and 2-AOD-ol toxins were detected by chemical analyses. Molecular genetic and morphological data were used to formally describe this novel crown rot pathogen to facilitate communication within the global scientific community. Results of this study will be of interest to plant disease specialists, quarantine officials, plant breeders, and mycotoxicologists whose research efforts are directed at combating FCR and other economically devastating cereal diseases globally.

Technical Abstract: A novel crown rot pathogen of wheat discovered during pathogen surveys of Algeria in 2014 and 2015 is formally described here as Fusarium algeriense. Multilocus molecular phylogenetic data resolved the eight isolates of this pathogen as a genealogically exclusive species lineage within the F. burgessii species complex. The described species within this complex, F. burgessii and F. beomiforme, produce abundant chlamydospores in culture and their optimal temperature for growth is 30 C. By comparison, F. algeriense did not produce chlamydospores under the conditions tested and it grew fastest at 25 C. Furthermore, F. algeriense differs from F. burgessii and F. beomiforme, respectively, because it doesn’t produce polyphialides and napiform-to-globose conidia in the aerial mycelium. Koch’s postulates were completed in a temperature controlled incubator, where isolates of F. algeriense induced moderate crown rot on the susceptible spring wheat cultivar Norm. Fusarium burgessii and F. beomiforme, by contrast, only produced mild symptoms of this disease. BLASTn searches of the whole-genome sequence of F. algeriense strains NRRL 66647 and 66648, using homologs of genes known to encode toxic secondary metabolites, indicated they have the potential to produce several polyketide and non-ribosomal peptide mycotoxins. However, moniliformin and 2-AOD-ol were the only mycotoxins detected by liquid chromatographic-mass spectrometric analyses of strains cultivated in vitro on a solid substrate. A PCR assay for MAT idiomorph revealed that MAT1-1 and MAT1-2 strains of F. algeriense were present in Algeria, which suggests this pathogen might possess a self-sterile or heterothallic sexual reproductive mode.