Surveys for crown rot (FCR) and head blight (FHB) of Algerian wheat conducted during 2014 and 2015 revealed that Fusarium culmorum strains producing 3-acetyl-deoxynivalenol (3ADON) or nivalenol (NIV) were the causal agents of these important diseases. Morphological identification of the isolates (n FCR=110, n FHB=30) was confirmed by sequencing a portion of TEF1. To assess mating type idiomorph, trichothecene chemotype potential and global population structure, the Algerian strains were compared with preliminary sample of F. culmorum from Italy (n=27), Australia (n=30) and the United States (n=28). A PCR assay for MAT idiomorph revealed that MAT1-1 and MAT1-2 strains were segregating in nearly equal proportions, except within Algeria where two-thirds of the strains were MAT1-2. An allele-specific PCR assay indicated that the 3ADON trichothecene genotype was predominant globally (83.8% 3ADON) and in each of the four countries sampled. In vitro toxin analyses confirmed trichothecene genotype PCR data and demonstrated that most of the strains tested (77%) produced culmorin. Global population genetic structure of 191 strains was assessed using nine microsatellite markers (SSRs). AMOVA of the clone corrected data indicated that 89% of the variation was within populations. Bayesian analysis of the SSR data identified two globally distributed, sympatric populations within which both trichothecene chemotypes and mating types were represented.

A novel crown rot pathogen of wheat discovered during pathogen surveys in Algeria in 2014 and 2015 is formally described as Fusarium algeriense. Multilocus molecular phylogenetic data resolved the eight isolates of this pathogen as a genealogically exclusive species lineage in the F. burgessii species complex. The previously described species of this complex, F. burgessii and F. beomiforme, produce abundant chlamydospores in culture, and their optimal temperature for growth is 30 C. In comparison, F. algeriense did not produce chlamydospores under the conditions tested and its optimal temperature for growth is 25 C. Furthermore, F. algeriense differs from F. burgessii because it does not produce polyphialides and F. beomiforme, because it does not produce globose-to-napiform conidia in the aerial mycelium. Isolates of F. algeriense induced moderate crown rot on the susceptible spring wheat cultivar Norm in a temperature-controlled incubator. Fusarium burgessii and F. beomiforme, in contrast, only induced mild symptoms of this disease. BLASTn searches of the whole-genome sequence of F. algeriense strains NRRL 66647 and 66648, using homologs of genes that are responsible for synthesis of toxic secondary metabolites, indicated that they have the potential to produce several polyketide and non-ribosomal peptide-derived mycotoxins. However, moniliformin and 2-AOD-ol (2-amino-14,16-dimethyloctadecan-3-ol) were the only mycotoxins detected by liquid chromatography-mass spectrometry (LC-MS) analyses of strains cultivated in vitro on a solid medium. A polymerase chain reaction (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 heterothallic sexual reproductive mode.