Identification and Genetic Division of Fusarium graminearum and Fusarium asiaticum by Species-Specific SCAR Markers

Fusarium head blight (FHB), also called scab, is a devastating and insidious disease of cereals including wheat (Triticum spp.) and barley (Hordeum vulgare L.) worldwide. Apart from direct yield losses, the most serious concern about FHB is the contamination of the crop with mycotoxins, which pose a health risk to human and livestock. Recent research reported that phylogenetic species F. asiaticum (Fa) and F. graminearum (Fg) were the major causal agents of FHB from infected wheat heads in China. To investigate the population structure of Fusarium species in China by species-specific as well as the chemotype-specific markers, sequence-related amplified polymorphism (SRAP) markers were screened on representative isolates of F. asiaticum-NIV, F. asiaticum- 3ADON and F. graminearum-15ADON to find amplification products characteristic of either species or chemotypes. Selected amplified fragments were cloned and sequenced so that sequence-characterized amplified region (SCAR) primer pairs could be developed which permit specific detection of Fusarium species using conventional PCR. Primer pairs SCAR-Fa1 and SCAR-Fg1 were confirmed to be able to amplify specific products only in F. asiaticum and F. graminearum isolates, respectively. These species-specific primers were applied to determine genetic division of F. asiaticum and F. graminearum isolates collected in Yangtze–Huaihe valley. The results indicated that F. asiaticum was the predominant species causing FHB in this wheat production area. It is the first report that SRAP markers were adapted for species characterization in Fusarium isolates.