HEAD BLIGHT OF BARLEY IN SOUTH AFRICA IS CAUSED BY FUSARIUM GRAMINEARUM WITH A 15ADON CHEMOTYPE
A.-L. Boutigny, I. Beukes, A. Viljoen
In the past 4 years, the emergence of Fusarium head blight (FHB) of irrigated barley in the Northern Cape Province (NCP) became a concern to the malting and brewing industries, and the food and feed companies in South Africa. This motivated an epidemiological survey whereby 320 single-spored Fusarium isolates were obtained from diseased barley kernels collected in the NCP over 2 consecutive crop years (2008-2009) on two barley cultivars (potential malting varieties) at several locations. A multiplex PCR using previously published species-specific primers was utilized to simultaneously detect the most frequently encountered species of the FHB complex, including Fusarium graminearum, F. culmorum, F. avenaceum and F. poae. For isolates that could not be identified using PCR, further characterization was performed through sequence analyses. Fusarium graminearum (91.9%) was the dominant species, while F. boothii (6.25%), one of the species within the F. graminearum species complex, F. equiseti (1.25%) and F. poae (0.6%) were isolated far less frequently. Within the F. graminearum species complex, most of the isolates (99.7%) belonged to the 15-ADON chemotype. A real-time PCR assay based on SYBR Green technology was used to accurately quantify F. graminearum in barley samples. This is the first report on Fusarium species and their mycotoxin profiles associated with FHB of barley in South Africa.