EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
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SESSION 3: PATHOGENESIS – EPIDEMIOLOGY AND POPULATION<br />
GENETICS<br />
P51 - Selective pathogenicity and virulence <strong>of</strong><br />
Fusarium graminearum species complex members on<br />
maize, wheat and sorghum<br />
I. Beukes 1 , C. de Klerk 1 , L. J. Rose 1 , G. J. van Coller 1, 2 , B. Flett 3 , A. Viljoen 1<br />
1 University <strong>of</strong> Stellenbosch, Department <strong>of</strong> Plant Pathology, Private Bag X1, Matieland 7602, South<br />
Africa; 2 Directorate Plant Science, Western Cape Department <strong>of</strong> Agriculture, Private Bag X1,<br />
Elsenburg 7607, South Africa; 3 Grain Crops Institute, Agricultural Research Council, Private Bag<br />
X1251, Potchefstroom 2520, South Africa<br />
E-mail: ibeukes@sun.ac.za<br />
Fusarium head blight (FHB) <strong>of</strong> wheat, gibberella ear rot (GER) <strong>of</strong> maize and grain<br />
mold (GM) <strong>of</strong> sorghum is caused by, amongst others, members within the<br />
Fusarium graminearum species complex (FGSC). Grains infected with these<br />
pathogens are commonly contaminated with trichothecene mycotoxins, which is<br />
associated with health complications in humans and animals. It has been<br />
suggested that host specificity exists within the FGSC, possibly due to differences<br />
in cyclic hydroxamic acids and related benzoxazolinone compounds or other<br />
antimicrobial composites in different cereal hosts. In this study, the host<br />
preference <strong>of</strong> five FGSC members, represented by 26 isolates obtained from<br />
different South African grains was assessed on wheat, maize and sorghum.<br />
Radial growth <strong>of</strong> these isolates on potato dextrose agar at 12 and 24-h<br />
illumination did not differ significantly between the members. Sporulation <strong>of</strong><br />
cultures under the same light conditions resulted in F. boothii producing the most<br />
and F. acaciae-mearnsii the least spores. Wheat heads were inoculated with five<br />
isolates each from five FGSC members, previously isolated from South African<br />
grown wheat, to establish whether a difference in virulence could be observed<br />
between them. Inoculations showed that all FGSC members were pathogenic to<br />
wheat, with F. cortaderiae being the least and F. graminearum s.s the most<br />
virulent. Macroconidia from different isolates <strong>of</strong> the same FGSC member were<br />
then combined and inoculated onto sorghum and maize plants in the field, and<br />
disease development and trichothecene production measured after harvest.<br />
Inoculation with F. meridionale resulted in the highest disease incidence and<br />
severity on maize kernels. Infection with F. meridionale was supported by the<br />
production <strong>of</strong> nivalenol in both maize and a brown sorghum cultivar. Fusarium<br />
graminearum s.s. and F. cortaderiae could not be associated with GER <strong>of</strong> maize<br />
or GM <strong>of</strong> brown sorghum, and was unable to produce their associated mycotoxins<br />
within these grains.<br />
Keywords: Fusarium graminearum species complex, host preference<br />
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