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SESSION 3: PATHOGENESIS – EPIDEMIOLOGY AND POPULATION
GENETICS
P57 - Analysis of the Fusarium graminearum species
complex in Brazil shows high diversity and changes
in species prevalence affected by host and
geographic region
E. M. Del Ponte 1 , T. J. Ward 2 , D. J. Tessmann 3 P. R. Kuhnem 1 , C. N. Silva 3 , L.
B. Gomes 1 , P. Spolti 1 , C. P. Nicoli 1
1 UFRGS, Av. Bento Gonçalves, 7712, 91540-000, Porto Alegre, RS Brazil; 2 USDA-ARS 1815 N.
University St., 61604, Peoria, IL, USA; 3 UEM, Av. Colombo 5790, 87020-900, Maringá, PR, Brazil
E-mail: emerson.delponte@ufrgs.br
A deeper understanding of F. graminearum species complex (FGSC) diversity in
central and southern Brazil based on the analysis of a large number (n=1050) of
isolates distributed in four new populations that were obtained between 2009 and
2011 from: 1) diseased heads from >150 wheat fields (n= 663 strains); 2) maize
kernels from fields at both central and southern regions (n=104); 3) maize stubble
showing perithecia obtained from 20 cultivated and non-cultivated fields (n=271);
and 4) rice kernels from fields in the southern growing-region (n=12). Multilocus
genotyping (MLGT) was used to determine species identity and trichothecene
genotypes for most isolates. For those from maize kernels, partial gene
sequences of TEF, tri3 and tri12 were used. For the wheat population, it was
found that F. graminearum with a 15-ADON genotype was dominant (83%),
followed by F. meridionale with a NIV genotype (12.8%), F. cortaderiae with
mostly NIV and a few 3-acetyl deoxynivalenol (3-ADON) (2.6%), F.
austroamericanum with mostly 3-ADON and a few NIV (1.2%) and F. asiaticum
with the NIV genotype (0.4%). Frequency of F. meridionale in wheat increased
with the decrease of latitudes. For the maize kernel population, F. meridionale
was dominant (72%), followed by F. graminearum with the 15-ADON genotype
(14.5%) and F. cortaderiae with the 3-ADON and NIV genotypes (13.5%). For the
maize stubble population, F. meridionale was dominant (50%), followed by F.
graminearum with the 15-ADON genotype (30%) and F. cortaderiae with the NIV
and 3-ADON genotypes (20%). For both maize populations, higher diversity was
found at higher latitude and elevation. Finally, F. asiaticum with the NIV genotype
was the sole species found in rice kernels. These results show that several
species coexist in the subtropical to tropical agricultural regions of Brazil where
host and geographic (climatic) region shape species composition.
Keywords: Gibberella zeae, multilocus genotype, trichothecenes
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