EFS12- Book of abstracts - Contact

SESSION 3: PATHOGENESIS – EPIDEMIOLOGY AND POPULATION
GENETICS
P76 - Fusarium verticillioides and F. subglutinans
mating types – distribution and molecular structure
E. Jabłońska, M. Wit, W. Wakuliński
Department of Plant Pathology, Warsaw University of Life Sciences; 159 Nowoursynowska St., 02-776
Warsaw, Poland
E-mail: emilia.jablonska@gmail.com
Fusarium genus comprises several toxigenic species associated with maize,
including F. verticillioides and F. subglutinans. Both species are the members of
Liseola section and causative agents of the ear rot of maize, while F. verticillioides
is also considered to be the most prolific producer of fumonisins.
The teleomorphs of F. verticillioides and F. subglutinans belong to the Gibberella
fujikuroi species complex. Both species are heterothallic fungi with a dimictic
mating system typical for numerous Ascomycota and governed by two
idiomorphic alleles, MAT1-1 and MAT1-2. High genetic diversity observed in these
species and the coexistence of the two mating types in fungal populations at the
same geographical scale may suggest the occurrence of the so-called cryptic sex.
As the proportion of the two complementary thalli of opposite mating types is an
important factor for the occurrence of the sexual process in heterothallic Fusarium
species, the aim of the study was to determine the frequency of both idiomorphs
(MAT1-1 and MAT1-2) and to describe the MAT locus structure.
For this purpose a total of ninety-nine Fusarium isolates collected from infected
corn kernels were examined. On the basis of classical mycological methods of
morphological identification, 47 isolates were identified as F. verticillioides, and 52
– as F. subglutinans. Subsequently, morphological identification was verified
molecularly using SCAR markers.
The mating type identification revealed frequency proportions different from an
expected result of 1:1 distribution of MAT1-1 and MAT1-2, according to the chisquare
test. In the F. subglutinans population the MAT1-1 and MAT1-2 idiomorphs
occurred with frequency 35% and 65% respectively, while F. verticillioides mating
type proportion was unexpectedly highly segregated with the ratio of 15% MAT1-1
and 85% MAT1-2.
The analysis of the MAT locus structure of F. verticillioides revealed the presence
of substitutions, most of them being transitions, and deletions occasionally.
Keywords: Fusarium, maize, idiomorphs, mating types
169