8th INTERNATIONAL WHEAT CONFERENCE

ReSISTANCe To SePToRIA TRITICI BLoTCh
IN ARgeNTINeAN WheAT CuLTIVARS
Castillo, N. 1, 3 , Cordo, C. 1, 2 , Juliano, F. 1 , Kripelz, N. 1, 2 ,
Simón, M.R. 1
1 Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, Cerealicultura.60
y 119. CC 31. 1900- La Plata. Argentina;
2 CIDEFI- CIC; 3 CONICET.
E-mail Address of presenting author: nadiacastillo22@yahoo.com.ar
Bread wheat (Triticum aestivum L.) is the most widely grown and consumed food crop
in the world. In 2020, world population will reach 7500 million and will generate increased
demand for food. To increase yield, the breeding is an important tool which
allow increase yield. Genetic resistance against major diseases is a sustainable control
method, with a relatively low cost effectiveness and no impact on the environment. Septoria
tritici blotch (anamorph Septoria tritici Rob. ex Desm., teleomorph Mycosphaerella
graminicola (Fuckel) Schroeter, in Cohn) is one of the major fungal wheat diseases and
causes global damage ranging from 31 to 54% yield reduction. It is known that in the
pathosystem Triticum aestivum -septoria tritici blotch qualitative and quantitative resistance
are present, however a few commercial varieties show acceptable resistance levels.
In Argentina there is a lack of information about the type and level of resistance of the
commercial cultivars using a wide spectrum of isolates. In addition, the characterization
of the population of this pathogen has been limited; therefore cultivars have not been
tested with isolates grouped by molecular patterns. In this regard, the objectives of this
work were to investigate the genetic variability of the pathogen in Argentina and to test a
set of Argentinean cultivars, lines with known genes to the pathogen and differential lines
with a set of those isolates with different molecular patterns. The genetic structure and
diversity of Mycosphaerella graminicola population was investigated using a high number
of isolates from different locations of the Argentinean wheat region, sub region IV (SE
of Buenos Aires Province) and II South (Central Part of Buenos Aires Province) through
characterization with ISSR molecular markers. One hundred twenty seven isolates were
tested with 10 ISSR primers: (GACA) 4 , (AAC) 7 , (ATC) 7 , (AC) 9 , (AAG) 7 , (AG) 9 , (AGC) 5 ,
(CAG) 5 , (GTG) 5 and (GACAC) 3 . Only 83 amplified and 81 different haplotypes were obtained
(genotypic diversity= 98%). The size of the polymorphic bands ranged from 200
to 8000 bp and the highest number of polymorphic DNA fragments was produced using
ISSR primers (ATC) 7 and (GTG) 5 which detected bands in 38 isolates. Results revealed a
high degree of genotypic variability in M. graminicola populations. From the molecularly
characterized isolates, 16 representing different haplotypes were selected: FALP 0105,
0205 1405, 2005, 2405, 5205, 20107, 20507, 21707, 22607, 23007, 24307, 24407, 24707,
24807 y 25405. They were inoculated on nine Argentinean commercial cultivars showing
some level of resistance in the field and fourteen international lines with known genes
and differentials of Triticum aestivum L., with the purpose of identifying specific resistance
or partial resistance. Two trials were conducted in different environments, one in
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