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be conducted. They also recommended selection of individual resis-
tant plants in the F
3
generation given that the reaction of several plants
would better represent the range of resistance genes in the original F
2
plant. Additionally, a successful breeding strategy based on a modi
ed
recurrent selection approach (Correa-Victoria and Martinez 2009) was
implemented, which was able to accumulate both major and minor blast
resistance genes conferring durable blast resistance originating in those
parental lines selected over several years of evaluation and selection.
De
t from the use of molec-
ular markers associated with major resistance genes to assure that
selected lines carry them and we expect that in the near future molecular
markers associated with relevant minor genes will be identi
nitely, this breeding approach would bene
ed to assure
their presence in the background of the resistant material.
Rice blast is probably the disease receiving the most attention within
rice breeding programs focused on resistance in Latin America. The
disease is widespread in Brazil and several research institutes in the
country are dedicated to solving their local or state blast problems. IRGA
has implemented a resistance breeding program based on
field evalua-
tions and selections of breeding lines under high disease pressure
(Funck 2010). Field evaluations for blast are made at both the vegetative
and reproductive stages. Sources for resistance are selected and breed-
ing populations developed based on speci
c crosses for the incorpora-
tion and accumulation of major blast resistance genes (Funck 2010). All
rice breeding and pathology researchers share their breeding material
through a national nursery distributed every year for the evaluation
and selection of blast-resistant material under local conditions. Spreader
rows that are inoculated under
field conditions with different local races
of the pathogen are used to maintain high blast disease pressure and
diversity of the pathogen, thus minimizing possible escapes from infec-
tion. The breeding program has been very successful in the identi
cation
of resistant material developed in the institute as well as introductions
received from FLAR.
Additionally, a successful breeding program for improvement of
blast resistance in Brazil has been implemented at Embrapa. The struc-
ture of blast pathogen populations has been genotypically characterized
in genetic lineages using molecular markers and, presently, genes con-
ferring resistance to the different genetic groups of the pathogen have
been identi
ed using international and local blast differentials (Barata
da Silva et al. 2011). The use of local blast differentials has allowed
Embrapa researchers to identify additional pathotypes relevant for
resistance breeding purposes that cannot be distinguished by the inter-
national set. The researchers believe that knowledge of the pathotype
