Genetic structure and mating type analysis of the Pyricularia oryzae population causing widespread epidemics in southern Brazil
- 269 Downloads
Blast is a major disease of rice in Brazil, the largest rice-producing country outside Asia. This study aimed to assess the genetic structure and mating-type frequency in a contemporary Pyricularia oryzae population, which caused widespread epidemics during the 2012/13 season in the Brazilian lowland subtropical region. Symptomatic leaves and panicles were sampled at flooded rice fields in the states of Rio Grande do Sul (RS, 34 fields) and Santa Catarina (SC, 21 fields). The polymorphism at ten simple sequence repeats (SSR or microsatellite) loci and the presence of MAT1-1 or MAT1-2 idiomorphs were assessed in a population comprised of 187 isolates. Only the MAT1-2 idiomorph was found and 162 genotypes were identified by the SSR analysis. A discriminant analysis of principal components (DAPC) of SSR data resolved four genetic groups, which were strongly associated with the cultivar of origin of the isolates. There was high level of genotypic diversity and moderate level of gene diversity regardless whether isolates were grouped in subpopulations based on geographic region, cultivar host or cultivar within region. While regional subpopulations were weakly differentiated, high genetic differentiation was found among subpopulations comprised of isolates from different cultivars. The data suggest that the rice blast pathogen population in southern Brazil is comprised of clonal lineages that are adapting to specific cultivar hosts. Farmers should avoid the use of susceptible cultivars over large areas and breeders should focus at enlarging the genetic basis of new cultivars.
KeywordsMagnaporthe oryzae Oryza sativa Population structure Microsatellite
Thanks are due to CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) for a research grant (Edital Universal 14/2012 - 478476/2012-4), a graduate scholarship to the first author, and a research fellowship to the senior author. The authors are indebted to Dr. Gustavo Funck (IRGA) and Dr. Cley Donizete Nunes (Embrapa Clima Temperado) for the support during planning of field collections.
- CONAB (2016) Companhia Nacional de Abastecimento. Arroz. Safra de 2015/2016. Sexto Levantamento, março de 2016. URL: http:www.conab.gov.br
- Lehner MS, Paula Júnior TJ, Hora Júnior BT, Teixeira H, Vieira RF, Carneiro JES, Mizubuti ESG (2015) Low genetic variability in Sclerotinia sclerotiorum populations from common bean fields in Minas Gerais State, Brazil, at regional, local and micro-scales. Plant Pathol 64:921–931CrossRefGoogle Scholar
- Maciel JL, Rodrigues PC, Avozani OA, Moraes MG (2004) Padrão molecular e de virulência de isolados de Pyricularia grisea do Estado do Rio Grande do Sul. Fitopatol Bras 29:504–510Google Scholar
- Milgroom MG (2015) Population biology of plant pathogens genetics, ecology, and evolution. Cornell University, Ithaca, New York. The American Phytopathological SocietyGoogle Scholar
- Peixoto LF (2014) Identificação da compatibilidade, sexualidade, fertilidade e AVR1-CO39 em populações de Magnaporthe aryzae coletadas em lavouras de arroz no Brasil: Universidade Federal de Goiás, MSc thesisGoogle Scholar
- Prabhu AS, Filippi MC, Araújo LG, Faria JC (2002) Genetic and phenotypic characterization of isolates of Pyricularia grisea from the rice cultivars Epagri 108 and 109 in the State of Tocantins. Fitopatol Bras 27:566–573Google Scholar
- SOSBAI - Sociedade brasileira de arroz irrigado (2014) Arroz irrigado: recomendações técnicas da pesquisa para o Sul do Brasil. Bento Gonçalves: SOSBAI, 189pGoogle Scholar
- Takan JP, Chipili J, Muthumeenakshi S, Talbot NJ, Manyasa EO, Bandyopadhyay R, Sere Y, Nutsugah SK, Talhinhas P, Hossain M, Brown AE, Sreenivasaprasad S (2012) Magnaporthe oryzae populations adapted to finger millet and rice exhibit distinctive patterns of genetic diversity, sexuality and host interaction. Mol Biotechnol 50:145–158CrossRefPubMedGoogle Scholar
- Tharreau D, Fudal I, Andriantsimialona D, Santoso D, Utami D, Fournier E, Lebrun MH, Notteghem JL (2009) In: Wang GL, Valent B (eds) World population structure and migration of the rice blast fungus, Magnaporthe oryzae. Springer, Netherlands, pp 209–215Google Scholar
- Valent B, Crawford MS, Weaver CG, Chumley FG (1986) Genetic studies of fertility and pathogenicity in Magnaporthe grisea (Pyricularia oryzae). Iowa State J Res 60:569–594Google Scholar