Genetic population structure and trichothecene genotypes of Fusarium graminearum isolated from wheat in southern Brazil

Abstract

A sample of 140 Fusarium graminearum isolates from Rio Grande do Sul, Brazil, representing three populations at least 150 km from one another, were examined for trichothecene genotype based on PCR amplification of portions of the Tri3 and Tri12 genes and a species-specific (Fg16F ⁄ R) primer pair. Genetic diversity was assessed in a sample of 103 F. graminearum lineage 7 (F. graminearum sensu stricto) isolates using amplified fragment length polymorphism (AFLP) markers. The 15-ADON genotype was dominant, followed by the NIV genotype (2-18% prevalence), across all three populations. All NIV-type isolates were in lineage 2 (F. meridionale) and all 15-ADON-type isolates were in lineage 7. Isolates with the same haplotype were rare and genotypic diversity was uniformly high ( ‡98% of the count), suggesting that recombination has played a significant role. The number of migrants (N m ) was estimated between 5 and 6 across all loci and all populations, but the high frequency of private alleles (up to 30%) suggests a historical, rather than contemporary, gene flow. Regarding linkage disequilibrium, 0AE8, 1AE5 and 2AE2% of the locus pairs from the three populations were in disequilibrium, which is lower than values reported in other locations. Thus, Brazilian populations differ from those found in Europe, North America and most of Asia in the presence of a significant frequency (7AE8%) of isolates of the NIV genotype in lineage 2.

Agressividade diferencial de espécies do complexo Fusarium graminearum em interação com o fungicida tebuconazole na redução do rendimento de trigo

“…No Brasil, a giberela em trigo é causada por espécies do complexo Fusarium graminearum, especialmente F. graminearum sensu stricto (Fgss) (SCOZ et al, 2009;ASTOLFI et al, 2012). Os danos ocasionados por giberela em trigo no Brasil incluem a redução no rendimento e a contaminação com as micotoxinas de desoxinivalenol (DON) e nivalenol (NIV) (CASA et al, 2004;DEL PONTE et al, 2012).…”

“…Os danos ocasionados por giberela em trigo no Brasil incluem a redução no rendimento e a contaminação com as micotoxinas de desoxinivalenol (DON) e nivalenol (NIV) (CASA et al, 2004;DEL PONTE et al, 2012). No Sul do Brasil, as populações de Fgss (a dominante, com 90% de frequência em isolamentos) e Fmer têm apresentado consistentemente genótipo tricoteceno15-A(acetil)DON, uma forma acetilada de DON, e NIV, respectivamente, o que sugere que podem produzir diferentes concentrações de DON e nivale nol (SCOZ et al, 2009;ASTOLFI et al, 2012). SPOLTI et al (2012a) , evidenciando que as populações produzem ambas as micotoxinas.…”

“…Assim, objetivou-se: i) avaliar características fenotípicas de um conjunto de isolados das duas espécies do complexo (Fgss e Fmer), discriminando-as por meio de análise multivariada; ii) avaliar o efeito fungistático de tebuconazole no controle da doença e redução de danos em grãos de espigas inoculadas com as duas espécies. (ASTOLFI et al, 2012). Esses isolados foram distintos dos quatro isolados utilizados em um estudo prévio (SPOLTI et al, 2012a).…”

Sensitivity of Fusarium graminearum causing head blight of wheat in Brazil to tebuconazole and metconazole fungicides

“…Fusarium graminearum species complex (Fg complex) comprises more than a dozen lineages or phylogenetic species (Sarver et al, 2011) and is the main causal agent of Fusarium head blight (FHB) of small grain in Brazil and around the world (Goswami and Kistler, 2005;Astolfi et al, 2012). In the Americas, Fusarium graminearum sensu stricto is the dominant species of the Fg complex associated with head blight of wheat (Alvarez et al, 2011;Schmale et al, 2011;Astolfi et al, 2012).…”

Phylogenetic analyses of the Fusarium graminearum species complex isolated from soybean in Argentina and Brazil

“…In Argentina, F. graminearum sensu stricto was the only phylogenetic species isolated from wheat in different subregions of the main wheat production area (Ramirez et al 2007;Alvarez et al 2011), but F. meridionale and F. boothii were the most important on maize in the Northwest area of Argentina (Sampietro et al 2011). In Brazil, surveys of FGSC isolates from wheat showed that F. graminearum sensu stricto was the dominant species (Astolfi et al 2012), while F. meridionale represented an 80 % of the isolates from maize kernels in the Central and Southern maize growing regions of Brazil (Tessmann et al 2011). In soybean, a preliminary report showed the presence of three species, F. austroamericanum, F. meridionale and F. cortaderiae in soybean samples from Brazil (Martinelli et al 2004).…”