Relationships among Brazilian and worldwide isolates of Fusarium oxysporum f. sp. lactucae race 1 inferred from ribosomal intergenic spacer (IGS-rDNA) region and EF-1α gene sequences.

Autor: Cabral, Cléia S., de N. Fonseca, Maria Esther, Brunelli, Kátia R., Rossato, Mauricio, Costa, Hélcio, Boiteux, Leonardo S., Reis, Ailton
Zdroj: European Journal of Plant Pathology; Sep2018, Vol. 152 Issue 1, p81-94, 14p
Abstrakt: Fusarium wilt, caused by Fusarium oxysporum f. sp. lactucae (FOLac), is amongst the main diseases affecting lettuce in subtropical regions. Although nationwide surveys indicated the exclusive presence of FOLac race 1 in Brazil, no detailed studies are available providing molecular evidences if these isolates were introduced into the country via contaminated seeds or if they are endemic populations. The translation elongation factor 1α (EF-1α) gene and rDNA intergenic spacer (IGS-rDNA) region represent the most comprehensive databases for comparative analyses of Fusarium isolates. Our aim was to assess the genetic relationships of 23 Brazilian FOLac race 1 isolates with a collection of FOLac isolates of worldwide origin, using the information from these genomic regions. A consistent single-cluster pattern was observed for FOLac race 1 isolates from Brazil, California-USA, Arizona-USA, Japan, Italy, as well as the novel FOLac race 4 isolates from the Netherlands based upon the EF-1α (604 nucleotides) and the IGS-rDNA (1859 nucleotides) sequences. Our analysis (based upon six single nucleotide polymorphisms identified only in the IGS-rDNA sequence) allowed the identification of intra-race 1 variation with the discrimination of four haplotypes. Isolates from Brazil, Italy, and a subset from the USA were classified into a single haplotype. The low diversity levels and the presence of only a single haplotype across the entire country are strong indications that Brazilian FOLac race 1 isolates are result of recent introduction event(s). This fast and widespread distribution of FOLac race 1 in Brazil has occurred more likely via importation and planting of contaminated seeds. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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