DIVERSIDADE DE RIZÓBIOS ISOLADOS DE NÓDULOS DE Mimosa gymnas Barneby NATIVAS DOS CAMPOS GERAIS DO PARANÁ (BRASIL)

Abstract

Floristic surveys performed in the “Campos Gerais” (Paraná, Brazil) indicate that Fabaceae is one of the most species-rich and abundant families. These studies also pointed out the high diversity and endemism of Mimosa spp. Our study report the diversity of rhizobia isolated from root nodules of native Mimosa gymnas Barneby. Twenty-nine strains were obtained from from nodulating M. gymnas in three areas of Guartelá State Park, one of the most important conservation unities of the “Campos Gerais”; soils of these areas were characterized as sandy, acid, poor in nutrients and organic matter and with high aluminum contents. The phylogenetic tree constructed with partial 16S rDNA sequences grouped the strains in a larger cluster and some strains were more related with Paraburkholderia nodosa, although some strains were more related to P. bannensi. The analysis of the genomic profile by BOX-PCR revelead a high degree of intraspecific variability among the isolates. Results based on phylogeny of concatened genes recA-gyrB divided the strains in two large clusters. The cluster II didn’t grouped with any type strain and the isolates showed a nucleotide identity of 16S rDNA of at most 97% with P. nodosa. The nodC phylogeny grouped all the strains into a well-supported clade, not grouping with any know strain of Paraburkholderia genus. Our results support that Paraburkholderia are the main symbionts of Mimosa in South America and the association of nodulating strains of this genera with particular edaphic conditions. Also, the results of the phylogenetic analysis suggest that the isolates grouped in cluster II in the recA-gyrB phylogenetic tree may represent a new species of Paraburkolderia, highlighting the importance of diversity studies with native and endemic leguminous plants.