Phylogenetic analysis of Rhizoctonia sp. associated with sore shin, damping off and target spot symptoms on tabacco based on ITS-rDNA

MERCADO CÁRDENAS G; GALVÁN M; BARRERA V; CARMONA M; MARCH G; RAMALLO A; MONJE J

Bento Gonçalves, RS, Brasil

Congreso; 44° Congresso Brasileiro de Fitopatología; 2011

Sociedade Brasileira de Fitopatologia

In the last decade, sore shin, damping off and target spot caused by Rhizoctonia sp. became important diseases of Nicotiana tabacum L. in northwestern Argentina. The increasing prevalence and intensity of these diseases forced to realize etiologic studies in the region. The aim of this work was to characterize 43 isolates of Rhizoctonia sp. collected from different commercial tobacco fields in Salta and Jujuy provinces, by means of DNA sequence analysis. Molecular characterization was carried out using the specific ribosomal DNA internal transcribed spacer region (ITS-rDNA). Fragments amplified using primers ITS1 and ITS4 were sequenced and aligned using Clustal W. Additional sequences of known R. solani anastomosis groups (AG) available in the NCBI GenBank database were included in the analysis. Isolations from other hosts (bean, chickpea, sorghum and peanut) were also analyzed. A Neighbor Joining tree was generated and the isolates were grouped in different AG clusters. Most of the isolates were characterized as AG1, AG2, AG4-HGI, AG4-HGII and AG4-HGIII. To our knowledge, these results represent the first molecular analysis of the pathogen in northwestern Argentina and revealed a great variability in the isolates analyzed.