assessment of the genetic diversity of rhizoctonia zeae population in the field soils of mazandaran and golestan provinces

rhizoctonia zeae causes root rot and sheath blight on corn (zea mays) and several other gramineous plants. in order to determine the genetic diversity of the r. zeae population in mazandaran and golestan provinces, samples were collected from cultivatd soils of both provinces in 2011 and 2012.the identity of isolates as r. zeae were verified by amplification and sequencing of the 18s and 28s rdna of five representative isolates. genetic diversity of 20 isolates from different geographic regions were assessed by amplification of the its region of rdna by pcr, using its4 and its5 primers and sequencing of the amplified fragments. the isolates appeared to be genetically heterogeneous and were differentiated into four clusters based on their its sequences. there was substantial correlation between the morphological variation and genetic heterogeneity observed among isolates.