study on mycelial compatibility of sclerotinia sclerotiorum isolates from canola field of golestan

abstract sclerotinia sclerotiorum is the causal necrotroph pathogen with wide host range and showed various phenotipic intraspecies variability. considering to difficult identification of intraspecies heterogeneity on the basis of phenotypic factors, compatible mycelium groups introduced as an appropriate tool for classification and intraspecies heterogeneity distinction. in this research, 19 fungal isolates purified from canola and paired on modified patterson,s medium (mpm) with red food colour. pairings were scored as compatible when isolates merged to form one colony but mycelia incompatibility pairings resulted in an interaction zone in which a distinct reaction line and abundant aerial mycelia or thin mycelial were observed. but, incompatible mycelial with occurrence of interaction zone by red food colour in reaction zone on medium showed there is no potential of heterokaryon to be stable when two isolates were paired. all pairings of self isolates were compatible and five mycelial incompatible groups in isolates observed. microscopically, mycelial interactions in pairings of isolates were complex. anastomosis between paired isolates was not always observed. incompatible pairings were followed by hyphal deterioration, that was not observed in compatible interaction. the result showed that a high level of mycelial incompatibility exists among isolates of s. sclerotiorum, comparable to level of vegetative incompatibility reported in other ascomycetes. the extent of mycelial incompatibility indicates that the genetic heterogeneity exists within the species and the mycelial compatibility- incompatibility reactions may be an effective way of categorizing intraspecific heterogeneity.