HETEROGENEITY IN THE INTERNAL TRANSCRIBED SPACERS OF THE RIBOSOMAL DNA IN COCHLIOBOLUS SATIVUS AS REVEALED BY IRAP
M. Jawhar, M.I.E. Arabi
Cochliobolus sativus, the causal agent of barley spot blotch disease, is an economically important fungus with a worldwide distribution. The heterogeneity within the nuclear rDNA [internal transcribed spacers (ITS)] of C. sativus isolates was studied using the amplified fragments through inter-retrotransposon amplified polymorphism (IRAP). A total of 173 scorable DNA bands were obtained from 7 primer pairs, and 20 of these (11.5%) were polymorphic. A neighbour-joining diagram, based on Nei’s genetic distances, showed that isolates formed three phylogenetic groups, and did not fall into clusters specific to geographical origin or colour of the isolate, which suggests a regional dispersal of C. sativus. The information obtained from this study is crucial for studying genetic variation in this fungus; in addition, IRAP-ITS markers can illustrate other types of polymorphism which can help to clarify the genetic structure of C. sativus isolates.