Arabi M. I. E., El-Shehadah E., Batarni A. & Jawhar M. (2013) Heterogeneity in the ITS region of ribosomal DNA of Cochliobolus sativus isolates differing in virulence patterns. – Sydowia 65 (2): 193–200.

Spot blotch of barley (Hordeum vulgare) caused by the fungus Cochliobolus sativus has been the major yield-reducing factor for crop production during the last decade. In this study, the nucleotide sequences of internal transcribed spacer (ITS) regions of rRNA genes of C. sativus isolates differing in virulence patterns were examined. The results indicate that the sequences of ITS regions in different isolates are not identical. Sequence variations were found at nine positions in the 600 bp that were sequenced. A neighbour-joining diagram, based on Nei’s genetic distances, showed that isolates split into two phylogenetic groups and did not result in any clusters/clades specific to virulence pattern or lesion shape. Hence, the results presented here suggest that identification of C. sativus isolates by their morphological and biological characteristics should be appropriately supported by molecular analysis.

Keywords: Bipolaris sorokiniana, virulence, internal transcribed spacer, rRNA.