Variability of Pyrenophora tritici-repentis isolated from different wheat areas of Tunisia: Morpho-cultural characterization, pathogenic analysis and virulence effector genes

Sixty-three isolates of Pyrenophora tritici-repentis collected from various wheat areas of the north of Tunisia were characterized and studied for their variability. Under in vitro conditions, morpho-cultural characterization showed the presence of several colors of colonies. An inoculation bioassay was performed identifying the presence of three symptoms type i.e., small brown spots, chlorosis, and necrosis with chlorosis. ANOVA of leaf infected area and lesion length data caused by isolates showed significant difference, and Ascending Hierarchical Clustering discriminated them into two distinct pathogenic profiles. Molecular detection of virulence effector genes demonstrated the presence of ToxA, ToxB, and toxb gene individually or in combination, resulting in five different gene profiles. These results indicate large variability of features. Multiple Correspondence Analysis and Ascending Hierarchical Clustering identified four distinct isolates classes. Both pathogenic profiles of isolates appeared in all the groups. Hence, it was not possible to establish a relationship between variability characters and geographical regions from which the isolates were collected.