Abstract

Ceaser Edwardo

Wheat is presently considered as one of the most important crops world-wide. Among the fungal diseases of this crop, tan spot produced by Pyrenophora tritici-repentis is one of the most important. Tan spot increased its incidence, prevalence and severity in Argentina and South America. The aim of this work was to generate information about the morphocultural and pathogenic variability on wheat cultivars from Argentina. The results showed that isolates of P. tritici-repentis, originated from diverse localities of Argentina differed in their morphocultural characteristics and in their level of severity. The cluster analysis of morphocultural characteristics among 155 isolates of the pathogen defined 44 morphotypes according with the Jaccard’s coefficient (CCC=0.79). Pathogenicity tests determined on a set of eight wheat cultivars under greenhouse conditions showed the presence of physiological specialization in 33 isolates of P. tritici-repentis. The efforts to link morphocultural and pathogenicity features to the geographical origin of the isolates were mostly unsuccessful. The isolates tested appeared in different groups and most of the isolates which shared the highest similarity coefficient were collected from different localities and different wheat cultivars.