Characterization of fungi causing lesion blight on Papaver dubium in Iran

Papaver dubium (common name, blindeyes, Papaveraceae) is widespread throughout Europe and America and is an important weed in western Iran. Since 2009, a blight disease has occurred in several areas in Hamedan Province, Iran, causing significant damage to plants of P. dubium. Small, yellow-brown lesions appeared on lower leaves and eventually expanded to the whole plant, resulting in necrosis and complete wilting. This study was conducted to identify the causal agent(s) of the blight disease on blindeyes plants. On the basis of cultural and microscopic characters, as well as representative DNA sequence data of the 5.8S rRNA (ITS), partial LSU rRNA partial β-tubulin (TUB2), and partial G3PD genes, 82 isolates were identified as follows: Ascochyta pisi M. A. Libert. (42), Neodidymelliopsis longicolla L.W. Hou, Crous & L. Cai. (28), and Allophoma zantedeschiae (Dippen.) Q. Chen & L. Cai (12). Pathogenicity tests in the greenhouse showed that all the isolates of A. pisi and Neod. longicolla caused typical spots on inoculated blindeyes plants, and the fungi were successfully re-isolated from the symptomatic tissues. Based on the high isolation frequency for A. pisi, and the severity of symptoms induced by this species in pathogenicity tests, this fungus was indicated as the major pathogen causing the blight disease on blindeyes. It has potential as a biocontrol agent against P. dubium. To the best of our knowledge, Al. zantedeschiae and Neod. longicolla observed in this study are new taxa for the mycobiota of Iran.