Identification and molecular characterization of Phyllosticta yuccae isolates causing Yucca leaf spot in Iran

During 2017-2018, the leaf spot disease was observed in mound-lily Yucca (Yucca gloriosa) and Spineless Yucca (Y. elephantipes) in Tehran, Fars and Bushehr provinces of Iran. In order to identify the causal agents of the disease, infected tissues were collected and transferred to the laboratory and 27 fungal isolates were isolated. Fungal isolates were identified based on morphological characteristics and molecular data of the internal transcribed spacer (ITS) region and parts of the actin (act) and the translation elongation factor 1-alpha (tef1) genes. According to the morphological and phylogenetic analysis, the isolates were identified as Phyllosticta yuccae. The pathogenicity test was performed on healthy and attached leaves of Y. gloriosa and Y. elephantipes plants. Inoculated plants showed leaf spot symptoms in seven days post inoculation, while control plants remained symptomless. To complete the Koch’s postulate, P. yuccae was re-isolated from inoculated plants. The results of this study revealed that the causal agent of leaf spot disease of Yucca plants was P. yuccae.