No abstract

Leaves of Sansevieria trifasciata with leaf blight symptoms were collected from greenhouses of Miyandoab, West Azerbaijan province, Iran, during the summer of 2016. Leaf blight symptoms were large, elongated and gray to pale brown with brown margins. Three single spore isolates were obtained from diseased leaves and the pathogenicity of each isolate to plants was confirmed by inoculation tests based on Koch's postulates. The pathogen was identified as Stemphylium vesicarium, based on both morphological characteristics and sequencing of the Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene. This is the first report of Stemphylium vesicarium causing leaf blight on Sansevieria trifasciata in Iran and the world.

Eggplant (Solanum melongena L.) is an economically important solanaceous crop in Iran with fruits used for food and traditional medicine. Despite the importance of Alternaria leaf spot and blight disease of solanaceous crops which is commonly seen in the fields, our knowledge about the causal agents on eggplant is limited. In this study, a set of large-spored Alternaria isolates was recovered from eggplant with leaf spot and blight symptoms in Somehsara region, Guilan province, Iran. All recovered isolates shared conspicuous morphological characteristics e.g. production of large, solitary conidia with several transverse disto- and eusepta and long tapering filamentous beak resemble those seen in the members of Alternaria section Porri. Multi-locus phylogenetic analyses based on the internal transcribed spacer region of nrDNA (ITS-rDNA) and parts of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), second largest subunit of RNA Polymerase II (RPB2), translation elongation factor 1-alpha (TEF1-α) and Alternaria major allergen (Alt a 1) gene sequences provided further evidence supporting not only their exact placement in Alternaria sect. Porri, but also in a distinct lineage representing a new species. The new species was named, described and illustrated herein as Alternaria guilanica sp. nov.. The phylogenetic and morphological comaprisions of the new species with other closely related species were also provided. Pathogenicity test conducted for the new strains revealed that they were capable to induce disease symptoms on eggplant leaves under greenhouse conditions, and re-isolation of the inoculated isolates confirmed Koch’s postulates.

In the continuation of studies on Alternaria species from wheat plants with black head mold symptoms, 10 isolates with typical characteristics of the section Pseudoalternaria were isolated and studied by a combined approach based on morphological characteristics and phylogenetic analyses using sequence data sets of the internal transcribed spacer of ribosomal DNA (ITS-rDNA), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and plasma membrane adenosine triphosphatase (ATPase) genes. These isolates represented a new and previously undescribed species in this section which is illustrated and described here as Alternaria ershadii sp. nov. Also based on our phylogenetic analyses, it was revealed that Alternaria brassicifolii, which was recently described from Brassica rapa subsp. pekinensis in Korea and placed in this section, formed a well separated monotypic lineage distinct from the other members in the section Pseudoalternaria. Comparisons of three-dimensional sporulation patterns and conidial characteristics supported the molecular results. So, at present, Alternaria section Pseudoalternaria contains only seven species viz. Alternaria altcampina, A. arrhenatheri, A. ershadii, A. inflata, A. kordkuyana, A. parvicaespitosa and A. rosae. Morphological comparisons of Alternaria ershadii with other species in the section Pseudoalternaria and with Alternaria brassicifolii is also provided.