نخستین گزارش از Exserohilum gedarefense همراه با ریشه‌ی ذرت در استان خوزستان

Cereals are very important in human and animals nutrition. The leaves, roots and stems of these plants are damaged by graminicolous fungi such as Exserohilum species. In order to study these fungi on cereals in southern Iran, During the spring and summer of 2017, some roots, stems and rhizosphere soil were collected from barley, maize, millet, rice, turf grass and wheat fields of Khuzestan Province (Andymeshk, Behbahan, Tang-Sulak, Ramhormoz, Shush, Shushtar, Gatvand and Masjed-Soleiman). Isolates were identified based on morphological characters including form and size of conidia and conidiophores, the number of septa in each conidia, presence or absence of hilum in conidia, growth rate and colony morphology on potato dextrose agar. An isolate of Exserohilum gedarefense had recovered from the healthy roots of maize (without any sign of leaf spot or root rot) in Behbahan. Phylogenetic analysis based on maximum likelihood of internal transcribed spacer region of rDNA confirmed the position of this isolate in Clade B of Exserohilum species phylogeny. Pathogenicity of this isolate was tested by both spore-suspension spraying on leaves and inoculation of rhizosphere around roots of barley, maize, millet, rice, turf grass and wheat. The isolate induced yellow spots on the leaves of barley, maize and wheat; brown spots on the leaves of barley and maize, and leaf blight in maize. No signs were observed on the leaves of other tested plants. The rhizosphere soil inoculation of the plants suppressed the growth of roots and plants in all cases. Furthermore, seed decay in barley, turf grass and maize were also observed.