Isolation and Identification of Fungal Endophytes of the Cowpea in Khuzestan Province

Endophytes are microorganisms that colonize internal tissues of plants without causing obvious symptoms. This study was conducted to isolate and identify endophytic fungi of the cowpea in Khuzestan province. During 2016, eight healthy samples of the cowpea plants were collected from the important areas under cultivation in the northern Khuzestan province. The small parts of the roots, stems, leaves and pods were deeply surface sterilized for each samples and plated on Potato-Dextrose-Agar. Sixty fungal isolates obtained in this study were purified by single spore method. Based on morphological characteristics, 21 out of 60 isolates were selected for molecular study. The isolates were grown in Potato-Dextrose-Broth and mycelial biomass was recovered by passing through filter paper. DNA extraction was performed using a phenol- and chloroform- based organic method. The parts of the nrRNA gene (ITS and 28S-D1/D2 regions) were amplified using appropriate primer pair and then sequenced. The isolates were analyzedon the basis of morphological characteristics in combination with BlASTn search algorithm and ITS sequence-based phylogeny. Accordingly, the isolates were identified as follows: Alternaria destruens, Alternaria sp., Curvularia mosaddeghii, Curvularia sp., Fusarium chlamydosporum, F. nygamai, F. falciforme, F. proliferatum, Fusarium sp. Macrophomina phaseolina and Penicillium oxalicum.
Discussion and Alternaria, Fusarium and Curvularia genera were the most abundant fungal endophytes into cowpea plants, growing in warm climate of the Khuzestan Province. To the best of our knowledge, this is the first study to report endophytic growth of A. destruens, Alternaria sp., M. phaseolina, F. chlamydosporum, F. nygamai, F. falciforme, F. proliferatum and P. oxalicum within cowpea plants.