Distribution and diversity of Alt a 1 gene in Alternaria species isolated from outdoor air of Tehran

In the present study، distribution pattern and phylogeny of Alternaria species isolated from Tehran air was determine based on the homology of Alt a1 gene. A number of 48 Alternaria isolates belonging to A. alternata (33. 4%)، A. solani (23%)، A. tenuissima (23%)، A. porri (16. 6%)، and A. brassicicola (4%) obtained from Tehran air were cultured on Sabouraud dextrose agar. Genomic DNA was extracted from the isolates and amplified with forward and reverse specific primers of Alt a1 gene. The resultant fragments of 500 to 600 bp of genomic DNA were sequenced and compared with genomic data of NCBI gene bank to evaluate phylogenetic relationship of Alternaria species. Based on the resulting dendrogram، isolates belonging to A. alternata and A. solani were distributed in 4 clusters and those of A. brassicicola، A. porri، and A. tenuissima each in 2 clusters. Approximately، 81% of A. alternata isolates، 73% of A. solani isolates، 45. 5% of A. tenuissima isolates and 12. 5% of A. porri isolates showed a similarity of 99% and resided in clusters I، II، IV and VII، respectively. Our results indicated that Alt a1 gene was present in all examined species and differences of sequence similarities of this gene shows the importance of species and strains of Alternaria in induction of allergenic reactions in suspected patients especially those with allergic asthma.