Investigation of Alternaria alternata pathogenicity on corm and leaves of saffron in vitro and greenhouse conditions

Saffron is one of the most important herbs and spices in the East of Iran and its production is affected by various pathogens. This study is aimed at isolation, identification and pathogenicity detection of Alternaria alternata isolates as leave spot and corm rot of saffron agents. Soil samples and infected plant tissues were collected from different areas of the Birjand plain (Birjand, Khusf and Sarbishe) during the years 2014-15. Alternaria species were isolated by potato dextrose agar medium and their morphological characteristics were studied on the potato carrot agar medium. For molecular studies, genomic DNA was extracted by the CTAB method and ribosomal subunits of fungal isolates were amplified using ITS1 and ITS4 primers. Based on morphological characteristics, 80 isolates of A. alternata were isolated. The ITS regions sequences of selected isolates had 100 similarities with A. alternata spices sequences in NCBI and MycoBank. These isolates caused chlorosis and necrosis on detached leaves, the inoculated corm was rotten and inoculated plants showed chlorosis and necrosis on leaves after 3-5 days. The results showed that A. alternata in the Birjand plain can cause corm rot and leaf chlorosis and necrosis is saffron. This study is the first report of the virulence of this fungus on saffron tissue in the East of Iran.