FIRST REPORT OF ROSEMARY LEAF SPOT CAUSED BY PHOMA GLOMERATA IN IRAN

Abstract

Rosemary (Rosemarinus officinalis) is an ornamental and medicinal plant grown in Iran. During a survey in November 2012, symptoms of wilt and leaf spot were observed in almost half of rosemary fields of Kerman (southeast of Iran). Samples of infected leaves were surface sterilized with 0.5% sodium hypochlorite, rinsed with sterile distilled water, cultured onto potato dextrose agar (PDA) medium and incubated at 25°C for seven days. The isolated fungus produced a pale brown to dark green colony. Ovoid or ellipsoidal, hyaline, and aseptate conidia were produced abundantly in subglobose pycnidia. Numerous dictyochlamydospores and chlamydospores were also observed. Based on the morphological characters, the fungus was identified as Phoma glomerata (Boerema et al., 2004). To confirm the species of the fungus, DNA was extracted from a single spore isolate and the internal spacer regions (ITS) were amplified with universal primers ITS1 and ITS4. The resulting sequence (532 bp), which showed more than 99% identity with Phoma glomerata, was submitted to NCBI GenBank (Accession No. KM114267). To test the pathogenicity, two month old plants were sprayed by a suspension of 104 spores per ml, covered with plastic bags and incubated under greenhouse conditions at 25-28°C. Pale brown small spots were developed on an average of 31.48% of the leaves after seven days. This fungus has been previously reported from Iran on cucumber (Hatami et al., 2008) and Ficus elastica (Aghapour et al., 2009). To the best of our knowledge, this is the first report of Phoma glomerata on rosemary in Iran and possibly in the world.