FIRST REPORT OF POWDERY MILDEW, CAUSED BY ARTHROCLADIELLA MOUGEOTII, ON GOJI BERRY IN TURKEY

Abstract

Lycium barbarum, known as Goji berry or wolfberry, is a Chinese medicine plant in the family Solanaceae, and has been recently cultivated in Bolu, Turkey. During autumn 2015, severe powdery mildew symptoms were observed on Goji berry plantation area. White to grayish white fungal mycelia were shown on leaves and stems. Also, brownish discolorations and defoliation were exhibited. Microscope examination showed that conidia were formed in chains, hyaline, short-cylindrical and their length and width ranged from 19 to 31 (mean=26.2) μm and from 10 to 14.5 (mean=13.2) μm, respectively. Apothecial structures were not observed. The fungus was identified as Arthrocladiella mougeotii on the basis of morphological characteristics and the host specialization (Braun, 1987). To verify the identification, DNA isolation was performed by using the conidia collected by scraping from surface of infected leaves. The rDNA internal transcribed spacer (ITS) region including 5.8S rDNA was amplified using primers ITS5 (White et al., 1990) and p3 (Kusaba and Tsuge, 1995) and sequenced. The amplified 640 bp product (GenBank accession No. KX017568) revealed 99% genetic similarity with the sequences of an A. mougeotii isolate previously reported (AB022380). Pathogenicity was performed by gently pressing diseased leaves onto young leaves of one-year-old healthy plants. Non-inoculated Goji berry plants were used as control. All plants were transferred to a greenhouse. A month later, the fungus having identical morphological features was observed only on infected plants. To the best of our knowledge, this is the first report of A. mougeotii on Goji berry in Turkey.