Isolation, Morphological and Molecular Characterization of Rubbery Rot Disease Disease Agent Geotrichum candidum on Potato Tubers Grown in Konya Province

Potato is the one of the most consumed vegetable in Turkey. During field surveys in June of 2019, new disease symptoms on potato tubers, displaying a water-soaked soft rubbery rot with a sour, fermented smell, and white mycelial growth, were observed in commercial fields in Cumra district of Konya, Turkey. Diseased tubers were collected and small tissue pieces from surface disinfected symptomatic tuber were placed on potato dextrose agar (PDA) and incubated at 25 degrees C. Fast growing, flat, white to cream, dry and finely suede-like with no reverse pigmented fungal colonies were subsequently developed from infected tissues. Hyphae were hyaline, dichotomously branched and septate, producing aerial chains of hyaline, smooth, one-celled, cylindrical arthroconidia. Cultural and morphological characters were consistent with Geotrichum candidum. All artificially inoculated tubers displayed the same symptoms as seen for naturally infected tubers and the fungus having same morphological characters was re-isolated from inoculated tubers. Morphological identification of disease agent was confirmed molecularly based on protein profiling by using MALDI-TOF MS and also by sequencing amplified Internal Transcribed Spacer (ITS) region ((ITS1-5.8S rDNA-ITS4). The sequence was 99% identical and a representative sequence of isolate was submitted to GenBank. The presence of potato rubbery rot disease caused by G. candidum has not been previously reported in Turkey. This is the first report of morphological and molecular characterization of G. candidum causal disease agent of rubber rot on potato tubers grown in Turkey.