FIRST REPORT OF BOTRYTIS BLIGHT CAUSED BY BOTRYTIS CINEREA ON HELICHRYSUM BRACTEATUM IN ITALY
A. Garibaldi, D. Bertetti, S. Franco Ortega, P. Pensa, M.L. Gullino
In the winter 2016, a leaf and stem blight was observed on 5-month-old plants of Helichrysum bracteatum growing in a farm located in Albenga (Savona province, northern Italy). Chlorosis and browning of leaves, stems and inflorescences were followed by necrosis and affected tissues wilted and desiccated. Most affected plants eventually died. The fungus isolated from affected stem tissues showed morphological characteristics typical of Botrytis cinerea (Ellis, 1971). Genomic DNA from pure culture was extracted using E.Z.N.A. Plant DNA Kit (Omega Bio-Tek). PCR reaction was carried out using primers ITS1/ITS4 (White et al., 1990) to amplify the Internal Transcribed Spacer (ITS) region. PCR product was purified and sequenced (GenBank accession No. KX906371). A 460 bp sequence was analyzed and showed a 100% homology with Botrytis cinerea. Symptoms of the disease were reproduced on three healthy plants of H. bracteatum artificially inoculated with a conidial suspension of the pathogen sprayed on leaves (4 ml/plant). Inoculum was obtained from pure cultures of the fungus grown on PDA (Potato Dextrose Agar). Three control plants were sprayed with sterilised water. Successively, all the plants were kept in a humid chamber and maintained at the temperature of 19°C ± 1. About 11 days after the inoculation, only inoculated plants showed the first symptoms of the disease and B. cinerea was consistently reisolated. B. cinerea on H. bracteatum was previously reported in Denmark and in Japan (Izutsu et al., 1997). This is the first report of B. cinerea on H. bracteatum in Italy.