Journal of Plant Pathology Archive

Abstract:

Sweet pepper is an important vegetable crop in Taiwan. A postharvest fruit decay disease of goat-horn sweet pepper (Capsicum annuum cv. Madrid), stored at 4-7°C, was observed and sampled during a fresh market survey in Chiayi, Taiwan, in January 2017, consisting of slightly shrunken, irregular, soft, gray or grayish-brown lesions on 33% of fruits. The skin of diseased peppers remained intact but the discolored fruit tissue was rotted. A fungus was isolated from surface-sterilized diseased tissue on water agar, purified and maintained on potato dextrose agar (PDA). Three purified isolates, Bc001, Bc002 and Bc003, were obtained,,with single-celled conidia,,ellipsoid or ovoid, colorless or pale brown, 10.4 to 20.4 × 8.3 to 16.6 µm in size. The isolates did not produce sclerotia on PDA. The colony and conidia morphology was similar to that of Botrytis sp. Three surface-sterilized fruits of C. annuum cv. Madrid and three of green sweet pepper (C. annuum var. grossum), pin-prick inoculated with spore suspensions (1×106 spores/ml) of each isolate and kept under moist conditions at 25°C, exhibited irregular, soft, grayish-brown lesions one day post inoculation similar to those observed in natural infections. The same fungus could be consistently re-isolated from the inoculated sweet pepper fruits, fulfilling Koch’s postulates. The control fruits remained disease-free. Sequences of the internal transcribed spacer (ITS) region of the rDNA of the three isolates with the universal primers ITS1 and ITS4 (White et al., 1990).showed 100% identity with B. cinerea by MEGABLAST analysis and were deposited in GenBank (accession Nos. KY616853, KY616854 and KY616855). Since B. cinerea symptoms on field-grown hot chili pepper (C. annuum var. acuminatum) were not recorded in detail (Sawada, 1919), to our knowledge, this is the first report of B. cinerea causing postharvest fruit decay of goat-horn sweet pepper in Taiwan.