First Report of Anthracnose on Pepper Fruit Caused by Colletotrichum scovillei in Brazil

Abstract

Anthracnose is major disease of pepper (Capsicum annum) in the tropics and causes severe damage both in the field and postharvest. In Brazil, this disease is caused by Colletotrichum acutatum, C. boninense, C. capsici, C. coccodes, and C. gloeosporioides, where the first species is responsible for 70% of all occurrences (3). Recently, C. acutatum has been considered a species complex (1); thus, the aim of this study was to verify the etiology of anthracnose on peppers using a morphological and molecular approaches. In 2011, pepper fruits with typical symptoms of anthracnose (dark, sunken spots with concentric rings of orange conidial masses) were collected in Viçosa, Minas Gerais, Brazil. A single spore isolate was obtained on potato dextrose agar (PDA), and the derived culture was deposited in the Coleção de Culturas de Fungos Fitopatogênicos “Prof. Maria Menezes” (code CMM-4200). The upper side colonies on PDA were gray, cotton-like, and pale gray to pale orange. Conidia were hyaline, aseptate, smooth, straight, cylindrical with round ends or occasionally with end ± acute, 12.5 to 17 μm long and 3.5 to 4 μm wide on synthetic nutrient deficient agar. The isolate was morphologically typical of species belonging to the C. acutatum complex. Molecular identification of the pathogen was carried out and sequences of the regions internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and β-tubulin (βt) were obtained and deposited in GenBank (Accession Nos. KJ541821 to KJ541823). A search in the Q-bank fungi database using the ITS, βt, and GAPDH sequences retrieved C. scovillei with 100% identity for all three genes. This pathogen was previously reported in Capsicum spp. only in Thailand, Indonesia, and Japan (1,2). To confirm pathogenicity, drops with 105 spores/ml were deposited in 10 artificially wounded fruits (cv. Itapuã 501 and Melina). In control fruits, drops of sterilized water were deposited onto wounds. The fruits were covered for one day with a transparent plastic bag with moisture supplied by a wet filter paper. The fruits were detached and mature. The bags were removed, and the fruits were incubated for 10 days in a growth chamber at 25°C with a photoperiod of 12 h. After 4 days, gray-brown to black sunken spots with concentric rings were observed on 100% of the wounded fruits that had been inoculated. No disease was observed on the control fruits. The fungus C. scovillei was successfully re-isolated from symptomatic fruits to fulfill Koch's postulates. To our knowledge, this is the first report of anthracnose on pepper fruit caused by C. scovillei in Brazil. Due to the diversity of species that cause anthracnose in Capsicum, future studies using morphological and molecular tools are essential for the correct identification of Colletotrichum spp. on pepper in Brazil. References: (1) U. Damm et al. Stud. Mycol. 73:37, 2012. (2) T. Kanto et al. J. Gen. Plant. Pathol. 80:73, 2014. (3) M. J. Z. Pereira et al. Hortic. Bras. 29:569, 2011.