First Report of Colletotrichum aenigma Causing Anthracnose on Sedum kamtschaticum in Korea

Abstract

HomePlant DiseaseVol. 101, No. 12First Report of Colletotrichum aenigma Causing Anthracnose on Sedum kamtschaticum in Korea PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Colletotrichum aenigma Causing Anthracnose on Sedum kamtschaticum in KoreaH.-W. Choi, Y. K. Lee, and S. K. HongH.-W. ChoiSearch for more papers by this author, Y. K. LeeSearch for more papers by this author, and S. K. Hong†Corresponding author: S. K. Hong; E-mail: E-mail Address: [email protected]Search for more papers by this authorAffiliationsAuthors and Affiliations H.-W. Choi Y. K. Lee S. K. Hong † , National Institute of Agricultural Sciences, Rural Development Administration, Wanju 55365, Republic of Korea. Published Online:10 Oct 2017https://doi.org/10.1094/PDIS-07-17-0938-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Orange stonecrop (Sedum kamtschaticum Fisch. and C.A. Mey.) is a perennial herbaceous plant belonging to the family Crassulaceae. It has been used as an ornamental vegetable and for folk medicine for treating inflammatory disorders in Korea. In October 2010, anthracnose occurred on leaves of orange stonecrop grown in a field in Bonghwa, Korea (36.92°N, 128.77°E). Diseased plants were about 5 to 10% of 1,000 total orange stonecrops in the field. Symptoms appeared as circular to irregular lesions with blackish brown discoloration on margins of leaves. Fragments of diseased leaves were surface sterilized with 1% NaOCl for 30 s, then rinsed in sterile water. Tissue pieces were placed on water agar (WA) and incubated at 25°C for 5 days. Three isolates were cultured on potato dextrose agar (PDA) at 25°C in darkness for 7 days. Colonies were at first cottony, floccose, grayish white, becoming gray with age, dark brown at the center in reverse, with mycelial growth of 58.3 mm after 7 days at 25°C. Conidiomata on PDA were slimy, dark brown, forming setae in abundance. Setae were brown, 1 to 3 septate, with tapering acute apices, and 41.5 to 103.2 × 4.6 to 5.9 μm (mean 78.1 × 5.2). There were some differences between shape and size of conidia from natural lesions and those from cultures. The former was cylindrical, tapering toward one or both ends, rarely fusiform, sometimes slightly curved, and 14.1 to 19.1 × 6.7 to 8.8 μm (mean 16.6 × 7.5, l/b 2.2) in size, while the latter was usually cylindrical, straight, with both ends rounded, rarely tapering toward one end, and 16.5 to 22.7 × 6.0 to 7.0 μm (mean 18.7 × 6.4, l/b 2.9) in size. Appressoria were brown to dark brown, usually clavate to ovate, crenate or irregular, and 8.7 to 15.2 × 6.1 to 10.2 μm (mean 11.1 × 8.6) in size. Based on morphological and cultural characteristics, the three isolates were identified as Colletotrichum gloeosporioides species complex (Phoulivong et al. 2010; Weir et al. 2012). To clarify taxonomic placement of the present isolate (IY1059) within the C. gloeosporioides complex, chitin synthase 1 (CHS-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), calmodulin (CAL), β-tubulin (TUB2), actin (ACT), rDNA internal transcribed spacers regions (ITS), and glutamine synthetase (GS) from IY1059 were amplified by PCR as previously described (Prihastuti et al. 2009). The PCR products were sequenced and deposited in GenBank with accession numbers KY820888–93, and MF401417, respectively. Six sequences of IY1059, except the GS gene, were 99 or 100% identical with the reference strains, C. aenigma C1253.4 or ICMP 18608. The GS sequence of IY1059 showed 98% identity with the reference strain. Based on morphological and molecular characteristics, the isolate was identified as C. aenigma. A pathogenicity test of the three isolates was made on wounded and unwounded leaves of orange stonecrop by dropping 30 µl of conidial suspensions (5 × 105 conidia ml−1). The same quantity of sterile distilled water placed on unwounded or wounded leaves was used as control. Both inoculated and control leaves were placed in plastic boxes with 100% relative humidity at 25°C. After 3 days, symptoms started to develop only on inoculated and wounded leaves. No symptoms developed on the unwounded and control leaves for 7 days after inoculation. The fungus was consistently reisolated from the only inoculated leaves, thus fulfilling Koch’s postulates. To our knowledge, this is the first report that C. aenigma causes anthracnose on leaves of orange stonecrop. Further studies are required to better define the host range of C. aenigma in Korea.