First Report of Leaf Spot Caused by Colletotrichum fructicola on Japanese Fatsia (Fatsia japonica) in Fujian Province in China

Abstract

HomePlant DiseaseVol. 101, No. 8First Report of Leaf Spot Caused by Colletotrichum fructicola on Japanese Fatsia (Fatsia japonica) in Fujian Province in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Leaf Spot Caused by Colletotrichum fructicola on Japanese Fatsia (Fatsia japonica) in Fujian Province in ChinaN. N. Shi, Y. X. Du, F. R. Chen, H. C. Ruan, and X. J. YangN. N. ShiSearch for more papers by this author, Y. X. DuSearch for more papers by this author, F. R. ChenSearch for more papers by this author, H. C. RuanSearch for more papers by this author, and X. J. YangSearch for more papers by this authorAffiliationsAuthors and Affiliations N. N. Shi Y. X. Du F. R. Chen H. C. Ruan X. J. Yang , Institute of Plant Protection, Fujian Academy of Agricultural Science, Fuzhou, Fujian, 350013, China; and Fujian Key Laboratory for Monitoring and Integrated Management of Crop Pests, Fuzhou, Fujian, 350013, China. Published Online:15 May 2017https://doi.org/10.1094/PDIS-12-16-1720-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Fatsia japonica (syn. Aralia japonica Thunb.), family Araliaceae (Lee et al. 2008), is valued in both landscape and interior decoration in South China. In addition, it has potential medicinal uses (Ye et al. 2014; Yu et al. 2014). In September 2015, leaf spot symptoms were observed on leaves in Fujian Province, China. The disease incidence was 50 to 80% in three commercial nurseries, which had about 15 acres each. Early symptoms appeared as small, slightly sunken, brown spots. With expansion, lesions became tawny in the center, dark brown at the margin bordered by a tan halo, water-soaked, obvious warts on back, and cracks in the center of the lesions. Ultimately, severely infected leaves wilted and died. Symptomatic leaves were cut into 5 × 5 mm slices, dipped in 75% (v/v) alcohol for 30 s, then in 0.1% (w/v) mercuric chloride solution for 90 s. Samples were subsequently rinsed three times in sterilized water and placed on potato dextrose agar (PDA). Six Colletotrichum-like isolates were obtained by single-spore isolation. All isolates produced white fluffy aerial hyphae that later became gray with bright orange conidial masses near the inoculum point, in reverse grayish green with white halo max. Ascomata were globose, black, covered by aerial mycelium. Asci were clavate, straight or slightly curved, thin-walled, 8-spored, and 53.4 to 79.8 × 11.1 to 15.5 μm. Ascospores were uni- or biseriately arranged, hyaline, aseptate, ellipsoidal or ovoid with rounded ends, and 11.1 to 22.1 × 3.9 to 7.4 μm. Conidiophores were pale brown, septate, and branched. Conidia were cylindrical with obtuse to slightly rounded ends, hyaline, guttulate, and aseptate, smooth-walled, 13.4 to 19.1 × 4.4 to 6.6 μm, and single celled with one or two oil globules. Conidial appressoria were ovoid to slightly irregular in shape, dark brown, and 5.9 to 11.1 × 4.9 to 7.1 μm. The internal transcribed spacer (ITS) of rDNA, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-tubulin 2 (Tub2), and actin (ACT) genes were amplified with ITS1/ITS4, GDF1/GDR1 (Prihastuti et al. 2009), Bt2F/Bt2R, and ACT-512F/ACT-783R primers, respectively. The ITS consensus sequence (GenBank accession no. KU366691) shared 99% homology with the ITS sequence of C. gloeosporioides (KR183777). The other three consensus sequences (KU377147, KU377146, and KU377148, respectively) showed 99 to 100% identity to the corresponding sequences of C. fructicola in GenBank (KU552337, KC835392, and KP823798, respectively). Based on the above, the isolates were identified as C. fructicola (Liu et al. 2016; Prihastuti et al. 2009). Pathogenicity assay was performed on three 2-year-old plants. Conidial suspension (105 conidia ml–1) of three isolates were sprayed on four leaves per plant. Control plants were sprayed with distilled water. The inoculated plants were incubated at 28°C in a greenhouse (12 h light and RH >90%). The experiment was performed three times. Ten days later, spot symptoms similar to those observed on naturally infected leaves appeared on all inoculated leaves, whereas control leaves remained asymptomatic. Further, C. fructicola was re-isolated from symptomatic leaves. Morphological and molecular characterizations confirmed the isolates as C. fructicola. To our knowledge, this is the first report of C. fructicola causing anthracnose on F. japonica in Fujian Province, China. This disease causes leaf spots that affect urban greening and tourism, so proper control strategies should be implemented promptly.