First Report of Root and Basal Rot of Angelica acutiloba Caused by Fusarium solani in Taiwan.

Abstract

Angelica (Angelica acutiloba (Siebold. & Zucc.) Kitag.) is one of the most important traditional Chinese medicines in Taiwan. The medicinal herb has been mainly imported from China, but cultivation at a commercial scale has also been established in recent years in Hualien County, Taiwan. In September 2008, angelica plants in a field at Liou-shih-dan Mountain displayed symptoms of yellowing, stunting, rotting of roots and basal stem, and wilting. A severe brown discoloration of vascular tissue along the stems of infected plants was observed. One or more Fusarium spp. was consistently isolated from the roots and stems of diseased plants. Isolates R3, R4, and R5 were incubated for 14 days on celery tissues to produce chlamydospores, and 33 g of celery tissue with chlamydospores were mixed with 500 ml of soil per pot as inoculum. One 4-month-old angelica seedling was planted per pot. Three angelica plants were inoculated with each isolate in the first test and nine plants were inoculated with each isolate in the second test. Other seedlings were inoculated with water as checks. Pathogenicity tests were conducted twice. Incidence of diseased plants was 66, 100, and 33% in the first test, and 66, 100, and 44% in the second test for the R3, R4, and R5 isolates, respectively. Symptoms similar to those on the diseased plants in the field were produced, with leaves turning yellow starting 7 days after inoculation and wilt and discoloration of roots 14 days after inoculation. Fusarium spp. also were reisolated from the diseased plants. Genomic DNA was extracted from mycelium with a fungal genomic DNA purification kit, and the internal transcribed spacer (ITS) rDNA region was amplified and sequenced with primers ITS-4 and ITS-5. The sequence of the resulting ~550-bp amplicon was compared with those in GenBank. The ITS sequences of the R3, R4, and R5 isolates shared 98.7, 98.7, and 97.9% similarity with F. solani isolate AF129104 (3), respectively. Phylogenetic analysis also showed that the three isolates were closer to F. solani than to other Fusarium species. Both macroconidia and microconidia of the R4 isolate were produced on potato dextrose agar. Macroconidia were three to five septate and 27.2 to 37.8 × 4.4 to 6.2 μm; microconidia were zero to one septate and 9.3 to 14.7 × 2.9 to 4.8 μm. Chlamydospores produced on celery juice agar were terminal or intercalary, solitary, in pairs or in chains, and 9.3 to 12.1 μm. Morphological characteristics identified the three isolates as F. solani (Martius) Snyder & Hansen according to Fu and Chang (2) and Chung et al. (1), which agrees with the ITS comparison. To our knowledge, this is the first report of root and basal rot caused by F. solani on angelica in Taiwan.