Investigation of Camellia Tree Diseases in Taiwan and Establishment of a Rapid Detection Method for Colletotrichum spp.

摘要

Camellia is commonly used for afforestation and as an important oil-producing crop with high economic value. Diseases that occur on aboveground parts of Camellia are considered to be major reasons causing declines in the quality and quantity of tea oil, but little is known about them. In this study, we investigated disease occurrence of Camellia in Taiwan and discovered that blister blight, leaf spot, and soft rot were major symptoms on Camellia farmlands in the north, while leaf spot and anthracnose were found on Camellia farmlands in central Taiwan. Through tissue isolation, fungal pathogen candidates of Camellia diseases were identified; 15 fungal isolates were obtained, subjected to nucleic acid extraction, and sequenced. Sequence blast results showed that these isolates included Colletotrichum spp. (known as an anthracnose disease pathogen), Alternaria sp., Botryosphaeria dothidea, Botryotinia fuckeliana (Botrytis cinerea), Lasiodiplodia pseudotheobromae, Neofusicoccum parvum, Pestalotiopsis spp., Phomopsis sp., and Sclerotinia sclerotiorum. All isolates were reported to be plant pathogens, but Camellia-related research is still lacking. A phylogenetic tree constructed with internal transcribed spacers (ITSs) of the 15 isolates in this study showed that pathogens of Camellia anthracnose were clustered into 2 species complexes of C. gloeosporioides and C. acutatum. Colletotrichum spp. isolates from different regions were all classified into the same group and were evolutionally closer than other potential Camellia leaf pathogens. Anthracnose is considered to be the most important Camellia disease with 2 species complexes, and a rapid detection method was first established in this study. Three primer sets were designed for the rapid detection by a polymerase chain reaction (PCR) based on our ITSs to identify anthracnose disease on Camellia. The primer sets designed in this study showed high specificity and sensitivity and could successfully detect Colletotrichum spp. and distinguish between the C. gloeosporioides and C. acutatum species complexes. This will contribute to achieving prevention strategies and early disease prevention of Camellia anthracnose. In this study, Colletotrichum spp. and 8 other potential fungal pathogens were isolated from Camellia leaves, and results will be useful in understanding potential pathogens. With the establishment of a rapid detection method for serious anthracnose disease of Camellia, our study can be used as an important reference for early diagnosis, which will be valuable for disease control and management.