Evaluation of anthracnose resistance among tea [Camellia sinensis] genetic resources by wound-inoculation assay

Tea anthracnose, caused by Colletotrichum theae-sinensis (Miyake) Yamamoto, is one of the most serious diseases of cultivated tea (Camellia sinensis L.) in Japan. In the present study, we evaluated tea plants genetically resistant to anthracnose by using a novel wound-inoculation assay. Conidia of C. theae-sinensis were suspended in an adhesive mixture consisting of potato-sucrose broth and methylcellulose 400 cP (3% w/v). Detached mature tea leaves were wounded crosswise by a screwdriver with an adhesive conidial suspension. Inoculated leaves were cultivated on ROOTCUBES(R) growing medium for 2 weeks in a growth chamber. The degree of resistance was estimated from lesion size. Five hundred tea genetic resources at the Makurazaki Tea Research Station were assayed in screening for anthracnose-resistant tea plants. Most of the foreign-introduced tea plants showed resistance, whereas native Japanese tea plants showed wide variation in the resistance to anthracnose. These results suggest that crossbreeding of native Japanese tea cultivars with foreign introduced varieties will be useful for breeding anthracnose-resistant tea plants of suitable quality.