Isolation and identification of two pathogens causing leaf spot of Fritillaria taipaiensis P. Y. Li. in China.

Abstract

Fritillaria taipaiensis P. Y. Li is one of the biological sources for Fritillariae Cirrhosae Bulbus. Its bulbs are widely used for treating respiratory diseases such as pneumonia, bronchitis and influenza. Cultivated F. taipaiensis suffers from many diseases during its growing season. Leaf spot is a destructive disease that is increasingly affecting F. taipaiensis and can cause an incidence of up to 30% in severe cases. Leaf spot inhibits the growth of F. taipaiensis by causing disease spots on the surface of leaves. In severe cases, these spots can result in leaf desiccation and blackspot formation at the lesion site, leading to a decrease in photosynthesis. Leaf spot has shown little benefit, and it can even result in a reduced yield of bulbs and the death of plants. According to previous studies, Alternaria alternata has been identified as the pathogen of leaf spot in many medicinal plants, but the main pathogens of the leaf spot of F. taipeiensis remains uncertain. In this paper, five isolates from diseased leaves of F. taipaiensis were isolated and purified and the pathogenicity test showed that isolates B-5 and B-7 induced leaf spot symptoms on healthy F. taipaiensis leaves. Integrating multiple phylogenetic analyses of rDNA using Internal transcribed spacer region (ITS), Beta-tubulin (TUB2), RNA polymerase II second largest subunit (RPB2) and Translation elongation factor 1-alpha (TEF1-a) primers, strain B-5 and strain B-7 were eventually identified as Didymella segeticola and A. alternata. This is also the first report on the pathogens that cause leaf spot in F. taipaiensis in China.