Isolation and Molecular Characterization of a Wild Type B. cinerea from Infected Bottle Gourd (Lagenaria sicerari) in China

Abstract

Botrytis cinerea is an important phytopathogenic fungus that causes diseases in wide range of hosts, including various fruits, vegetables and ornamental plants. In this study, infected bottle gourd was collected from the commercial farm of Wuhan, China to characterize the pathogen. Morphological identification was done based on colony characteristics, shape and size of conidia, conidiophores and formation of sclerotia. Results showed that conidiophores arise straight from the mycelia with length of 2-8 µm × 220-480 µm, an average conidial dimension of 5-8.5 μm × 9-13 μm, and a size of the sclerotia ranging from 0.7-4.5 mm × 1 – 8.5 mm. Species specific primers, Bc-f /Bc-r and Bc108+/Bc563- produced 354 and 450 bp fragments, respectively. Sequence of PCR amplification of the rDNA- ITS region produced a 547 bp fragment using the universal primer pair ITS1/ITS4. In the phylogenetic tree based on ITS nucleotide sequences, the representative isolate was located within a clade comprising reference isolates of B. cinerea. Strain XT5-2 germ tubes formed infection cushion on heat-killed onion epidermis and successfully entered into the epidermal cells. In this study, it was found that B. cinerea grew well at 20°C rather than below 15°C and above 25°C, respectively. Pathogenicity assays showed B. cinerea strain was virulent and displayed water-soaked lesions after 3 days. Based on morphological symptoms, mycological features, molecular analysis and pathogenicity bio assay, this fungus was identified as B. cinerea. To the best of our knowledge, this is the first study on bottle gourd (Lagenaria siceraria (Molina) Standl.) as a new host of B. cinerea in China.