First report on molecular identification of species causing fruit rot of mandarin ( ) in Bangladesh.

Fusarium rot is a newly introduced, devastating disease of citrus fruits. The current investigation was undertaken to characterize the microbes responsible for fruit rot in . Pathogens were isolated from infected citrus fruits using morphological and molecular approaches. For confirmation of the isolated fungi, polymerase chain reaction (PCR) amplification and internal transcribed spacer gene sequencing techniques were used. The isolated fungus was grown on potato dextrose agar for three days and it produced clamydospores, hyphae and macroconidia. PCR amplification of isolated fungal DNA gave a 650 bp product. The sequence obtained from isolated fungi had 99.42% similarity with the reference sequence in NCBI GenBank. The obtained sequence was deposited in GenBank (Accession No. MT856371). Two isolates showed virulence capability on fresh guava, sweet orange and tomato fruits, which confirmed species identification and Koch's postulates. Artificially inoculated fungal species grown on tested fruits showed typical species symptoms. Outcomes of the present study are beneficial for the detection of this detrimental disease in postharvest fruits. Further research is needed for the control of this economically important disease. This is the first study of fruit rot in caused by in Bangladesh.