Diagnosis and Characterization of Ditylenchus destructor Isolated from Mazus japonicus in China

The potato rot nematode (Ditylenchus destructor) is one of the most destructive pests in the production of tuber crops, resulting in severely decreased yields and inferior product quality. In 2021, a great number of nematodes were detected in the roots ofMazus japonicus, a weed that is harmful to crop growth, in Qingdao, Shandong Province, China. The present study was undertaken to characterize and identify the nematodes isolated fromM. japonicusthrough morphological identification and molecular approaches. Their morphological characteristics were highly consistent with the descriptions ofD. destructorThorne, 1945. The nematodes collected fromM. japonicuswere identified asD. destructorhaplotype B using D1/D2 and sequence characterized amplified region (SCAR) primers. PCR-ITS-RFLP analysis was conducted to monitor intraspecific variations. In addition, the phylogenetic analysis of the internal transcribed spacer (ITS) demonstrated that thisD. destructorpopulation was clustered in haplotype B, supported by a 100% bootstrap value. Another assay, in whichM. japonicuswas inoculated with a mixture of the life stages ofD. destructor, was performed. This assay showed thatM. japonicusexhibited a high susceptibility toD. destructorin pots. This is the first record ofD. destructorparasitizingM. japonicusin China, and it is of great importance becauseM. japonicuscould be a potential reservoir forD. destructorin the field.Keywords:Ditylenchus destructor;Mazus japonicus;morphological characterization;molecular analysis