Morphological and molecular identification of the nematodes parasitizing the roots and the stems of Astragalas membranaceus and Dioscorea opposite from China

Two nematode populations were extracted from infested roots of Astragalas membranaceus and stems of Dioscorea opposite from China. The two nematode populations shared morphological and morphometric characteristics and were similar to Ditylenchus destructor. Amplification of DNA sequences from the ITS-rDNA region of the two populations yielded products of 891 bp and 751 bp, with both of the sequences bearing more than 98% identity with the sequences of D. destructor deposited in the GenBank database. Partial 18S rRNA sequence amplification yielded a 1225 bp length product from both populations, with only 1.2% variance between the two populations and both having more than 98% identity with sequences deposited in the Gen-Bank database for D. destructor. Therefore, the two nematode populations were identified as D. destructor and the two plant species must be considered new hosts for this nematode.