First Detection of Ditylenchus destructor Parasitizing Maize in Northeast China

Maize is one of the most important crops in the world. Heilongjiang province has the largest maize area in China. Plant-parasitic nematodes are important agricultural pests, which cause huge economic losses every year and have attracted global attention. Potato rot nematode Ditylenchus destructor is a plant-parasitic nematode with a wide range of hosts and strong survival ability in different environments, which brings risks to agricultural production. In 2020, D. destructor was detected in seven maize fields in Heilongjiang province. Morphological identification and molecular approach were used to characterize the isolated D. destructor. The observed morphological and morphometric characteristics were highly similar and consistent with the existing description. The DNA sequencing on the D2/D3 region of the ribosomal DNA 28S and the phylogenetic analysis showed that D. destructor population obtained from maize and other isolates infesting carrot, sweet potato, and potato were in subclade I supported by a 96% bootstrap value. Additionally, the phylogenetic analysis of the ITS rRNA gene sequence further indicated that this D. destructor population from maize clustered in a clade I group and belonged to ITS rRNA haplotype C. An inoculation experiment revealed that D. destructor was pathogenic on the maize seedlings in pots and caused the disease symptoms in the stem base of maize seedlings. This is the first report of D. destructor causing stem rot of maize in Heilongjiang province, and contributes additional information on disease control and safe production of maize in the region.