The potato rot nematode, Ditylenchus destructor, poses a serious threat to numerous root and tuber crops, yet the functional characterization of effectors from this migratory endoparasitic plant nematode remains limited. Despite inhabiting distinct habitats, sedentary and migratory plant parasitic nematodes share the structurally conserved effectors, such as venom allergen-like proteins (VAPs). In this study, a variant of DdVAP2 was cloned from D. destructor. The transcription profile analysis revealed that DdVAP2 was higher expressed in D. destructor feeding on either potato or sweet potato compared to on fungus via qRT-PCR. And DdVAP2 was highly expressed at all life stages feeding on sweet potato, except for eggs. DdVAP2 was confirmed to be specifically expressed in the subventral esophageal glands of D. destructor through in situ hybridization assays. Combined with functional validation of the signal peptide of DdVAP2, it suggested that DdVAP2 could be secreted from nematode into host. Heterologous expression of DdVAP2 in Nicotiana benthamiana revealed that the protein localized in both cytosol and nuclei of plant cells. Knocking down DdVAP2 by RNAi in D. destructor resulted in infection and reproduction defects on plants. All the results suggest that DdVAP2 plays a crucial role in the interaction between D. destructor and plants by facilitating the nematode infection.

Salvia miltiorrhiza is a perennial herbaceous plant for traditional Chinese medicine. It has been extensively applied for many hundred years to treat various diseases (Su et al. 2015). It is also a...

Root-knot nematodes (Meloidogyne spp.) are plant-parasitic nematodes that cause serious damage worldwide. There are many species of traditional Chinese medicine (TCM) plants, but only a few have been reported to be infected by Meloidogyne species. From 2020 to 2022, a survey was conducted in the Qinling mountain area, which is the main production region of TCM plants in China. Obvious galling symptoms were observed on the root systems of 15 species of TCM plants. Females were collected from diverse diseased TCM plants and subsequently identified at morphological and molecular levels. Among the 20 diseased root samples collected, Meloidogyne hapla populations were identified in 12 samples (60%), and M. incognita populations were identified in eight samples (40%). Among the 15 species of diseased TCM plants, eight species, namely, Scutellaria baicalensis, Leonurus japonicus, Dioscorea zingiberensis, Cornus officinalis, Viola philippica, Achyranthes bidentata, Senecio scandens, and Plantago depressa, were reported to be infected by Meloidogyne species for the first time. The host status of five species of TCM plants for two M. hapla isolates and one M. incognita isolate from TCM plants in this study was then evaluated. Differences in TCM plants’ response to nematode infection were apparent when susceptibility was evaluated by the egg counts per gram of fresh root and the reproduction factor of the nematodes. Among the five species of TCM plants tested, Salvia miltiorrhiza and Gynostemma pentaphyllum were the most susceptible, while S. baicalensis and V. philippica were not considered suitable hosts for M. hapla or M. incognita.

Siegesbeckia orientalis L., belonging to the family of Asteraceae and also known as ‘Xi-Xian Cao’ or Herba Siegesbeckiae, has been an important traditional Chinese medicine since the Tang Dynasty (...