Identification of Meloidogyne species on traditional Chinese medicine plants in the Qinling mountain area of China and their aggressiveness to different medicinal herbs.

ABSTRACT

Root-knot nematodes (Meloidogyne spp.) are plant-parasitic nematodes that cause serious damage on a worldwide basis. 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 producing region of TCM plants in China. Obvious galling symptoms were observed on the root systems of fifteen species of TCM plants. Females were collected from diverse diseased TCM plants and subsequently identified at morphological and molecular level. Among the twenty diseased root samples collected, Meloidogyne hapla populations were identified in twelve samples (60%) and Meloidogyne incognita populations were identified in eight samples (40%). Among the fifteen species of diseased TCM plants, eight of them, 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 fresh weight of 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.