Nematotoxicity of Paeonia spp. extracts and Camellia oleifera tea seed cake and extracts to Heterodera glycines and Meloidogyne incognita

Authors: WEN, YANHUA - South China Agricultural University; Meyer, Susan; Macdonald, Margaret; ZHENG, LIUCHUN - South China Agricultural University; JING, CHUNYUE - South China Agricultural University; Chitwood, David

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2019
Publication Date: 7/10/2019
Citation: Wen, Y., Meyer, S.L., MacDonald, M.H., Zheng, L., Jing, C., Chitwood, D.J. 2019. Nematotoxicity of Paeonia spp. extracts and Camellia oleifera tea seed cake and extracts to Heterodera glycines and Meloidogyne incognita. Plant Disease. 103:2191-2198. https://doi.org/10.1094/PDIS-09-18-1663-RE.
DOI: https://doi.org/10.1094/PDIS-09-18-1663-RE

Interpretive Summary: Plant-parasitic nematodes are small worms that attack crop plants, resulting in U.S. crop losses of ten billion dollars annually. Root-knot nematodes attack many agriculturally important plants, and soybean cyst nematode is the major pathogen of soybean worldwide. Environmentally safe controls are needed for managing these nematodes. One approach for solving this problem is to use naturally occurring plant parts or compounds that are toxic to nematodes and can be applied to soil. Therefore, a team of ARS and Chinese researchers examined camellia and two species of tree peony, plants that are used in traditional Chinese medicine, for production of compounds that can kill plant-parasitic nematodes. In the laboratory, extracts from camellia tea seed cake (a waste product that results from production of oil from the plant seeds) and from tree peony stems suppressed hatch and killed juveniles of both nematode species. In greenhouse tests with soybean, powdered camellia tea seed cake mixed into soil as an amendment reduced soybean cyst nematode numbers compared with soil that did not receive amendment. These results are significant because they demonstrate that products from these plants have potential for management of these nematodes. This work will be used by researchers developing safe, plant-derived products for use in reducing crop losses caused by nematodes.

Technical Abstract: Tea-oil camellia (Camellia oleifera) is grown for tea seed oil production, with tea seed cake produced as a byproduct. Rather than disposing of the cake, agricultural uses increase the value of oil production. Constituents of C. oleifera are also utilized for traditional Chinese medicine, as are compounds produced by tree peony. Consequently, C. oleifera and two tree peony species (Paeonia rockii and Paeonia suffruticosa), were studied for compounds antagonistic to soybean cyst nematode (Heterodera glycines) and root-knot nematode (Meloidogyne incognita). Extracts from C. oleifera cake and P. rockii stems suppressed hatch and were nematotoxic to second-stage juveniles (J2) of both nematode species. Paeonia rockii extracts were more effective than P. suffruticosa extracts for decreasing M. incognita hatch and J2 viability. In greenhouse trials with soybean (Glycine max cv. 'Essex'), powdered C. oleifera cake applied as a soil amendment suppressed H. glycines cysts/g root by up to 66% compared with nonamended controls. These results indicate that the extracts and cake contain compounds active against H. glycines and M. incognita, with activity varying between the two Paeonia species. Camellia oleifera tea seed cake, and constituents of the cake or of P. rockii, are candidates for further studies on management of these nematodes.