Chia: Host status for Meloidogyne incognita and activity of plant extracts

Authors: Meyer, Susan; Macdonald, Margaret; Reetz, Nathan; KANTOR, MIHAIL - Oak Ridge Institute For Science And Education (ORISE); Carta, Lynn; Handoo, Zafar; Camp, Mary; PHILLIPS, TIM - University Of Kentucky

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2020
Publication Date: 9/14/2020
Citation: Meyer, S.L.F., MacDonald, M.H., Reetz, N.D., Kantor, M.R., Carta, L.K., Handoo, Z.A., Camp, M.J., Phillips, T.D. 2020. Chia: Host status for Meloidogyne incognita and activity of plant extracts. Plant Disease. 104:2979–2985. https://doi.org/10.1094/PDIS-10-19-2171-RE.
DOI: https://doi.org/10.1094/PDIS-10-19-2171-RE

Interpretive Summary: Plant-parasitic nematodes are small worms that attack crop plants, resulting in U.S. crop losses of ten billion dollars annually. Chia has increased in economic importance as a crop plant, and the growing demand for the seed has created a need for management of chia pathogens. However, while plant-parasitic nematodes have been found attacking plants related to chia, none have been reported from this species. Chia was therefore tested as a host for root-knot nematode, an economically important pathogen on many crop plants. A team of scientists from ARS and the University of Kentucky tested six chia lines and found that all were hosts for this nematode. In the laboratory, extracts from chia roots and shoots killed root-knot nematode juveniles. However, when cucumber seedlings were transplanted into soil amended with chopped chia shoots, galling and egg production on cucumber roots were not suppressed. These results are significant because, to our knowledge, this is the first report that chia is a host to any plant-parasitic nematode, and that chia leaves and roots produce compounds active against a nematode. This work will be used by researchers and growers to determine whether plant-parasitic nematodes are affecting chia production.

Technical Abstract: Chia (Salvia hispanica L.) seeds are used for food, drinks, oil, and animal feed, and all plant parts are employed in traditional medicine. The growing demand for the seed has created a need for improved disease management. Plant-parasitic nematodes have been found on other Salvia spp., but none have been reported from S. hispanica. Chia has also not been tested for production of compounds active against these nematodes. Therefore, aqueous extracts from shoots and roots of six chia lines, Brad’s Organic, Cono, E2, G3, G5, and W13.1, were tested in laboratory assays. Some concentrations of all extracts were nematotoxic, killing about one-third of Meloidogyne incognita (Kofoid & White) Chitwood second-stage juveniles (J2s) in shoot extracts and up to nearly half of J2s in root extracts. Hatch was generally not affected by the extracts. In greenhouse trials, all six chia lines were hosts of M. incognita. Chia line G3 had approximately two times or more eggs per gram of root than Brad’s Organic or Cono. When cucumber seedlings were transplanted into soil amended with chopped chia shoots (2.3 or 2.5% weight of fresh shoots/weight of dry soil), galling and egg production on cucumber roots were not suppressed. To our knowledge, this is the first report that chia is a host to M. incognita (or any phytoparasitic nematode) and that chia shoots and roots produce compounds active against a nematode.