Isoflavonoid levels in soybean (Glycine max) cultivars and associated anti-herbivore activity
Krolikowski, S., L. Chen, T. McDowell, J. Renaud, S. Dhaubhadel, I. Scott. 2018. Isoflavonoid levels in soybean (Glycine max) cultivars and associated anti-herbivore activity. Poster presentation at the Canadian Society of Plant Biologists Eastern General Meeting, November 24, 2018, London, ON.
Plain language summary
This presentation was given to summarize the research on soybean host plant resistance, specifically which Ontario soybean cultivars show resistance to soybean aphids and two-spotted spider mite. We focused on the leaf isoflavonoids, a recognized class of secondary plant metabolites known for defense against pathogens and herbivores. The leaf metabolites in 12 cultivars were analyzed and resistant soybean cultivars were compared using insect and mite bioassays. There was low correlation between leaf isoflavonoid concentration and resistance for both aphids and TSSM, however, leaf metabolite profiles were different between susceptible and resistant cultivars. These findings are useful for soybean breeders for future breeding considerations and future work will analyze metabolite differences between soybeans to identify the chemical differences between susceptible and resistant cultivars.
Soybean aphid (Aphis glycines) and two-spotted spider mite [(TSSM) Tetranychus urticae] are damaging herbivore pests of soybean (Glycine max) in Southern Ontario. Management of these two pests includes monitoring for economic thresholds and applying insecticides when necessary. Host plant resistance is a recognized strategy in integrated pest management (IPM); therefore, it is useful to know which soybean cultivars at different maturity groups are resistant to aphids and TSSM. Isoflavonoids, a group of legume-specific compounds, are known to have a negative effect on crop pests. Based on preliminary HPLC analysis of isoflavonoid concentrations in soybean leaves, twelve cultivars were selected to screen aphid and TSSM resistance. A qualitative assessment of each plant at the end of the 4-week experiment indicated the more tolerant cultivars were OAC Lakeview and OT06-22 to both aphids and TSSM. However, the observed resistance to aphid and mites is not completely explained by the levels of the six most common isoflavonoids. A metabolomics approach has since provided much additional information on a broader phytochemical profile allowing us to evaluate trends between low and high resistant lines. Soybean farmers will benefit from this research through improved knowledge of which soybean cultivars have higher resistance to insect and mite pests.