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Effect of 6 Exogenous Soybean Isoflavones on Heterodera glycines

Yuanyuan Wang: Shenyang Agricultural University

<div>Soybean cyst nematode (SCN, <em><i>Heterodera glycines</i></em>) is one of the most destructive pathgons of soybean in many countries. Approximately 3.2 billions are considered lost to SCN each year<strong><b>.</b></strong> Isoflavones are a kind of secondary metabolites formed in the process of legume growth. They are structural component of plants that can be induced when plants are infected by microorganisms. They are also called plant antitoxins.In this article, 6 exogenous soybean isoflavones were selected to identify the inhibition of hatching and mortality of J2. In addition, field efficiency trials of seeds coated with isoflavones were determined. The results showed that all 6 isoflavones could inhibit <em><i>H</i></em><em><i>.</i></em><em><i>glycines</i></em>, and genistein had the highest mortality of 45.46% on J2 and inhibition rate of 43.48% on hatching at concentration of 100μg /mL after 24 h treatment, also had inhibition rate of 49.47% at concentration of 50μg /mL in field trials. Genistin and daidzein significantly killed J2 and inhibited hatching, but their control efficacies were weaker than those of others in field trials. Glycitin and glycitein had weaker toxicity on J2 and higher inhibition on hatching than genistin and daidzein. Furthermore, daidzin showed the weakest inhibition of J2 and hatching than other 5 isoflavones in vitro, but its control efficacy in the field showed no significant differences compared with genistein. The research confirmed that soybean isoflavones had positively suppressive ability on <em><i>H</i></em><em><i>.</i></em><em><i>glycines</i></em>, especially genistein, showed better comprehensive efficacy. The results suggested that isoflavones played an important role in resistance mechanism of soybean against nematode infection, and also provided clues in control SCN by soybean isoflavones.</div>