Location: Nematology Laboratory
Title: Benzyl isothiocyanate affects development, hatching and reproduction of the soybean cyst nematode Heterodera glycines Authors
Submitted to: Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 20, 2013
Publication Date: January 15, 2014
Citation: Wu, H., Masler, E.P., Rogers, S.T., Chen, C., Chitwood, D.J. 2014. Benzyl isothiocyanate affects development, hatching and reproduction of the soybean cyst nematode Heterodera glycines. Nematology. 16(4):495-504. Interpretive Summary: Plant-parasitic nematodes attack all crops of agricultural importance, causing over $10 billion in losses annually to U.S. farmers. Because several chemical pesticides used to control nematodes have been withdrawn from use, growers possess a critical need for the discovery of environmentally and economically sound nematode control agents. One approach to discovering new ways to control nematodes is to identify ways to inhibit their growth and reproduction by using naturally derived compounds. We discovered that a plant metabolite called benzyl isothiocyanate, used at very low doses and for a very short time, inhibits hatch in the soybean cyst nematode, one of the most important nematode pathogens of crops worldwide. We also discovered that hatch inhibition correlates with decreased reproduction of the nematode on soybean, and that both movement and development of the nematode are affected. These results are significant because they show that natural agents can potentially be used to protect host plants through nontoxic and effective methods. Consequently, this information will be used by researchers in the agrochemical and agricultural biotechnology industries who are developing safe, selective methods for nematode control.
Technical Abstract: Benzyl isothiocyanate (BITC) applied at micromolar doses decreased Heterodera glycines J2 movement, H. glycines hatching, and reproduction of H. glycines on soybean, Glycine max. Direct exposure of J2 to 30 microM BITC caused an immediate decrease (17%; P < 0.05) in J2 movement relative to 1% methanol controls, and within 3 hours exposure eliminated > 99% of movement (P < 0.05). Continuous exposure of H. glycines eggs to 30 microM or 60 microM BITC significantly (P < 0.05) decreased percent J2 hatch measured at 7 days (15.75 plus/minus 2.43, 30 microM; 7.88 plus/minus 2.15, 60 microM) relative to controls (44.88 plus/minus 4.07). Control percent hatch increased (P < 0.05) between days 7 and 14 (87.50 plus/minus 2.26), whereas there was no significant increase in hatch after day 7 in either treatment group. The effect of BITC on hatch was rapid and persistent. Following 4-hour exposure of eggs to either 30 microM or 60 microM BITC, followed by transfer to water, percent hatch at day 14 was 51.25 plus/minus 6.27 and 15.57 plus/minus 1.44, respectively. Each was significantly less (P < 0.05) than control percent hatch (96.51 plus/minus 0.24). The same treatment method also resulted in decreased reproduction. The mean number of cysts per plant harvested 5 weeks after inoculation with control eggs (173.04 plus/minus 12.05) was significantly greater (P < 0.05) than the numbers from plants inoculated with either 30 microM (78.88 plus/minus 8.22) or 60 microM (38.33 plus/minus 4.51) BITC treated eggs. The effect of BITC on hatch and reproduction were strongly correlated (r2 > 0.60 for both 30 microM or 60 microM treatments). The effects of BITC were primarily on the early embryo. The percent of all embryos in the multicellular stage at day 14 in control eggs was 4.94 plus/minus 0.72, but increased (P < 0.05) to 35.08 plus/minus 4.28 (30 microM) and 56.29 plus/minus 4.49 (60 microM) in BITC treated eggs. BITC has multiple effects on H. glycines, affecting both infective juvenile movement and embryonic development, and decreasing reproduction.