Induction of ethylene inhibits development of soybean sudden death syndrome by inducing defense-related genes and reducing Fusarium virguliforme growth
N. ABDELSAMAD (1), G. MacIntosh (2) (1) Iowa State Univ, U.S.A.; (2) Iowa State University, U.S.A.

Ethylene is a gaseous hormone that regulates plant responses to biotic and abiotic stresses. To investigate the importance of ethylene in soybean resistance to Fusarium virguliforme (Fv), the casual agent of sudden death syndrome (SDS), plants were treated 24 hours before and after Fv inoculation with either ethephon (ethylene inducer), cobalt chloride (ethylene biosynthesis inhibitor), or 1-MCP (ethylene perception inhibitor). Inoculated soybean plants were grown for 21 days at 24 °C in the greenhouse and then evaluated for SDS severity and expression of soybean defense genes. Plants treated with ethephon showed a reduction (P<0.05) in SDS foliar severity compared to the other treatments, whereas those treated with cobalt chloride or 1-MCP showed the same or higher SDS foliar severity compared to the water treated control. Ethephon application resulted in activation of genes involved in ethylene biosynthesis, such as ethylene synthase (ACS), and ethylene oxidase (ACO), and genes involved in soybean defense response, such as pathogenesis-related protein (PR), basic peroxidase, chalcone synthase, and transcription factors. Cobalt chloride and 1-MCP treatments had little or no effect on these genes. Moreover, ethephon had an inhibitory effect on in-vitro growth of Fv on PDA media. Taken together, these results suggest that ethephon application inhibits SDS development directly by slowing Fv growth, and indirectly by inducing soybean ethylene signaling and defense related genes

Abstract Number: P16-438
Session Type: Poster