Identification of a NAC Transcription Factor for the Elicitation of Glyceollin Biosynthesis in Soybean Reveals a Conserved Phytoalexin Regulatory Pathway

Glyceollins are inducible defense metabolites (phytoalexins) that belong to the isoflavonoid family of molecules that are biosynthesized in soybean in response to pathogens and some abiotic stresses. Glyceollin metabolite accumulation was elicited in Harosoy63 soybean seedlings that were transferred to germination paper saturated with pH 3.0 medium compared to paper saturated with pH 5.8 medium (control) at 9 days after transfer, whereas seedlings transferred to germination paper that was saturated with pH 5.8 medium then allowed to dry for 6 days (dehydration treatment) had reduced glyceollin metabolite levels compared to the control pH 5.8 filter paper that was continuously saturated with medium (not allowed to dry). Media was half-strength Murashige and Skoog (MS) salts, 1% sucrose, with MS vitamins.