Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/4/2009
Publication Date: 8/1/2009
Citation: Lygin, A., Li, S., Vittal, R., Hartman, G.L., Widholm, J., Lozovaya, V. 2009. Glyceollin and Lignin Limit the Growth of Phakopsora pachyrhizi. Phytopathology. 99(5):S77
Technical Abstract: Soybean rust, caused by Phakopsora pachyrhizi, is a devastating foliar disease of soybean. Understanding the biochemistry of the plant defense mechanism to this disease will assist in development of cultivars resistant to soybean rust. In this study, differences in phenolic metabolism were analyzed between inoculated and non-inoculated, two susceptible and three resistant soybean lines with known resistance genes. Accumulation of isoflavonoids and flavonoids in soybean leaves was greatly increased in response to rust infection in all genotypes tested. While the soybean phytoalexin glyceollin was not detected in leaves of uninfected plants, accumulation of this compound at marked levels occurred in rust infected leaves. There was a correlation between glyceollin concentration in soybean leaves and rust resistance. In addition, there was inhibition of P. pachyrhizi spore germination by glyceollin measured on agar plates. Lignin synthesis also increased in all inoculated soybean lines while there was no significant difference in all non-inoculated soybean lines. Cell wall lignification was markedly higher in inoculated resistant lines compared to inoculated susceptible lines indicating possible protective role of lignin in rust infection development.