Plant Defense Systems

Oxidant Evasion

Science's STKE  05 Dec 2000:
Vol. 2000, Issue 61, pp. tw8
DOI: 10.1126/stke.2000.61.tw8

The fungus Sclerotinia sclerotiorum can infect a broad range of plants, including economically important crop plants. A key aspect of its pathogenicity is its secretion of oxalic acid. However, the mechanism by which oxalic acid influences virulence has been unclear. One of the plant's primary defense systems is activation of a signaling pathway that leads to an oxidative burst of released O2- and H2O2 at the point of infection by pathogens. Cessna et al. show that such oxidant biosynthesis is blocked by wild-type S. sclerotiorum, but not by a strain deficient in the production of oxalic acid. Other experiments indicate that oxalic acid inhibits the defensive signaling pathway downstream of Ca2+ influx and kinase activation but before activation of oxidase activity.

Cessna, S.G., Sears, V.E., Dickman, M.B., and Low, P.S. (2000) Oxalic acid, a pathogenicity factor for Sclerotinia sclerotiorum, suppresses the oxidative burst of the host plant. Plant Cell 12: 2191-2200. [Abstract] [Full Text]