Editors' ChoicePlant biology

Break It Down, Sweep It Out

Sci. Signal.  08 Mar 2011:
Vol. 4, Issue 163, pp. ec71
DOI: 10.1126/scisignal.4163ec71

Why do some bacteria and viruses cause disease on certain plant species but not on others? Fan et al. analyzed the resistance mechanisms that keep some strains of Pseudomonas syringae from infecting the plant Arabidopsis. The analysis pointed to a three-gene bacterial operon, sax. Analysis of the plant defense compounds identified an isothiocyanate, a breakdown product of aliphatic glucosinolates, as the key. Similar compounds can also contribute to defenses against insect herbivores. It seems that bacteria can cause the plant to release these defensive compounds. In turn, successful bacterial pathogens use the sax operon to evade the plant’s defenses by producing an efflux system that pumps the toxic agent out of the bacteria.

J. Fan, C. Crooks, G. Creissen, L. Hill, S. Fairhurst, P. Doerner, C. Lamb, Pseudomonas sax genes overcome aliphatic isothiocyanate–mediated non-host resistance in Arabidopsis. Science 331, 1185–1188 (2011). [Abstract] [Full Text]