Intracellular expression of a host-selective toxin, ToxA, in diverse plants phenocopies silencing of a ToxA-interacting protein, ToxABP1
Article first published online: 14 JUL 2010
© The Authors (2010). Journal compilation © New Phytologist Trust (2010)
Special Issue: Featured papers on ‘Effectors in plant–microbe interactions’
Volume 187, Issue 4, pages 1034–1047, September 2010
How to Cite
Manning, V. A., Chu, A. L., Scofield, S. R. and Ciuffetti, L. M. (2010), Intracellular expression of a host-selective toxin, ToxA, in diverse plants phenocopies silencing of a ToxA-interacting protein, ToxABP1. New Phytologist, 187: 1034–1047. doi: 10.1111/j.1469-8137.2010.03363.x
- Issue published online: 12 AUG 2010
- Article first published online: 14 JUL 2010
- Received: 28 February 2010, Accepted: 19 May 2010
- Barley stripe mosaic virus;
- host-selective toxin;
- Nicotiana benthamiana;
- Pyrenophora tritici-repentis;
- viral-induced gene silencing;
- •ToxA, a host-selective toxin of wheat, can be detected within ToxA-sensitive mesophyll cells, where it localizes to chloroplasts and induces necrosis. Interaction of ToxA with the chloroplast-localized protein ToxABP1 has been implicated in this process. Therefore, we hypothesized that silencing of ToxABP1 in wheat would lead to a necrotic phenotype. Also, because ToxABP1 is highly conserved in plants, internal expression of ToxA in plants that do not normally internalize ToxA should result in cell death.
- •Reduction of ToxABP1 expression was achieved using Barley stripe mosaic virus (BSMV)-mediated, viral-induced gene silencing. The BSMV system was modified for use as an internal expression vector for ToxA in monocots. Agrobacterium-mediated expression of ToxA in a dicot (tobacco-Nicotiana benthamiana) was also performed.
- •Viral-induced gene silencing of ToxABP1 partially recapitulates the phenotype of ToxA treatment and wheat plants with reduced ToxABP1 also have reduced sensitivity to ToxA. When ToxA is expressed in ToxA-insensitive wheat, barley (Hordeum vulgare) and tobacco, cell death ensues.
- •ToxA accumulation in any chloroplast-containing cell is likely to result in cell death. Our data indicate that the ToxA–ToxABP1 interaction alters ToxABP1 function. This interaction is a critical, although not exclusive, component of the ToxA-induced cell death cascade.