Intracellular expression of a host-selective toxin, ToxA, in diverse plants phenocopies silencing of a ToxA-interacting protein, ToxABP1.
*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.
Manning
Viola A
VA
Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.
Chu
Ashley L
AL
Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.
Scofield
Steven R
SR
United States Department of Agriculture, Agricultural Research Service, Crop Production and Pest Control Research Unit, West Lafayette, IN 47907, USA.|Department of Agronomy, Purdue University, West Lafayette, IN 47907, USA.
Ciuffetti
Lynda M
LM
Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.
D001203:Ascomycota / Q000235:genetics / Q000472:pathogenicity*; D016923:Cell Death; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D020868:Gene Silencing; D005800:Genes, Fungal; D017343:Genes, Plant; D001467:Hordeum / Q000235:genetics / Q000378:metabolism; D054884:Host-Pathogen Interactions / Q000502:physiology; D009029:Mosaic Viruses; D009183:Mycotoxins / Q000235:genetics / Q000378:metabolism*; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014908:Triticum / Q000235:genetics / Q000378:metabolism
D005656:Fungal Proteins; D009183:Mycotoxins; D010940:Plant Proteins; C105776:TOXA protein, Pyrenophora tritici-repentis