Phosphorylation of alfalfa mosaic virus movement protein in vivo.

The 32-kDa movement protein, P3, of alfalfa mosaic virus (AMV) is essential for cell-to-cell spread of the virus in plants. P3 shares many properties with other virus movement proteins (MPs); however, it is not known if P3 is posttranslationally modified by phosphorylation, which is important for the function of other MPs. When expressed in Nicotiana tabacum, P3 accumulated primarily in the cell walls of older leaves or in the cytosol of younger leaves. When expressed in Pischia pastoris, P3 accumulated primarily in a soluble form. Metabolic labeling indicated that a portion of P3 was phosphorylated in both tobacco and yeast, suggesting that phosphorylation regulates the function of this protein as it does for other virus MPs.

Insect resistance conferred by 283-kDa Photorhabdus luminescens protein TcdA in Arabidopsis thaliana.

The tcdA gene of Photorhabdus luminescens encodes a 283-kDa protein, toxin A, that is highly toxic to a variety of insects, including some agriculturally important pests. We tested the efficacy of transgenic toxin A in Arabidopsis thaliana for control of feeding insects. Plants with toxin A expression above about 700 ng/mg of extractable protein were highly toxic to tobacco hornworm (Manduca sexta). Toxin A isolated from transgenic plants also strongly inhibited growth of the southern corn rootworm (Diabrotica undecimpunctata howardi). Addition of 5' and 3' untranslated regions of a tobacco osmotin gene (osm) increased toxin A production 10-fold and recovery of insect-resistant lines 12-fold. In the best line, high toxin A expression and insect resistance were maintained for at least five generations in all progeny. The intact tcdA mRNA represents the largest effective transgenic transcript produced in plants to date. These results may open a new route to transgenic pest control in agriculture.