Cloning, expression, and biological activity of recombinant alpha-cinnamomin: toxicity to cranberry and other plant species.

Elicitins produced by the pathogenic fungi Phytophthora are known to exhibit The elicitin cinnamomin is of nonspecific toxicity to different solanaceous plant species. particular interest for its potential role in the hypersensitive-like cell death and in the biological response of cranberry plants to the fungal pathogen Phytophthora cinnamomi. In order to understand the biochemical steps of the Phytophthora root rot disease in cranberry, we investigated the alpha-cinnamomin-induced plant responses. Toxicity of alpha-cinnamomin, which shows a high degree of sequence homology to the alpha-elicitin group, was tested on Vaccinum macrocarpon, Nicotiana tabacum, Capsicum annuum, Lycopersicon esculentum, Lactuca sativa, and Phaseolus vulgaris plants. Gene corresponding to alpha-cinnamomin gene fused with maltose binding protein gene, was cloned into a pMALTEV expression vector, which was transformed into E. coli cells. Cells containing alpha-cinnamomin clones were cultured and extracted protein was purified on a maltose binding protein affinity column. Biological activity of alpha-cinnamomin fusion protein was examined on propagated plants and cuttings. In cranberry plants treated with cinnamomin necrotic hypersensitive-like response in the proximal areas of the leaf lamina of lower plant leaves was observed after 48-72 hr of incubation. Limited leaf necrosis observed days after application of low amounts of recombinant cinnamomin directly on the leaves of other plants indicates that the recombinant protein might be functioning as a toxin, capable of inducing aging accompanied by plant cell death.