Michigan State University

United States of America, As Represented by the Secretary of Agriculture

Cornelius Barry

Eliana Gonzales-Vigil

James J Giovannoni

The invention relates to nucleic acids encoding a zingiberene synthase that enables host cells and plants to make zingiberene that is useful in fragrances and for repelling or killing insects. The invention also relates to isolated zingiberene synthases and to methods for making zingiberenes.

Enzymes that synthesize zingiberene

To achieve full development of the ripe phenotype, climacteric fruits, such as tomato, apple and banana, require synthesis, perception and signal transduction of the plant hormone ethylene. The non-ripening phenotype of the dominant Green-ripe (Gr) and Never-ripe 2 (Nr-2) mutants of tomato is the result of reduced ethylene responsiveness in fruit tissues. In addition a subset of ethylene responses associated with floral senescence, abscission and root elongation are also impacted in mutant plants but to a lesser extent. Using positional cloning we have identified an identical 334 by deletion in a gene of unknown biochemical function residing at the Gr/Nr-2 locus. Consistent with a dominant gain of function mutation, this deletion causes ectopic expression of GR/NR-2, which in turn leads to ripening inhibition. A CaMV35:GR transgene recreates the Gr/Nr-2 mutant phenotype but does not lead to a global reduction in ethylene responsiveness suggesting tissue-specific modulation of ethylene responses in tomato. GR/NR-2 encodes a novel evolutionary conserved membrane localized protein of unknown biochemical function that has not previously been associated with ethylene signaling. Because GR/NR-2 has no sequence homology with the previously described Nr (Never-ripe) ethylene receptor of tomato we now refer to this gene only as GR. Identification of GR expands the current repertoire of ethylene signaling components in plants and provides a tool for further elucidation of ethylene response mechanisms and for controlling ethylene signal specificity in crop plants.

Growing community of inventors

Haslett, MI, United States of America

Cornelius Barry