SOLANUM BREVIDENS POSSESSES A NON-SUCROSE-INDUCIBLE PATATIN GENE

The patatin gene is the best known ''tuberspecific'' gene of potato (S olanum tuberosum). Patatin is encoded by a multigene family that can b e divided into two classes. Class I genes are highly expressed in tube rs and are sucrose inducible, while class II genes are under developme ntal control and are expressed mainly in root tips. Here we report the isolation and characterization of cDNA clones corresponding to a pata tin gene of the non-tuberizing Solanum species S. brevidens. We show t hat the gene is 94-100% homologous to the class I type patatin genes o f S. tuberosum; the homology includes the sequences in the 5' and the 3' untranslated regions. However, the patatin gene of S. brevidens is regulated like class II type patatin genes and cannot be transcription ally activated by elevated levels of sucrose. This result further supp orts the idea that the components required for tuberization may be pre sent in non-tuberizing solanaceous plants, but are regulated different ly.