Characterization of a predominantly pistil-expressed gene encoding a gamma-thionin-like protein of Petunia inflata.

We isolated a cDNA clone from a pistil cDNA library of Petunia inflata which encodes a protein, PPT, with sequence similarity to gamma-thionins. Characterization of a genomic clone containing a PPT gene revealed the presence of a single intron. Northern analysis revealed that the PPT gene was predominantly expressed in the pistil during all stages of flower development. Since thionins have been implicated in plant defense against pathogens, PPT may play a role similar to that of other defense-related proteins found in the pistil, defending the pistil against pathogen infection.