The library was screened at low stringency with a tobacco PR-R cDNA probe. An 832 bp
cDNA from a mRNA present only in infected tissue was isolated. Nucleotide sequence
showed high homology with the osmotin from both tobacco and tomato (NP24). This cDNA
probably corresponds to the AP24 and P23 proteins previously described in tomato and
induced upon fungal and viroid infection.