Tomato ‘pathogenesis-related’ P1(p14) protein was synthesized . mRNAs were isolated from leaves showing characteristic symptoms of viroid infection, followed by chromatography on oligo(dT)-cellulose and the poly(A) fraction was translated with a rabbit reticulocyte lysate system. No significant differences were found between the levels of [S]methionine incorporation directed by mRNA preparations from healthy and viroid-infected leaves. Only mRNA from infected leaves incorporated label into a protein that could be immunoprecipitated with rabbit IgG specific for tomato P1(p14) protein. Analysis by SDS-PAGE of the immunoprecipitated protein from the translation system revealed that P1 (p14) was translated as a precursor protein of 2K to 3K larger than the P1(p14) that accumulated . This protein was converted to the mature form when translation was carried out in the presence of canine pancreatic microsomal membranes. By using Protein A-gold immunocytochemistry we have detected P1(p14) concentrated in dense inclusion bodies within the vacuole as well as in association with electron-dense material present in the intracellular spaces. The presence of the additional polypeptide sequence in the newly synthesized protein indicates that P1(p14) undergoes post-translational processing. The additional sequence is probably the signal peptide that directs its transport through the endoplasmic reticulum into the vacuolar compartment of tomato leaf cells and/or the intercellular space.

Keyword(s): PR protein , tomato plants and viroid

Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error