Gelelectrophoretic analysis of phenol-extractable leaf proteins from different viroid/host combinations.

The phenol-soluble proteins from leaves of healthy and viroid-infected plants were compared after separation on SDS-polyacrylamide gels. After staining with Coomassie blue, alterations in the protein patterns of infected plants were found which resulted from an increase or decrease of certain protein bands. After infection with the same viroid, different hosts show characteristic changes in the protein pattern which suggest that these alterations are host-specific rather than pathogenspecific. After infection of tomato plants with different viroid "species" a protein with the apparent MW of 14,000 (p14 tom) was found to accumulate dramatically. This protein also accumulates in tomato plants after viral and fungus infections and the rate of its accumulation is directly related to the severity of symptoms developed by the diseased plants. It is assumed, therefore, that it is a response of tomato plants to infection in general.