Cell wall protrusions induced by cauliflower mosaic virus in Chinese cabbage leaves: A cytochemical and autoradiographic study

The mesophyll cells of Chinese cabbage leaves systemically infected with cauliflower mosaic virus (CaMV) often show outgrowths of their cell walls, which are generally traversed by one or more canals and sometimes assume the aspect of long tubules. By means of specific staining of the plasmalemma with a phosphotungstic-chromic acid solution (PTA), it was demonstrated that these tubular protrusions are lined by plasmalemma not only on the outside, but also on the inside, and that they should be considered as plasmodesma-related structures. By autoradiographic methods it was shown that the cell wall protrusions become heavily labeled after glucose- 3H administration. The rest of the cell wall remains almost unlabeled. Thus, CaMV induces the deposition of cell wall material only in preferential sites. After phenylalanine- 3H administration, no label was found in cell wall protrusions, showing that no lignification occurs in these structures.