Cytological and ultrastructural responses of Platanus acerifolia(Ait.) Willd. leaves to cerato-platanin, a protein fromCeratocystis fimbriata f. sp. platani.

Cerato-platanin (CP) is a purified protein isolated from the culture filtrate of the ascomycete Ceratocystis fimbriata f. sp. platani (Cfp), the causal agent of canker stain disease of plane. The responses of cells/tissues of plane leaves to CP was studied by light microscopy (LM) and by transmission electron microscopy (TEM) using two experimental procedures. The most significant responses occurred already at 24 h after treatments, and were also visible at 48 h. The main effects of CP were to cause a great increase in primary starch and a certain degree of intercellular and intracellular disorganization of the spongy parenchyma cells and plasmolysis processes. In addition, an increase of intracellular phenolic compounds was observed in the palisade cells. The effects of Cfp were similar but less evident than those of CP.