The variability induced by the in vitro culture has been shown in several cases, at callus, and cell level, and after regeneration from well organized tissues, Cell suspension and calli can be selected for different characterization of growth curves and polymorphisms of the isoenzymes. Polymorphisms also appear in acid-phosphatase, glutamate-dehydrogenase and peroxidase of regenerated plants, The in vitro naturally occurring variability has been used for selecting cell lines to be resistant Colletotrichum acutatum crude culture filtrates; the selection effectiveness is shown to be dependent on the age of the fungus cultures and on the dosage of filtration liquid, The regenerated plants show polymorphism at RAPDs analysis.