CONSTITUTIVE EXPRESSION OF EXTRACELLULAR PEROXIDASE ISOENZYMES CAPABLE OF OXIDIZING 4-HYDROXYSTILBENES DURING THE GROWTH-CYCLE OF GRAPEVINESUSPENSION CELL-CULTURES

The constitutive expression of peroxidase isoenzymes which are capable of oxidizing 4-hydroxystilbenes was studied during the growth cycle o f suspension cell cultures from grapevine (Vitis vinifera L. cv. Monas trell) berries. The results showed that the growth of suspension cell cultures is accompanied by the constitutive expression of the peroxida se isoenzymes HSPrx 1 and HSPrx 2, previously characterised by their p roperties for oxidizing 4-hydroxystilbene, the expression of these iso enzymes being characteristic of Monastrell vines brought to a resistan t state. However, although the differential catalytic properties of th ese grapevine isoenzymes are also shown by the horseradish peroxidase, no immunological relationships have been found between the peroxidase s from either source.