INACTIVATION OF THE PEROXIDASE ISOENZYME GROUPS, APRX AND LPL BPRX, MARKERS OF THE IN-VITRO CULTURE OF GRAPEVINE, BY FOSETYL-AL (ALUMINUM TRIS[ETHYL PHOSPHONATE])

Grapevine (Vitis vinifera cv. Monastrell) fruits contain, as the only component of peroxidase polymorphism, the peroxidase isoenzyme B-5, wh ich is the sole component of the peroxidase isoenzyme group HpI BPrx i n grapevines. Establishment of suspension cell cultures from grapevine fruits is accompanied by the de novo expression of one acidic (APrx) and one basic (LpI BPrx) peroxidase isoenzyme group in the culture med ium, which indicates that the in vitro culture is associated with the new expression of two groups of cell wall-located peroxidase isoenzyme s. Treatment of suspension cultured cells with aluminum tris [ethyl ph osphonate] (fosetyl-Al) reduces the level of peroxidase activity found in the culture medium, this effect being specific to those isoenzymes that are expressed de novo during cell culture, the isoenzyme groups APrx and LpI BPrx. Thus, fosetyl-Al selectively inactivates the peroxi dase isoenzyme groups, APrx and LpI BPrx, which are markers of the pro cess that accompanies the establishment of grapevine cell cultures.