QUANTIFICATION OF LATE BLIGHT RESISTANCE OF POTATO USING TRANSGENIC PHYTOPHTHORA-INFESTANS EXPRESSING BETA-GLUCURONIDASE

A transgenic Phytophthora infestans strain that constitutively produce s and secretes beta-glucuronidase (GUS) was used in detached leaf assa ys to quantify the levels of resistance to late blight in potato culti vars Surprise, Irene, Pimpernel, Alpha and Bintje. Four days after ino culation levels of GUS activity were determined in infected leaves. Si gnificant differences between the various cultivars were observed. Dis crimination between resistant and susceptible cultivars was possible b ased solely on levels of GUS activity. Regression analysis revealed a positive correlation between in planta GUS levels and field resistance expressed as Area under Disease Progress Curve (ADPC).