In vitro evaluation of Phytophthora cactorum (Lebert and Cohn) culture filtrate influence on apple rootstock

Friable and cream coloured calli were induced from leaf explant of apple rootstock MM 106 on MS medium supplemented with 7 mg/l NAA and 1 mg/l BAP. Twenty three days old fungal culture filtrate (FCF) of Phytophthora cactorum, tested as highly toxic, was used for selecting tolerant calli. Calli were subjected to different concentrations of FCF (5 to 25%) and 5.35 percent callus lines were selected at 20 percent level of FCF. The selected callus lines survived three cycles of selection in two methods: continuous and discontinuous. Fresh weight of normal and selected callus lines increased more rapidly on normal medium as compared to that on selective medium. Biochemical analysis revealed that phenol content was three times higher in selected callus lines.