The isolation of auxotrophs from Datura innoxia Mill. cell cultures following recovery of arsenate-treated cells on feeder plates.

Wild-type (Ph1) and adenine-requiring (Ad1) cell lines of Datura innoxia Mill. were used in experiments to evaluate arsenate as a growth-lethal compound and its use as a counterselection agent. These experiments led to the devising of methods for the recovery of Ph1 and Ad1 cells after arsenate treatment when plated at low density on feeder plates. The modified counterselection technique was then used to isolate three new auxotrophs from mutagenized suspensions of Ph1 cells, two of which were partially characterized. One, C18, requires casein hydrolysate for growth and lacks an active nitrate reductase; the other, JM3, will grow only when the medium contains threonine.