Preparation and Regeneration of Protoplasts from Axenic Mycelia Derived from the Wheat Stem Rust Fungus

Protoplasts were prepared from axenic suspension cultures of the wheat stem rust fungus Puccinia graminis f. sp. tritici, race 126 Anz-5,6,7,11. Protoplasts were released in 3 hr from 3- to 7-day-old mycelia with a mixture of Novozym 234 and cellulase (5 mg each/ml) osmotically stabilized by 0.8 M MgSO 4 . Protoplast regeneration was detected microscopically within 10 hr after incubation in a nutrient medium containing 0.5 M sorbitol, and colonies usually were visible after a further 3 days of growth. The regeneration frequency ranged from 19 to 39%