Factors affecting oospore germination of heterothallic Pythium splendens

Abstract

Oospores from a cross between (+) and (-) mating types of Pythium splendens had a germination rate of only 2–3% on nutrient media. When oospores from 20-day-old cultures were treated with 0.25% KMnO₄ for 20 minutes, germination was increased to 49% in 2 days on a medium consisting of mineral salts, lecithin, glucose and agar (S+L agar). Amendment of S+L agar with 0.15% L-sorbose reduced growth but without affecting germination, enabling the germination rate to be determined after incubation for 3 rather than 2 days. Germination increased with increasing age of cultures up to 30 days for all treatments. Exposure to light during germination also increased the germination rate of oospores matured either under light or in darkness. Oospores from 40-day-old cultures treated with KMnO₄ for 30 minutes had a germination rate of more than 90% under light on S+L agar amended with L-sorbose.

Key Words:

• L-sorbose
• maturation
• potassium permanganate
• Pythium splendens
• oospore germination