Effects of medium composition and light on formation of apothecia and sclerotia by Pyronema domesticum

Abstract

Pyronema domesticum (Sow.) Sacc. was cultured in a 12 h light: 12 h dark cycle and in the dark on water agar; an inorganic salts medium (Claussen's agar); Claussen's agar supplemented with casein hydrolysate, biotin, thiamine, asparagine, glycine, or urea; and media containing a variety of natural materials, either supplemented or not with dextrose or another carbohydrate. Apothecial formation was favored by illumination, while sclerotial formation was favored by darkness. Maximum production of apothecia and sclerotia occurred on low-carbohydrate media supporting scant to moderate mycelial growth but was prevented on medium with a high carbohydrate concentration (20 g/L). Large numbers of well-developed apothecia formed on dilute media containing only inorganic nutrients (Claussen's agar), a small amount (3.0 g/L) of casein hydrolysate, or the extract from 20 g potatoes/L. Fewer incompletely developed apothecia formed on 2% water agar. Apothetical production was depressed or prevented by the addition of asparagine, glycine, urea, biotin, or thiamine to Claussen's agar. Sclerotia formed in maximum numbers on rabbit food agar, vegetable juice agar, and on dilute potato extract agar. Fewer sclerotia were produced on Claussen's agar.