Morphogenesis of Powdery Mildew Fungi in Water (3) Decrease of the Formation and Penetration Frequency of Short Germ Tubes from Water-Immersed Conidia of Erysiphe graminis.

Abstract

Frequencies of the formation and penetration of the short germ tubes of Erysiphe graminis conidia on barley coleoptiles, which were immersed in 0.01M CaCl2 solution (water condition) or floated on the same solution (air condition) were examined. Under air condition, short germ tubes were formed and penetrated barley coleoptile cells at a high frequency, while their formation frequency in water condition was significantly low, and if any, their penetration frequency was extremely low. These results suggest that the role of short germ tubes is most likely to take up water from host cells when conidia are exposured to the environment of low humidity, as reported by Carver and Bushnell (1983).