Title: Cytological studies of early stages of powdery mildew in barley and wheat. IV. Direct ingress from superficial primary germ tubes and appressoria of Erysiphe graminis hordei on barley leavest
Abstract: Breaching of barley leaf epidermal walls from superficial primary germ tubes and appressoria of Erysiphe graminis hordei on barley leaves was examined by micromanipulation within a scanning electron microscope. At 2 h after inoculation, penetration pegs, approximately 0·6 μm in diameter, were first observed on the contact surfaces of some primary germ tubes. Concurrently, penetration pores of 0·4 to 0·6 tsm diameter were observed in tracks of the same primary germ tubes on the cuticular surfaces. Similar penetration pores were also first visible below appressoria 6 h or more after inoculation. By 4 h after inoculation, epidermal walls were breached and papillae were induced by nearly 71 % of primary germ tubes; by 8 h, nearly 91 %. By 6 h after inoculation, host walls were breached and papillae were induced by about 5% of appressoria and by 18 h, 84%. By 8 h after inoculation, host walls were breached from both primary germ tubes and appressoria which had emerged from the same conidia. These results suggest that primary germ tubes of E. graminis hordei make physiological contact with host cells before appressorial penetration.
Publication Year: 1978
Publication Date: 1978-11-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 43
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