6.26
CONIDIAL GERMINATION ENVIRONMENT OF PESTALOTIOPSIS NEGLECTA
K WATANABE 1, K HIGASHI1 ,N ISHIMORI1, T KOBAYASHI2 and Y DOI3

1Faculty of agriculture, Tamagawa University, Tamagawagakuen,Tokyo194-8610, Japan; 2Faculty of agriculture, Tokyo University of Agriculture, Sakuragaoka, Tokyo156-0054, Japan;3 Faculty of agriculture, University of Tokyo, Yayoi, Tokyo113-0032,Japan


Background and objective
Conidial disperse is the first step in the reproduction of Deuteromycetous fungi. The next stage is conidial germination. The first stage occur randomly due to wind, rain or insect, etc. Conversely, second stage is not random and is regulated by environment. Conidial germination is something of a mystery because TEM microgrphs show that mature conidia contain lipid and glycogen as energy sources for germination. Regulation of conidial germination, however, may have some advantages for fungal reproduction and each fungus may require different conditions for conidial germination.
GenusPestalotiopsis is classified Coelomycetes, forming conidia on acervuli. Conidia is embed by mucilage. This fungi is polyxeny fungi and is frequently isolated by diseased plant which caused by other fungi, bacteria, injury etc.


Material and methods
Fungi: P. neglecta (Thuemen) Stey. (MAFF: 0238 ) was studied. This fungi are isolated by Quercus myrsinaefolia. Environment: Conidial germination was studied under various conditions to determine the effect of temperature, pH, carbon-nutrient, air, number of conidia, and self-inhibitor. Self-inhibitors were extracted from hyphae and mucilage after inoculation on PDA, using water and diethyl.


Results and conclusion
Conidia germinated between 15℃ and 30℃ at pH values ranging from 2.0 to 8.8. The conidial germination rate (CGR) varied with carbon source. (The CGR on 0.2% glucose and 0.2%yeast-extract was taken as the baseline of 100.) The CGR for may carbon sources was less than 20, but was considerably higher on pectin (CGR 182). The conidial germination (CG) at air flows of 35cm3/min was 42.9%, but was only 2.4% with no air flow. When the number of conidia was 2x102 conidia /ml, the CG was 51.7%, falling to 2x105 conidia/ml. The effect of mucilage was marked; unwashed conidia had CG of 20,5% which increased to 57.3% after five washings (20ml of matrix of mucilage-conidia/ 4ml distilled water ). The best conditions for conidial germination of P.neglecta are: 25℃(CG 29.9%), pH 7.8 (CG 45.1%), 2x102conidia/ml, pectin source, aerated, and releases from mucilage. Some substance(s) extracted by diethyl ether from hyphae and mucilage inhibits conidial germination. conidial germination is also facilitated by release from colony. This study suggests to conidial germination is regulated by factors unsuitable to conidial dispersion. Conidial germination does not occur high conidial number, in mucilage, and parent colony. Germination occurs easily on pectin. An important point substance in plant cell walls. Andrews [1] noted that dispersal and related process (which in fungi include sexual and asexual propaguls, sporulating structures, and release mechanisms) are undoubtedly adaptive. Conidial germination of P.neglecta also suggests adaptation.


Reference
1.Andrews JH (1995) Can.J. Bot. 73:s1206-s1212.