APPRESSORIA AND APPRRESSORIUM-LIKE MORPHOLOGIES OFPYTHIUM APHANIDERMATUMAND NINE OTHER PYTHIUM SPECIES ON AGAR CULTURES
APPRESSORIA AND APPRRESSORIUM-LIKE MORPHOLOGIES OFPYTHIUM APHANIDERMATUMAND NINE OTHER PYTHIUM SPECIES ON AGAR CULTURES T WATANABE 1 , Y WATANABE 1 ,2, T FUKATSU 1 and R KURANE 1 1 NEDO Bioconsortia Program, Nat. Inst. Biosci. and Human Tech. Agency of Industrial Science and Technology, 1-1, Higashi, Tsukuba, lbaraki 305-0046, Japan;2Cent. Res. Lab., Mercian Corp. , 9- 1, Johan 4 Chome, Fujisawa, 251-0057 Japan Background and objectives Only a few detailed reports on appressoria or appressorium-like morphologies of Pythium species have been reported[ 1,2]. In this study, appressoriuin as one of morphological characters was evaluated using 10 representative species so far studied. Results and conclusions Appressoria or appressorium-like morphologies of Pythium species have been observed on agar cultures. Appessoriumphores are sessile, simple, or branched, bearing appressoria apically. For example, appressoriumphores of four isolates of P. aphanidermatum branched dichotomously with apical globose appessoria. In P. myriotylum(3 isolates studied), globose or cylindrical appressoria developed in cluster on secondary branched appressoriumphores. InP. splendens(one isolate) teardrop-shaped appressoria were formed on once- or twice-branched appressoriumphores. Appressoria of several other species were globose, clavate, cylindrical or various in shape and their iiiorphologies were occasionally different with culture age. Further works are necessary to use appressoria as morphological characters of respective species. References 1. Agnihotri VP, 1969. Mycologia 61, 967-980. 2. Plaats-Niterink AJ van Der, 198 1. Stud. Mycol. 21, 1-242.