Poster: Plant Pathogen/Symbiont Interactions

Abs # 700: IAA production of Rhizoctonia solani and Colletotrichum spp. changed by culture fitrate and by interaction with plants

Presenter:	Furukawa, Toshiko , furukawa@tmca.ac.jp
Authors	Furukawa, Toshiko  (A)   Syono, Kunihiko  (B)
Affiliations:	(A): Tokyo Metropolitan College (B): Japan Women's University

Rhizoctonia solani, which is plant pathogenic fungi, produces IAA, and the production increased adding culture filtrate (CF) from rice suspension culture to the medium. In this system, CF from many suspension cultures caused the induction of IAA production, and no host specificity was observed. The same induction was observed when fungi were interacted with plant roots. When R. solani MAFF 305219, that caused sheath blight on rice, contacted with rice roots, its IAA production increased. IAA production, however, decreased when the fungi contacted with root of read bean. As there were the possibility that the induction of IAA production and host specificity, we used Colletotrichum and examined. Fungi were cultured in potato dextrose medium with 0.01% Trp and CF for two days. IAA in the medium was detected by HPLC. Fresh MS medium was used in replace of CF for control. IAA production of 6 strains of C. gloeosporioides, that were omnivorous parasite, produced more IAA (1-40 mM) than monoxenic genus such as C. coffeanum and C. fragarie (0.1-0.3 nM). IAA production of C. graminicola whose host was corn was induced, but that of C. acuatum whose host was mulberry decreased by rice CF. That of C. trancatum whose host was soybean increased by CF of Lotus japonicus but decreased by CF of rice. Fungal growth was the same as control in any case. These facts revealed that IAA production changed dependent on the kinds of plants with who fungi interacted. The induction of IAA production of R. solani and Colletotrichum is possible to be related to host specificity.