Nuclear condition, types of hyphal development from differentiating, and nondifferentiating uredosporelings, and effect of 3,3′-bis-indolylmethane on Puccinia graminis f.sp. tritici in vitro

Abstract

In vitro P. graminis f. sp. tritici, race 32, produced dikaryotic hyphae from infection structures, corresponding to appressoria and substomatal vesicles (differentiated), which are formed by germ tubes as a response to a heat shock within 24 h after seeding the spores. Dikaryotic hyphae also formed spontaneously from nondifferentiated senescing germ tubes 3-4 days after seeding the spores. The hyphae which originated from the different structures did not appear to be different with regard to nuclear condition, morphological appearance and fluorescence properties as a consequence of Feulgen staining. 3,3''-Bis-indolylmethane (BIM) increased the hyphal growth rate in contrast with the germ tube growth rate. It also supported the transition from germ tube growth to hyphal growth. The possible mode of action of BIM and the involvement of an unknown factor which represses hyphal growth are discussed.