Nucleus of Fusion Body and Infection Structure Produced by Uredospores of three Rust Fungi

Abstract

The present paper deals with studies on the nucleus of fusion body produced on glucose solution by uredospores of Puccinia coronata Corda, Uromyces alopecuri Seym. and U. durus Dietel, and also nucleus of infection structures of the former 2 species produced on peeled epidermis of host plants and artificial media. The majority of uredospores and germ tubes have two nuclei, and the others only one. Appressorium, substomatal vesicle and infection hypha (no longer than about 200μ), on the other hand, have two to four, two to eight, two to ten nuclei, respectively. The division of nucleus on germination begins at appressorium, and it continues at substomatal vesicle and infection hypha too. In the septated infection hypha, although it is rare, one cell has two nuclei. Organs closely resembling to substomatal vesicle and infection hypha in morphology, which are produced on the outer side of peeled epidermis or artificial media, are the same in nucleus behavior with the respective structures produced just inside the stoma of peeled epidermis. Fusion body usually has two nuclei. The portion where it fuses each other, however, becomes multinuclear because of the nucleus migration out of the original fusion body.