FINE STRUCTURE OF MYCOTA

Transcription

1 FINE STRUCTURE OF MYCOTA XI. OCCURRENCE OF THE GOLGI DICTYOSOME IN THE HETEROBASIDIOMYCETE P UCCINIA POD OPHYLLI ROYALL T. MOORE Electron Microscope Laboratory, University of California, Berkeley, California Received for publication 24 June 1963 ABSTRACT MOORE, ROYALL T. (University of California, Berkeley). Fine structure of mycota. XI. Occurrence of the Golgi dictyosome in the heterobasidiomycete Puccinia podophylli. J. Bacteriol. 86: The Golgi dictyosome is reported for the first time in the subclass Heterobasidiomycetidae in the rust Puccinia podophylli Schw. It is observed that the dictyosome appears to be limited to primordial cells, particularly those nearest the host, and does not occur in the aeciospores. In comparison with the Golgi systems of plant and animal cells, the Golgi complex of P. podophylli is found to be more similar to those of the latter. Also discussed is the distribution of the Golgi complex in fungi described in published reports and the need for more such reports so that the range of its variation and distribution may be established. The Golgi dictyosome has only recently been demonstrated in the fungi. First described in the Ascomycete Neobulgaria pura (Moore and Mc- Alear, 1962, 1963), it has most recently been described in Peronospora rmnshurica (Peyton and Bowen, in press) and Pythium debaryanum (Hawker, 1963), both biflagellate Phycomycetes, and in the Homobasidiomycete Armillaria mellea (Roskin, Snyder, and McAlear, in preparation). The following communication relates the occurrence of what is believed to be an example of the Golgi system in the Heterobasidiomycete Puccinia podophylli, a representative of the other Basidiomycete subclass. MATERIALS AND METHODS Young aecia of P. podophylli Schw. were excised from the lower stem of Podophyllum peltatum L. (Berberidaceae) collected from the field. (Reference material from the same specimen 866 has been deposited in the Cornell University Plant Pathology Herbarium, CUP ) These were prefixed for about 10 min in 2% aqueous unbuffered KMnO4, then fixed in buffered OS04 for 3 to 5 hr, dehydrated in an ethanol series, and embedded in a methacrylate mixture (Moore, 1962). Sections cut with a diamond knife were examined in a Siemens Elmiskop I electron microscope. RESULTS Figure 1 shows a cell of the aecial primordium contiguous with a thick-walled epidermal cell (E, E) of the host. A Golgi dictyosome (G) with numerous marginal vesicles (X) is prominent near the fungal nucleus (N). Above this are what appear to be two smaller complexes. Figure 2 is a similar plane of section at a higher magnification. The dictyosome membranes display frequent swellings at their margins (arrows), and adjacent vesicle aggregations (X) are conspicuous. Figure 3 presents a somewhat tangential section of a Golgi complex proximate to a nucleus (N). The fungal wall (W) is identified. Figure 4 is interpreted as a section cut approximately perpendicular to the vertical stack of saucer-shaped sacs that form the dictyosome. The three dictyosome membrane aggregates (G) are believed all to belong to one complex. The great accumulation of Golgi vesicles (X) spacially is probably at the inner region of the complex (similar to those in Fig. 1 and 3). DISCUSSION The Golgi system, thought classically to occur only in animal cells, owes its present delimitations to the early studies of zoological fine structure. These established the following criteria: (i) stacks of flattened sacs-the "fingerprint" of the dictyosome; (ii) propinquity of the dictyosome to the

2 lz FIG. 1. Contiguity of fungal and host epidermal (E, E) cells. A Golgi dicytosome (G) and vesicles (X) are prominent near the nucleus (N). Scale line = 1,; X 20,

3 FIG. 2. Dictyosome lamellae showing blebbing (arrows) and adjacent vesicle clusters (X). Scale line = 1 /A; X 50,

4 FIG. 3. Tangential section through a Golgi complex near a nucleus (N). W', the fungal cell wall. Scale line = 1 IA; X 60,

5 FIG. 4. Section through the Golgi apparatus approximately perpendicular to the plane of stacking; G, dictyosome; X, vesicles. Scale line = 1 p; X 30,

6 VOL. 86, 1963 GOLGI DICTYOSOME IN P. PODOPHYLLI 8371 nucleus; (iii) the apparent blebbing off of small vesicles from the margin of the dictyosome; (iv) membranes that are smooth, i.e., ribosome-free. Criteria i and iv appear to be invariable: the dictyosome is, ipso facto, the defining attribute of the Golgi complex, and in no examples of osmium-fixed material have ribosomes been reported on Golgi membranes. An exception to criterion iii was reported by imoore and McAlear (1963) in the fungus Neobulgaria in which marginal vesicles were not observed. Plant cells tend to be exceptions to criterion ii. In these cells, the dictyosomes generally appear to be rather scattered in the cytoplasm. Also, the dictyosomes as most frequently observed are more compact and more numerous, and the quantity of marginal vesicles is sparser than is generally characteristic of the dictyosomes of animal cells. From the numerous electron microscopic studies of plant tissues during the past several years, it now is quite evident that the Golgi system is as widely occurring in plant cells as in animal cells. The same is not yet true for the fungi. The Golgi dictyosome for these organisms was first reported from the monotypic discomycete N. pura (MIoore and MIcAlear, 1963). This still remains our only example from the Ascomycetes. However, as mentioned above, there are now several reports of the Golgi apparatus from the Phycomycetes. All of these, curiously enough, are from the biflagellate series, a series uniquely characterized by cellulose in the hyphal walls (J. M. Aronson, personal communication) and a series which Bessey (1942) believed to be phylogenetically linked with the Vaucheriaceae of the yellow-green algae. The first report of the Golgi dictyosome in the Basidiomycetes was made by Roskin et al. (in preparation) from A. mellea. The present report is believed to be the second for this class. The thallus of P. podophylli is composed of disarticulated cells (Moore, in press), and the Golgi formation is observed most frequently in the several layers of cells nearest the host. At the outer face of the aecium, aesciospores are produced. These are dikaryotic, filled with storage vesicles, and bounded by a thick, warty wall. No Golgi-like membranes have been observed in them, and their appearance is quite similar to the aeciospores of Uromyces caladii (Moore and McAlear 1961). The observed membrane complex in P. podophylli complies with the first three criteria. (Information on the fourth criterion is precluded by the permanganate fixation.) Its micromorphology appears most similar, broadly speaking, to the dictyosomes observed in animal cells; that is, the lamellae forming the dictyosome are quite broad, the number of marginal vesicles is large, and the complex occupies the perinuclear region. Further, there is seldom more than one fully developed complex per cell. From this r6sum6 of all the reports of the occurrence of the Golgi dictyosome in the fungi, it is quite evident that it is still rather a novelty in the Eumycota. It is, therefore, important that as examples of the Golgi system are encountered in these organisms they be reported so that the range of the micromorphology and the distribution of the organelle may be established. From an accumulation of such information, there may perhaps be derived in the future a clearer understanding of the phylogenetic position of the fungi. ACKNOWLEDGMENTS The technical assistance of Lloyd Thibodeau and Philip Spencer of our Laboratory is gratefully acknowledged. This investigation was supported by Postdoctoral Fellowships and 2 F2 AI from the National Institute of Allergy and Infectious Diseases, U.S. Public Health Service; James H. McAlear, sponsor. LITERATURE CITED BESSEY, E. A Some problems in fungus phylogeny. Mycologia 34: HAWKER, L. E Fine structure of Pythium de bar yanum Hesse and its probable significance. Nature 197:619. MIOORE, R. T Fine structure of mycota. 1. Electron microscopy of the discomycete Ascodesmis. Nova Hedwigia 5: MOORE, R. T., AND J. H. MCALEAR Fine structure of mycota. 8. On the aecidial stage of Uromyces caladii. Phytopathol. Z. 42: MOORE, R. T., ANI) J. H. McALEAR Characterization of the Golgi dictyosome of the fungus Neobulgaria pura. Intern. Conf. Electron Microscopy, 5th 2:UU-7. MOORE, R. T., AND J. H. McALEAR Fine structure of mycota. 4. The occurrence of the Golgi dictyosome in the fungus Neobulgaria pura (Fr.) Petrak. J. Cell Biol. 16: