Related Experiment Videos
Protoplasmic organization of hyphal tips among fungi: vesicles and Spitzenkörper
Abstract:
Hyphal tips of fungi representing Oömycetes, Zygomycetes, Ascomycetes, Basidiomycetes, and Deuteromycetes were examined by light and electron microscopy and compared with respect to their protoplasmic organization. In all fungi studied, there is a zone at the hyphal apex which is rich in cytoplasmic vesicles but nearly devoid of other cell components. Some vesicle profiles are continuous with the plasma membrane at the apices of these tip-growing cells. The subapical zones of hyphae contain an endomembrane system which includes smooth-surfaced cisternae associated with small clusters of vesicles. The findings are consistent with the hypothesis that vesicles produced by the endomembrane system in the subapical region become concentrated in the apex where they are incorporated at the expanding surface. Septate fungi (Ascomycetes, Basidiomycetes, and Deuteromycetes) have an apical body (Spitzenkörper) which is associated with growing hyphal tips. In electron micrographs of these fungi, an additional specialized region within the accumulation of apical vesicles is shown for the first time. This region corresponds on the bases of distribution among fungi, location in hyphae, size, shape and boundary characteristics to the Spitzenkörper seen by light microscopy. This structure is not universally associated with tip growth, whereas apical vesicles are widespread among tip-growing systems.
Insights
Fungal hyphal tip growth involves a concentration of cytoplasmic vesicles at the apex, which are incorporated into the expanding cell surface. Septate fungi also possess a specialized apical body (Spitzenkörper) within these vesicles.
Area of Science:
- Mycology
- Cell Biology
- Plant Pathology
Background:
- Fungal hyphae exhibit tip growth, a crucial process for development and infection.
- The apical organization of fungal hyphae is key to understanding growth mechanisms.
Purpose of the Study:
- To compare the protoplasmic organization of hyphal tips across diverse fungal groups.
- To investigate the role of apical vesicles and the Spitzenkörper in fungal tip growth.
Main Methods:
- Light and electron microscopy were employed to examine hyphal tips.
- Comparative analysis of protoplasmic organization in Oömycetes, Zygomycetes, Ascomycetes, Basidiomycetes, and Deuteromycetes.
Main Results:
- A universal apical zone rich in cytoplasmic vesicles was observed in all studied fungi.
- Vesicles are continuous with the plasma membrane, suggesting incorporation into the cell surface.
- Septate fungi exhibit a specialized apical region (Spitzenkörper) within the apical vesicles, visualized via electron microscopy.
- The Spitzenkörper's characteristics align with light microscopy observations, but apical vesicles are more widespread.
Conclusions:
- Fungal tip growth relies on the concentration and incorporation of apical vesicles.
- The Spitzenkörper is a specialized structure within apical vesicles in septate fungi, but not essential for all tip growth.