Abstract
By computer-enhanced videomicroscopy, we mapped the trajectory of external and internal cell surface markers in growing fungal hyphae to determine the pattern of cell wall expansion during apical growth. Carbon particles (India ink) were chosen as external markers for tip expansion of Rhizoctonia solani hyphae. Irregularities in the growing apical walls of R. solani served as internal markers. Marker movement was traced in captured frames from the videotaped sequences. External and internal markers both followed orthogonal trajectories; i.e., they moved perpendicular to the cell surface regardless of their initial position in the hyphal apex. We found no evidence that the tip rotates during elongation. The discovery that the cell wall of a growing hypha expands orthogonally has major repercussions on two fronts: 1) It supports the long-held view that turgor pressure is the main force driving cell wall expansion. 2) It provides crucial information to complete the mathematical derivation of a three-dimensional model of hyphal morphogenesis based on the vesicle supply center concept. In three dimensions, the vesicle gradient generated by the vesicle supply center is insufficient to explain shape; it is also necessary to know the manner in which the existing surface is displaced during wall expansion.
Full Text
The Full Text of this article is available as a PDF (980.1 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bartnicki-Garcia S., Bartnicki D. D., Gierz G., López-Franco R., Bracker C. E. Evidence that Spitzenkörper behavior determines the shape of a fungal hypha: a test of the hyphoid model. Exp Mycol. 1995 Jun;19(2):153–159. doi: 10.1006/emyc.1995.1017. [DOI] [PubMed] [Google Scholar]
- CASTLE E. S. The topography of tip growth in a plant cell. J Gen Physiol. 1958 May 20;41(5):913–926. doi: 10.1085/jgp.41.5.913. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cosgrove D. J. Wall relaxation and the driving forces for cell expansive growth. Plant Physiol. 1987;84:561–564. doi: 10.1104/pp.84.3.561. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Heath I. B., Steinberg G. Mechanisms of hyphal tip growth: tube dwelling amebae revisited. Fungal Genet Biol. 1999 Nov;28(2):79–93. doi: 10.1006/fgbi.1999.1168. [DOI] [PubMed] [Google Scholar]
- López-Franco R., Bartnicki-Garcia S., Bracker C. E. Pulsed growth of fungal hyphal tips. Proc Natl Acad Sci U S A. 1994 Dec 6;91(25):12228–12232. doi: 10.1073/pnas.91.25.12228. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Merson-Davies L. A., Odds F. C. Expansion of the Candida albicans cell envelope in different morphological forms of the fungus. J Gen Microbiol. 1992 Mar;138(3):461–466. doi: 10.1099/00221287-138-3-461. [DOI] [PubMed] [Google Scholar]
- Ortega J. K., Harris J. F., Gamow R. I. The analysis of spiral growth in phycomyces using a novel optical method. Plant Physiol. 1974 Mar;53(3):485–490. doi: 10.1104/pp.53.3.485. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Reynaga-Peña C. G., Gierz G., Bartnicki-Garcia S. Analysis of the role of the Spitzenkörper in fungal morphogenesis by computer simulation of apical branching in Aspergillus niger. Proc Natl Acad Sci U S A. 1997 Aug 19;94(17):9096–9101. doi: 10.1073/pnas.94.17.9096. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Riquelme M., Gierz G., Bartnicki-García S. Dynein and dynactin deficiencies affect the formation and function of the Spitzenkörper and distort hyphal morphogenesis of Neurospora crassa. Microbiology. 2000 Jul;146(Pt 7):1743–1752. doi: 10.1099/00221287-146-7-1743. [DOI] [PubMed] [Google Scholar]
- Riquelme M., Reynaga-Peña C. G., Gierz G., Bartnicki-García S. What determines growth direction in fungal hyphae? Fungal Genet Biol. 1998 Jun-Jul;24(1-2):101–109. doi: 10.1006/fgbi.1998.1074. [DOI] [PubMed] [Google Scholar]
- Sherwood-Higham J., Zhu W. Y., Devine C. A., Gooday G. W., Gow N. A., Gregory D. W. Helical growth of hyphae of Candida albicans. J Med Vet Mycol. 1994 Dec;32(6):437–445. doi: 10.1080/02681219480000591. [DOI] [PubMed] [Google Scholar]
- Staebell M., Soll D. R. Temporal and spatial differences in cell wall expansion during bud and mycelium formation in Candida albicans. J Gen Microbiol. 1985 Jun;131(6):1467–1480. doi: 10.1099/00221287-131-6-1467. [DOI] [PubMed] [Google Scholar]