Invasive hyphal growth: An F-actin depleted zone is associated with invasive hyphae of the oomycetes Achlya bisexualis and Phytophthora cinnamomi

We have compared F-actin patterns in invasive and non-invasive oomycete hyphae. In Achlya bisexualis an F-actin depleted zone is present in 70% of invasive but only 9% of non-invasive hyphae. In Phytophthora cinnamomi these figures are 74 and 20%, respectively. Thus, the F-actin depleted zone appear...

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Bibliographic Details
Published in:Fungal genetics and biology 2006-05, Vol.43 (5), p.357-365
Main Authors: Walker, Sophie K., Chitcholtan, Kenny, Yu, YuPing, Christenhusz, Gabrielle M., Garrill, Ashley
Format: Article
Language:English
Subjects:
Achlya - chemistry
Achlya - growth & development
Achlya - ultrastructure
Achlya bisexualis
Achyla bisexualis
actin
Actins - analysis
cytochemistry
Cytoplasmic Vesicles - ultrastructure
F-actin
F-actin depleted zone
hyphae
Hyphae - chemistry
Hyphae - growth & development
Hyphae - ultrastructure
Invasive growth
invasive hyphae
microbial growth
Microscopy, Electron, Transmission
Microscopy, Fluorescence
Oomycete
Oomycetes
Osmotic Pressure
Phytophthora - chemistry
Phytophthora - growth & development
Phytophthora - ultrastructure
Phytophthora cinnamomi
Tip growth
Turgor
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Summary:We have compared F-actin patterns in invasive and non-invasive oomycete hyphae. In Achlya bisexualis an F-actin depleted zone is present in 70% of invasive but only 9% of non-invasive hyphae. In Phytophthora cinnamomi these figures are 74 and 20%, respectively. Thus, the F-actin depleted zone appears to be associated with invasive growth. TEM images indicate that it is unlikely to represent areas of vesicle accumulation. Measurements of turgor indicate no significant increase under invasive conditions (0.65 MPa (invasive) and 0.63 MPa (non-invasive)). Similarly we found no difference in burst pressures (1.04 MPa (invasive) and 1.06 MPa (non-invasive)), although surrounding agarose may lead to overestimates of invasive tip strength. An F-actin depleted zone has the potential, along with wall softening, to increase protrusive force in the absence of turgor increases. Staining of F-actin in hyphae under hyperosmotic conditions suggests that decreases in F-actin at growing tips may also enable non-invasive growth at very low turgor.
ISSN:1087-1845
1096-0937
DOI:10.1016/j.fgb.2006.01.004