a) Wilcoxina mikolae on pine roots (courtesy of Nhu Nguyen); b) Wilcoxina rehmi, a close relative of W. mikolae (courtesy of Oluna & Adolf Ceska).

Wilcoxina mikolae is a member of the Ascomycota in the family Pyronemataceae.  Like other members of the family it produces meiotically-produced ascospores in small cup-shaped fruiting bodies, and these spores are dispersed through the air.  It also produced chlamydospores in the soil via mitosis, and these spores serve as local inoculum.

Wilcoxina mikolae is an important ectomycorrhizal symbiont of the Pinaceae and many hardwood species.  It occurs naturally in Eurasia and North America, and has been accidentally introduced along with pine throughout the Southern Hemisphere [1-3].   The early mycorrhizal literature refers to it as “E-stain” because on pine and larch it forms an “ectendo” type of mycorrhiza in which host cortex cells are penetrated by the fungus, but a mantel and Hartig net, typical of ectomycorrhizae, is also formed [4, 5].

Wilcoxina species are among the most common colonizers of young pine, spruce, and larch in nurseries and in post-fire or post-disturbance forests [6-10].   Their occurrence in disturbed settings is due primarily to its presence in the spore bank, where it can persist for many years [11]. Wilcoxina fruiting bodies are rarely collected perhaps because of their small size and bland colors, and only four species [12] and two varieties have been described. However the diversity of Wilcoxina sequences retrieved from roots suggests that additional taxa exist [13].

References

1. Barroetavena, C., et al., Molecular identification of ectomycorrhizas associated
with ponderosa pine seedlings in Patagonian nurseries (Argentina). Canadian 
Journal of Forest Research-Revue Canadienne De Recherche Forestiere, 2010.
40(10): p.1940-1950.

2. Ivory, M.H. and R.B. Pearce, Wilcoxina mikolae newly identified as
mycorrhizalfungus on pines in Africa. Mycological Research, 1991. 95: p. 250-253.

3. Walbert, K., et al., Ectomycorrhizal species associated with Pinus radiata in
New Zealand including novel associations determined by molecular analysis.
Mycorrhiza, 2010. 20(3): p. 209-215.

4. Piche, Y., C.A. Ackerley, and R.L. Peterson, Structural characteristics of
endomycorrhizas synthesized between roots of Pinus resinosa and the E-strains
fungus, Wilcoxina mikolae var mikolae. New Phytologist, 1986. 104(3): p. 447-&.

5. Yu, T., K.N. Egger, and R.L. Peterson, Ectendomycorrhizal associations -
characteristics and functions. Mycorrhiza, 2001. 11(4): p. 167-177.

6. Baar, J., et al., Mycorrhizal colonization of Pinus muricata from resistant
propagules after a stand-replacing wildfire. New Phytologist, 1999. 143(2): p.
409-418.

7. Rudawska, M., et al., Ectomycorrhizal status of Norway spruce seedlings from
bare-root forest nurseries. Forest Ecology and Management, 2006. 236(2-3): p.
375-384.

8. Torres, P. and M. Honrubia, Changes and effects of a natural fire on
ectomycorrhizal inoculum potential of soil in a Pinus halepensis forest. Forest
Ecology and Management, 1997. 96(3): p. 189-196.

9. Danielson, R.M. and S. Visser, Host response to inoculation and behavior of
introduced and indigenous ectomycorhizal fungi of jack pine grown in oil-sands
tailings. Canadian Journal of Forest Research-Revue Canadienne De Recherche
Forestiere, 1989. 19(11): p. 1412-1421.

10. Lobuglio, K.F. and H.E. Wilcox, Growth and survival of ectomycorrhizal and
ectendomycorrhizal seedlings of Pinus resinosa on iron tailings. Canadian
Journal of Botany-Revue Canadienne De Botanique, 1988. 66(1): p. 55-60.

11. Nguyen, N.H., N.A. Hynson, and T.D. Bruns, Stayin' alive: survival of
mycorrhizal fungal propagules from 6-yr-old forest soil. Fungal Ecology, 2012.
5(6): p. 741-746.

12.  Index Fungorm Website:  http://www.indexfungorum.org/

13. Egger, K.N., Molecular systematics of E-strain mycorrhizal fungi: Wilcoxina
and its relationship to Tricharina (Pezizales). Canadian Journal of Botany-Revue
Canadienne De Botanique, 1996. 74(5): p. 773-779.