American Jouranal of Botany
2000: 87(12): 1778-1782.
Regional specialization of Sarcodes sanguinea (Ericaceae)
on a single fungal symbiont from the Rhizopogon ellenae
(Rhizopogonaceae) species complex
Annette M. Kretzer2,4,
Martin I. Bidartondo2,3,
Joseph W. Spatafora4,
Timothy M. Szaro1 and
Thomas D. Bruns1
1University of California at Berkeley, Department of Plant and Microbial Biology, 111 Koshland Hall, Berkeley, California 94720-3102
2These authors have contributed equally to this study.
3University of California at Berkeley, Department of Environmental Science, Policy and Management, 111 Koshland Hall, Berkeley, California 94720-3102.
4Corresponding author, current address: Oregon State University, Department of Botany and Plant Pathology, 2082 Cordley Hall, Corvallis, Oregon 97331-2902.
We have sampled the mycorrhizal roots of 76 snow plants
(Sarcodes sanguinea, Ericaceae) in two areas of the
Sierra Nevada of California that are approx. 180 km apart.
ITS-RFLPs were produced from the fungal symbionts either
directly from roots using fungus-specific PCR primers or
indirectly after isolation in axenic culture. In total,
fungal ITS-RFLPs were successfully produced from 57 plants
sampled, and all symbionts shared the same fragment pattern.
The morphology of S. sanguinea mycorrhizae was
consistent with that expected from a Rhizopogon
species in section Amylopogon. To confirm and refine
this identification, a total of 6 fungal ITS sequences were
determined from S. sanguinea mycorrhizae. These
sequences were analyzed together with 7 existing as well as 8
newly determined sequences from Rhizopogon section
Amylopogon. The newly determined sequences include an
ITS sequence from the fungal symbiont of pine drops
(Pterospora andromedea, Ericaceae), a species that was
previously reported to be exclusively associated with the
Rhizopogon subcaerulescens group. When these sequences
were analyzed together, all samples from S. sanguinea
grouped tightly with collections of R. ellenae and
R. idahoensis, and were distinct from the lineage
comprising collections of R. semireticulatus, R.
subgelatinosus, R. subcaerulescens, and the P.
andromedea symbiont. We conclude that S. sanguinea
associates exclusively with a member of the R. ellenae
species complex throughout our sampling range. These results
show a much higher level of specificity in S. sanguinea
than was previously reported.
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