A continental view of ectomycorrhizal fungal spore banks: A quiescent functional guild with a
strong biogeographic pattern!Sydney I. Glassman1, Kabir G. Peay2, Jennifer M. Talbot2, Dylan P. Smith2, John W.
Taylor1, Rytas Vilgalys3, Thomas D. Bruns1 1University of California, Berkeley, CA, USA 2 Stanford University, Stanford, CA, USA 3Duke University, Durham, NC, USA
What is a Spore Bank?
Seed bank: seeds of plants that persist in soil for long periods of 0me and colonize a4er a disturbance. Ectomycorrhizal spore bank: EMF spores and sclero0a persist in soil for long periods of 0me and germinate in presence of plant roots.
How do you sample a spore bank?
Sieve and air dry soil to negligible soil moisture so all ac0ve mycelium dies and only spores and sclero0a are le4. Plant a pine seedling as a bioassay for the responsive spore bank. Collect root 0ps under dissec0ng microscope and extract their DNA. We then sequenced the ITS region with 454 pyrosequencing.
Acknowledgements The Bruns, Taylor, Peay, and Vilgalys labs, Angela DiRocco, Judy Chung, Lisa Rosenthal, Michael Ernandes, Leslie Forero, Greg Bonito, MaS Smith, and all of the wonderful labs who hosted us during our sampling trips.
1. What paSerns will emerge from a con0nental survey of EMF spore banks? Will EMF spore banks be dispersal limited and thus structured by their biogeography? Yes, EMF spore banks are geographically pa6erned.
Figure 1 (A) Each circle represents the fungal community (beta diversity metric = binary sorensen dice) at a single plot and plots are colored by loca0on within a state. Ellipses represent SD of point scores based on loca0on of a plot within a bioregion. (B) Fungi within plots are more similar to each other than expected by chance (mantel r = 0.1; p <0.001), and distance decay occurs between 300m and 1 km. Samples over 1 km – 6000 km apart are more dissimilar than expected by chance.
The future: We currently are harves=ng bioassays growing in soils from 49 more plots: 15 in Alberta, Ontario, Bri=sh Columbia in Canada and 34 in the USA (Connec=cut, Michigan, Montana, Oregon, Texas, Virginia, Wyoming).
3. Are there only a few fungal genera capable of forming resistant spore banks? Yes, a few genera dominate EMF spore banks. Some genera reflect previous knowledge (Rhizopogon, Wilcoxina, Cenococcum, Tomentella) but some (Laccaria, Suillus, Tuber) were not known to be major players in spore banks.
AK
MN
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MS#FL CA
PR YO
PR = Point Reyes Na0onal Seashore; YO = Yosemite Na0onal Park ; CA = Stanislaus Na0onal Forest; AK = Alaska; MN = Minnesota; MS = Mississippi; NC = North Carolina; FL = Florida
Sampled from 19 plots x 13 samples per plot (+ aerial control) x 2 tree hosts (common and na0ve) x 3-‐5 reps per tree = 1,806 seedlings
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Pb Pc Pg Pm Pmo Pp Pt
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Figure 2 In all cases, the common host Pm recovered ≥ EMF OTUs than the na0ve tree host. There is no significant main effect of tree host on alpha diversity, but there is a significant tree by host interac0on due to differences in EMF richness across the con0nent. For beta diversity, with the excep0on of Pb in Minnesota, Pm did not recover significantly different EMF communi0es than na0ve host plant. Pb = Pinus banksiana; Pc = Pinus contorta; Pg = Picea glauca; Pm= Pinus muricata; Pmo= Pinus mon=cola; Pp = Pinus ponderosa; Pt = Pinus taeda.
2. Does bioassay plant host affect diversity of EMF taxa? No. In general, Pinus muricata, is an effec=ve bioassay host and recovered similar EMF communi=es as na=ve hosts.
Where did we sample?
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AKCAFLMNMSNC
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Rhizopogon)arctostaphyli,"""R.)rubescens)gr.,""R.)salebrosus)
CA
Most Frequent EMF Spore Bank Taxa Across the N. America
Wilcoxina))mikolae,))Rhizopogon)fuscorubens,))R.)rubescens)gr.,)
YO
Sphaerosporella""sp,"Wilcoxina)sp,""Piloderma"sp"
AK Laccaria"sp,""Suillus)brevipes,"Rhizopogon)rubescens)gr."
MN
Rhizopogon)occidentalis,"""R.)salebrosus,""R.)fuscorubens)
PR
Rhizopogon)rubescens)gr.,"Cenococcum)sp,""R.)fuscorubens))
MS
Rhizopogon)rubescens)gr.,""Tuber"sp1,""Tuber)sp2"
NC
Rhizopogon)fuscorubescens,""Cenococcum)sp,"Thelephora"sp"
FL
Common host
4. Will EMF taxa in spore banks will be rare or absent from fresh soil EMF communi0es from the exact same sampling loca0on? Yes, there was minimal overlap between soil and spore bank EMF.
AK CA FL
MN MS NC
Soil%v%Spore%Bank%EMF%Venn%Diagrams%Soil
Spore bank
Figure 4 In all loca0ons, over half the EMF OTUs recovered from the spore bank are never recovered from the fresh soil. Furthermore, there is liSle community overlap between EMF sequenced from fresh soils versus those in spore banks, indica0ng that similar to plants, those EMF that will dominate post disturbance will unlikely be the same as the major players in older forests.
