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

NC#

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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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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Boreal

Southeastern

Western

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AKCAFLMNMSNC

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0.001 0.01 0.1 1 50 1000 5000

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1"

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.