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Gen. Mycorrhizal interactions & ERH effect on range of SFL orchids -…
Gen. Mycorrhizal interactions & ERH effect on range of SFL orchids
Introduction
globalization effect on plant range
orchids have less naturalization and invasion rates than other plants
germinating seeds recieve nutrient from OMF (Orchid Mycorrhizal Fungi)
Enemy-release hypothesis -pathogenic fungi interactions lead to success in new areas
OMF interactions regulate distance and abundance of orchid sp.
compatible mycorrhizal fungi = success in new area
Two Hypotheses
invasive orchids have more generalized OMF than natives
invasive orchids have more pathogenic fungi than natives
Exoeriment - comparing 2 invasive orchids and 2 native orchids in SFL area
Methods
Species
brazilian yellow cowhorn (Cryptopodium flavum) - terrestrial nonnative
wild cococ (Eulophia alta) - terrestrial native
Florida cowhorn (Cryptopodium punctatum (L.) Lindl) - epiphytic native
chinese ground orchid (Eulophia graminea) - terrestrial nonnative
Collection
102 plants
E. graminea - 26 plants, 3 sites in SFL, China
C. flavum - 32 plants, 2 sites in SFL
E. alta - 9 plants, 1 site in SFL
C. punctatum - 35 plants, 2 sites in SFL
protocorm collection from seedlings and bait traps
Protocorm and root tissue collections 2013-2018
Fungal bait traps
C. puntatum - 30 traps, 2 sites - 45,000 seeds 2013-2014
epiphytic baits on host trees
Terrestrial baits buried under some humus
165 traps in total - approx. 123,750 seeds
C. flavum - 30 traps, 2 sites 45,000 seeds 2013-2014
E. alta - 15 traps, 1 site, 2014
E. graminea - 30 traps, 1 site 2014-2015
checked every 6 weeks
111 protocorms collected from traps in total
Isolation of peloton
pure fungal culture from root tissue - structure inside root
root surface sterilized, tissue isolated, fungal culture derived from pelotons
Tissue remnants - DNA identification
Isolates - germination assays
Ex situ germination
incubation period 25 celcius in the dark , 4-16 week
protocorm development monthly charting
seeds sterilized - wood agar dish inoculated with fungi and designated into four sections - 5-20 seeds of each sp. in each section
calculation of germination rates
isolates from phylum Basidiomycota
19 fungal isolate - tested on all 4 sp.
took place 2015-2017
Molecular Analysis
BLAST search against known fungal sequences
Consensus tress - three
OMF designation
OTU per species
MPD, PD, SES
Shannon-Weiner Index
DNA extraction, PCR, sequencing
3 fungal primer pairs - universal, basidiomycota, Tul. specific
PCR amplification
Gel electrophoresis - PCR storage
plant tissue = genomic DNA, liquid culture = isolates -DNeasy kit
Post PCR clean up - storage
sequence rxns - storage
Sanger seq. - storage
GenBank
Results
4 shared OTU between native/nonnative
52% of sequences were OMF - 48% sequences pathogenic assoc. (ERH)
6 shared OTU between atleast 2 sp.
29 OTU - 2 native sp.
53 fungal OTU
27 OTU - 2 invasive sp.
89 fungal ITS sequences
Natives - 52% of fungi OTU were pathogenic
Nonnatives - 75% of fungi OTU were OMF
Phylogenetic Analyses
Ascomycota - 21 fungal OTUs - 23 sequences
most sequences were assoc. with root pathogens
2 fungi common among all plants
more ascomycota in native than nonnative in all sites
consensus trees
NTB - 22 fungal OTUs - 31 sequences
TUL - 11 distinct OTU - 35 sequences
second most abundant - TUL - OMF
2 distinct clades - nonnatives associated with one clade more
Clade A - 2 OTUs - associated with nonnative
Clade B - 4 OTUs - one assoc. with native and nnonnative
Fungal Diversity
OMF - NTB and Tul. combined - higher at nonnative areas - more diversity as well at nonnative sites
more asco. in natives than nonnative - more diversity in natives than nonnatives
extent of diversity
nonnatives assoc. with a wider extent of fungi than natives
Discussion
association with TUL - tulsanella sp. OMF 50 perfect or more in both natives and nonnatives
tulsanella and biodiversity - site specific
Invasives associate with diverse OMF - moreso than natives - invasives also assoc. less with pathogen fungi ascomycota
epi vs terrestrial rhizosphere differences
ERH role in nonnative spreading
root pathogen interaction with mycorrhizal fungi
Conclusion
nonnatives
more OMF diversity
less pathogenic fungi - ascomycota
higher germination rates
ERH and generalist trait allow range expansion
fungal interactions effect population variables
fungal interactions also effect range
variables that effect fungal communities - climate
CSE Citation
Downing JL, Liu H, McCormick MK, Arce J, Alonso D, Lopez-Perez J. 2020. Generalized mycorrhizal interactions and fungal enemy release drive range expansion of orchids in southern Florida. Ecosphere. 11(8). doi:10.1002/ecs2.3228.
http://dx.doi.org/10.1002/ecs2.3228
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