DOI: 10.5061/dryad.7d7wm381z
title: Decadal survival of tropical pioneer seeds in the soil seedbank is accompanied by fungal infection and dormancy release

description: Pioneer trees require high-light environments for successful seedling
 establishment. Consequently, seeds of these species often persist in the
 soil seed bank (SSB) for periods ranging from several weeks to decades.
 How they survive despite extensive pressure from seed predators and
 soilborne pathogens remains an intriguing question. This study aims to
 test the hypotheses that decades-old seeds collected from the SSB in a
 lowland tropical forest remain viable by i) escaping infection by fungi,
 which are major drivers of seed mortality in tropical soils, and/or ii)
 maintaining high levels of seed dormancy and seed coat integrity when
 compared to inviable seeds. We collected seeds of Trema micrantha
 and Zanthoxylum ekmanii at Barro Colorado Island, Panama, from sites where
 adult trees previously occurred in the past 30 years. We used carbon
 dating to measure seed age and characterized seed coat integrity, seed
 dormancy, and fungal communities. Viable seeds from the SSB ranged in age
 from 9 to 30 years for T. micrantha, and 5 to 33 years for Z.
 ekmanii. We found no evidence that decades-old seeds maintain high levels
 of seed dormancy or seed coat integrity. Fungi were rarely detected in
 fresh seeds (no soil contact), but phylogenetically diverse fungi were
 detected often in seeds from the SSB. Although fungal infections were more
 commonly detected in inviable seeds than in viable seeds, a lack of
 differences in fungal diversity and community composition between viable
 and inviable seeds suggested that viable seeds are not simply excluding
 fungal species to survive long periods in the SSB. Synthesis: Our findings
 reveal the importance of a previously understudied aspect of seed
 survival, where the impact of seed-microbial interactions may be critical
 to understand long-term persistence in the SSB.
description: Seeds were extracted from soil cores by rinsing the soil with tap
 water under a series of sieves, with a minimum pore diameter of 2 mm for
 <em>Z. ekmanii</em> and 1 mm for <em>T.
 micrantha</em>. Seeds were identified to species and then
 partitioned for tests of i) seed viability measured using the tetrazolium
 test and seed-endophyte isolation frequency (692 and 593 seeds of
 <em>T. micrantha</em> and <em>Z. ekmanii,</em>
 respectively), ii) germination (% of germinated and dormant seeds) and
 carbon dating (a total of 239 and 196 seeds of <em>T. micrantha
 </em>and <em>Z. ekmanii</em>, respectively, where 9
 viable seeds of each species were carbon dated), and iii) average seed
 fracture resistance as a measure of seed coat integrity (224 and 142 seeds
 of <em>T. micrantha </em>and <em>Z. ekmanii</em>,
 respectively).
description: This README file was generated on 2023-11-07 by Carolina Sarmiento and
 Paul-Camilo Zalamea. GENERAL INFORMATION 1\. Title of the dataset: Decadal
 survival of tropical pioneer seeds in the soil seedbank is accompanied by
 fungal infection and dormancy release 2\. Author information: Principal
 Investigator - Corresponding author Name: Paul-Camilo Zalamea Institution:
 University of South Florida (Tampa, FL - USA) and Smithsonian Tropical
 Research Institute (Panama, Republic of Panama) E-mail:
 paulcamiloz@usf.edu or camilozalamea@gmail.com 3\. Date of data
 collection: July \- December\, 2014 4\. Geographic location of data
 collection: Barro Colorado Island\, Republic of Panama 5\. Funding sources
 that supported the collection of the data: NSF DEB\-1120205\, NSF
 DEB\-1119758\, Lawrence Livermore National Laboratory\-Contract
 DE\-AC52\-07NA27344 SHARING/ACCESS INFORMATION 1\. Licenses/restrictions
 placed on the data: CC0 1\.0 Universal \(CC0 1\.0\) Public Domain 2\.
 Publications that use the data: Zalamea, P.-C., Sarmiento, C., Arnold, A.
 E., Kuo, V., Delevich, C., Davis, A. S., Brown, T. A., & Dalling,
 J. W. (2023). Decadal survival of tropical pioneer seeds in the soil
 seedbank is accompanied by fungal infection and dormancy release.
 Functional Ecology 3\. Recommended citation for this dataset: Zalamea,
 Paul-Camilo et al. (2023). Decadal survival of tropical pioneer seeds in
 the soil seedbank is accompanied by fungal infection and dormancy release
 [Dataset]. Dryad. https://doi.org/10.5061/dryad.7d7wm381z DATA AND FILE
 OVERVIEW 1\. File list and description: A)
 Zalamea\_et\_al\_Isolation\_Frequency.csv: Isolation frequency of fungi
 from fresh and old seeds of Trema micrantha and Zanthoxylum ekmanii B)
 Zalamea\_et\_al\_Germination\_Dormancy.csv: Percentage of seeds that were
 dormant and germinable from fresh and old seeds of Trema micrantha and
 Zanthoxylum ekmanii C) Zalamea\_et\_al\_Seed\_Fracture\_Resistance.csv:
 Seed fracture resistance of fresh and old seeds of Trema micrantha and
 Zanthoxylum ekmanii 2\. Are there multiple versions of the dataset? No
 ###################################################################
 DATA-SPECIFIC INFORMATION FOR: Zalamea\_et\_al\_Isolation\_Frequency.csv
 1\. Number of variables: 5 2\. Number of rows: 27 3\. Variable list: \*
 species: Plant species included in this study (Trema micrantha,
 Zanthoxylum ekmanii) \* seed\_age\_years: Seed age (years) estimated using
 accelerator mass spectrometry (ages represent averages of three dated seed
 coats) or using the census year when the tree under which we collected the
 seed sample was first reported dead in the 50ha plot in BCI. Seed age 0
 refers to fresh seeds i.e., seeds that were collected from trees and were
 not buried \* viability: Seed viability estimated using 2, 3, 5-triphenyl
 tetrazolium chloride (viable = alive, inviable = dead) \*
 total\_number\_seeds: Total number of seeds that were screened for fungal
 growth \* isolation\_frequency: Fungal isolation frequency estimated as
 the number of seeds/cultures that had fungal growth divided by the total
 number of screened seeds 4\. Missing data codes: None 5\. Specialized
 formats or other abbreviations used: None
 ###################################################################
 DATA-SPECIFIC INFORMATION FOR: Zalamea\_et\_al\_Germination\_Dormancy.csv
 1\. Number of variables: 5 2\. Number of rows: 21 3\. Variable list: \*
 species: Plant species included in this study (Trema micrantha,
 Zanthoxylum ekmanii) \* seed\_age\_years: Seed age (years) estimated using
 accelerator mass spectrometry (ages represent averages of three dated seed
 coats) or using the census year when the tree under which we collected the
 seed sample was first reported dead in the 50ha plot in BCI. Seed age 0
 refers to fresh seeds (i.e., seeds that were collected from six different
 maternal sources and were not buried) \* total\_number\_seeds: Total
 number of seeds that were used for the germination/dormancy assays \*
 germination\_percentage: Percentage of germinated seeds calculated as the
 number of germinated seeds that germinated divided by the total number of
 seeds that were used for the germination assays \* dormancy\_percentage:
 Percentage of dormant seeds calculated as the number of seeds that did not
 germinate in the germination assays but that were viable (alive) after
 testing with 2, 3, 5-triphenyl tetrazolium chloride (i.e., dormant seeds)
 divided by the total number of screened seeds 4\. Missing data codes: None
 5\. Specialized formats or other abbreviations used: None
 ###################################################################
 DATA-SPECIFIC INFORMATION FOR:
 Zalamea\_et\_al\_Seed\_Fracture\_Resistance.csv 1\. Number of variables: 5
 2\. Number of rows: 25 3\. Variable list: \* species: Plant species
 included in this study (Trema micrantha, Zanthoxylum ekmanii) \*
 seed\_age\_years: Seed age (years) estimated using accelerator mass
 spectrometry (ages represent averages of three dated seed coats) or using
 the census year when the tree under which we collected the seed sample was
 first reported dead in the 50ha plot in BCI. Seed age 0 refers to fresh
 seeds (i.e., seeds that were collected from six different maternal sources
 and were not buried) \* viability: Seed viability estimated using 2, 3,
 5-triphenyl tetrazolium chloride (viable = alive, inviable = dead). For
 fresh seeds (i.e., seed age = 0) viability was not recorded (NA, data not
 available) \* total\_number\_seeds: Total number of seeds that were used
 for the seed fracture resistance test \* seed\_fracture\_resistance: Seed
 fracture resistance (in Newtons (N)) defined as the minimum force required
 to initiate seed coat rupture, measured using an Instron Single Column
 Testing System Model 3342 (Instron Company, USA). The shown values
 represent the average seed fracture resistance of the total number of
 seeds individually tested 4\. Missing data codes: NA \(data not
 available\) 5\. Specialized formats or other abbreviations used: None