Abstract
Preservation of genetic diversity within germplasm repositories represents an important tool for plant conservation. However, seeds must tolerate extreme levels of post-harvest desiccation and cold to realize benefits of ex situ storage. Factors including local climate and habitat impact expression of desiccation and freezing tolerance especially for widely distributed species. Our aim here was to understand the influence of a latitudinal gradient on seed desiccation and cryo-freezing tolerance. We sampled mature U. paniculata seeds from two geographically and genetically distinct populations then examined seed-water relations and germination following desiccation via equilibrium drying assays (0.5 to 91% RH; −797 to −12.9 MPa). Germination ability after drying and subsequent cryo-freezing treatments (−196 °C, 1 to 1440 min) was also evaluated. Seeds of both populations displayed similar reverse sigmoid moisture sorption isotherms characteristic of desiccation tolerant tissues. Furthermore, initial seed water potential (−63 and −90 MPa) was considerably lower than the lethal limit (−20 MPa) identified for desiccation sensitive tissues. Final germination (range 58–93%) and temporal patterns differed significantly between populations following desiccation and cryo-freezing stress, but these germination responses were similar to initial germination. A higher proportion of non-germinated, yet viable seeds remained for the northern compared to southern population. Location does influence germination response, but differential germination is related to seed dormancy rather than desiccation or cryo-freezing sensitivity. Ex situ conservation of U. paniculata is therefore feasible across the latitudinal gradient studied here.
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Abbreviations
- LN:
-
Liquid nitrogen
- NEF:
-
Northeast Florida
- SWF:
-
Southwest Florida
- t50 :
-
Time in days for germination of the 50th (median) percentile of the seed population.
- 1 t50 −1 :
-
Germination rate
- U :
-
Germination uniformity
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Acknowledgements
We thank Fé Almira, James Sadler, Nancy Philman and Dale Haskell for technical assistance with experimental set up, data collection and data processing. We are grateful to Aquatic Plants of Florida Inc., for seed cleaning services. We also thank Gabriel Campbell, Amber Gardner, Nicholas Genna, Tia Tyler and anonymous reviewers for their constructive comments. This work was supported by the U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Sea Grant Office (Grant No. NA100AR4170079). The funding agency was not involved with study design; date collection, analysis and interpretation; report writing; and the decision to submit the article for publication.
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The Florida Department of Environmental Protection, Division of Recreation and Parks, Florida Park Service granted permission (permit # 09181420) for seed collection.
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HEP and MEK conceived and designed the research. HEP analyzed data and wrote the manuscript. MEK provided editorial comments. All authors read and approved the manuscript.
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Pérez, H.E., Kane, M.E. Different plant provenance same seed tolerance to abiotic stress: implications for ex situ germplasm conservation of a widely distributed coastal dune grass (Uniola paniculata L.). Plant Growth Regul 82, 123–137 (2017). https://doi.org/10.1007/s10725-016-0244-1
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DOI: https://doi.org/10.1007/s10725-016-0244-1