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Seed dormancy cycling and mortality differ between two locally adapted populations of Arabidopsis thaliana
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution. WWF Norway, Postboks 6784, N-0130 Oslo, Norway..
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
2016 (English)In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 117, no 2, 249-256 p.Article in journal (Refereed) PublishedText
Abstract [en]

Background and Aims Intraspecific variation in seed bank dynamics should contribute to local adaptation, but is not well studied. The extent to which genetic and environmental factors affect dormancy cycling and seed mortality was investigated in the annual herb Arabidopsis thaliana by conducting a reciprocal seed burial experiment. Methods Seeds from two locally adapted populations (from Italy and Sweden) were buried at both of the sites of origin, and seed mortality and germinability were determined during the following 2 years for initially non-dormant glasshouse-matured seeds and dormant field-matured seeds. Key Results Mean soil temperature was higher at the Italian site compared with the Swedish site throughout the year, and the germination proportions were in general higher for seeds buried in Italy than in Sweden. The rate of secondary dormancy induction of the Italian genotype was faster than that of the Swedish genotype at both sites, while the opposite was true for the rate of dormancy release, at least at the Swedish site. The comparison of nondormant glasshouse seeds with dormant field seeds demonstrated that A. thaliana seeds can adjust their dormancy levels to current environmental conditions, and suggests that maternal environmental conditions have only minor effects on dormancy cycles. At both sites, locally produced seeds had low germinability in the first year compared with the second year, suggesting that a considerable fraction of the seeds would enter the seed bank. In Italy, but not in Sweden, seed mortality increased rapidly during the second year of burial. Conclusions This is the first demonstration of intraspecific genetic differentiation in the annual seed dormancy cycle of any species, and the documented difference is likely to contribute to local adaptation. The results suggest that the contribution of a seed bank to seedling recruitment should vary among environments due to differences in the rate of seed mortality.

Place, publisher, year, edition, pages
2016. Vol. 117, no 2, 249-256 p.
Keyword [en]
Arabidopsis thaliana, bet-hedging, dormancy cycling, local adaptation, natural variation, physiological dormancy, secondary dormancy, seed bank, seed mortality, seed predation
National Category
URN: urn:nbn:se:uu:diva-281828DOI: 10.1093/aob/mcv171ISI: 000370194800003PubMedID: 26637384OAI: oai:DiVA.org:uu-281828DiVA: diva2:917260
Swedish Research Council
Available from: 2016-04-06 Created: 2016-03-30 Last updated: 2016-09-12Bibliographically approved
In thesis
1. Selection during Early Life Stages and Local Adaptation in Arabidopsis thaliana
Open this publication in new window or tab >>Selection during Early Life Stages and Local Adaptation in Arabidopsis thaliana
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Organisms are often adapted to their local environment, but the role of early life stages in adaptive differentiation among populations remains poorly known. The aim of my thesis was to investigate the contribution of early life stages to the magnitude and genetic basis of local adaptation, and to identify the underlying adaptive traits. For this, I used two natural populations of the annual plant Arabidopsis thaliana from Italy and Sweden, and a Recombinant Inbred Line (RIL) population derived from a cross between these populations. By combining greenhouse and field experiments, Quantitative Trait Loci (QTL) mapping, and path analysis, I examined (1) the genetic basis of seed dormancy, (2) the contribution of differential seedling establishment to local adaptation, (3) among-year variation in selection during seedling establishment, (4) direct and indirect effects of seed dormancy and timing of germination on fitness, and (5) the adaptive value of the seed bank.

I found that both the level and the genetic basis of seed dormancy were affected by the maternal environment. One major-effect QTL was identified in all maternal environments, which overlaps with the dormancy gene DELAY OF GERMINATION 1 (DOG1).

Selection through seedling establishment success contributed strongly to local adaptation and genetic tradeoffs, and varied among years. Variation in seedling establishment and overall fitness among RILs could be explained by genetically based differences in seed dormancy and timing of germination. Seed dormancy affected fitness throughout the life cycle, by affecting the proportion of germinated seeds, and indirectly via effects on timing of germination, plant size and flowering time.

My results suggest that a considerable portion of A. thaliana seeds enter the seed bank. I found genetic differences in dormancy cycling behaviour between the two populations, which could contribute to local adaptation. The value of a seed bank should be higher at the Swedish study site than at the Italian study site due to lower rate of seed mortality in the soil.

Overall, the results of this thesis demonstrate that early life stages contribute strongly to both the magnitude and the genetics of local adaptation.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 51 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1425
Dormancy cycling, Germination timing, Maternal effects, Natural variation, QTL mapping, Seed bank, Seed dormancy, Structural Equation Modeling
National Category
Evolutionary Biology Ecology Botany
Research subject
Biology with specialization in Ecological Botany
urn:nbn:se:uu:diva-302862 (URN)978-91-554-9687-6 (ISBN)
Public defence
2016-10-28, Zootissalen, Villavägen 9, Uppsala, 10:00 (English)
Available from: 2016-10-05 Created: 2016-09-12 Last updated: 2016-10-11

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