Raw data of germination tests for dormancy study (three experimental trials)

Seeds should not germinate under conditions in which seedling development cannot be sustained. Dormancy, which allows seeds to remain inactive in an environment that would otherwise enable germination, helps optimize the timing of germination. The induction of a secondary type of dormancy after seed dispersal allows a close fine-tuning of germination to prevailing environmental conditions. In this study, we explore the relevance of secondary dormancy in response to heat for adaptation to local environments by characterizing natural variation in heat-induced secondary dormancy within a collection of 361 Arabidopsis thaliana accessions originating from across the European geographical range. We observed a latitudinal pattern in the variation of heat-induced secondary dormancy in European Arabidopsis thaliana, reflecting adaptation to variation in temperature and precipitation along this gradient. Species distribution models suggest that the phenotypic distribution of secondary dormancy has shifted in the past, in response to changes in temperature and precipitation changes, and is predicted to continue so in the coming years. We found that the acquisition of secondary dormancy varies with levels of primary dormancy and after-ripening. However, we identified several regions in the genome that specifically controlled the levels of secondary dormancy. Our findings show that secondary dormancy is a complex adaptive mechanism contributing to the dormancy trait syndromes that favors plant survival under harsh climates.
The samples used in this study originated from a collection of 361 accessions across Europe (Table S1). Genotype and accession information was obtained from the 1001 Genome database (1001genomes.org; 1001 Genomes Consortium, 2016) as well as from Wieters et al. (2021). Seed material was amplified at University of Cologne: plants were grown in growth chamber (producer, model) under long day condition 16:8 (hours) light: dark at 200C (day) : 180C night (termed “standard condition” hitherto); mature dry seeds were harvested, and packed in paper bags. The experiment was replicated on one seed batch, approximately six months (May 2022 - “Trial1”, one year (December 2022) - “Trial2”, and two years (December 2023) - “Trial3”, after seed harvest. Due to practical limitations, the first batch used a set of 295 accessions, the second batch used a full set of 361 accessions, and the third batch a set of 344 accessions.