Format: ORAL

Diana Mara Cruz Tejada1,Clara Espinosa del Alba2, Alessio Mo1, Alice Fuggirai1, Stefania Bottega1,Eduardo Fernndez Pascual2, Angelino Carta1

1 University of Pisa, Pisa, Italy 2 IMIB Biodiversity Research Institute (University of Oviedo CSIC Principality of Asturias), University of Oviedo, Mieres, Spain

Plant species living in coastal sand dunes face survival challenges from harsh environmental conditions like high soil temperature and low water availability that climate changes could exacerbate. The regeneration of annual plant species depends on seeds, thus they may be particularly vulnerable to climate-induced environmental changes. We studied seed responses of annual dune species to environmental cues in the laboratory, with the aim of identifying the thermal and water potential germination limits, as these could be critical to forecast the germination risk. We sampled characteristic annual species in Mediterranean back dune grasslands: Festuca fasciculata(Poaceae), Marcus-kochia ramosissima (Brassicaseae)and Silene canescens (Caryophyllaceae). Fresh and after-ripened seeds were exposed to different temperature and light regimes. To explore water stress responses, seeds were exposed to different water potential levels. After-ripening overcame dormancy allowing for germination responses at most temperatures and light conditions in F. fascitulata and S. canescens. M. ramossima had very low germination under all treatments except when exposed to GA3, thus this species probably exhibits deeper dormancy compared to the other two annuals. While F. fasciculata exhibited broader temperature and water potential germination niches (Psib50 = -0.83) compared to S. canescens (Psib50 = -0.24), the former species exhibited a thermal germination risk compared to the latter, which did not exhibit a risk.Whilst light positively affected seed germination under no water stress, a negative effect was detected when seeds were exposed to water stress, indicating photoinhibition of seed germination under these conditions for all species. In conclusion, we found common responses among phylogenetically distant species (F. fasciculata and S. canescens) concerning the environmental cues examined. In particular, seeds can integrate water and light signals from their environment to modulate their germination responses to avoid the risk of seedling mortality that may occur in water stress scenarios.