Abstract
AbstractSeeds have evolved to be highly efficient environmental sensors that respond not only to their prevailing environment, but also their environmental history, to regulate dormancy and the initiation of germination. In the present work we investigate the combined impact of a number of environmental signals (temperature, nitrate, light) during seed development on the mother plant, during post-shedding imbibition and during prolonged post-shedding exposure in both dry and imbibed states, simulating time in the soil seed bank. The differing response to these environments was observed in contrasting winter (Cvi, Ler) and summer (Bur) annualArabidopsisecotypes. Results presented show that environmental signals both pre- and post-shedding determine the depth of physiological dormancy and therefore the germination response to the ambient environment. The ecotype differences in seed response to ambient germination conditions are greatly enhanced by seed maturation in different environments. Further variation in response develops following shedding when seeds do not receive the full complement of environmental signals required for germination and enter the soil seed bank in either dry or imbibed states. Species seed dormancy characteristics cannot therefore be easily defined, as seed dormancy is a dynamic state subject to within-species adaptation to local environments.
Highlights
Seeds have evolved to be highly efficient sensors and interpreters of the prevailing environment, and their environmental history, in order to regulate physiological dormancy and the initiation of germination
To increase understanding of the flexibility of germination responses within a single species, we compared the impact of environmental signals preand post-shedding on dormancy and the germination of seeds from contrasting winter- (Cvi or Ler) and summer-annual (Bur) ecotypes of Arabidopsis
In a series of experiments the seeds were produced under different controlled environments and, to indicate behaviour in the soil seed bank, seeds were exposed to a range of dry and moist post-shedding environments
Summary
Seeds have evolved to be highly efficient sensors and interpreters of the prevailing environment, and their environmental history, in order to regulate physiological dormancy and the initiation of germination This takes the form of sensing the maternal environment (light, nitrate and temperature) (Sawhney et al, 1985; Alboresi et al, 2005; Kendall et al, 2011; Kendall and Penfield, 2012; Penfield and Springthorpe, 2012; He et al, 2014; Huang et al, 2014) and the environment of the soil seed bank (light, nitrate and temperature) (Footitt et al, 2011, 2013, 2014; Finch-Savage and Footitt, 2012; Penfield and Springthorpe, 2012). In the present work we consider the combined impact of a number of environmental signals (described below) upon the depth of seed dormancy in Arabidopsis ecotypes with contrasting life cycles, to improve understanding of environmental adaptation
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