With climate change, germination cuing to water availability is expected to be especially important for seedling survival. Here, we examined germination responses to low water potential and tested whether dormancy status mediates these responses. We considered both genetically based dormancy (genotypes with allelic variation in dormancy genes) as well as dormancy imposed by the environment (low seed-maturation temperature or short duration of dry afterripening). We examined (a) germination capacity at low water potential, (b) germination acceleration in response to pre-incubation at low water potential, and (c) secondary dormancy induction by low water potential. We found that both environmentally imposed dormancy and genetically based dormancy influenced germination responses to low water potential. Specifically, dormancy established via introgression of a strong dormancy allele and dormancy induced by low seed-maturation temperatures both reduced the ability to germinate at low water potential. Pre-incubation at low water potential accelerated germination, but the rate differed between both dormancy-inducing environments and among dormancy genotypes. Prolonged incubation at low water potential induced secondary dormancy, and this effect was greater in fresher (more dormant) seeds and in seeds that were matured at low temperature (a dormancy-inducing treatment). Although genotypes also varied in secondary dormancy induction, their level of primary dormancy did not predict their induction into secondary dormancy. Environmentally induced dormancy also influenced the expression of genetic differences in germination responses to low water potential. Thus environmentally determined dormancy influences not only germination responses to low water potential but also their evolutionary potential.
Bibliographical noteFunding Information:
We thank M. Koorneef and L. Bentsink for providing the genetic material. We are grateful to the staff at the Duke Phytotron for providing excellent plant care. We would also like to thank Lien Hoang, Meg Dalrymple and the Donohue lab undergraduate team who participated in the data collection for these experiments. The manuscript benefitted enormously from conversations with and specific suggestions from Lindsay Leverett, Gabriela Auge, Toshiyuki Imaizumi, Michelle D’Aguillo, and Chunhui Zhang. This work was supported by NSF grants DEB-1020963 and NSF-IOS-11-46383 to KD. The work was also supported by sabbatical fellowships to KD from the John Simon Guggenheim Foundation and the National Evolutionary Synthesis Center , National Science Foundation EF-0905606 .
© 2016 Elsevier B.V.
- Genetic variation
- Maternal effects
- Secondary Dormancy
- Water availability