Seed dormancy is an important component of plant fitness
that causes a delay of germination until the arrival of a
favourable growth season. Dormancy is a complex trait that
is determined by genetic factors with a substantial environmental
influence. Several of the tissues comprising a seed
contribute to its final dormancy level. The roles of the plant
hormones abscisic acid and gibberellin in the regulation of
dormancy and germination have long been recognized. The
last decade saw the identification of several additional
factors that influence dormancy including dormancyspecific
genes, chromatin factors and non-enzymatic processes.
This review gives an overview of our present
understanding of the mechanisms that control seed dormancy
at the molecular level, with an emphasis on new
insights. The various regulators that are involved in the
induction and release of dormancy, the influence of environmental
factors and the conservation of seed dormancy
mechanisms between plant species are discussed. Finally,
expected future directions in seed dormancy research are
considered.