The suspensor: not just suspending the embryo.

The suspensor is a terminally differentiated embryonic region that connects the embryo to surrounding tissues during early seed development. Most seed-bearing plant embryos contain suspensor regions, which occur in a wide variety of sizes and shapes, and suspensor-like structures are present in the embryos of some lower land plants. Recent technological advances, including novel genomics approaches, have provided insights into the function of the suspensor and the DNA sequences that control suspensor-specific gene expression. The molecular mechanisms controlling embryo basal-cell lineage specification and suspensor differentiation events are also beginning to be illuminated. Here, we summarize the role of the suspensor in plant embryogenesis and discuss future directions of suspensor biology, including the dissection of suspensor gene regulatory networks.