Embryogenesis in flowering plants establishes multicellularity from a single reproductive cell, the zygote. After fertilization, the zygote undergoes several rounds of controlled cell divisions to generate a mature embryo. However, embryo formation can also be induced in a variety of other cell types. These non-zygotic embryos go through analogous developmental phases and are morphologically similar to the zygotic embryo, although their initial cell division pattern is often less regular. Despite its fundamental importance and enormous application potential, the mechanisms that alter cell fate from non-embryonic to embryonic are elusive. In the past decades, a variety of different model systems have been used to identify regulators of embryo induction, but it is unclear if these act in a common network. We recently found that inhibition of auxin response in the extra-embryonic suspensor cells cell autonomously and predictably triggers a switch towards embryo identity. We here use the suspensor as a uniform model system to studying the crucial first reprogramming step of embryo initiation. To identify a complete set of genes that can induce embryogenesis, we established a systematic targeted misexpression screen using the two-component GAL4/UAS system.
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Waki et al. (2013). Plant J 73, 357-367.