www.landesbioscience.com Plant Signaling & Behavior e25422-1

Somatic embryogenesis (SE) is a process by which somatic cells become dedifferentiated and are able to reprogram to follow an embryogenic pathway. It is important agronomically to regener-ate plants from transformed cells and to propagate desirable gen-otypes. What determines competence for SE remains a mystery that was featured in “What don’t we know ” in Science magazine several years ago.1 Explants from different tissues can exhibit very different competence for SE and this can vary with age of the tissue and particular genotype within a species. Some genes have been identified that can promote SE when ectopically expressed and these include the MADS-box transcription factor AGAMOUS-Like 15 (AGL15) that can promote SE in two systems in the model plant Arabidopsis thaliana.2,3 Furthermore, a Glycine max (soy-bean) ortholog of AGL15, designated GmAGL15, can promote recovery of transgenic plants when constitutively expressed via the 35S promoter, presumably by enhancing regeneration of the Decreased GmAGL15 expression and reduced ethylene synthesis may contribute to reduced somatic embryogenesis in a poorly embryogenic cultivar of Glycine ma