The embryo sheath is an anti-adhesive structure that facilitates cotyledon emergence during germination in Arabidopsis ($) (Curr. Biol.)

The embryo sheath is a glycoprotein structure formed during seed maturation in Arabidopsis thaliana. However, its function and its persistence after germination have been uncertain. Here, Doll et al. examined germination and seedling establishment of krs mutants deficient in the KERBEROS peptide that had been previously identified as contributing to embryo sheath formation. By using immunolabelling, the authors demonstrate that the embryo sheath is maintained on the seedling surface after germination. However, in the krs seedlings this structure is missing. Moreover, Doll et al. found that the genetic basis of sheath and cuticle formation is independent, given the cuticle-deficient mutants do have the embryo sheath. Interestingly, the authors found the embryo sheath facilitated cotyledon emergence because it reduces embryo adhesiveness with the rest of seed internal components. Moreover, competition assays showed that wild type seedlings outperformed the krs mutants, suggesting that the embryo sheath has a significant impact on seedling establishment. (Summary by Carlos A. Ordóñez-Parra) Curr. Biol. j.cub.2019.12.057