LEE, K. P., PISKUREWICZ, U., TUREČKOVÁ, Veronika, STRNAD, Miroslav, LOPEZ-MOLINA, L. A seed coat bedding assay shows that RGL2-dependent release of abscisic acid by the endosperm controls embryo growth in Arabidopsis dormant seeds. Proceedings of the National Academy of Sciences of the United States of America. 2010, 107(44), 19108-19113. ISSN 0027-8424. E-ISSN 1091-6490

Seed dormancy is an ecologically important adaptive trait in plants whereby germination is repressed even under favorable germination conditions such as imbibition with water. In Arabidopsis and most plant species, dormancy absolutely requires an unidentified seed coat germination-repressive activity and constitutively higher abscisic acid (ABA) levels upon seed imbibition. The mechanisms underlying these processes and their possible relationship are incompletely understood. We developed a "seed coat bedding" assay monitoring the growth of dissected embryos cultured on a layer of seed coats, allowing combinatorial experiments using dormant, nondormant, and various genetically modified seed coat and embryonic materials. This assay, combined with direct ABA measurements, revealed that, upon imbibition, dormant coats, unlike nondormant coats, actively produce and release ABA to repress embryo germination, whatever the embryo origin.