Endosperm development is an autonomously programmed process independent of embryogenesis

Abstract

The seeds of land plants contain three genetically distinct structures: the embryo, endosperm, and seed coat. The embryo and endosperm need to interact and exchange signals to ensure coordinated growth. Accumulating evidence has confirmed that embryo growth is supported by the nourishing endosperm and regulated by signals originating from the endosperm. Available data also support that endosperm development requires communication with the embryo. Here, using single-fertilization mutants, Arabidopsis dmp8/9 and gex2, we demonstrate that in the absence of a zygote and embryo, endosperm initiation, syncytium formation, free nuclear cellularization, and endosperm degeneration are as normal as in the wild type in terms of the cytological process and time course. Although rapid embryo expansion accelerates endosperm breakdown, our findings strongly suggest that endosperm development is an autonomously organized process, independent of egg cell fertilization and embryo-endosperm communication. This work confirms both the altruistic and self-directed nature of the endosperm during coordinated embryo-endosperm development. The findings provide novel insights into the intricate interaction between the two fertilization products and will help to distinguish the real roles of the signaling between endosperm and embryo. These finding also shed new light on agro-biotechnology for crop improvement.