Research Article

Central Cell–Derived Peptides Regulate Early Embryo Patterning in Flowering Plants

Science  11 Apr 2014:
Vol. 344, Issue 6180, pp. 168-172
DOI: 10.1126/science.1243005

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Tripeptide Maternal Support

In flowering plants, fertilization involves multiple gametes. The diploid zygote, which will form the embryonic plant, is surrounded by the often triploid endosperm, which provides a supportive and nourishing function. Working in Arabidopsis, Costa et al. (p. 168; see the Perspective by Bayer) identified a trio of small signaling peptides that derive from the endosperm but that regulate growth of the embryo. RNA interference was used to down-regulate expression of all three peptides. Fertilization was not affected, but seed growth was. The peptides were critical for normal development of the suspensor, which tethers and nourishes the growing embryo.

Abstract

Plant embryogenesis initiates with the establishment of an apical-basal axis; however, the molecular mechanisms accompanying this early event remain unclear. Here, we show that a small cysteine-rich peptide family is required for formation of the zygotic basal cell lineage and proembryo patterning in Arabidopsis. EMBRYO SURROUNDING FACTOR 1 (ESF1) peptides accumulate before fertilization in central cell gametes and thereafter in embryo-surrounding endosperm cells. Biochemical and structural analyses revealed cleavage of ESF1 propeptides to form biologically active mature peptides. Further, these peptides act in a non–cell-autonomous manner and synergistically with the receptor-like kinase SHORT SUSPENSOR to promote suspensor elongation through the YODA mitogen-activated protein kinase pathway. Our findings demonstrate that the second female gamete and its sexually derived endosperm regulate early embryonic patterning in flowering plants.

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