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First published online December 15, 2006; 10.1105/tpc.106.047266 The Plant Cell 18:3491-3501 (2006) © 2006 American Society of Plant Biologists The Female Gametophyte and the Endosperm Control Cell Proliferation and Differentiation of the Seed Coat in Arabidopsis[W]Chromatin and Reproduction Group, Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Republic of Singapore 1 To whom correspondence should be addressed. E-mail fred{at}tll.org.sg; fax 65-68727007.
Double fertilization of the female gametophyte produces the endosperm and the embryo enclosed in the maternal seed coat. Proper seed communication necessitates exchanges of signals between the zygotic and maternal components of the seed. However, the nature of these interactions remains largely unknown. We show that double fertilization of the Arabidopsis thaliana female gametophyte rapidly triggers sustained cell proliferation in the seed coat. Cell proliferation and differentiation of the seed coat occur in autonomous seeds produced in the absence of fertilization of the multicopy suppressor of ira1 (msi1) mutant. As msi1 autonomous seeds mostly contain autonomous endosperm, our results indicate that the developing endosperm is sufficient to enhance cell proliferation and differentiation in the seed coat. We analyze the effect of autonomous proliferation in the retinoblastoma-related1 (rbr1) female gametophyte on seed coat development. In contrast with msi1, supernumerary nuclei in rbr1 female gametophytes originate mainly from the endosperm precursor lineage but do not express an endosperm fate marker. In addition, defects of the rbr1 female gametophyte also reduce cell proliferation in the ovule integuments before fertilization and prevent further differentiation of the seed coat. Our data suggest that coordinated development of the seed components relies on interactions before fertilization between the female gametophyte and the surrounding maternal ovule integuments and after fertilization between the endosperm and the seed coat. This article has been cited by other articles:
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