In Arabidopsis, rapid expansion of the coenocytic endosperm after fertilisation has been proposed to drive early seed growth, which is in turn constrained by the seed coat. This hypothesis implies physical heterogeneity between the endosperm and seed coat compartments during early seed development, which to date has not been demonstrated. Here, we combine tissue indentation with modelling to show that the physical properties of the developing seed are consistent with the hypothesis that elevated endosperm-derived turgor pressure drives early seed expansion. We provide evidence that whole-seed turgor is generated by the endosperm at early developmental stages. Furthermore, we show that endosperm cellularisation and seed growth arrest are associated with a drop in endosperm turgor pressure. Finally, we demonstrate that this decrease is perturbed when the function of POLYCOMB REPRESSIVE COMPLEX 2 is lost, suggesting that turgor pressure changes could be a target of genomic imprinting. Our results indicate a developmental role for changes in endosperm turgor pressure in the Arabidopsis seed.
The authors declare no competing or financial interests.
L.B., C.F., N.D. and Y.B. carried out experiments, analysed results and prepared figures. All authors participated in experimental design and in manuscript preparation. G.I. and A.B. planned and directed the project.
This work was funded by a fellowship from AgreenSkills (CESETAB project) and Institut National de la Recherche Agronomique (to C.F.); a ‘Chaire d'excellence’ from l’Agence Nationale de la Recherche, France [ANR-10-CHEX-0011: mécanograine to G.I.]; and a European Research Council Starting Grant [Phymorph #307387 to A.B.].
Supplementary information available online at http://dev.biologists.org/lookup/doi/10.1242/dev.137190.supplemental
- Received March 7, 2016.
- Accepted May 24, 2016.