Fig. 6: Upregulation of NRPD4b alters the distribution of histone marks.
a, The whole pistil labelled by antibody to detect histone modification in the fluorescent channel (top) and DIC channel (bottom). The white and black rectangles indicate the region of interest shown in b. Scale bars, 50 μm. b, Immunolabelling of H3K9me2 (left) and H3K27me1 (right) in wild-type, mads31 and Ubi::NRPD4b ovules at Ov7/8 stage. White dotted lines indicate the embryo sac and inner nucellus regions. PI, propidium iodide. Scale bars, 25 μm. c, Relative H3K9me2 (left) and H3K27me1 (right) modification levels (measured as antibody signal intensity/DNA signal intensity) in the inner nucellus region of wild-type, mads31 and Ubi::NRPD4b ovules. Data are shown as mean ± s.d.; n = 30 nuclei; two-sided t-test for unpaired two-sample data. The immunolabelling was repeated 3 times, with similar results. d, Proposed model of MADS31 in nucellus patterning. In wild type, MADS31 is preferentially expressed in the inner nucellus, repressing post-fertilization programmes such as seed gene expression and nucellus degradation to maintain the tissue integrity and support embryo sac development. In mads31 ovules, the lack of repression from MADS31 causes activation of NRPD4b and premature cell death, which further alters cell properties and accelerates tissue degeneration, respectively.
