Additional file 5 of Conservation of the dehiscence zone gene regulatory network in dicots and the role of the SEEDSTICK ortholog of California poppy (Eschscholzia californica) in fruit development
Creators: name: Lotz, Dominik
name: Rössner, Le Han
name: Ehlers, Katrin
name: Kong, Doudou
name: Rössner, Clemens
name: Rupp, Oliver
name: Becker, Annette
Publisher: name: figshare
Year: 2024
Subjects: subject: Genetics
subject: FOS: Biological sciences
subject: Plant Biology

description: Supplementary material 5: Supplemental Figure 5: Development of the inner fruit wall tissues in E. californica. (A-C) Wild type capsules; (D, E) capsules from EscaSTK-VIGS treated plants in cross-section. (A, 16 dap) Stomata (arrowheads) occur in the endocarp layer composed of large cells with thick tangential cell walls, which remain non-lignified throughout capsule development. The arrows point at a sporadically occurring tangential cell division of the endocarp. (B, 20 dap) 4-6 parenchymatous cell layers separate the vascular bundles from the endocarp layer. At the valve margins, the adaxial parenchyma layer(s) bordering the endocarp are slightly enlarged (asterisks in B). Starting at the median region of the valves, endodermal cells and adjacent parenchyma layers collapse successively (B) and this process proceeds towards the valve margins (C, 22 dap). Two clearly delimited testa layers cover the surface of the developing WT seeds (arrowheads in C). They are probably derived from the outer and inner integument of the ovule. Single integument layers could hardly be discriminated, as testa cells had been considerably flattened in radial direction during seed growth. The seed epidermis is still turgescent at this developmental stage and has an irregular outline, due to its differentiation into flat facet cells and elongated, partially multilayered ridge cells (F and R in C). In a phenotypically less conspicuous and closed EscaSTK-VIGS treated capsule of the same developmental stage (D), histology of the fruit wall and the seed coat largely resemble that of WT capsules (cf. B, C). Yet, endocarp cells and underlying cell layers at the valve margins, as well as epidermal cells at the seed surface are slightly enlarged. In a severely affected and prematurely opened EscaSTK-VIGS treated capsule (E), histology of the dehiscence zone and the abaxial valve tissues largely resembles that of WT capsules in the same developmental stage (cf. B, C). Lignified sclerenchyma of the lateral and median valve ridges, intervening sclerenchyma caps and sclereids, as well as the still non-lignified separation layer (white arrows in B and E) have an ordinary appearance. Apparently, the centrifugal differentiation of the lignified rs is lagging behind, and more non-sclerified cells layers separate the replum sclerenchyma from the outer abaxial fruit epidermis than in WT capsules (compare E to B, C). Yet, the endocarp and several of the adjacent pericarp layers at the adaxial side of the EscaSTK-VIGS treated fruit wall are enlarged and strongly elongated in radial direction, so that they fill the locule almost completely. Elongated cells may undergo additional tangential divisions (arrows in E). Bars represent 200 µm e: endocarp, F: facet cells, mvr: median valve ridge, lvr: lateral valve ridge, R: ridge cells, rs: replum sclerenchyma, s: seed, sc: small sclerenchyma caps; scl: sclereids, vb: vascular bundle.