Fig. 3.

Indeterminate carpel development in atring1a;atring1b mutant. a Wild-type (WT) carpel. b–d Defective carpel development in atring1a;atring1b mutant. b Bulged carpels. c Stigma papilla-like structures growing outside the replums between carpels. d Unclosed carpel development. e–h Cross sections of various stages of carpel and ovule development in WT flower. e Ovule primordia initiation within the gynoecial cylinder of a stage 8 WT flower. f Gynoecial cylinder in a stage 9 WT flower. g Gynoecial cylinder in a stage 11 WT flower. h Mature ovule within a stage 13 WT flower. i–m Cross sections of various stages of carpel and ovule development in atring1a;atring1b mutant. Medial ridges fail to fuse but continue to expand and produce stigmatic papilla-like tissues on the top. Arrows denote various stages of ovules. n–p SEM observation of ectopic carpelloid features inside mutant mature gynoecia. n Ectopic additional ovules arising from overproliferated carpel-like structure inside the mutant central gynoecium. o Carpelloid-like ovules with stigma papilla-like organs (arrowheads) on the top. p Overproliferating carpel-like structures crowded inside a gynoecium. Bars =200 μm, except 10 μm in e–l