Fig 1.
Dynamic transformation of morphology and OSH1 accumulation pattern in shoot apical meristem during a plastochron in rice.
(A–D) Differential interference-contrast images of a SAM during a plastochron in wild type rice. (E–H) FITC (OSH1) and PI double staining of longitudinal sections of a SAM during a plastochron. Red signals indicate PI-stained nuclei. Green signals indicate OSH1 localization visualized by anti-OSH1 antibody and FITC. PI signals and OSH1 signals were captured independently and overlaid. P0, P1, and P2 indicate the stage of leaf development [29]. Labels at the top indicate the four stages within a plastochron that we defined. (A, E) Early P0 stage. (B, F) Late P0 stage. (C, G) Early P1 stage. (D, H) Late P1 stage. (*) Leaf base. (**) Leaf edge. Dashed line indicates the border of meristem and bulge of P1. Scale bars: 50 μm.
Fig 2.
Transitions in numbers of total cells, OSH1-positive cells, and OSH1-negative cells in wild type shoot apical meristem during a plastochron.
Through OSH1 immunostaining, we measured the numbers of (A) total cells (blue line), (B) OSH1-positive cells (pink line, indicating unspecified cells), and (C) OSH1-negative cells (green line, indicating specified cells) in the SAM. The x-axis indicates the leaf initiation stage at the SAM: early P0, late P0, early P1, and late P1 stages (see Fig 1). The y-axis indicates the number of cells. Data are means; error bars indicate s.d. Number of samples (meristems) measured: early P0 stage (n = 3), late P0 stage (n = 3), early P1 stage (n = 6), late P1 stage (n = 7). Different letters above the error bars represents significant differences of number of cells among the stages by Tukey-Kramer’s test (P < 0.01).
Fig 3.
Selected mutants of shoot apical meristem with altered size and shape.
(A–D) Morphology of the SAM of 8-day-old (A) wild type and (B–D) mutant plants at the early P1 stage observed through a microscope equipped with Nomarski differential interference-contrast optics. (E–H) Morphology of the SAM of 3-week-old (E) wild type and (F–H) mutant plants observed through SEM. (I–L) Morphology of the shoot of 8-day-old (I) wild type and (J–L) mutant plants. (M–P) Aboveground plant parts of (M) wild type and (N–P) mutants grown for 4 months after germination. Position of panicles are marked with braces. Insets indicate magnification of a flag leaf from each plant. (Q–T) Panicle architecture of (Q) wild type and (R–T) mutants. Number of branching are labelled and shortened branches are indicated by arrowheads. (A, E, I, M, Q) wild type; (B, F, J, N, R) CM761; (C, G, K, O, S) CM829; (D, H, L, P, T) CM873. Scale bars: 50 μm in A–H; 1 cm in I–L; 20 cm in M–P; 1 cm in M–P insets; 5 cm in Q–T.
Table 1.
Width, height, shape, and volume of shoot apical meristem of wild type and mutants at early P1 stage.
Fig 4.
FON2 and histone H4 expression in meristems of wild type and mutants.
(A–H) FON2 expression (A–D) in SAM and (E–H) axillary meristem in the early vegetative phase of (A, E) wild type, (B, F) CM761, (C, G) CM829, and (D, H) CM873. (I–L) Histone H4 expression in SAM in the early vegetative phase of (I) wild type, (J) CM761, (K) CM829, and (L) CM873. Meristems are outlined. Scale bars: 50 μm.
Fig 5.
Numbers of total cells, OSH1-positive cells, and OSH1-negative cells in the shoot apical meristem of wild type and mutants at the late P0 and early P1 stages during a plastochron.
Numbers of cells were compared among wild type (blue bars), CM761 (orange bars), CM829 (gray bars), and CM873 (yellow bars) at the (A) late P0 and (B) early P1 stages. The x-axis indicates the type of cell; the y-axis indicates the number of cells. Data are means; error bars indicate s.d. Asterisks indicate significant differences from wild type (Student’s t-test; **P < 0.01, *P < 0.05). Numbers of samples (meristems) measured: wild type (n = 3), CM761 (n = 4), CM829 (n = 3), CM873 (n = 3) at late P0 stage; wild type (n = 6), CM761 (n = 9), CM829 (n = 7), CM873 (n = 8) at early P1 stage.