Relationship between initiation of embryogenic suspensor mass (ESM) and zygotic embryo development in Pinus densiflora

Figures & data

Table 1. Collection locations, dates and developmental stages of embryos used for ESM initiation in P. densiflora.

	Embryo developmental stage (%)
Collection site (year)	Collection date	Proembryo	Globular	Precotyledon	Cotyledon	ESM initiation (%)
Suwon (2004)	31 May	0	0	0	0	0
	7 June	0	0	0	0	0
	13 June	100	0	0	0	0
	21 June	100	0	0	0	0.57de^a
	28 June	100	0	0	0	0.88cd
	5 July	70	20	10	0	0.33def
	13 July	0	33.3	66.7	0	0
	20 July	0	0	49.1	50.9	0
Suwon (2005)	28 June	100	0	0	0	0.93c
	1 July	100	0	0	0	1.4b
	5 July	100	0	0	0	0.24f
Anmyeondo (2005)	28 June	100	0	0	0	0.97c
	l July	100	0	0	0	2.31a
	5 July	100	0	0	0	1.65b
Suwon (2006)	28 June	100	0	0	0	0.49de
	l July	100	0	0	0	0.91c
	5 July	89.9	10.1	0	0	0.27f

^a Different letters within columns indicate significant differences at P = 0.05.

Figure 1. Developmental embryo stages of P. densiflora. (a) Archegonia (arrows) from a 31 May seed. (b) No embryos found in 7 June seeds. (c) Early-stage embryos in corrosion cavity (13 June). (d) Magnified picture of Figure 1c. One small globular zygotic embryo in corrosion cavity, e: embryonal head, s: suspensor, m: micropyle. (e) Proembryos in the corrosion cavity (cc), s: suspensor (21 June). (f) Numerous suspensors in the corrosion cavity (magnified Figure 1e). (g) Late-stage proembryos in corrosion cavity (28 June). (h) Embryonal head of each embryo (arrow) has more divided cells and longer suspensors than shown in those of Figure g. (i) One surviving dominant embryo (arrow); the other embryo has degenerated (5 July). (j) Magnified picture of Figure c. (k) A zygotic embryo developed more vigorously (13 July). (l) Cotyledon-stage embryo in the corrosion cavity (20 July). Bars: 420 μm (a–d), 179 μm (e), 159 μm (i), 140 μm (j), 117 μm (k), and 147 μm (l).

Figure 2. Mucilaginous ESM extruded from the micropyle end of megagametophyte after 8 weeks in culture. Bar: 8 mm.

Figure 3. Sections of immature P. densiflora embryos correlated with collection dates and locations. (a) Two embryos on the left (28 June 2005, Suwon), two in middle (1 July 2005, Suwon), two on the right (5 July 2005, Suwon). (b) Two embryos on left (28 June 2005, Anmyeondo), two in middle (1 July 2005, Anmyeondo), two on right (5 July 2005, Anmyeondo) (c) two embryo on left (28 June 2006, Suwon), two in middle (1 July 2006, Suwon), two on right (1 July 2006, Suwon). Bar: 1.2 mm (a–c).