Fig. 6

Immunohistochemical analysis of auxin distribution at different developmental stages. a At stage F, auxin is approximately evenly distributed throughout the stigma and early ovary primordial; the patterns of staining in female inflorescences and single female flower with two stigmas are shown in (g). b Intenser auxin staining is observed in ovary primordia at stage S; stigmas with ovary primordia are shown in (h). c and d Intenser auxin staining are observed in the pollen tube cavity in stigmas after rudimentary ovary formation at stage S (May 10 and May 15); an early rudimentary ovary and its pollen tube cavity are shown in (i). e Auxin staining in ovules is much higher than in other tissues of early fruit at stage T; an ovary with two ovules is shown in (j). f Auxin content in the nucellus of ovules is much higher than in other tissues of early fruit at stage FO; an ovary with ovules, and the microstructure of ovule and fruit cluster are shown in (k) and (l). Key: S, stigma; Op, ovary primordial; Pc, pollen tube cavity; O, ovary; Ov, ovule; P, parenchyma; Int, integument; Nu, nucellus; E, embryo; Sh, shell. Scale bars: A, B = 150 μm, C, D, E and F = 300 μm; G, H = 400 μm; I = 800 μm; J, K = 1 mm; L = 5 mm