Fig. 5.

Expression pattern of PIN1, LAX3, and AUX1 during AR formation in IBA-cultured TCLs at day15. a–e PIN1::GUS expression. a Signal in a wide population of endodermis derivatives and in meristemoids. b–c Signal in the basal part of young ARPs (b), all along the developing vasculature (c), and in the central cells of the apex of elongating ARPs (d). e Expression in the vasculature (Inset), and faintly in the apex of mature ARs. f–j LAX3::GUS expression. f–g Onset of expression in the meristematic cell clusters formed by the endodermis. h Expression at the base of the differentiating ARPs (h). i–j Strong LAX3 signal in the procambium (i), and vasculature of the maturing ARs (j). k–o AUX1::GUS expression. k–l Uniform signal in the meristematic cell clusters formed by the endodermis (k), and in early primordia (l). m Signal in the cap, protodermis, and developing procambium in the elongating ARPs. n AUX1 expression in the cap, protodermis, and faintly in the niche and procambium (arrow) in a mature AR. o Expression in the vascular parenchyma of the AR primary structure zone. a-e, f-i, k-n, longitudinal sections, j, o, and Inset in e, transections. Bars = 40 μm (a, b, f–k, n, o), 50 μm (c-e, l, m, and Inset in e)