Localization of GmEXP1 mRNA in the primary root of 5-d-old soybean seedlings by in situ hybridization. A to C, Longitudinal sections from the root tip region. A was hybridized with the antisense probe for the GmEXP1 gene. B was hybridized with the sense probe for the GmEXP1 gene. C is the magnification image of the region of cell elongation in A. D to G, Cross sections from the root were hybridized with the antisense probe for the GmEXP1 gene. D is the region that is 80 μm apart from the root tip, which is the region of the root cap. E is the region that is 1.0 mm apart from the root tip. F is the region that is 1.3 mm apart from the root tip. G is the region that is 4.0 mm apart from the root tip. rc, Root cap; e, epidermis; v, vascular cylinder; m, meristem; c, cortex. In A and B, bars = 250 μm; in D, bar = 50 μm; in C, E, F, and G, bars = 100 μm.