The effect of penetration in soil on cortical microtubules of wild-type root tips.

<p>Single CLSM section (a) or maximum projections of CLSM sections (b-d). (a) Cortical microtubules are transversely oriented in the meristematic zone. (b) In protodermal cells, loosely longitudinal orientation (cells included in bracket) shifts to transverse (arrows) in the transition zone. (c) In this extremely short root tip (see root tip in Figure S2) cortical microtubules are not transverse even in the shorter protodermal/epidermal cells of the elongation zone (arrows). (d) In this root tip, cortical microtubules exhibit random orientation in the longer epidermal cells of the elongation zone (arrows). Scale bars, 20 μm.