Fig. 6. Root phenotypes induced by transient expression of axr3-1 or shy2-6 transgenes from the heat shock promoter. (A) Heat shocked wild-type Columbia root, showing no effect of the heat shock (administered at the time when the part of the root indicated by the arrow was entering the root hair initiation zone). (B) HS:axr3-1 root following a 2-hour HS (arrow), showing blocked hair growth and root agravitropism. (C) Close up of HS:axr3-1 root treated as in B showing the transition back to hair growth: a few shorter hairs appear before normal hair growth resumes. (D) Transient induction of axr3-1 transcription from the heat shock promoter in the shy2-2 genetic background. Following induction, all hairs arrest at their current stage of development, and initiation is blocked. (E) Close up of HS:axr3-1, shy2-2 root treated as in D showing the transition back to hair growth: an area of the root becomes gnarled and produces depolarised root hairs. Scale bar: 0.5 mm.