Figure 4.

Heat Shock–Induced Expression of ARF1-Q71L and ARF1-T31N Strongly Affects Root Growth and Root Hair Formation.

(A) to (E) Root hair formation upon strong heat-shock induction (37°C, 4 h).

(A) to (C) Transgenic line carrying hspGV and UAS-ARF1-WT (A), UAS-ARF1-Q71L (B), or UAS-ARF1-T31N (C). Root hair formation in ARF1-Q71L lines could recover within 2 d ([B], boxed region). Abnormal root meristem in ARF1-T31N line is shown ([C], boxed region).

(D) and (E) Enlarged views of boxed regions in (B) and (C). Arrows in (D) indicate proper root hair formation.

(F) and (I) Root hair formation of Columbia wild-type line upon BFA treatment (5 μM, 20 h). Double root hairs ([F], arrows) and apical-shifted root hair ([I], arrow) were observed.

(G), (H), and (J) Root hair formation in transgenic lines carrying hspGV and UAS-ARF1-T31N. Apical-shifted root hair ([G], arrow), double root hairs ([H], arrows), and a combination of both phenotypes ([J], arrows) were observed. Bulging epidermal cells in (G) suggest deregulation of cell expansion.

Bars = 100 μm in (A) for (A) to (C), 50 μm in (D) for (D) and (E), 100 μm in (F) for (F) to (H), and 20 μm in (I) for (I) and (J).