Figure 8.

Tip Localization of the EYFP-RabA4b Compartment Does Not Require Intact Microtubules.

(A) Root hairs treated with LB show significant loss of tip localization within 2 min of treatment. In the same time frame, root hairs treated with 10 μM oryzalin to depolymerize microtubules and control treatment with DMSO display no obvious defects in tip localization.

(B) In contrast with root hairs treated with EYFP-RabA4b, the overall distribution of EYFP-RabF2a in root hairs was not significantly changed upon treatment with LB.

(C) LB treatment did not significantly alter the characteristics of EYFP-RabA4b–labeled compartments. Plants expressing EYFP-RabA4b were treated with LB for 15 min before subcellular fractionation of the membranes over a sucrose density gradient. The fractionation pattern of EYFP-RabA4b in membranes treated with LB was similar to that in nontreated plants (cf. with fractionation patterns in Figure 4). These results demonstrate that tip localization of RabA4b compartments is dependent on an intact actin cytoskeleton and that the nature of the compartment is not demonstrably changed by LB treatment.