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Research Papers

Actin Turnover-Mediated Gravity Response in Maize Root Apices: Gravitropism of Decapped Roots Implicates Gravisensing Outside of the Root Cap

Stefano Mancuso, Peter W. Barlow, Dieter Volkmann and Frantisek Baluska

volume 1 | issue 2

march/april 2006
Pages: 52-58

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The dynamic actin cytoskeleton has been proposed to be linked to gravity sensing in plants but the mechanistic understanding of these processes remains unknown. We have performed detailed pharmacological analyses of the role of the dynamic actin cytoskeleton in gravibending of maize (Zea mays) root apices. Depolymerization of actin filaments with two drugs having different mode of their actions, cytochalasin D and latrunculin B, stimulated root gravibending. By contrast, drug-induced stimulation of actin polymerization and inhibition of actin turnover, using two different agents phalloidin and jasplakinolide, compromised the root gravibending. Importantly, all these actin drugs inhibited root growth to similar extent suggesting that high actin turnover is essential for the gravity-related growth responses rather than for the general growth processes. Both latrunculin B and cytochalasin D treatments inhibited root growth but restored gravibending of the decapped root apices, indicating that there is a strong potential for effective actin-mediated gravity sensing outside the cap. This elusive gravity sensing outside the root cap is dependent not only on the high rate of actin turnover but also on weakening of myosin activities, as general inhibition of myosin ATPases induced stimulation of gravibending of the decapped root apices. Collectively, these data provide evidence for the actin turnover-mediated gravity sensing outside the root cap.



We now provide open access to journal articles published online for one year or more. This article may be downloaded at the following link:
 Download PDF

If the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.