A Rho family GTPase controls actin dynamics and tip growth via two counteracting downstream pathways in pollen tubes

Ying Gu, Ying Fu, Peter Dowd, Shundai Li, Vanessa Vernoud, Simon Gilroy, Zhenbiao Yang

Research output: Contribution to journalArticle

220 Scopus citations


Tip growth in neuronal cells, plant cells, and fungal hyphae is known to require tip-localized Rho GTPase, calcium, and filamentous actin (F-actin), but how they interact with each other is unclear. The pollen tube is an exciting model to study spatiotemporal regulation of tip growth and F-actin dynamics. An Arabidopsis thaliana Rho family GTPase, ROP1, controls pollen tube growth by regulating apical F-actin dynamics. This paper shows that ROP1 activates two counteracting pathways involving the direct targets of tip-localized ROP1 : RIC3 and RIC4. RIC4 promotes F-actin assembly, whereas RIC3 activates Ca 2+ signaling that leads to F-actin disassembly. Overproduction or depletion of either RIC4 or RIC3 causes tip growth defects that are rescued by overproduction or depletion of RIC3 or RIC4, respectively. Thus, ROP1 controls actin dynamics and tip growth through a check and balance between the two pathways. The dual and antagonistic roles of this GTPase may provide a unifying mechanism by which Rho modulates various processes dependent on actin dynamics in eukaryotic cells.

Original languageEnglish (US)
Pages (from-to)127-138
Number of pages12
JournalJournal of Cell Biology
Issue number1
StatePublished - Apr 11 2005


All Science Journal Classification (ASJC) codes

  • Cell Biology

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