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Plant Physiology 132:1982-1988 (2003) © 2003 American Society of Plant Biologists Nod Factor-Induced Root Hair Curling: Continuous Polar Growth towards the Point of Nod Factor Application1Laboratory of Plant Cell Biology, Department of Plant Sciences, Wageningen University, Arboretumlaan 4, 6703 BD Wageningen, The Netherlands
A critical step in establishing a successful nitrogen-fixing symbiosis between rhizobia and legume plants is the entrapment of the bacteria between root hair cell walls, usually in characteristic 180° to 360° curls, shepherd's crooks, which are formed by the host's root hairs. Purified bacterial signal molecules, the nodulation factors (NFs), which are lipochitooligosaccharides, induce root hair deformation in the appropriate host legume and have been proposed to be a key player in eliciting root hair curling. However, for curling to occur, the presence of intact bacteria is thought to be essential. Here, we show that, when spot applied to one side of the growing Medicago truncatula root hair tip, purified NF alone is sufficient to induce reorientation of the root hair growth direction, or a full curl. Using wild-type M. truncatula containing the pMtENOD11::GUS construct, we demonstrate that MtENOD11::GUS is expressed after spot application. The data have been incorporated into a cell biological model, which explains the formation of shepherd's crook curls around NF-secreting rhizobia by continuous tip growth reorientation.
Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.103.021634. 1 This work was supported by the Dutch Organization for Scientific Research, Division of Earth and Life Sciences (Nederlandse organisatie voor Wetenschappelijk Onderzoek-Aard-en Levens Wetenschappen, ALW no. 80533342 to J.J.E.), by the European Community Training and Mobility of Researchers Program (grant no. FMRX CT 98 0239 to F.G.P.L.), and by the Region Haute-Normandie (postdoctoral fellowship to F.G.P.L.). 2 These authors contributed equally to the paper. * Corresponding author; e-mail annemie.emons{at}wur.nl; fax 31317 485005. Received February 3, 2003; returned for revision April 21, 2003; accepted May 12, 2003. This article has been cited by other articles:
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