Auxin-Callose-Mediated Plasmodesmal Gating Is Essential for Tropic Auxin Gradient Formation and Signaling

Xiao Han, Tae Kyung Hyun, Minhua Zhang, Ritesh Kumar, Eun ji Koh, Byung Ho Kang, William J. Lucas, Jae Yean Kim

Research output: Contribution to journalArticlepeer-review

136 Scopus citations


In plants, auxin functions as a master controller of development, pattern formation, morphogenesis, and tropic responses. A sophisticated transport system has evolved to allow the establishment of precise spatiotemporal auxin gradients that regulate specific developmental programs. A critical unresolved question relates to how these gradients can be maintained in the presence of open plasmodesmata that allow for symplasmic exchange of essential nutrients and signaling macromolecules. Here we addressed this conundrum using genetic, physiological, and cell biological approaches and identified the operation of an auxin-GSL8 feedback circuit thatregulates the level of plasmodesmal-localized callose in order to locally downregulate symplasmic permeability during hypocotyl tropic response. This system likely involves a plasmodesmal switch that would prevent the dissipation of a forming gradient by auxin diffusion through the symplasm. This regulatory system may represent a mechanism by which auxin could also regulate symplasmic delivery of a wide range of signaling agents.

Original languageEnglish (US)
Pages (from-to)132-146
Number of pages15
JournalDevelopmental Cell
Issue number2
StatePublished - Jan 27 2014
Externally publishedYes

Bibliographical note

Funding Information:
We thank I.J. Park for assistance with figure preparation, D. Baulcombe, H.T. Cho, C.S. Kim, I. Hwang, D. Jackson, J.M. Kim, and J. Friml for seeds and plasmids, and W. Briggs, V. Sundaresan, D. Smyth, D. Jackson, and J.J. Harada for their critical reading of the manuscript. This work was supported by the World Class University Program (R33-10002) and by the Basic Science Research Program (NRF-2013R1A1A2007230) through the National Research Foundation of Korea funded by the Ministry of Education, Next-Generation BioGreen 21 Program (Systems and Synthetic Agrobiotech Center; grant PJ009495), Rural Development Administration, Republic of Korea, the National Science Foundation (IOS-0918433) (to W.J.L.), and by the Agriculture and Food Research Initiative, U.S. Department of Agriculture (2010-04196) (to B.-H.K.).


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