Interaction between Meristem Tissue Layers Controls Phyllotaxis
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BORIS DOI
Date of Publication
September 30, 2013
Publication Type
Article
Division/Institute
Subject(s)
Series
Developmental cell
ISSN or ISBN (if monograph)
1534-5807
Publisher
Cell Press
Language
English
Publisher DOI
PubMed ID
24091013
Description
Phyllotaxis and vein formation are among the most conspicuous patterning processes in plants. The expression and polarization of the auxin efflux carrier PIN1 is the earliest marker for both processes, with mathematical models indicating that PIN1 can respond to auxin gradients and/or auxin flux. Here, we use cell-layer-specific PIN1 knockouts and partial complementation of auxin transport mutants to examine the interaction between phyllotactic patterning, which occurs primarily in the L1 surface layer of the meristem, and midvein specification in the inner tissues. We show that PIN1 expression in the L1 is sufficient for correct organ positioning, as long as the L1-specific influx carriers are present. Thus, differentiation of inner tissues can proceed without PIN1 or any of the known polar transporters. On theoretical grounds, we suggest that canalization of auxin flux between an auxin source and an auxin sink may involve facilitated diffusion rather than polar transport.