Journal Article

Overexpression of miR165 Affects Apical Meristem Formation, Organ Polarity Establishment and Vascular Development in <i>Arabidopsis</i>

Gong-Ke Zhou, Minoru Kubo, Ruiqin Zhong, Taku Demura and Zheng-Hua Ye

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 48, issue 3, pages 391-404
Published in print March 2007 | ISSN: 0032-0781
Published online March 2007 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcm008
Overexpression of miR165 Affects Apical Meristem Formation, Organ Polarity Establishment and Vascular Development in Arabidopsis

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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The class III homeodomain leucine-zipper (HD-ZIP III) genes are thought to be targets of microRNAs (miRNAs) 165 and 166, but it is not known whether all the developmental processes affected by mutations of the HD-ZIP III genes could be recapitulated by an alteration in the expression of miR165 and miR166. Previous work showed that overexpression of miR166 by activation tagging results in down-regulation of the ATHB-9/PHV, ATHB-14/PHB and ATHB-15 genes, and concomitantly causes an enlargement of shoot apical meristems (SAMs) and an enhancement in vascular development. Here we demonstrated that overexpression of miR165 causes a drastic reduction in the transcript levels of all five HD-ZIP III genes in Arabidopsis. The miR165 overexpressors display prominent phenotypes reminiscent of loss-of-function mutants of rev phb phv and rev/ifl1, including loss of SAM, alteration of organ polarity, abnormal formation of carpels, inhibition of vascular development and aberrant differentiation of interfascicular fibers. Global gene expression analysis revealed a link between miR165 overexpression and altered expression of genes involved in auxin signaling and vascular development. Our results demonstrate that overexpression of miR165 recapitulates the phenotypes caused by loss-of-function mutations of HD-ZIP III genes, such as loss of SAM, altered organ polarity and defects in development of vascular tissues and interfascicular fibers.

Keywords: Arabidopsis thaliana; Homeodomain proteins; Meristem; MicroRNA; Organ polarity; Vascular development

Journal Article.  7129 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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