Journal Article

<i>MACCHI-BOU 2</i> is Required for Early Embryo Patterning and Cotyledon Organogenesis in Arabidopsis

Jun Ito, Takako Sono, Masao Tasaka and Masahiko Furutani

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 52, issue 3, pages 539-552
Published in print March 2011 | ISSN: 0032-0781
Published online January 2011 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcr013
MACCHI-BOU 2 is Required for Early Embryo Patterning and Cotyledon Organogenesis in Arabidopsis

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  • Biochemistry
  • Molecular and Cell Biology
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The phytohormone auxin is a key regulator of organogenesis in plants and is distributed asymmetrically via polar transport. However, the precise mechanisms underlying auxin-mediated organogenesis remain elusive. Here, we have analyzed the macchi-bou 2 (mab2) mutant identified in a pinoid (pid) enhancer mutant screen. Seedlings homozygous for either mab2 or pid showed only mild phenotypic effects on cotyledon positions and/or numbers. In contrast, mab2 pid double mutant seedlings completely lacked cotyledons, indicating a synergistic interaction. We found that mab2 homozygous embryos had defective patterns of cell division and showed aberrant cotyledon organogenesis. Further analysis revealed that the mab2 mutation affected auxin response but not auxin transport in the embryos, suggesting the involvement of MAB2 in auxin response during embryogenesis. MAB2 encodes an Arabidopsis ortholog of MED13, a putative regulatory module component of the Mediator complex. Mediator is a multicomponent complex that is evolutionarily conserved in eukaryotes and its regulatory module associates with Mediator to control the interaction of Mediator and RNA polymerase II. MAB2 interacts with a regulatory module component in yeast cells. Taken together, our data suggest that MAB2 plays a crucial role in embryo patterning and cotyledon organogenesis, possibly through modulating expression of specific genes such as auxin-responsive genes.

Keywords: Arabidopsis thaliana; Auxin response; Cotyledon; Embryogenesis; MED13

Journal Article.  6886 words.  Illustrated.

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

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