Journal Article

CRM1/BIG-Mediated Auxin Action Regulates Arabidopsis Inflorescence Development

Nobutoshi Yamaguchi, Mitsuhiro Suzuki, Hidehiro Fukaki, Miyo Morita-Terao, Masao Tasaka and Yoshibumi Komeda

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 48, issue 9, pages 1275-1290
Published in print September 2007 | ISSN: 0032-0781
Published online September 2007 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcm094
CRM1/BIG-Mediated Auxin Action Regulates Arabidopsis Inflorescence Development

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

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The shape of the inflorescence in Arabidopsis thaliana ecotype Columbia is a raceme with individual flowers developing acropetally. The ecotype Landsberg harboring the erecta (er) mutation shows a corymb-like inflorescence, namely a compact inflorescence with a flattened arrangement of flower buds at the tip. To gain insight into inflorescence development, we previously isolated corymb-like inflorescence mutants, named corymbosa1 (crm1), and found that the corymb-like inflorescence in crm1-1 was due to reduced cell elongation of pedicels and stem internodes. Double mutants of crm1 with er and crm2, and crm1-1 crm2-1 er-105 triple mutants show an additive phenotype. crm1-1 is caused by a mutation in BIG, which is required for polar auxin transport. CRM1/BIG is expressed in inflorescence meristems, floral meristems and vascular tissues. We analyzed a collection of 12 reduced lateral root formation (rlr) mutants, which are allelic to crm1-1, and categorized the mutants into three classes, depending on the plant developmental defects. Although all 12 alleles had new stop codons, the phenotype of heterozygous crm1-1/doc1-1 and Northern blotting suggest that new crm1/big mutant alleles are hypomorphic. Auxin-responsive DR5rev::GFP expression was decreased in crm1-1 vasculature of pedicels and stem internodes. PINFORMED1 (PIN1) and CRM1/BIG are expressed in vasculature of pedicels and stem internodes. The severity of corymb-like inflorescence in crm1/big mutants correlated with increased levels of PIN1. Our results suggest that CRM1/BIG controls the elongation of the pedicels and stem internodes through auxin action.

Keywords: Arabidopsis thaliana; BIG gene; Corymb-like inflorescence; corymbosa1; Inflorescence development; Polar auxin transport

Journal Article.  9674 words.  Illustrated.

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

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