Journal Article

A Loss-of-Function Mutation in the Rice <i>KNOX</i> Type Homeobox Gene, <i>OSH3</i>

Yutaka Sato, Yumiko Aoki and Makoto Matsuoka

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 1, pages 44-51
Published in print January 2002 | ISSN: 0032-0781
Published online January 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf003
A Loss-of-Function Mutation in the Rice KNOX Type Homeobox Gene, OSH3

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

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KNOX homeodomain (HD) proteins encoded by KNOTTED1-like homeobox genes (KNOX genes) are thought to work as switches for cells to change from an indeterminate to a determinate state, although their direct functions are not clear. In the process of isolating KNOX genes from rice, we found that one gene, named OSH3, has two amino acid substitutions in three of the invariant amino acid residues in the HD of KNOX proteins. These amino acid substitutions are not universal in rice: two of the cultivars from the Indica variety of rice do not carry those substitutions but two of the cultivars from Japonica variety do. We tested the effect of these amino acid substitutions on their ability to form dimers and to induce abnormal morophologies when overexpressed in transgenic plants. We found that OSH3 without those substitutions can form dimers and can induce an abnormal phenotype in overexpression studies, and that OSH3 with those amino acid substitutions is defective in both. Based on these observations, we concluded that OSH3 from two of the cultivars from the Japonica variety could have lost its original function, or could have acquired a novel function by modifying the action of HD, or both.

Keywords: Key words: Dimer formation — Homeobox gene — Rice — TALE-homeodomain protein.; Abbreviations: GAD, GAL4 activation domain; GBD, GAL4 DNA binding domain; GST, glutathione S-transferase; HA, hemagglutinin; HD, homeodomain; IPTG, isopropyl-β-d-thiogalactoside; KNOX gene, KNOTTED1-like homeobox gene; RT, reverse transcription; SAM, shoot apical meristem; TALE, three amino acid loop extension; X-gal, 5-bromo-4-chloro-3-indolyl-β-d-galactoside.

Journal Article.  5346 words.  Illustrated.

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

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