Journal Article

An Orchid (<i>Oncidium</i> Gower Ramsey) <i>AP3</i>-like MADS Gene Regulates Floral Formation and Initiation

Hsing-Fun Hsu and Chang-Hsien Yang

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 10, pages 1198-1209
Published in print October 2002 | ISSN: 0032-0781
Published online October 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf143
An Orchid (Oncidium Gower Ramsey) AP3-like MADS Gene Regulates Floral Formation and Initiation

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cDNA for a B group MADS box gene OMADS3 was isolated and characterized from Oncidium Gower Ramsey, an important species of orchid. OMADS3 encoding a 204 amino acid protein showed high sequence homology to both paleoAP3 and TM6 lineage of B group MADS box gene such as monocots AP3 homologue LMADS1 in lily and GDEF1 in Gerbera hybrida. Despite the sequence homology, consensus motifs identified in the C-terminal region of B group genes were absent in OMADS3. Southern analysis indicated that OMADS3 was present in O. Gower Ramsey genome in low copy numbers. Different from most B group genes, OMADS3 mRNA was detected in all four floral organs as well as in vegetative leaves. This is similar to the expression pattern of GDEF1. 35S::OMADS3 transgenic plants showed novel phenotypes by producing terminal flowers similar to those observed in transgenic plants ectopically expressed A functional genes such as AP1. Ectopic expression of OMADS3 cDNA truncated with the MADS box or C terminal region in Arabidopsis generated novel ap2-like flowers in which sepals and petals were converted into carpel-like and stamen-like structures. Yeast two-hybrid analysis indicated that OMADS3 is able to strongly form homodimers. Our results suggested that OMADS3 might represent an ancestral form of TM6-like gene which was conserved in monocots with a function similar to A functional gene in regulating flower formation as well as floral initiation.

Keywords: Keywords: Arabidopsis thaliana — Floral formation — Floral initiation — MADS box genes — Oncidium Gower Ramsey.; Abbreviations: CaMV, cauliflower mosaic virus; CTAB, hexadecyl trimethyl-ammonium bromide; MS medium, Murashige and Skoog medium; RT, reverse transcription.

Journal Article.  8366 words.  Illustrated.

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

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