Ectopic expression of an orchid (Oncidium gower ramsey) AGL6-like gene promotes flowering by activating flowering time genes in Arabidopsis thaliana

• Published in: Plant and cell physiology 2003-08, Vol.44 (8), p.783-794
• Main Authors: Hsu, H.F. (National Chung Hsing Univ., Taichung (Taiwan)), Huang, C.H, Chou, L.T, Yang, C.H
• Format: Article
• Language: English
• Subjects: AGAMOUS-like 6 protein; AGL6-like protein; Amino Acid Sequence; amino acid sequences; APETALA1 protein; Arabidopsis - genetics; Arabidopsis - growth & development; ARABIDOPSIS THALIANA; Blotting, Southern; Cloning, Molecular; complementary DNA; Dimerization; DNA, Complementary - isolation & purification; DNA, Plant - isolation & purification; FLOWERING; FLOWERING LOCUS T protein; flowering time; Flowers - genetics; Flowers - growth & development; GENE EXPRESSION; gene expression regulation; GENE TRANSFER; Genes, Homeobox; Genes, Plant; LEAFY protein; MADS box gene; Molecular Sequence Data; Nicotiana - genetics; Nicotiana tabacum; OMADS1 protein; OMADS3 protein; ONCIDIUM; Orchidaceae - genetics; ornamental plants; phenotypic variation; phylogeny; plant morphology; plant proteins; Plants, Genetically Modified; protein binding; Recombinant Proteins - genetics; SUPPRESSOR OF OVEREXPRESSION OF CO 1 protein; TIME; transgenic plants
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcg099

An AP1/AGL9 group of MADS box gene, OMADS1, with extensive homology to the Arabidopsis AGAMOUS-like 6 gene (AGL6) was characterized from orchid (Oncidium Gower Ramsey). OMADS1 mRNA was detected in apical meristem and in the lip and carpel of flower. Yeast two hybrid analysis indicated that OMADS1 is able to strongly interact with OMADS3, a TM6-like protein that was involved in flower formation and floral initiation in orchid. Transgenic Arabidopsis and tobacco ectopically expressed OMADS1 showed similar novel phenotypes by significantly reducing plant size, flowering extremely early, and losing inflorescence indeterminacy. In addition, homeotic conversion of sepals into carpel-like structures and petals into staminoid structures were also observed in flowers of 35S:: OMADS1 Arabidopsis. This result indicated that OMADS1 was involved in floral formation and initiation in transgenic plants. Further analysis indicated that the expression of flowering time genes FT, SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1) and flower meristem identity genes LEAFY (LFY), APETALA1 (AP1) was significantly upregulated in 35S::OMADS1 transgenic Arabidopsis plants. Furthermore, ectopic expression of OMADS1 rescued late flowering phenotype in gi-1, co-3 but not for ft-1 and fwa-1 mutants. These results supported that ectopic expression of OMADS1 influenced flower transition and formation by acting as an activator for FT and SOC1 in Arabidopsis.