Functional analysis of an APETALA1-like MADS box gene from Eustoma grandiflorum in regulating floral transition and formation
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An Eustoma grandiflorum APETALA1 (EgAP1) gene showing high homology to the SQUA subfamily of MADS-box genes was isolated and characterized. EgAP1, containing a conserved euAP1 motif at the C-terminus, showed high sequence identity to Antirrhinum majus SQUAMOSA in the SQUA subfamily. EgAP1 mRNA was detected in the leaf and expressed significantly higher in young flower buds than in mature flower buds. In flowers, EgAP1 mRNA was strongly detected in sepal, weakly detected in petal and was absent in stamen and carpel. Transgenic Arabidopsis plants ectopically expressing EgAP1 flowered early and produced terminal flowers. In addition, the conversion of petals into stamen-like structures was also observed in 35S::EgAP1 flowers. 35S::EgAP1 was able to complement the ap1 flower defects by restoring the defect for sepal formation and significantly increasing second whorl petal production in Arabidopsis ap1 mutant plants. These results revealed that EgAP1 is the APETALA1 homolog in E. grandiflorum and that the function of EgAP1 is involved in floral induction and flower formation.
KeywordsAPETALA1 Arabidopsis thaliana Eustoma grandiflorum Floral induction MADS box genes SQUAMOSA
This work was supported by grants to C-H Y from the National Science Council, Taiwan, ROC, Grant nos. NSC98-2622-B-005-001–CC2 and NSC99-2622-B-005-001-CC2. This work was also supported in part by the Ministry of Education, Taiwan, R.O.C. under the ATU plan.
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