Isolation and characterization of an AGAMOUS-like gene from Hosta plantaginea.

Based on genetic and molecular analyses, the ABC model was proposed to explain the genetic control of floral development. The C-class MADS box gene AGAMOUS (AG) plays crucial roles in Arabidopsis thaliana development through regulation of the organ identity of stamens and gynoecium. The present research reports for the first time the cloning of an AG homologue (HpAG) from Hosta plantaginea Aschers. Phylogenetic analysis shows HpAG is a homologue of AG that is closely related to C-lineage AG homologues from monocot species. Semi-quantitative PCR and real-time PCR analyses show that HpAG is stamen- and gynoecium-specific in expression and has spatial and temporal expression patterns in the reproductive organs of H. plantaginea. The transcriptional activation property of HpAG is also verified by a yeast one-hybrid. Functional analysis is carried out in Arabidopsis by overexpression of HpAG. The homeotic transformations of petals into staminoid organs are observed in 35S::HpAG transgenic plants. All these results show that HpAG1 plays a crucial role in stamen specification and gynoecium development.