Disentangling the roles of TM8-like genes in reproductive organ development in Gnetum montanum Markgr.

TM8 genes, belonging to the ancient subfamily of type Ⅱ MADS-box genes, have been lost in various angiosperm lineages but have undergone a dramatic expansion in gymnosperms. While TM8 genes are known to participate in female flower development in angiosperms, their roles in gymnosperms remain poorly understood. In this study, three TM8-like genes, including one gene with two transcripts, were characterized in Gnetum montanum Markgr. using fluorescence in situ hybridization (FISH) and transgenic experiments. Results indicated that all three genes were involved in the development of female ovules, sterile ovules, and antherophores, but their expression levels, and presumably their roles, differed substantially among these organs. The morphology of transgenic Arabidopsis thaliana (L.) Heynh. flowers suggested that the TM8-like genes had a substantial effect on the emergence and development of short stamens. In addition, the expression patterns of the two transcripts were different and associated with different phenotypes in A. thaliana flowers, suggesting divergent functions in reproductive organ development in G. montanum.