Transcriptome analysis of Duckweed Lemna aequinoctialis Nd.

TDuckweeds (Araceae: Lemnoideae) are small aquatic monocot plants, which are characterized by their reduced morphology, fast-proliferation and wider distribution. The developmental processes of leaf-like structure, frond, and their tiny flower is unclear, and the regulation of flowering at the molecular level are less well understood. In this study, we characterized the course of developmental changes during frond development and flower formation in Lemna aequinoctialis Nd, a short day plant. Detailed observation of frond and flower development revealed that higher cell proliferation in early stage of frond development, which can be seen at the separate regions corresponding to two budding pouches at the proximal region of mother frond. L. aequinoctialis produces two stamens with different length, and longer stamen seems to grow faster. Using high throughput RNA sequencing (RNA-seq) and de novo assembly of transcripts of flowering-induced plants, we identified L. aequinoctialis FT and FD genes, whose products form a transcriptional complex to promote flowering. We characterized protein-protein interaction in yeast and functions by overexpression in Arabidopsis, and found that L. aequinoctialis FT1 promotes whereas FTL2 suppresses flowering.