Characterization of Frond and Flower Development and Identification of FT and FD Genes From Duckweed Lemna aequinoctialis Nd

Abstract

Duckweeds (Araceae: Lemnoideae) are aquatic monocotyledonous plants that are characterized by their small size, rapid growth, and wide distribution. Developmental processes regulating the formation of their small leaf-like structures, called fronds, and tiny flowers are not well characterized. In many plant species, flowering is promoted by the florigen activation complex, whose major components are florigen FLOWERING LOCUS T (FT) protein and transcription factor FD protein. How this complex is regulated at the molecular level during duckweed flowering is also not 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 observations of frond and flower development revealed that cell proliferation in the early stages of frond development is active as can be seen in the separate regions corresponding to two budding pouches in the proximal region of the mother frond. L. aequinoctialis produces two stamens of different lengths with the longer stamen growing more rapidly. Using high-throughput RNA sequencing (RNA-seq) and de novo assembly of transcripts from plants induced to flower, we identified the L. aequinoctialis FT and FD genes, whose products in other angiosperms form a transcriptional complex to promote flowering. We characterized the protein-protein interaction of duckweed FT and FD in yeast and examined the functions of the two gene products by overexpression in Arabidopsis. We found that L. aequinoctialis FTL1 promotes flowering, whereas FTL2 suppresses flowering.

Circadian-period variation underlies the local adaptation of photoperiodism in the short-day plant Lemna aequinoctialis

“…The top five FT homologs were named as LaFTh1-5 based on their expression patterns and positions in the maximum likelihood phylogenetic tree with their estimated amino acid sequences ( Figure S4 B). LaFTh2 and LaFTh3 have the similar sequence as previously reported FT homologs, LaFTL3 and LaFTL1, respectively ( Yoshida et al., 2021 ). CO homologs were searched with a query for the OsHd1 amino acid sequence (UniProt-ID: Q9SK53).…”

The genomes and epigenomes of aquatic plants (Lemnaceae) promote triploid hybridization and clonal reproduction

“…We found that the key flowering regulator SUPPRESSOR OF CONSTANS 1 (SOC1) was missing from all analyzed Lemnaceae (N4.HOG0006359), contrary to a recent study in the short day duckweed L. aequinoctialis 51 , but in accord with prior analysis of MADS-box genes in S. polyrhiza 32 . In Arabidopsis , SOC1 controls drought induced flowering 52 as well as light induced stomatal opening 53 .…”

Multifunctional chemical inhibitors of the florigen activation complex discovered by structure‐based high‐throughput screening

“…For duckweed flowering assays, two species differing in their light requirement for flowering were used: L. gibba p8L and L. aequinoctialis 5356 (formerly named Nd strain) (Hillman, 1961; Miwa et al., 2006; Yoshida et al., 2021). The p8L strain is a pure line (eight generations of selfing) produced from the L. gibba 7741 (G3) strain.…”