Cytokinin promotes flowering of Arabidopsis via transcriptional activation of the FT paralogue TSF

Abstract

SUMMARYCytokinins are involved in many aspects of plant growth and development, and physiological evidence also indicates that they have a role in floral transition. In order to integrate these phytohormones into the current knowledge of genetically defined molecular pathways to flowering, we performed exogenous treatments of adult wild type and mutant Arabidopsis plants, and analysed the expression of candidate genes. We used a hydroponic system that enables synchronous growth and flowering of Arabidopsis, and allows the precise application of chemicals to the roots for defined periods of time. We show that the application of N 6 -benzylaminopurine (BAP) promotes flowering of plants grown in non-inductive short days. The response to cytokinin treatment does not require FLOWERING LOCUS T (FT), but activates its paralogue TWIN SISTER OF FT (TSF), as well as FD, which encodes a partner protein of TSF, and the downstream gene SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1). Treatment of selected mutants confirmed that TSF and SOC1 are necessary for the flowering response to BAP, whereas the activation cascade might partially act independently of FD. These experiments provide a mechanistic basis for the role of cytokinins in flowering, and demonstrate that the redundant genes FT and TSF are differently regulated by distinct floral-inducing signals.

GIGANTEA Enables Drought Escape Response via Abscisic Acid-Dependent Activation of the Florigens and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1

“…GAs accelerate flowering through the up-regulation of FT and TSF in the leaves (Galvão et al, 2012;Porri et al, 2012). Cytokinins specifically activate TSF transcription (D'Aloia et al, 2011). However, the mode of action of GAs and cytokinins with respect to FT and TSF up-regulation appears to be independent of the photoperiod conditions.…”

The Transcription Factors BEL1 and SPL Are Required for Cytokinin and Auxin Signaling During Ovule Development in Arabidopsis

“…BAP treatment has already been successfully used for flower meristem studies (Venglat and Sawhney, 1996;D'Aloia et al, 2011).…”

TEMPRANILLO Reveals the Mesophyll as Crucial for Epidermal Trichome Formation

“…Furthermore, hormones play an important role in trichome initiation by controlling essential downstream genes (Schellmann et al, 2002;Gan et al, 2006;Zhao et al, 2008a). In particular, gibberellins (GAs) and cytokinins (CK) overlap in stimulating this process (Nemhauser et al, 2006;Gan et al, 2007;D'Aloia et al, 2011). GAs are required in the epidermis for trichome proliferation in rosette leaves, stem, and inflorescences (Chien and Sussex, 1996;Perazza et al, 1998;An et al, 2012), while CK action is limited to trichome initiation in upper inflorescence organs, including cauline leaves, stems, and sepals (Gan et al, 2007).…”