SPL3/4/5 Integrate Developmental Aging and Photoperiodic Signals into the FT-FD Module in Arabidopsis Flowering.
Environmental sensitivity varies across developmental phases in flowering plants. In the juvenile phase, microRNA156 (miR156)-mediated repression of SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE (SPL) transcription factors renders Arabidopsis plants incompetent to floral inductive signals, including long-day (LD) photoperiod. During the vegetative phase transition, which accompanies a reduction of miR156 and a concomitant elevation of its targets, plants acquire reproductive competence such that LD signals promote flowering. However, it remains largely unknown how developmental signals are associated with photoperiodic flowering. Here, we show that SPL3, SPL4, and SPL5 (SPL3/4/5) potentiate the FLOWERING LOCUS T (FT)-FD module in photoperiodic flowering. SPL3/4/5 function as transcriptional activators through the interaction with FD, a basic leucine zipper transcription factor which plays a critical role in photoperiodic flowering. SPL3/4/5 can directly bind to the promoters of APETALA1, LEAFY, and FRUITFULL, thus mediating their activation by the FT-FD complex. Our findings demonstrate that SPL3/4/5 act synergistically with the FT-FD module to induce flowering under LDs, providing a long-sought molecular knob that links developmental aging and photoperiodic flowering.
Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK; Department of Chemistry, Seoul National University, Seoul 151-742, Korea.
Jae-Hoon
JH
Jung
Department of Chemistry, Seoul National University, Seoul 151-742, Korea.
Hyo-Jun
HJ
Lee
Department of Chemistry, Seoul National University, Seoul 151-742, Korea.
Jae Yong
JY
Ryu
Department of Chemistry, Seoul National University, Seoul 151-742, Korea; Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-742, Korea. Electronic address: cmpark@snu.ac.kr.
Chung-Mo
CM
Park
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D017440:Photoperiod; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C108465:SPL3 protein, Arabidopsis; C483287:SPL4 protein, Arabidopsis; C559760:SPL5 protein, Arabidopsis; D014157:Transcription Factors
FT-FD complex; SPL transcription factors; developmental aging; photoperiodic flowering