MAC3A and MAC3B Modulate FLOWERING LOCUS M Splicing to Repress Photoperiod-Dependent Floral Transition
Yu-Wen Huang1, Chih-Yen Tseng1,2, Yu-Sen Wang1
1Institute of Plant Biology, National Taiwan University, Taipei, Taiwan.
Plant, Cell & Environment
|June 2, 2025
Summary
The MOS4-associated complex (MAC), involving MAC3A and MAC3B, regulates flowering time by altering RNA splicing. Mutants flower earlier under short days, showing MAC
Area of Science:
- Plant Biology
- Molecular Genetics
- Developmental Biology
Background:
- Flowering time is crucial for plant reproduction and is regulated by complex genetic networks integrating environmental cues.
- RNA splicing is a key post-transcriptional mechanism modulating gene expression in response to developmental and environmental signals.
- The MOS4-associated complex (MAC), comprising MAC3A and MAC3B E3 ubiquitin ligases, is known to be involved in splicing regulation.
Purpose of the Study:
- To investigate the role of the MOS4-associated complex (MAC) in regulating the floral transition in plants.
- To understand how MAC3A and MAC3B influence flowering time in response to photoperiodic cues.
- To elucidate the molecular mechanisms by which MAC components modulate flowering pathways.
Main Methods:
- Phenotypic analysis of mac3a/mac3b mutants under short-day (SD) and long-day (LD) conditions.
- Gene expression analysis, including transcriptomic profiling, of wild-type and mutant plants.
- Identification and characterization of target genes and splicing events regulated by MAC3A and MAC3B.
Main Results:
- mac3a/mac3b mutants exhibited significantly earlier flowering under SD conditions, but not LD conditions.
- Early flowering in mutants correlated with increased expression of flowering time genes FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1).
- MAC3A and MAC3B were found to associate with FLOWERING LOCUS M (FLM) transcripts, modulating their splicing and influencing flowering time, particularly under SD conditions.
Conclusions:
- The MAC complex, through MAC3A and MAC3B, plays a critical role in integrating environmental signals to control flowering time via RNA splicing.
- MAC3A and MAC3B modulate the splicing of thermosensory regulators like FLM, adding a new regulatory layer to flowering pathway crosstalk.
- This study reveals a novel mechanism by which splicing factors contribute to the photoperiodic control of floral transition.
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