We investigated the transcriptomic changes in the shoot apices during floral transition in Arabidopsis mutants of two closely related splicing factors: AtU2AF65a (atu2af65a) and AtU2AF65b (atu2af65b). The atu2af65a mutants exhibited delayed flowering, while the atu2af65b mutants showed accelerated flowering. The underlying gene regulatory mechanism of these phenotypes was unclear. We performed RNA-seq analysis using shoot apices instead of whole seedlings and found that the atu2af65a mutants had more differentially expressed genes than the atu2af65b mutants when they were compared to wild type. The only flowering time gene that was significantly up- or down-regulated by more than two-fold in the mutants were FLOWERING LOCUS C (FLC), a major floral repressor. We also examined the expression and alternative splicing (AS) patterns of several FLC upstream regulators, such as COOLAIR, EDM2, FRIGIDA, and PP2A-b’ɤ, and found that those of COOLAIR, EDM2, and PP2A-b’ɤ were altered in the mutants. Furthermore, we demonstrated that AtU2AF65a and AtU2AF65b genes partially influenced FLC expression by analyzing these mutants in the flc-3 mutant background. Our findings indicate that AtU2AF65a and AtU2AF65b splicing factors modulate FLC expression by affecting the expression or AS patterns of a subset of FLC upstream regulators in the shoot apex, leading to different flowering phenotypes.
Bibliographical noteFunding Information:
This research was supported by the Basic Science Research Program of the National Research Foundation (NRF) funded by the Ministry of Education of the Republic of Korea (2019R1F1A1060009 to J.-K.K. and 2021R1I1A3050195 to J.H.L.). This study was funded by a grant from Korea University to J.-K.K.
© 2023 by the authors.
- alternative splicing
- flowering time
- shoot apical meristem
- splicing factors
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Plant Science